IPAC2011 - List of Keywords (vacuum)

Paper	Title	Other Keywords	Page
MOXBA01	J-PARC Beam Commissioning Progress	beam-losses, injection, linac, extraction	6
	H. Hotchi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The J-PARC is a multi-purpose proton accelerator facility amiming at MW-class output beam power, consisting of a 400 MeV H⁻ linac, a 3-GeV RCS, a 50-GeV MR (Main Ring) and three experimental facilities, the MLF (materials and life science experimental facility), the HD (hadron experimental hall) and the NU (neutrino beam line). The J-PARC beam commissioning started in November 2006 from the linac to the downstream facilities. The current output beam power from the RCS to the MLF users is 210 kW, and the MR delivers 145 kW beam to the NU by fast extraction and a few kW beam to the HD by slow extraction. In this talk, we present a current status of the J-PARC beam commissioning, in which a recent progress in the course of the RCS beam power ramp-up scenario will be described in more detail. This talk will focus on the issues (including beam dynamics), challenges, solutions, and lessons learned during the commissioning and user operation of J-PARC and future plans.
	Slides MOXBA01 [2.615 MB]

MOPC004	352.2 MHz HOM Damped Normal Conducting ESRF Cavity: Design and Fabrication	cavity, HOM, coupling, storage-ring	68
	V. Serrière, A.K. Bandyopadhyay, D. Boilot, L. Goirand, J. Jacob, B. Ogier, A. Triantafyllou ESRF, Grenoble, France
	Funding: This work, carried out within the framework of the ESRFUP project, has received research funding from the EU Seventh Framework Programme, FP7. The ongoing ESRF upgrade included an option for an increase of the storage ring current from 200 to 300 mA, which has been tested successfully with the existing RF system. At this current level the HOM tuning of the existing five-cell copper cavities becomes extremely delicate and in view of a future reliable operation in user mode, new HOM free normal conducting cavities were developed at the ESRF. The design is based on the existing BESSY/ALBA cavity. However, several substantial modifications have been implemented and different fabrication processes elaborated to improve the design. Three operational prototypes will be delivered by three manufacturers in the coming months and will be fully tested on the ring. Although the 300 mA option has finally not been retained for the first phase of the ESRF upgrade, the aim is now to validate the new cavity design for a possible later increase in current.

MOPC007	Cold Photocathode RF Gun	cavity, gun, cathode, cryogenics	77
	V. Vogel, K. Flöttmann, S. Schreiber DESY, Hamburg, Germany
	Heating and thermal expansion in the normal conductivity RF-photo electron gun, are the main limitations to achieve high accelerating gradient and consequently a low emittance beam. Some pure materials show a significant increase in thermal conductivity with a small coefficient of temperature expansion at temperatures around 20 degrees Kelvin. Possible materials are Molybdenum, Iridium or Tungsten. However, machining of these materials is very difficult. Therefore we propose a simplified shape for an L-band RF gun. We expect to achieve a significant increase in gradient for similar RF powers as used in the present DESY RF-gun. On the other hand, it would also be possible to increase the duty cycle keeping a moderate gradient. In this report we discuss one possible design of an RF-gun using hard metals and present simulations on thermal properties.

MOPC012	Fabrication of the CERN/PSI/ST X-band Accelerating Structures	wakefield, alignment, FEL, coupling	86
	M.M. Dehler, A. Citterio, R. Zennaro PSI, Villigen, Switzerland S. Atieh, D. Gudkov, S. Lebet, G. Riddone, J. Shi CERN, Geneva, Switzerland G. D'Auria, C. Serpico ELETTRA, Basovizza, Italy
	Within a collaboration between CERN, PSI and Sincrotrone Trieste (ST), a multi- purpose X-band accelerating structure has been designed and fabricated, used for high gradients tests in the CLIC structure testing program and in the FEL projects of PSI and ST. The structure has 72 cells with a phase advance of 5 pi/6 and includes upstream and downstream wakefield monitors to measure the beam alignment. The SLAC mode launcher design is used to feed it with RF power. Following the CERN fabrication procedures for high-gradient structure, diffusion bonding and brazing in hydrogen atmosphere is used to assemble the cells. After tuning, a vacuum bakeout is required before the feedthroughs for the wake field monitors are welded in as a last step. We describe the experiences gained in finishing the first two structures out of a series of four and present the results from the RF tuning and low level RF tests.

MOPC015	S-band Vacuum Isolator and Circulator for Injector System of SPring-8 Linac	linac, cavity, insertion, injection	95
	T. Taniuchi, H. Hanaki, S. Suzuki JASRI/SPring-8, Hyogo-ken, Japan A. Miura, K. Shinohara, S. Tsuruoka Nihon Koshuha Co. Ltd, Yokohama, Japan
	A pressurized sulfur hexafluoride (SF6) waveguide system at an injector section of SPring-8 linac, will be replaced with a vacuum waveguide system in order to renew aged equipments and improve a phase stability. For this renewal, RF isolator and a circulator operated in vacuum, are newly developed. High power RF test for these components were performed and a good result for RF and vacuum characteristics were obtained.

MOPC024	Construction Status of the CPHS RFQ at Tsinghua University	rfq, quadrupole, dipole, cavity	122
	Q.Z. Xing, Y.J. Bai, J.C. Cai, C. Cheng, L. Du, T. Du, X. Guan, Q. Qiang, X.W. Wang, Z.F. Xiong, S.Y. Yang, H.Y. Zhang, S.X. Zheng TUB, Beijing, People's Republic of China J.H. Billen TechSource, Santa Fe, New Mexico, USA W.Q. Guan, Y. He, J. Li NUCTECH, Beijing, People's Republic of China J. Stovall CERN, Geneva, Switzerland L.M. Young AES, Medford, NY, USA
	Funding: Work supported by the “985 Project” of the Ministry of Education of China. We present, in this paper, the construction status of a Radio Frequency Quadrupole (RFQ) accelerator for the Compact Pulsed Hadron Source (CPHS) at Tsinghua University. The 3-meter-long RFQ will deliver 3 MeV protons to the downstream Drift Tube Linac (DTL) with the peak current of 50 mA, pulse length of 0.5 ms and beam duty factor of 2.5%. The RFQ has been mechanically separated into three sections. A ball-end mill, instead of a forming cutter, is adopted to machine the vane tip due to its varying radius of curvature. The precision of the numerically controlled milling machine has been verified by machining test pieces of aluminum and copper. Fine machining of the vanes was completed in July, 2011. The pre-braze tuning was completed at the beginning of this August.

MOPC030	The C-band Traveling-wave Accelerating Structure for Compact XFEL at SINAP*	linac, controls, impedance, status	133
	W. Fang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China D.C. Tong TUB, Beijing, People's Republic of China
	The R&D of C-band accelerating structure has been launched two years ago at Shanghai Institute of Applied Physics, it will be used for the future compact hard X-ray FEL. The 1st C-band traveling-wave accelerating structure is ready for the high power test now. This structure is the preliminary model for the research of the technology of microwave test and tuning, arts and crafts and high power test. This paper presents the process of fabrication, cold test and tuning results.

MOPC035	Design and Machine Features of 2.2-m C-band Accelerating Structure	cavity, accelerating-gradient, linac, electron	148
	C.H. Yi, M.-H. Cho, S.H. Kim, H. Lee POSTECH, Pohang, Kyungbuk, Republic of Korea W. Namkung PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This work is partly supported by the MEST, Korea and POSTECH BK21 Program. And this work was supported by the Korea Student Aid Foundation (KOSAF) grant funded by the Korea government. A compact linac system is designed using a longer accelerating column in a C-band linac. It reduces the total number of RF units for the given linac beam energy and results in the cost-effective use of RF powers. For the 10 GeV PAL-XFEL project, a C-band accelerating column of 2.2-m long is investigated, which is 22% longer than 1.8-m for the SACLA at SPring-8. The detailed RF and thermal characteristics are presented by an analytic model.

MOPC037	Engineering Design and Fabrication of X-band Damped Detuned Structure for the CLIC Study	damping, alignment, controls, wakefield	154
	V. Soldatov, D. Gudkov, A. Samoshkin JINR, Dubna, Moscow Region, Russia S. Atieh, A. D'Elia, A. Grudiev, G. Riddone CERN, Geneva, Switzerland R.M. Jones, V.F. Khan UMAN, Manchester, United Kingdom
	A Damped Detuned Structure (DDS), known as CLIC_DDS_A, has been designed for the Compact Linear Collider (CLIC) study, and is presently under fabrication. The wakefield in DDS structures is damped using a combination of detuning the frequencies of beam-excited higher order modes and by light damping, through slot-coupled manifolds. The broad principles of the design are similar to that used in the NLC/GLC. This serves as an alternative to the present baseline CLIC design which relies on heavy damping. CLIC_DDS_A is conceived to be tested for its capacity to sustain high gradients at CERN. This structure operates with a 120 degrees phase advance per cell. We report on engineering design and fabrication details of the structure consisting of 24 regular cells plus 2 matching cells at both ends, all diffusion bonded together. This design takes into account practical mechanical engineering issues and is the result of several optimizations since the earlier CLIC_DDS designs. V. F. Khan et al., “Recent Progress on a Manifold Damped and Detuned Structure for CLIC”, Proc. of IPAC10, WEPE032, p. 3425 (2010). ** R.M. Jones et al., Phys. Rev. STAB 9, 102001 (2006).

MOPC038	Engineering Design and Fabrication of Tapered Damped X-band Accelerating Structures	damping, wakefield, alignment, HOM	157
	A. Solodko, D. Gudkov, A. Samoshkin JINR, Dubna, Moscow Region, Russia S. Atieh, A. Grudiev, G. Riddone, M. Taborelli CERN, Geneva, Switzerland
	The accelerating structures (AS) are one of the main components of the Compact LInear Collider (CLIC), under study at CERN. Each AS contains about 30 copper disks, which form the accelerating cavity. A fully featured AS is very challenging and requires several technologies. Different damping methods, waveguides, vacuum manifolds, slots and choke, result in various design configurations. In the CLIC multibunch AS, called TDS (Tapered Damped Structure), each cell is damped by its four waveguides, which are extended by channels machined in dedicated external vacuum manifolds. The manifolds combine few functions such as damping, vacuum pumping and cooling. Silicon carbide absorbers, fixed inside of each manifold, are required for effective damping of High Order Modes. CERN is producing X-band RF structures in close collaboration with a large number of laboratories taking advantage of their large expertise and test facilities. The fabrication includes several steps from the machining to the final assembly, including quality controls. This paper describes the engineering design and fabrication procedure of the X-band AS with damping material, by focusing on few technical solutions.

MOPC041	Cross-Field Multipactor Discharge in the X-Band Cylindrical Cavity	cavity, multipactoring, electron, radiation	166
	S.V. Kuzikov, E.V. Ilyakov, I.S. Kulagin, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia D. Lee NSRRC, Hsinchu, Taiwan
	The paper represents the experimental study of one-sided cross-field multipactor discharge in the copper cavity with the operating mode TM01 in external DC magnetic field. It was shown that discharge is very sensible to magnitudes of the external magnetic field and rf fields as well. At proper fields the multipactor discharge can be developed for 15 ns and the electron concentration can be comparable with critical one for the given rf frequency. As a result of discharging, the cavity changes its own resonant frequency and can play a role of a switch which can substitute full transmission by full reflection. Switching parameters could be controlled by DC magnetic field as well as by additional rf radiation at different frequency than operating frequency. The high rf absorption of multipactor discharge also can be used in electrically controlled powerful loads and attenuators.

MOPC042	RF and Accelerating Structure of 12 MeV UPC Race-track Microtron	linac, coupling, microtron, controls	169
	Yu.A. Kubyshin, X. Gonzalez Arriola UPC, Barcelona, Spain D. Carrillo, L. García-Tabarés, F. Toral CIEMAT, Madrid, Spain S.J. Mathot CERN, Geneva, Switzerland G. Montoro EPSC, Castelldefels, Spain V.I. Shvedunov MSU, Moscow, Russia
	We describe the design and technical characteristics of a C-band SW accelerating structure of a 12 MeV race-track microtron, which is under construction at the Technical University of Catalonia, and its RF system with a 5712 MHz magnetron as a source. Results of cold tests of the accelerating structure, before and after the brazing, and of high-power tests of the RF system at a special stand are reported. The main features of the magnetron frequency stabilization subsystem are also outlined.

MOPC043	Electromagnetic Simulations of the Input Power Couplers for the ESS-Bilbao RFQ	rfq, linac, cavity, radio-frequency	172
	O. Gonzalez, I. Bustinduy, N. Garmendia, J.L. Munoz, A. Velez ESS Bilbao, Bilbao, Spain F.J. Bermejo Bilbao, Faculty of Science and Technology, Bilbao, Spain V. Etxebarria, J. Portilla University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
	An input power system is currently being designed at ESS-Bilbao in order to inject the RF power provided by a klystron into the RFQ as part of the linac. In this work, some input power couplers based on a coaxial topology are carefully studied from an electromagnetic point of view. As we will show, the electrical properties of the ceramic window used to ensure the vacuum of the RFQ crucially deteriorates the matching of the devices. To overcome this drawback, a full-wave electromagnetic simulator is used to optimize the coupler dimensions in order to minimize both the return and insertion losses.

MOPC047	RF Design of the Re-buncher Cavities for the LIPAC Deuteron Accelerator	cavity, impedance, linac, beam-transport	184
	A. Lara, I. Podadera, F. Toral CIEMAT, Madrid, Spain
	Funding: Work partially supported by Spanish Ministry of Science and Innovation under project ENE2009-11230. Re-buncher cavities are an essential component of LIPAC (Linear IFMIF Prototype Accelerator), presently being built at Rokkasho (Japan). The deuteron beam exiting from the RFQ (Radio Frequency Quadrupole) structure has to be properly adapted to the superconducting RF (SRF) linac. Re-bunchers are placed in the Medium Energy Beam Transport (MEBT) line and their objective is to longitudinally focus the deuteron beam. IFMIF re-bunchers must provide a 350 kV E0LT at 175 MHz continuous wave (CW). The available length for the re-buncher is limited by the general layout of the MEBT. The high power dissipation derived from the high effective voltage and the short available length is an important design challenge. Four different normal conducting cavity designs were investigated: the pillbox type, double gap coaxial resonators, and multi-gap quarter wave and H resonators. The performance of these cavities was studied with the numerical codes HFSS and ANSYS. The fundamental frequency and field pattern of each re-buncher was investigated in HFSS. This work presents the results of such analyses.

MOPC052	Engineering Design and Fabrication of X-band RF Components	klystron, pick-up, coupling, diagnostics	196
	M. Filippova, A. Olyunin, V. Soldatov, A. Solodko JINR, Dubna, Moscow Region, Russia S. Atieh, G. Riddone, I. Syratchev CERN, Geneva, Switzerland
	The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.9942 GHz permitting beam independent power production using klystrons for accelerating structure testing. X-band klystron test facilities at 11.424 GHz are operated at SLAC and at KEK, and these facilities are used by CLIC study in the frame of the X-band structure collaboration for testing accelerating structures scaled to that frequency. Generally RF components are used in the transmission and the transformation of radio frequency signals generated by the power supply. The operating range of the devices accommodates the frequencies from 11.424 to 11.9942 GHz. RF components are needed for the Klystron test stand at CERN, and also for the X-FEL projects at PSI and Sincrotrone Trieste. Currently CERN is ordering tens of these companies to industry. The engineering design of the RF components (high power and compact loads, bi-directional couplers, X-band splitters, hybrids, phase shifters, variable power attenuators) and the main fabrication processes are presented here. K.M. Schirm et al., “A 12 GHZ RV Power source for the CLIC study”, Proc. of IPAC’10, THPEB053, p. 3990 (2010).

MOPC055	High Power Test of the First PIMS Cavity for Linac4	cavity, linac, pick-up, klystron	205
	F. Gerigk, J.-M. Giguet, P. Ugena Tirado, R. Wegner CERN, Geneva, Switzerland
	The PI-Mode Structure (PIMS) accelerates the Linac4 beam from 100 to 160 MeV. Twelve 7-cell cavities will be installed in the linac, with a gradient of ~4 MV/m and operating at a frequency of 352.2 MHz. A full-power prototype has been constructed at CERN in 2010 and was high- power tested in autumn 2010. Peak power tests at the Linac4 duty cycle and high-average power tests at increased duty cycles were completed successful, so that this prototype will be the first of the 12 cavities to be installed in Linac4. This paper reports on the high-power tests and the conditioning experience.

MOPC056	The Linac4 Power Coupler	cavity, linac, coupling, simulation	208
	F. Gerigk, J.-M. Giguet, E. Montesinos, B. Riffaud, P. Ugena Tirado, R. Wegner CERN, Geneva, Switzerland
	Linac4 employs 3 types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell-Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam to 160 MeV. The structures are designed for a peak power of 1 MW per coupler, which consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the wave-guides, and a so-called "coupling T", which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improved with respect to their commonly used design. On the coupler side, the wave-guide short circuit with its matched length has been replaced by a fixed length λ/4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually consists of a ceramic disc and 2 pieces of wave-guides with matching elements, the wave-guide sections could be completely suppressed, so that the window became very compact, lightweight, and much simpler to manufacture. In this paper we present electromagnetic simulations, and tests on first prototypes, which were constructed at CERN.

MOPC073	A Dual-mode Accelerating Cavity to Test RF Breakdown Dependence on RF Magnetic Fields	cavity, simulation, electron, radio-frequency	247
	A.D. Yeremian, V.A. Dolgashev, J. Neilson, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: * Work Supported by Doe Contract No. DE-AC02-76SF00515 RF Breakdown experiments on short accelerating structures at SLAC have shown that increased rf magnetic fields increase the probability of rf breakdowns. Moreover, the breakdown rate is highly correlated with the peak pulse-heating in soft-copper single-cell standing-wave structures of disk-loaded waveguide type. In these geometries the rf electric and magnetic fields are highly correlated. To separate effects of rf magnetic and electric fields on the rf breakdown rate, we have designed an X-band cavity with a geometry as close to that of a standing-wave accelerator cell as practically possible. This cavity supports two modes: an accelerating TM mode and a TE mode with no-surface-electric field but with a strong magnetic field. The cavity will be constructed and tested at the Accelerator Structure Test Area (ASTA) at SLAC.

MOPC079	Status of the Low Beta 0.07 Cryomodules for SPIRAL2	cavity, cryomodule, LLRF, linac	256
	P. Bosland, P. Carbonnier, F. Eozénou, P. Galdemard, O. Piquet CEA/DSM/IRFU, France M. Anfreville, C. Madec, L. Maurice CEA/IRFU, Gif-sur-Yvette, France P.-E. Bernaudin, R. Ferdinand GANIL, Caen, France Y. Gomez-Martinez LPSC, Grenoble Cedex, France A. Pérolat CEA, Gif-sur-Yvette, France
	The status of the low beta cryomodules for SPIRAL2, supplied by the Irfu institute of CEA Saclay, is reported in this paper. We summarise in three parts the RF tests performed on the cavities in vertical cryostat, the RF power tests of the qualifying cryomodule performed in 2010 and the RF power tests performed in 2011 on the first cryomodule of the series

MOPC088	Bead-pull Measurement using Phase-Shift Technique in Multi-cell Elliptical Cavity	cavity, linac, controls, monitoring	280
	S. Ghosh, A. Mandal, S. Seth, S.S. Som DAE/VECC, Calcutta, India
	The project on the development of high-beta multi-cell elliptical shape superconducting rf linac cavity at around 704 MHz has been funded at VECC, Kolkata, India. A full-scale copper prototype cavity has been designed and fabricated. There are 5 distinct modes exist in the cavity and the accelerating mode is pi-mode in which each cell operates at same frequency with phase difference of 180 degrees between two neighboring cells. A fully automated bead-pull measurement setup has been developed for analyzing these modes and field profile distribution at different modes in such type of linac cavity. A special measurement method inside the cavity using phase-shift technique is proposed in this paper, which describes the development of mechanical setup comprising pulleys and stepper motor–gear arrangement, PC-based control system for precise movement of bead using stepper motor, measurement using VNA, development of software for data acquisition & automation and measurement results for the 5-cell copper prototype cavity.

MOPC092	Effect of Current Densities on Sulfur Generation at Electropolished Niobium Surface	cavity, niobium, cathode, electron	292
	P.V. Tyagi Sokendai, Ibaraki, Japan H. Hayano, S. Kato, M. Nishiwaki, T. Noguchi, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	We conducted a series of electropolishing (EP) experiments in aged EP acid with high (≈50 mA/cm²) and low (≈30 mA/cm²) current densities on Nb surfaces. The experiments were carried out both for laboratory coupons and a real Nb single cell cavity with six witness samples located at three typical positions (equator, iris and beam pipe). All the samples surface were investigated by XPS (x-ray photoelectron spectroscopy), SEM (scanning electron microscope) and EDX (energy dispersive x-ray spectroscopy). The surface analysis showed the EP with a high current density produced a huge amount sulfate particles at Nb surface whereas the EP with a low current density is very helpful to mitigate sulfate at Nb surface in both the experiments.

MOPC103	Cryostat for Testing HIE-ISOLDE Superconducting RF Cavities	cavity, cryomodule, cryogenics, niobium	313
	O. Capatina, J.P. Brachet, G. Cuccuru, M. Pasini, T. Renaglia, M. Therasse, B. Vullierme CERN, Geneva, Switzerland
	The High Intensity and Energy ISOLDE (HIE-ISOLDE) project is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN [1], with the objective of increasing the energy and the intensity of the delivered radioactive ion beams (RIB). This project aims to fill the request for a more energetic post accelerated beam by means of a new superconducting (SC) linac based on Quarter Wave Resonators (QWRs). A research and development program looking at all different aspects of the SC linac has started in 2008 and continued throughout 2010. In particular the R&D effort has focused on the development of the high β cavity (β = 10.3%), for which it has been decided to adopt the Nb sputtered on Cu substrate technology. Two prototype cavities were manufactured and are undergoing RF cold tests. The pre-series cavity fabrication is under way using 3D forged Cu billets. A single vacuum cryostat was designed and built to test these cavities at liquid helium temperatures. The paper details the main design concepts of the test cryostat as well as the results of the cryogenic behavior of the complete set-up including the cryostat, the RF cavity, the tuner and the main coupler.

MOPC104	HIE-ISOLDE SRF Development Activities at CERN	cavity, cathode, niobium, SRF	316
	M. Therasse, O. Brunner, S. Calatroni, J.K. Chambrillon, B. Delaup, M. Pasini CERN, Geneva, Switzerland
	The HIE-ISOLDE project has initiated a new development phase on the SRF domain at CERN. In particular, the HIE-ISOLDE project aims at the construction of the 32 Quarter Wave Resonators (QWRs) using the Nb on Cu sputtering technology. The paper describes the refurbishment of the test infrastructure and the activities from the cavity production to the cold test, including quality assurance procedure for the correct handling of the resonators.

MOPC105	Design of the High Beta Cryomodule for the HIE-ISOLDE Upgrade at CERN	cavity, alignment, cryomodule, target	319
	L.R. Williams, A.P. Bouzoud, N. Delruelle, J. Gayde, Y. Leclercq, M. Pasini, J.Ph. G. L. Tock, G. Vandoni CERN, Geneva, Switzerland
	The major upgrade of the energy and intensity of the radioactive ion beams of the existing ISOLDE and REX-ISOLDE facilities at CERN will, in the long term, require downstream of the existing machine, the installation of four high-β and two low-β cryo-modules. The first stage of this upgrade, involving the design, construction, installation and commissioning of two high-β cryo-modules is approved and design work is underway at CERN. The high-β cryo-module houses five high-β superconducting cavities and one superconducting solenoid. As well as providing optimum conditions for physics, where the internal active components must remain aligned within tight tolerances, the cryo-modules need to function under stringent common vacuum and cryogenic conditions. To preserve the RF cavity performance their assembly and sub-system testing will need to be carried out using specifically designed tooling in a class 100 clean-room. We present the determining factors constraining the design of the high-β cryo-module together with the design choices that these factors have imposed.

MOPC114	Design, Fabrication and Testing of Medium-Beta 650 MHz SRF Cavity Prototypes for Project-X	cavity, SRF, linac, electron	343
	F. Marhauser, W.A. Clemens, J. Henry, P. Kneisel, R. Martin, R.A. Rimmer, G. Slack, L. Turlington, R.S. Williams JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A new type of superconducting radio frequency (SRF) cavity shape with a shallow equator dome to reduce electron impact energies for suppressing multipacting barriers has been proposed. The shape is in consideration for the first time in the framework of Project-X to design a potential multi-cell cavity candidate for the medium-beta section of the SRF proton CW linac operating at 650 MHz. Rationales covering the design of the multi-cell cavity, the manufacture, post-processing and high power testing of two single-cell prototypes are presented.

MOPC129	Compact Solid State RF-Modules for Direct Drive RF-linacs	linac, impedance, cavity, klystron	382
	R. Irsigler, M. Back, R. Baumgartner, O. Heid, T.J.S. Hughes, M. Kaspar, T. Kluge, J. Sirtl, K. Weidner, M. Zerb Siemens AG, Erlangen, Germany
	We present a modular RF power source concept based on solid state RF-modules with novel SiC transistors. The concept offers lower cost, better reliability and reduced maintenance compared to traditional RF-source technology. No circulators are required, which makes the RF-module very compact and reliable. The SiC power transistor has a very low input capacitance and was optimized for low gate resistance to enable fast switching in the VHF range. It delivers a maximum pulsed drain saturation current of 65 A. The transistor provides at 350 V supply voltage and 150 MHz an output power of 5,6 kW at a gain of 15,8 dB. It is essential to avoid high parasitic source inductances at RF and good thermal conductivity is required for operation at high duty cycle. We have built very compact 75 x 90 mm ceramic amplifier modules using a planar interconnect technology (SIPLIT) to connect the bare die transistors to the DCB substrate. The modules have a fully symmetric push-pull topology (circlotron) with four transistors in parallel in each leg. The RF-modules delivered at 150 MHz an impressive RF output power in the range of 40 kW. Further tests at 324 MHz are planned and will be presented.

MOPC134	Multifrequency High Power Microwave Electric-vacuum Devices	electron, klystron, acceleration, cavity	391
	K.G. Simonov, A.A. Borisov, A.V. Galdetsky, A.N. Korolev, A.V. Mamontov ISTOK, Moscow Region, Russia O.A. Morozov Research and Production Co. "MAGRATEP", Fryazino, Russia
	A new approach for the design of the multifrequency high power microwave vacuum devices is proposed. These devices provide simultaneously some output phased signals with operating frequencies ω, 2 ω, , nω while input frequency is ω. For example, it is possible obtain output power at frequencies ω and 2ω by using of double-gap output resonator tuned on two modes – sinphased mode at 2ω and antiphased mode at frequency ω. It is possible obtain power at four frequencies ω, 2ω, 3ω and 6ω by using of the two double-gap output resonators placed one inside the other. It is possible obtain power at multiple frequencies by using of the special coaxial resonator. A microwave vacuum device has been fabricated in which power was extracted at nine multiple frequencies simultaneously. The output signal has form of pulses with ultrashort duration and superhigh repetition frequency equal to the input signal frequency ω. Multifrequency high power microwave vacuum devices can be used for the development of compact accelerators of charged particles.

MOPC150	High Charge PHIN Photo Injector at CERN with Fast Phase Switching within the Bunch Train for Beam Combination	laser, cathode, gun, bunching	430
	M. Divall Csatari, A. Andersson, B. Bolzon, E. Bravin, E. Chevallay, A.E. Dabrowski, S. Döbert, V. Fedosseev, C. Heßler, T. Lefèvre, S. Livesley, R. Losito, O. Mete, M. Olvegård, M. Petrarca, A. Rabiller CERN, Geneva, Switzerland A. Drozdy BUTE, Budapest, Hungary D. Egger EPFL, Lausanne, Switzerland
	The high charge PHIN photo-injector was developed within the frame of the European CARE program to provide an alternative to the drive beam thermionic gun in CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 sub-trains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the scheme. Stability measurements are presented for the phase-coded system. The paper also discusses the latest 8nC charge production and cathode life-time studies on Cs2Te.

MOPO008	Design and Simulation of the Transverse Feedback Kicker for the HLSⅡ	kicker, impedance, feedback, simulation	496
	W.B. Li, P. Lu, B.G. Sun, F.F. Wu, Y.L. Yang, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	In order to suppress the coupled bunch instabilities in the HLSⅡ storage ring, a transverse feedback system is required. The vital component of the system is the kicker that is the feedback actuator. We design a stripline kicker for the HLSⅡ. The horizontal and vertical electrodes are combined in a structure on account of the space limit. In addition to the design issues, this paper focuses on the simulation results for the kicker using the computer codes. By the 2D code POSSION, we calculate and optimize the characteristic impedance of the stripline kicker to match the 50Ω external transmission lines so as to reduce the reflected power. The reflection coefficient and the shunt impedance in the working frequency range are obtained by the 3D code HFSS. The simulation results provide many important supports for the structure design.

MOPO010	Orbit Feedback System for the MAX IV 3 GeV Storage Ring	feedback, power-supply, storage-ring, simulation	499
	M. Sjöström, J. Ahlbäck, M.A.G. Johansson, S.C. Leemann, R. Nilsson MAX-lab, Lund, Sweden
	The paper describes the current orbit correction system design for the 3 GeV storage ring at the MAX IV laboratory, a light source facility under construction in Lund, Sweden. The orbit stability requirements for the 3 GeV storage ring are tight at roughly 200 nm vertical position stability in the insertion device (ID) straight sections. To meet this the ring will be equipped with 200 beam position monitors (BPMs) and 380 dipole corrector magnets, 200 in the horizontal and 180 in the vertical plane. The feedback loop solution, one slow orbit feedback (SOFB) loop and one fast orbit feedback (FOFB) loop in fast acquisition mode at 10,000 samples/second, will be presented. The paper will also discuss the various boundary conditions specific to the MAX IV 3 GeV storage ring design, such as a Cu vacuum chamber, and the impact on the corrector design.

MOPO023	Laser-based Alignment System at the KEKB Injector Linac	laser, alignment, linac, injection	529
	M. Satoh, N. Iida, T. Suwada KEK, Ibaraki, Japan K. Minoshima, S. Telada AIST, Tsukuba, Japan
	A laser-based alignment system is under development at the 500-m-long KEKB injector linac. The original system was designed and constructed more than thirty-years ago, and thus, we are revisiting our alignment system because the previous alignment system has become too obsolete. The new alignment system is again strongly required for the next generation SuperKEKB project. The new laser alignment system is similar to the previous one, which comprises a helium-neon laser and quadrant photodetectors installed in vacuum light pipes. A girder displacement of the accelerating structure can be precisely measured in the direction of the laser-ray trace, where the laser light must stably propagate up to 500-m downstream without any orbital and beam-size fluctuation. We tested the laser-ray propagation and the stability along a 100-m-long beam line under a vacuum condition of 0.1-1 Torr. In this paper, we will report the system description and test results in detail.

MOPO026	Design, Manufacturing and Tests of Closed-loop Quadrupole Mover Prototypes for European XFEL	quadrupole, controls, alignment, feedback	535
	J. Munilla, J. Calero, J.M. Cela-Ruiz, L. García-Tabarés, A. Guirao, J.L. Gutiérrez, T. Martínez de Alvaro, E. Molina Marinas, S. Sanz, F. Toral, C. Vazquez CIEMAT, Madrid, Spain
	Funding: Work partially supported by Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009 In this report the development of a quadrupole mover with submicron repeatability is reported, which will be used in the intersections of the Undulator Systems of the European XFEL (EXFEL). It is part of the Spanish in-kind contribution to this facility. The main specifications include submicron repeatability for a 70 kg quadrupole magnet within compact dimensions and a ±1.5 mm stroke in the vertical and horizontal direction. Compact linear actuators based on 5-phase stepping motors have been chosen. Vertical actuator works in a wedge configuration to take mechanical advantage. A closed-loop control system has been developed to achieve this repeatability. For the feedback, one LVDT sensor for each axis was used. Mechanical switches are used to limit movement. In addition, hard-stops are included for emergency. Prototyping stage is done and a serial production of more than 90 devices is expected, so intense work has been done to achieve a reliable industrial production and validation. In this report, results of mechanical measurements including reproducibility, tests of different operation strategies and critical situations will be reported.

MOPS006	Beam Tilt due to Transverse Wakefields for DAΦNE, SuperB, KEKB and SuperKEKB	impedance, closed-orbit, wakefield, collider	601
	D.M. Zhou, K. Ohmi KEK, Ibaraki, Japan A. Chao SLAC, Menlo Park, California, USA
	When a beam bunch traverses a transverse impedance, the bunch head generates a transverse wakefield that kicks the bunch tail, generating a betatron motion of the tail relative to the head. In a storage ring, in a steady state, this kick to the bunch tail produces a transverse closed orbit (e.g. in the y-direction) of the bunch tail relative to the bunch head, which means the beam now has a y-z tilt. Such beam tilt due to transverse wakefields may cause a loss of luminosity in storage ring colliders or loss of brightness in light sources. In this paper, we present a preliminary study of the beam tilt effect for the colliders DAΦNE, SuperB, KEKB and SuperKEKB.

MOPS017	Simulation Studies of Macro-particles Falling into the LHC Proton Beam	proton, beam-losses, simulation, injection	634
	F. Zimmermann, T. Baer, M. Giovannozzi, E.B. Holzer, E. Nebot Del Busto, A. Nordt, M. Sapinski CERN, Geneva, Switzerland N. Fuster Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain Z. Yang EPFL, Lausanne, Switzerland
	We report updated simulations on the interaction of macro-particles falling from the top of the vacuum chamber into the circulating LHC proton beam. The path and charge state of micron size micro-particles are computed together with the resulting beam losses, which – if high enough - can lead to the local quench of SC magnets. The simulated time evolution of the beam loss is compared with observations in order to constrain some macro-particle parameters. We also discuss the possibility of a "multiple crossing" by the same macro-particle, the effect of a strong dipole field, and the dependence of peak loss rate and loss duration on beam current and on beam size.

MOPS045	Coupling Impedance of Rough Resistive Pipe*	impedance, coupling, resonance, wakefield	700
	M. Ivanyan, V.M. Tsakanov CANDLE, Yerevan, Armenia
	A new version of modelling of the surface roughness impact by thin dielectric layer in the round resistive beam pipe is suggested. The calculation method of coupled resistive-roughness impedance is developed.

MOPS049	Study of Ion-induced Instabilities and Transverse Feedback Performance at SOLEIL	ion, feedback, simulation, electron	712
	R. Nagaoka, L. Cassinari, M.D. Diop, J.-M. Filhol, M.-P. Level, A. Loulergue, P. Marchand, R. Sreedharan SOLEIL, Gif-sur-Yvette, France
	Experimental studies indicate that the SOLEIL storage ring at its maximum designed current of 500 mA is under a large influence of ions, potentially capable of inducing the so called fast beam-ion instability. To avoid it, the following three conditions have been empirically found effective: A reduced RF voltage, uniform filling and a large vertical chromaticity. While the choice of uniform filling appears contradictory to raising the ion instability threshold, it goes well with lowering of the RF voltage if outgassing due to beam-induced heating of the vacuum components is the primary source of ions. Additional difficulties associated are frequent occurrence of sudden beam blowups despite the presence of transverse feedback, which are large enough to trigger machine interlocks leading to complete beam losses. These blow ups may even take place horizontally inside in-vacuum insertion devices. The present paper reports on the results and findings obtained through experimental and simulation studies carried out on the collective beam dynamics and the transverse feedback performance, which are deeply interlinked, in order to clarify the mechanism of the encountered phenomena.

MOPS056	An Analytical Formula of the Electron Cloud Linear Map Coefficient in a Strong Dipole	electron, dipole, simulation, storage-ring	733
	T. Demma INFN/LNF, Frascati (Roma), Italy S. Petracca, A. Stabile U. Sannio, Benevento, Italy G. Rumolo CERN, Geneva, Switzerland
	Electron cloud effects have been indentified as one of the most serious bottleneck for reaching design performances in presently running and proposed future storage rings. The analysis of these effects is usually performed with very time consuming simulation codes. An alternative analytic approach, based on a cubic map model for the bunch-to-bunch evolution of the electron cloud density, could be useful to determine regions in parameters space compatible with safe machine operations. In this communication we derive a simple approximate formula relating the quadratic coefficient in the electron cloud density map to the parameters relevant for the electron cloud evolution in a strong vertical magnetic field. Results are compared with simulations with particular reference to the LHC dipoles.

MOPS064	Longitudinal Beam Stability and Related Effects at the ALBA Storage Ring	kicker, impedance, resonance, injection	748
	T.F. Günzel CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	The risk of longitudinal instabilities excited by narrowband and broadband resonator impedance was studied. A campaign for the search of modes trapped in vacuum chamber elements of the ALBA storage ring via electromagnetic simulation was initiated. Several critical vacuum elements in the ring like the vertical scraper, the injection and feedback kickers were identified. The outlets of the injection kicker had to be protected with RF-fingers whereas the scraper only produces dangerous modes in the withdrawn state, both do not pose a real problem. However, the calculated power distribution generated in the feedback kickers could be an obstacle for reaching the nominal current of 400mA. Furthermore, the budget of Z(n)/n of the storage ring was computed and checked on the risk of microwave instability using the Boussard criterion.

MOPS065	Transverse Instability Studies at the ALBA Storage Ring	impedance, single-bunch, kicker, storage-ring	751
	T.F. Günzel CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	In the first phase of the ALBA storage ring operation 3 NEG-coated aluminum chambers, 2 in-vacuum undulators and one wiggler chamber will be installed. Under particular consideration of the multilayer character of these chambers and the injection kickers the thresholds of the transverse mode coupled instability(TMCI) were calculated using MOSES. The thresholds 17.5mA/40.5mA vertical/horizontal leave a rather large operative margin. The detrimental effect of the NEG-coating on the TMCI is relatively limited and on the resistive wall instability is even negligible. As well the thresholds of the head-tail instability were computed as function of chromaticity. Also the incoherent tune shifts generated by the quadrupolar resistive wall wake fields due to the flatness of the vacuum chambers were calculated. The computed results have been compared to first measurements of the storage ring commissioning. Y.H.Chin, MOSES 2.0, CERN/LEP-TH/88-05

MOPS070	Electromagnetic Modeling of C Shape Ferrite Loaded Kickers	impedance, kicker, simulation, ion	763
	C. Zannini EPFL, Lausanne, Switzerland E. Métral, G. Rumolo, B. Salvant, V.G. Vaccaro, C. Zannini CERN, Geneva, Switzerland
	The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of an intensity upgrade of the LHC. In this paper, analytical approach and CST Particle Studio time domain electromagnetic simulations are performed to obtain the longitudinal and transverse impedances/wake potentials of models of ferrite loaded kickers. It turns out that the existing models are not sufficient to characterize correctly these components from the coupling impedance point of view. In particular the results show that below few hundred MHz the real C-structure of the magnet cannot be neglected. Therefore an analytical model was developed and benchmarked with EM simulations to take into account the C-shape of the magnet.

MOPS071	Simulations of the Impedance of the New PS Wire Scanner Tank	simulation, impedance, beam-losses, extraction	766
	B. Salvant EPFL, Lausanne, Switzerland W. Andreazza, F. Caspers, A. Grudiev, J.F. Herranz Alvarez, E. Métral, G. Rumolo CERN, Geneva, Switzerland
	The CERN PS is equipped with 4 wire scanners. It was identified that the small aperture of the current wire scanner tank causes beam losses and a new tank design was needed. The interaction of the PS bunches with the beam coupling impedance of this new tank may lead to beam degradation and wire damage. This contribution presents impedance studies of the current PS tank as well as the new design in order to assess the need to modify the design and/or install lossy materials plates dedicated to damp higher order cavity modes and reduce the total power deposited by the beam in the tank.

MOPS073	Impedance Calculation for Simple Models of Kickers in the Non-ultrarelativistic Regime	impedance, kicker, coupling, neutron	772
	N. Biancacci, N. Mounet, E. Métral, B. Salvant, C. Zannini CERN, Geneva, Switzerland N. Biancacci, M. Migliorati, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy Q. Qin, N. Wang IHEP Beijing, Beijing, People's Republic of China
	Kicker magnets are usually significant contributors to the beam coupling impedance of particle accelerators. An accurate understanding of their impedance is required in order to correctly assess the machine intensity limitations. The field matching method derived by H. Tsutsui for the longitudinal and transverse dipolar (driving) impedance of simple models of kickers in the ultrarelativistic regime was already extended to the non-ultrarelativistic case, and to the quadrupolar (detuning) impedance in the ultrarelativistic case. This contribution presents the extension to the quadrupolar impedance in the non-ultrarelativistic case, as well as benchmarks with other available methods to compute the impedance. In particular, all the components of the impedances are benchmarked with Tsutsui's model, i.e. in the ultrarelativistic limit, with the model for a flat chamber impedance recently computed by N. Mounet and E. Métral, in the case of finite relativistic gamma, and with CST Particle Studio simulations.

MOPS090	Observation of Beam Ion Instability in SPEAR3	ion, emittance, single-bunch, quadrupole	814
	L. Wang, Y. Cai, W.J. Corbett, T.O. Raubenheimer, J.A. Safranek, J.F. Schmerge, J.J. Sebek SLAC, Menlo Park, California, USA D. Teytelman Dimtel, San Jose, USA
	Weak vertical coupled bunch instability with oscillation amplitude at μm level has been observed in SPEAR3. The instability becomes stronger when there is a vacuum pressure rise by partially turning off vacuum pumps and it becomes weaker when the vertical beam emittance is increased by turning off the skew quadrupole magnets. These confirmed that the instability was driven by ions in the vacuum. The threshold of the beam ion instability when running with a single bunch train is just under 200 mA. This paper presents the comprehensive observations of the beam ion instability in SPEAR3. The effects of vacuum pressure, beam current, beam filling pattern, chromaticity, beam emittance and bunch-by-bunch feedback are investigated in great detail.pattern, chromaticity, beam emittance and bunch-by-bunch feedback are investigated in great detail.

MOPZ011	An Automated Conditioning System for the MUCOOL Experiments at Fermilab	cavity, controls, pick-up, collider	844
	A. Kurup Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	The MUCOOL project aims to study RF cavities for the Neutrino Factory and the Muon Collider. The large emittance muon beams in these accelerators require high-gradient RF cavities at low-frequencies and they need to operate in the presence of relatively strong magnetic fields. MUCOOL is conducting a number of tests on 805MHz and 201 MHz cavities in order to develop a technology that can meet all of these requirements. An automated conditioning system was developed for the 805MHz test program for MUCOOL. This system was designed to replicate the logic a human operator would use when conditioning an RF cavity and to provide automated logging of the conditioning process. This paper describes the hardware and software of the system developed.

MOPZ029	Aperture Windows in High-Gradient Cavities for Accelerating Low-Energy Muons	cavity, linac, septum, target	862
	S.S. Kurennoy, A.J. Jason, W.M. Tuzel LANL, Los Alamos, New Mexico, USA
	A high-gradient linear accelerator for accelerating low-energy muons and pions in a strong solenoidal magnetic field has been proposed for homeland defense and industrial applications. The acceleration starts immediately after collection of pions from a target in a solenoidal magnetic field and brings muons to a kinetic energy of about 200 MeV over a distance of the order of 10 m. At this energy, both ionization cooling of the muon beam and its further acceleration become feasible. A normal-conducting linac with external-solenoid focusing can provide the required large beam acceptances. The linac consists of independently fed zero-mode (TM010) RF cavities with wide beam apertures closed by thin conducting windows. The high gradients lead to significant heat deposition on the aperture windows. Here we explore options for the edge-cooled thin windows in the zero-mode cavities. Electromagnetic and thermal-stress computations are complemented by thermal-test experiments to select the best solution for the aperture windows. S.S. Kurennoy, A.J. Jason, H. Miyadera, “Large-Acceptance Linac for Accelerating Low-Energy Muons,” Proc. of IPAC10, p. 3518 (2010).

TUZB02	Ultra High Vacuum for High Intensity Proton Accelerators	ion, radiation, proton, radioactivity	971
	N. Ogiwara JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In high intensity proton accelerators neutrons, as well as gamma rays, are generated. At the J-PARC synchrotron the cumulative energy dose will be of the order of several-mSv/h over 1 month user operation. In order to minimize the radiation exposure during maintenance, it is necessary to construct a vacuum system with reliable components which have a long life in such a high level of radiation. In addition, in all machines it is necessary to keep the operating pressure of the beam in ultra high vacuum (UHV) to suppress pressure instability. At J-PARC RCS the UHV conditions were realized without baking and the beam operation has been successful to date. General considerations for vacuum systems for high intensity linear and circular accelerators will be provided in the talk.
	Slides TUZB02 [3.380 MB]

TUODB01	Progress of the Construction for the TPS Vacuum System	photon, impedance, ion, storage-ring	976
	G.-Y. Hsiung, C.K. Chan, C.H. Chang, C.-C. Chang, C.L. Chen, C.M. Cheng, Y.T. Cheng, S-N. Hsu, H.P. Hsueh, I.T. Huang, T.Y. Lee, I.C. Sheng, L.H. Wu, H.Y. Yan, Y.C. Yang, C.S. huang NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	Vacuum system for the 3 GeV Taiwan Photon Source (TPS) has been started the construction since 2010. The critical components such as the bellows and gate valves with rf-contact shielding, pulsed magnet kicker ceramic chambers, BPM, crotch absorbers, etc. have been manufactured and tested. Aluminum alloy (Al-) vacuum chambers for the arc-cells have been machined and undergoing the in-house welding. Mass production of the vacuum equipments including the ion gauges, ion pumps, NEG pumps, and gate valves, has been contracted out and partially delivering following the schedule of the cell assembling. Each cell, contains two short Al-straight chambers and two Al-bending chambers, has been started the assembling and on-site welding on the pre-aligned girders in clean room forming an one-piece vacuum vessel about 14 m in length following by the vacuum baking to the ultra-high vacuum. The conceptual design of the vacuum systems for the long straight sections, the concentric booster, and the transport lines, will be addressed. The progress of prototyping development and the status of construction for the TPS vacuum system will be described in this paper.
	Slides TUODB01 [35.595 MB]

TUODB02	Extreme High Vacuum System of High Brightness Electron Source for ERL	gun, electron, ion, cathode	979
	M. Yamamoto, T. Honda, Y. Honda, T. Miyajima, Y. Saito, Y. Tanimoto, T. Uchiyama KEK, Ibaraki, Japan H. Akimichi, H. Yoshida AIST, Tsukuba, Japan H. Kurisu Yamaguchi University, Ube-Shi, Japan
	A compact test accelerator for Japan’s future light source based on energy recovery linac (ERL) is under construction in KEK, aiming to demonstrate key technologies such as a high-brightness photocathode DC-gun and superconducting RF cavities. A DC-gun using GaAs-type photocathode which has a negative electron affinity (NEA) surface is employed. The NEA surface plays an indispensable role to extract electrons from conduction band minimum into vacuum. It assures high quantum efficiency of the photocathode and very low intrinsic emittance of the extracted beam. However, the NEA surface is extremely delicate against residual gas in vacuum. In order to extract mA-level beam currents continuously for more than several tens of hours, the pressure should be lower than the order of ·10^-10 Pa to avid the backbombardment of positive ions produced by the collision of accelerated electrons with residual gas molecules in the beam path. Recent achievements in the development of a 500-kV photocathode DC-gun and in the fundamental studies of its extreme high vacuum system will be presented.
	Slides TUODB02 [1.606 MB]

TUPC008	CLIC Two-Beam Module for the CLIC Conceptual Design and Related Experimental Program	alignment, linac, quadrupole, RF-structure	1003
	A. Samoshkin, D. Gudkov, A. Solodko JINR, Dubna, Moscow Region, Russia G. Riddone CERN, Geneva, Switzerland
	The Compact LInear Collider (CLIC), being studied at CERN, involves the design and integration of many different technical systems, tightly bound and influencing each other. For the construction of two main linacs it has been decided to proceed with a modular design, and repetitive two-beam modules of a few types were defined. The modules consist of micro-precision components operating under ultra-high vacuum as required by the beam physics. For the CLIC Conceptual Design Report, the development and system integration is mainly focused on the most complex module type containing the highest number of components and technical systems. For proving the proper functioning of the needed technical systems and confirming their feasibility it has been decided to build four prototype modules and test them without beam. In addition, three modules have to be produced in parallel for tests in the CLIC Experimental Area with beam. This paper is focused on the design of the different technical systems and integration issues of the two-beam module. The experimental program for the prototype modules is also recalled.

TUPC010	Status of the Manufacturing of Accelerating Structures for LINACs	linac, controls, extraction, laser	1009
	F.M. Mirapeix, J. Añel, J. Castillo, A. Ortiz HTS, Mendaro, Spain X. Aldalur, J. Amores, A. Urzainki DMP, Mendaro, Spain
	Funding: HTS, DMP, ZEHATZ, CERN Particle accelerators need ongoing development in the state of the art of the field: high-quality manufacturing of accelerating structures, PETS, but also drift tubes, bunchers, high-power couplers, alignment systems, precision test stands, etc. They also require engineering projects in the range of mechatronics, thermodynamics, microwaves, ultra high vacuum, cryogenics, joining techniques, high precision manufacturing, 3D high precision scanning, etc. HTS together with DMP are actually working on all this fronts. In this paper, the actual status of the manufacturing capabilities concerning some accelerating structures will be described.

TUPC011	Striplines for CLIC Pre-Damping and Damping Rings*	impedance, kicker, damping, extraction	1012
	C. Belver-Aguilar, A. Faus-Golfe IFIC, Valencia, Spain M.J. Barnes, G. Rumolo CERN, Geneva, Switzerland F. Toral CIEMAT, Madrid, Spain C. Zannini EPFL, Lausanne, Switzerland
	The Compact Linear Collider (CLIC) study explores the scheme for an electron-positron collider with high luminosity and a nominal center-of-mass energy of 3 TeV: CLIC would complement LHC physics in the multi-TeV range. The CLIC design relies on the presence of Pre-Damping Rings (PDR) and Damping Rings (DR) to achieve, through synchrotron radiation, the very low emittance needed to fulfil the luminosity requirements. The specifications for the kicker systems are very challenging and include very low beam coupling impedance and excellent field homogeneity: striplines have been chosen for the kicker elements. Analytical calculations have been carried out to determine the effect of tapering upon the high frequency beam coupling impedance. In addition detailed numerical modeling of the field homogeneity has been performed and the sensitivity of the homogeneity to various parameters, including stripline cross-section, has been studied. This paper presents the main conclusions of the beam impedance calculations and field homogeneity predictions.

TUPC018	Progress on Modelling of the Thermo-Mechanical Behavior of the CLIC Two-Beam Module	RF-structure, simulation, linac, collider	1033
	R.J. Raatikainen, K. Osterberg HIP, University of Helsinki, Finland T.O. Niinikoski, G. Riddone CERN, Geneva, Switzerland
	The luminosity goal of the CLIC collider, currently under study, imposes micrometer mechanical stability of the 2-m long two-beam modules, the shortest repetitive elements of the main linacs. These modules will be exposed to variable high power dissipation during operation resulting in mechanical distortions in and between module components. The stability of the CLIC module will be tested in laboratory conditions at CERN in a full-scale prototype module. In this paper, the FEA model developed for CLIC prototype module is described. The thermal and structural results for the new module configuration are presented considering the thermo-mechanical behavior of the CLIC collider in its primary operation modes. These results will be compared to the laboratory measurements to be done during 2011 and 2012 with the full-scale prototype module. The experimental results will allow for better understanding of the module behaviour and they will be propagated back to the present thermo-mechanical model.

TUPC030	Recommendation for Mitigations of the Electron Cloud Instability in the ILC	electron, positron, emittance, quadrupole	1063
	M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA L.E. Boon, K.C. Harkay ANL, Argonne, USA J.A. Crittenden, G. Dugan, M.A. Palmer CLASSE, Ithaca, New York, USA T. Demma, S. Guiducci INFN/LNF, Frascati (Roma), Italy M.A. Furman LBNL, Berkeley, California, USA K. Ohmi, K. Shibata, Y. Suetsugu, J. Urakawa KEK, Ibaraki, Japan C. Yin Vallgren Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden
	Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515. Electron cloud has been identified as one of the highest priority issues for the ILC Damping Rings (DR). A working group has evaluated the electron cloud effect and instability, and mitigation solutions for the electron cloud formation. Working group deliverables include recommendations for the baseline and alternate solutions for the electron cloud mitigation in various regions of the ILC Positron DR, which is presently assumed to be the 3.2km design. Detailed studies of a range of mitigation options including coatings, clearing electrodes, grooves and novel concepts, were carried out over the previous several years by nearly 50 researchers, and the results of the studies form the basis for the recommendation. The assessments of the benefits or risks associated with the various options were based on a systematic ranking scheme. The recommendations are the result of the working group discussions held at numerous meetings and during a dedicated workshop. The mitigation choices will be also presented in a more detailed report later in 2012. In addition, a number of items requiring further investigation were identified and studies will be carried out at CesrTA and other institutions.

TUPC041	Self-consistent Time-dependent Quasi-3D Model of Multipactor in Dielectric-loaded Accelerating Structures	space-charge, electron, multipactoring, plasma	1090
	O.V. Sinitsyn, T.M. Antonsen, G.S. Nusinovich UMD, College Park, Maryland, USA
	Funding: This work is supported by the Office of High Energy Physics of the US Department of Energy. Multipactor (MP) manifests itself as a rapid growth of the number of secondary electrons emitted from a solid surface in the presence of the RF field under vacuum conditions. The secondary electrons appear as the result of surface impacts of energetic primary electrons accelerated by the RF field. MP occurs in various microwave and RF systems and usually severely degrades their performance. Therefore, theoretical and experimental studies of MP are of great interest to researchers working in related areas of physics and engineering. In this paper we study MP in dielectric-loaded accelerating (DLA) structures. We started our work with the development of a self-consistent time-dependent 2D model of MP in such structures. To benchmark that model, we compared its results with available experimental data. The comparison showed good agreement between theory and experiment for DLA structures of larger diameter, however for structures of smaller diameter a significant discrepancy was observed. Therefore, we decided to develop a new quasi-3D model of MP that would allow us to take into account the effects ignored in our 2D studies. Results of our 3D analysis are presented in this paper. O. V. Sinitsyn, G. S. Nusinovich and T. M. Antonsen, Jr., Phys. Plasmas, 16, 073102 (2009). ** O. V. Sinitsyn, G. S. Nusinovich and T. M. Antonsen, Jr., AIP Conf. Proc., 1299, 302 (2010).

TUPC042	First Beam to FACET	linac, electron, positron, controls	1093
	R.A. Erickson, C.I. Clarke, W.S. Colocho, F.-J. Decker, M.J. Hogan, S. Kalsi, N. Lipkowitz, J. Nelson, N. Phinney, P. Schuh, J. Sheppard, H. Smith, T.J. Smith, M. Stanek, J.L. Turner, J. Warren, S.P. Weathersby, U. Wienands, W. Wittmer, M. Woodley, G. Yocky SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Department of Energy contract DE-AC02-76SF00515. The SLAC 3km linear electron accelerator has been reconfigured to provide a beam of electrons to the new FACET facility while simultaneously providing an electron beam to the Linac Coherent Light Source (LCLS). FACET is a new experimental facility constructed in the linac tunnel that can transport, compress, and focus electron bunches to support a variety of accelerator R&D experiments. In this paper, we describe our first experiences with the operation of the linac for this new facility.

TUPC043	SEM Field Emission Probe Surface Science Study	cathode, electron, gun, laser	1096
	L. Laurent, R.E. Kirby, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This work is supported by Department of Energy Contract No. DE-AC03- 76SF00515. After decades of rf breakdown research, a common acknowledgement among researchers is that a better understanding of what is happening on the surface at a microscopic level needs to be the impetus for future studies. We are designing and fabricating an electron microscope-based high-electric-field current-emission probe to study topographic material features which will enable us to better understand and further advance the technology of high-brightness photocathode rf guns and enable the study of high gradient phenomena. The SEM field emission probe will provide an important diagnostic tool allowing cathodes and high gradient surfaces to be evaluated before and after testing and will help identify and understand the relationship between high field emission locations and vacuum breakdown, non-uniform emission, surface cracking, hotspots, etc. The preliminary results and 2012 goals will be presented.

TUPC050	Impedance Effects in the CLIC Damping Rings	impedance, wiggler, damping, simulation	1111
	E. Koukovini, K.S.B. Li, N. Mounet, G. Rumolo, B. Salvant CERN, Geneva, Switzerland
	Due to the unprecedented brilliance of the beams, the performance of the Compact Linear Collider (CLIC) damping rings is affected by collective effects. Single bunch instability thresholds based on a broad-band resonator model and the associated coherent tune shifts have been evaluated with the HEADTAIL code. Simulations performed for positive and negative values of chromaticity proved that higher order bunch modes can be potentially dangerous for the beam stability. This study also includes the effects of high frequency resistive wall impedance due to different coatings applied on the chambers of the wigglers for e-cloud mitigation and/or ultra-low vacuum pressure. The impact of the resistive-wall wake fields on the transverse impedance budget is finally discussed.

TUPC070	SAFARI, an Optimized Beam Stop Device for High Intensity Beams at the SPIRAL2 Facility	linac, beam-transport, neutron, beam-losses	1162
	E. Schibler IN2P3 IPNL, Villeurbanne, France L. Perrot IPN, Orsay, France
	The SPIRAL2 facility at GANIL-Caen is now in its construction phase, with a project group including the participation of many French laboratories (CNRS, CEA) and international partners. The facility will be able to produce various accelerated beams at high intensities: 40 MeV Deuterons, 33 MeV Protons with intensity until 5mA and heavy ions with A/Q=3 up to 14.5MeV/u until 1mA current. We will present the final status of the 200kW beam stop located in the high energy beam transport lines. From the beam characteristics (HEBT line up to beam stop) and activation constraints, we studied and developed a complete design of a new high efficiency Beam Stop that has been nicknamed SAFARI (Système Arrêt Faisceau Adapté Rayons Intenses - Optimized Beam Stop Device for High Intensity Beams). Special focus will be done on the adequacy between beam dynamic and thermo-mechanical behavior. The Beam Stop shape marries to the beam characteristics in order to smooth for the best power density and improve thermo-mechanical behavior under nominal and critical beams. Optimization by various fluids studies and calculations led us to a new high efficiency counter-current water cooling system.

TUPC084	Performance of the Scintillation Profile Monitor in the COSY Synchrotron	synchrotron, proton, electron, target	1201
	V. Kamerdzhiev, J. Dietrich, K. Reimers FZJ, Jülich, Germany
	Residual gas scintillation is used for measuring profile of the proton beam circulating in the COSY synchrotron. The problem of low rate of scintillation events detected by a multichannel photomultiplier is coped with by injecting small amounts of pure nitrogen into the SPM vacuum chamber. This leads to a temporary local pressure bump of no more than an order of magnitude. A commercially available piezo-electric dosing valve allows good control over the amplitude and duration of the pressure bump. Since the average pressure in the machine is hardly changed, the method is fully compatible with experiment operation. This approach offers a robust and inexpensive way to measure the beam profile. The design of the SPM is discussed. The latest measurement results and comparison to the ionization profile monitor data is presented.

TUPC085	Observation of Microwave Radiation using Low-cost Detectors at the ANKA Storage Ring	radiation, synchrotron, storage-ring, optics	1203
	V. Judin, N. Hiller, A. Hofmann, E. Huttel, B. Kehrer, M. Klein, S. Marsching, A.-S. Müller, M.J. Nasse, N.J. Smale KIT, Karlsruhe, Germany F. Caspers CERN, Geneva, Switzerland P. Peier PSI, Villigen, Switzerland
	Funding: Work supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 Synchrotron light sources emit Coherent Synchrotron Radiation (CSR) for wavelengths longer than or equal to the bunch length. At most storage rings CSR cannot be observed because the waveguide cuts off radiation with long wavelengths. There are different approaches for shifting the CSR to shorter wavelengths that can propagate through the beam pipe, e.g.: The accelerator optics can be optimized for a low momentum compaction factor, thus reducing the bunch length. Alternatively, laser slicing can modulate substructures on long bunches. Both techniques extend the CSR spectrum to shorter wavelengths, so that CSR is emitted at wavelengths above the waveguide cut off. Usually fast detectors, like superconducting bolometer detector systems or Schottky barrier diodes, are used for observation of dynamic processes in accelerator physics. In this paper, we present observations of microwave radiation at ANKA using an alternative detector, a LNB (Low Noise Block) system. These devices are usually used in standard TV-SAT-receivers and are very cheap. We determined the time response of LNBs to be below 100 ns. The sensitivity of LNBs is optimized to detect very low intensity "noise-like" signals.

TUPC088	An Ionization Profile Monitor for the Determination of the FLASH and PITZ Beam Parameters	electron, photon, diagnostics, ion	1212
	J. Mießner, H.-J. Grabosch, M. Markert, R. Sternberger DESY Zeuthen, Zeuthen, Germany A. Hofmann KIT, Karlsruhe, Germany K.I. Tiedtke DESY, Hamburg, Germany
	To operate FLASH (Free-electron LASer at Hamburg) successfully, accurate measurements of the photon beam parameters, like position and profile, are essential. The development of a specific Ionization Profile Monitor (IPM) is one contribution to the photon beam diagnostics, and currently one horizontal and one vertical oriented IPM are installed at FLASH. The working principle of the IPM is based on the detection of ions generated by interactions of the photon beam with the residual gas, which is always present in the beam line. An essential advantage of this method is that the beam is not influenced by the IPM, so it is possible to analyze the beam parameters without beam destruction. Moreover, the monitor is able to determine the relative position and the spatial profile of the beam with the precision of a few um. In this poster, the design and first measurements with the IPM taken at FLASH are presented. A good measuring accuracy of the IPM is obtained. Moreover, first results of measurements at PITZ (PhotoInjector Testfacility at Zeuthen) are given for one vertical oriented IPM with a up to 25 MeV electron beam.

TUPC092	Transverse C-band Deflecting Structure for Longitudinal Phase Space Diagnostics in the XFEL/SPring-8 “SACLA”	laser, coupling, diagnostics, emittance	1221
	H. Ego RIKEN/SPring-8, Hyogo, Japan T. Hashirano, S. Miura MHI, Hiroshima, Japan H. Maesaka, Y. Otake RIKEN Spring-8 Harima, Hyogo, Japan T. Sakurai RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	In SPring-8, the 8 GeV compact XFEL “SACLA” is under commissioning. A single bunch of electrons is compressed down to about 30 fs for brilliant SASE X-ray lasing. It is an important key of stable lasing to investigate the longitudinal phase space and the sliced emittance of a lasing part of the bunch by using a transverse RF deflector. We developed a high gradient C-band deflecting structure operated at 5712 MHz for the bunch diagnosis with a resolution of femtosecond regime at a limited space in the SACLA. The backward travelling-wave of the HEM11-5pi/6 mode is excited in the cylindrical structure periodically loaded with racetrack-shaped irises. The featuring irises suppress rotation of the deflection plane and generate strong cell-to-cell coupling for stable resonance. Two 1.8m-long structures were fabricated and installed in the SACLA. They successfully generated a deflection voltage over 40 MV and pitched the bunch at the zero-crossing RF phase. In this paper, we present the details of the fabrication and the deflecting performance of the structures applied to the diagnosis.

TUPC097	Status of Cold Cavity Beam Position Monitor for STF	cavity, linac, cryomodule, coupling	1236
	E.-S. Kim, A. Heo KNU, Deagu, Republic of Korea H. Hayano KEK, Ibaraki, Japan
	Cold cavity BPM was developed to meet high position resolution and bunch to bunch measurement time. It is designed based on re-entrant cavity and has Low-Q to achieve short signal decay time in L-band frequency with large aperture as 78mm. The beam test was performed to demonstrate position resolution at ATF main linac, which is operating with 1.6nC bunch charge, while BPM will be installed inside the ILC cyomodule with 3.2nC spacing 369ns like as ILC at STF. Stripline BPMs, ML2P and ML3P installed upstream and downstream of the BPM’s location respectively were used to predict its position. Reference cavity was optimized to use for synchronous detection. We had achieved ~340nm position resolution since position resolution was estimated due to limitation of system with noise, namely in case of ideal state. We will present configuration of beam test, procedure to measure position resolution and the result on the test. Furthermore, new design will be introduced to improve signal intensity and have heavy coupling.

TUPC099	New Measurements of Proton Beam Extinction at J-PARC	proton, injection, secondary-beams, linac	1242
	K. Yoshimura, Y. Hori, Y. Igarashi, S. Mihara, H. Nishiguchi, Y. Sato, M. Shimamoto, Y. Takeda, M. Uota KEK, Ibaraki, Japan M. Aoki, S. Hikida, H. Nakai Osaka University, Osaka, Japan Y. Hashimoto J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Proton beam extinction, defined as a residual to primary ratio of beam intensity, is one of the most important parameters to realize the future muon electron conversion experiment (COMET) proposed at J-PARC. To achieve the required extinction level of 10^-9, we started measuring extinction at main ring (MR) as its first step. According to the various measurements done at the different positions, empty RF buckets of RCS, which were considered to be swept away by the RF chopper, contained about 10^-7 ~ 10^-5 of the main beam pulse due to chopper inefficiency. We have developed a new beam monitor with improved performance for further studies at the abort line. In addition, we have started new measurements at the Hadron experimental hall by using slow-extracted beam. In this paper, we present recent results and future prospect of beam extinction measurements.

TUPC121	Development of MCP Based Photon Detectors for the European XFEL	photon, radiation, FEL, background	1299
	E. Syresin, M.N. Kapishin JINR, Dubna, Moscow Region, Russia O.I. Brovko, A.V. Shabunov JINR/VBLHEP, Moscow, Russia W. Freund, J. Grünert, H. Sinn European XFEL GmbH, Hamburg, Germany M.V. Yurkov DESY, Hamburg, Germany
	To provide successful operation of SASE XFEL the radiation detectors should operate in wide dynamic range from the level of spontaneous emission to the saturation level, in wide wavelength range from 0.05 nm to 0.16 nm for SASE1 and SASE2 and from 0.4 nm to 4.4 nm for SASE3. High relative accuracy of measurements is crucial for detection of a signature of lasing, tuning of amplification process, and characterization of statistical properties of the radiation. The XFEL radiation detector based on micro-channel plates (MCP) meets these requirements. Two types of the photon detector are used for measurements of the pulse radiation energy and the image of the photon beam. The dynamic range of photon pulse energies is between 1 nJ and 10 mJ. This applies to spontaneous and FEL radiation. The relative accuracy of pulse energy measurements is better than 1%. The visualization of a single bunch in a train, or average image over the full train will perform by the MCP imager at a spatial resolution of 30 μm.

TUPC129	A Beam Position System for Hadrontherapy Facilities	electron, photon, controls, proton	1323
	A. Faus-Golfe, C. Belver-Aguilar, C. Blanch Gutierrez, J.J. García-Garrigós IFIC, Valencia, Spain E. Benveniste, M. Haguenauer, P. Poilleux LLR, Palaiseau, France
	Funding: MICINN-FPA:AIC10-D-000518 Essential parts of the needed instrumentation for the beam control in the Hadrontherapy accelerators are the Beam Position Monitors (BPM). The measurement of the beam position in Hadronterapy accelerators become more important at the secondary transport lines towards the patient room where this parameter must be completely determined. The BPM described in this paper is a new type of BPM based on four scintillating fibers coupled to four photodiodes to detect the light produced by the fibers when intercepting the beam. We present here the study of the different photodiodes able to read the light emitted by the scintillating fiber, the tests performed in order to find the most suitable photodiode to measure the beam position from the variations in the beam current, the mechanical design and the corresponding acquisition electronics.

TUPC133	Instrumentation for the 12 GHz Stand-alone Test-stand to Test CLIC Acceleration Structures	electron, laser, diagnostics, ion	1335
	M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden J.W. Kovermann CERN, Geneva, Switzerland
	Vacuum breakdown is one of the primary limitations in the design and construction of high energy accelerators operating with warm accelerating structures (ACS) such as CLIC linear collider because the mechanisms that cause the breakdown are still a mystery. The ongoing experimental work is trying to benchmark the theoretical models focusing on the physics of vacuum breakdown which is responsible for the observed discharges. The CLIC collaboration is preparing a dedicated 12 GHz test-stand to observe the characteristics of the RF discharges and their eroding effects on the ACS. The instrumentation for the test-stand must be versatile and allow for the conditioning of the ACS with measurements of the breakdown rates at different power levels as well as detection of the dark current and light emission directly relevant to breakdown physics. For that purpose we are developing 2 novel instruments. A pepper-pot chamber with an external magnetic spectrometer for measurement of the spatial and energy distributions of the electrons emitted from the ACS and an optical laser system for probing the ACS to observe the effect of a discharge on the transmitted light.

TUPC147	A Micro-Channel Plate Based Gas Ionization Profile Monitor with Shaping Field Electrodes for the ISIS H⁻ Injector	ion, controls, radiation, beam-losses	1371
	P.G. Barnes, G.M. Cross, B.S. Drumm, S.A. Fisher, S.J. Payne, A. Pertica, C.C. Wilcox STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Beam profile measurements within the ISIS H⁻ injector line are achieved using destructive devices such as moving wire scanners. To avoid damage to the wires, measurements are made with the injector operating on reduced power. This paper reports the development of a Micro-Channel Plate based profile monitor which allows beam measurements to be made under normal operating conditions. The monitor produces profiles by measuring the +ion current resulting from the interaction of the H⁻ beam with the surrounding residual gas. The 32 channel Micro-Channel Plate is mounted on a rotating arm to enable it to be positioned parallel to the beam for calibration (all channels then measure the same +ion current) and perpendicular to the beam for profile measurements. A 15kV drift field is used together with field shaping electrodes to ensure a flat electric field gradient across the monitor, thereby minimising distortion of the profile due to the electric field. This paper details all aspects of the design and construction of this profile monitor. Beam profiles are compared to previous wire scanner results. Shaping field upgrades are discussed to improve the longitudinal field shape.

TUPC163	Experimental Results from Test Measurements with the USR Beam Position Monitoring System	pick-up, simulation, storage-ring, alignment	1416
	J. Harasimowicz, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom J. Harasimowicz, I. Takov The University of Liverpool, Liverpool, United Kingdom
	Funding: Work supported by STFC, the EU under GA-ITN-215080, the Helmholtz Association and GSI under VH-NG-328. A diagonal-cut capacitive pick-up (PU) was optimised for monitoring slow (v < 0.025c), long (~1 m) bunches consisting of only about 10⁶ antiprotons at the future Ultra-low energy Storage Ring (USR). Ultra-low noise (0.5 nV/Hz⁰.5) FET pre-amplifiers are used to allow detection of the weak signals generated in the PU plates. The amplified signals are then digitized by a 16-bit, 200 MS/s ADC and processed in a digital manner. The following contribution presents the beam monitoring system as it was tested with a stretched-wire method and compares the measurements with the results from 3D electromagnetic simulations.

TUPC178	Charge Lifetime Study of K2CsSb Photocathode Inside a Jlab DC High Voltage Gun	laser, cathode, gun, high-voltage	1443
	R.R. Mammei, M. Poelker, R. Suleiman JLAB, Newport News, Virginia, USA J.L. McCarter UVa, Charlottesville, Virginia, USA T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE Two photocathodes are frequently considered for generating high average current electron beams and/or beams with high brightness for current and future accelerator applications: GaAs:Cs and K2CsSb. Each photocathode has advantages and disadvantages, and need to demonstrate performance at “production” accelerator facilities. To this end a K2CsSb photocathode was manufactured at Brookhaven National Lab and delivered to Jefferson Lab within a compact vacuum apparatus at pressure ~ 5x10^-11 Torr. This photocathode was installed inside a dc high voltage photogun biased at voltages up to 200 kV, and illuminated with laser light at 440 or 532 nm, to generate beams up to 20 mA. Photocathode charge lifetime measurements indicate that under some conditions this cathode has exceptionally high charge lifetime, without measurable QE decay, even from the center of the photocathode where operation using GaAs photocathodes is precluded due to ion bombardment. These studies also suggest a complex QE decay mechanism likely related to chemistry and localized heating via the laser beam.

TUPO029	Status of the BERLinPro Optics Design	emittance, linac, optics, electron	1500
	A.N. Matveenko, M. Abo-Bakr, A.V. Bondarenko, A. Jankowiak, J. Knobloch, B.C. Kuske, Y. Petenev HZB, Berlin, Germany
	Following funding approval late 2010, Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a high-current (100 mA) low emittance beam (1 mm•mrad normalized), as required for future ERL-based synchrotron light sources. Given the flexibility ERLs provides, a short bunch operation mode will also be investigated. Current optics was designed to allow of low emittance and short bunch operation modes. Optics is flexible to suppress BBU and minimize CSR effects. Estimation of impact of ion accumulation, wake fields, halo and chromatic aberrations is given. Requirements for beam diagnostic system, alignment accuracy and power supply stability are investigated.

TUPS001	Upgrade of the ESRF Vacuum System	storage-ring, controls, cathode, synchrotron	1515
	M. Hahn, J.C. Biasci, H.P. Marques, A. Meunier ESRF, Grenoble, France
	The upgrade program of the ESRF concerns in terms of electron storage ring vacuum chambers mainly the insertion device (ID) sectors. Here the length available for the production of intense synchrotron light is being increased from five to six or even seven meters. The presence of canted ID sectors where two independent synchrotron light beams will be produced in the same straight section requires new quadrupole chambers compatible with the new geometry. A number of long insertion device vacuum chambers for the new ID sectors has already been produced by ESRF and coated with non-evaporable getter (NEG) material, a new generation of in vacuum undulators for the extended ID sections are under preparation. This paper outlines the status of the modification of the vacuum system and informs about consequences for the ESRF NEG coating activity and some recent improvements of the vacuum measurement and control system.

TUPS002	Photodesorption Measurements at ESRF D31	radiation, synchrotron, synchrotron-radiation, electron	1518
	H.P. Marques, G. Debut, M. Hahn ESRF, Grenoble, France
	Since 1998 exists at ESRF a dedicated beamline for photodesorption measurement from vacuum chambers - D31. The original goal of this installation was to study the wall pumping effect. When exposed to synchrotron radiation surfaces exhibit strong outgassing of the adsorbed gas layer despite UHV conditions. Long term outgassing leads to the depletion of the adsorbed layer and produces a very clean surface which turns the walls of the vacuum chamber into an active pumping surface. The desorption mechanisms can be described by the long standing models of Knotek-Feibelman (KF) and Menzel-Gomer-Redhead – (MGR) which are themselves encompassed under the name of Desorption Induced by Electronic Transitions (DIET). In these models the surface itself plays a fundamental role in the desorption mechanism. At D31 have been tested chambers of stainless steel, aluminum and copper, with or without coatings (e.g. NEG, copper), designed by ESRF and other institutes like ALBA, CERN, ELETTRA and Soleil. Here we review some of the results obtained and outline the future plans of D31.

TUPS003	Upgrade of the ESRF RGA System	controls, diagnostics, monitoring, survey	1521
	A. Meunier, M. Hahn, I. Parat, J.L. Pons ESRF, Grenoble, France
	In the frame of the ESRF upgrade program, the Residual Gas Analyzer (RGA) system has been reviewed. A campaign of RGA refurbishment has been started recently giving more reliability and accuracy on partial pressure vacuum control. Based on new technologies and our operating experience, new RGA monitoring application and diagnostic tools have been developed. This paper outlines the evolution of the actual RGA system focusing on the controlled hardware installation description, on software and user interface developments. The continuous follow up of a defined number of partial pressure measurements using different dynamic control modes will be described.

TUPS004	Enhanced High-voltage Holding under Vacuum by Field Induced Adsorption of Gas on Metal Surfaces	high-voltage, electron, cathode, plasma	1524
	A. Simonin, L. Christin, L. Doceul, F. Faisse, F. Villecroze, H. de Esch CEA, St Paul Lez Durance, France
	*The energy of future neutral beam injector heating systems of fusion power plants ranges from 1 to 2 MeV. The beam line and the reactor chamber are under vacuum, while all the electrical components (power supplies) are connected to the injector via a long pressured (SF6) high-voltage (1-2 MV) transmission line. The bushing is a key component that ensures the barrier between the transmission line and the injector under vacuum; the design of this component is very challenging as it faces several stringent constraints due to the nuclear environment, in which high-voltage holding, mechanical stresses, and radiations are combined. Moreover, it is a high-voltage feed-through that allows supply of the accelerator electrodes with electrical power, active water cooling, and gas. In this paper, a new high-voltage bushing concept based on experimental findings previously obtained in the laboratory is presented. The main advantages of the concept is a reduction of the electron field emission under vacuum, which is an issue for conventional bushings, a reduction in size, and mechanical simplification of the device resulting in cost reduction and greater reliability."

TUPS007	Construction and Test of a Cryocatcher Prototype for SIS100*	ion, heavy-ion, controls, beam-losses	1527
	L.H.J. Bozyk, D.H.H. Hoffmann TU Darmstadt, Darmstadt, Germany H. Kollmus, P.J. Spiller, M. Wengenroth GSI, Darmstadt, Germany
	Funding: EU-FP-7 project COLMAT, FIAS The main accelerator, SIS100, of the FAIR-facility will provide heavy ion beams of highest intensities. Ionization beam loss is the most important loss mechanism at operation with high intensity, intermediate charge state heavy ions. A special synchrotron design has been developed for SIS100, aiming for hundred percent control of ionization beam loss by means of a dedicated cold ion catcher system. To suppress dynamic vacuum effects, the cryo catcher system shall also provide a significantly reduced effective desorption yield. The construction and tests of a prototype cryo ion catcher is a workpackage of the EU-FP-7 project COLMAT. A prototype test setup including cryostat has been constructed, manufactured and tested at GSI under realistic conditions with heavy ion beams of the of the heavy ion synchrotron SIS18. The design and results are presented.

TUPS008	The Gas Attenuator Vacuum System of FERMI@Elettra	photon, radiation, FEL, electron	1530
	L. Rumiz, D. Cocco, C. Fava, S. Gerusina, R. Gobessi, E. Mazzucco, F. Zudini ELETTRA, Basovizza, Italy M. Zangrando IOM-CNR, Trieste, Italy
	The FERMI@Elettra Free Electron Laser aims to produce a coherent light in the EUV-soft X-ray range employing High Gain Harmonic Generation (HGHG) schemes. The ultrafast, high intensity pulses are delivered to the experimental stations by means of a section called PADReS (Photon Analysis Delivery and Reduction System). Since several experiments need to reduce the FEL radiation intensity without changing the machine parameters, PADReS provides an integrated system to measure and reduce it up to 4 orders of magnitude. It is composed by a windowless gas-filled cell, a gas injection system, a differential pumping system, and the intensity monitors. The gas cell can be filled up to 0.15 mbar of nitrogen and the differential pumping system can keep up over 6 orders of magnitude. The pressure is finely regulated in the ·10^-5 mbar range in the intensity monitor vacuum chamber, almost independently from the gas cell pressure level. The general layout and the performance of the differential pumping system prototype are presented.

TUPS010	A Novel Approach in UHV Pumping of Accelerators: the NEXTorr® Pump	ion, insertion, insertion-device, synchrotron	1536
	P. Manini, A. Bonucci, L. Caruso, A. Conte, F. Siviero, L. Viale SAES Getters S.p.A., Lainate, Italy
	In spite of the large dimensions of accelerators, like synchrotrons or colliders, the space available for mounting UHV pumps is getting smaller, due to design constraints, service equipments, conductances, magnets, various instrumentations. This poses challenges to traditional UHV pump designs which are called to provide more pumping performances in smaller spaces. A radically new approach is here presented which can mitigate this issue. In this approach Non Evaporable Getter (NEG) and ion pumping technologies are properly combined and integrated in one single device, called NEXTorr®, having a unique design. In this pump, the getter cartridge acts as the main UHV pumping element, leaving to a small sputter ion pump the ancillary task of removing noble gases and methane, not pumped by the NEG. This design allows achieving large pumping speed in a very small package as well as delivering interesting pumping synergies. Main features of this new pump, including pumping tests, and example of applications will be reported, with a special focus to accelerators and high energy physics systems. Its impact in the design of vacuum systems for accelerators will also be discussed.

TUPS011	Use of NEG Pumps to Ensure Long Term Performances of High Quantum Efficiency Photocathodes	ion, cathode, photon, gun	1539
	L. Monaco, P.M. Michelato, D. Sertore INFN/LASA, Segrate (MI), Italy P. Manini, F. Siviero SAES Getters S.p.A., Lainate, Italy
	Laser triggered photo-cathodes are key components of the electron sources of 4th generation light machines. However, they are very sensitive to the vacuum level and its composition. Photo-cathodes are usually prepared in UHV chamber and then transferred, keeping the extreme vacuum condition, to the operation sites. Since transportation/storage may last from several days to weeks, retaining UHV conditions is a fundamental task to the photocathode usage. In this paper the results obtained using a novel pumping approach are given. This approach is based on coupling a 20 l.s⁻¹ ion getter pump with a Capacitorr® D100 Non Evaporable Getter (NEG) pump. Pressure of 2x10-11 mbar was achieved with the NEG pump after 2 days bake-out, as compared to 8x10-10 mbar achieved with the ion pump alone, after 7 days bake-out. Such pressure values were retained even in absence of power, due to the ability of the NEG to remove gases by chemical reaction. Long term monitoring of cathodes QEs was also carried out at different photon wavelengths over more than 6 months, showing no degradation of the photo-emissive film properties.

TUPS012	The Present Status of Vacuum System of XFEL in SPring-8	shielding, electron, undulator, laser	1542
	T. Bizen RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan T. Hasegawa RIKEN/SPring-8, Hyogo, Japan
	The vacuum component assembly and installation were completed by February in 2011. The total length of the vacuum system is about 630 m. A 455 sputter ion pumps and a 10⁸ NEG cartridge pumps generate vacuum. The average pressures are on the order of ·10^-7 Pa or less. The flange developed for C-band waveguide shows high reliability of vacuum seal.

TUPS013	Development of the H0 Dump Branch Duct for the Additional Collimation System in J-PARC RCS	septum, shielding, collimation, beam-losses	1545
	M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	For the new collimation system in the J-PARC RCS, we have the H0 branch duct installed at the dump septum magnet remodeled. This new branch duct is made of the two kinds of the stainless steels as follows; austenitic stainless steel, SUS316L and ferritic stainless steel, SUS430. In order to research on the property of the SUS430, test ducts were made in various heat-treating condition. In this presentation, we report the design of the new H0 branch duct and the study results with the test ducts.

TUPS014	Vacuum Performance Simulation of C-band Accelerating Structures	cavity, linac, simulation, free-electron-laser	1548
	H. Lee, M.-H. Cho, S.H. Kim, C.H. Yi POSTECH, Pohang, Kyungbuk, Republic of Korea W. Namkung, C.D. Park PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This work is partly supported by the MEST and POSTECH Physics BK21 program. A C-band accelerating structure has a higher accelerating gradient than that of the S-band structure. It provides a good advantage of a shorter machine length. In order to effectively use RF power and for cost reduction, the accelerating structure should be as long as possible. We propose a 2.2-m long structure compared to 1.8-m at SACLA (SPring-8 Angstrom Compact free electron LAser). However, a longer accelerating structure has worse vacuum performance than a shorter accelerating structure. Thus, the vacuum conductance of 2.2-m long structure has to be checked. We calculate vacuum performance of the accelerating structure by 1-D analytical method and 3-D finite element method (FEM). It is shown that the vacuum performance for the 2.2-m long accelerating structure is safe enough for the XFEL LINAC.

TUPS015	ALBA Storage Ring Vacuum System Commissioning	storage-ring, photon, cavity, synchrotron	1551
	E. Al-dmour, D. Einfeld CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	The ALBA booster and storage ring vacuum system installation has been done in 2009, followed by the installation of the RF cavities and the booster to storage transfer line in 2010. Early 2011, the first phase of insertion devices (ID) installation took place, with three narrow gap NEG coated vacuum chambers have been installed, for the use of two Apple-II undulators and one conventional wiggler. On 8th of March 2011, the storage ring commissioning started and it was marked with the achievement of the first turn in the storage ring on the 9th of March and on the 1st of April 2011, 100 mA of beam current has been accumulated. During this period the vacuum system conditioning took place with very good performance. The base pressure without beam was 4·10^-10 mbar and the average pressure with 100 mA was 7.7·10^-9 mbar. The results of the conditioning together with the latest developments are introduced.

TUPS016	Vacuum System Design for the MAX IV 3 GeV Ring	storage-ring, synchrotron, lattice, radiation	1554
	E. Al-dmour, D. Einfeld, J. Pasquaud, M. Quispe CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain J. Ahlbäck, M.J. Grabski, P.F. Tavares MAX-lab, Lund, Sweden
	We describe the conceptual design of the vacuum system of the 3 GeV electron storage ring in the MAX IV facility currently under construction in Lund, Sweden. The standard vacuum chambers are for the most part a cylindrical copper tube with 11 mm inner radius whereas stainless steel will be used at selected locations for beam position monitors, bellows and corrector vacuum chambers. In order to cope with the low vacuum conductance, distributed pumping will be provided through NEG coating of all chambers, including those in dipole magnets making MAX IV the first storage ring to be fully NEG coated. We present the mechanical and thermal design of these chambers and discuss the challenges involved in extracting insertion device radiation as well as coping with the heat load from both IDs and bending magnets in a machine with large bending radius, narrow chambers and tight mechanical tolerance requirements.

TUPS017	The LHC Experimental Beam Pipe Neon Venting, Pumping and Conditioning	injection, ion, monitoring, shielding	1557
	V. Baglin, G. Bregliozzi, D. Calegari, J.M. Jimenez, G. Lanza, G. Schneider CERN, Geneva, Switzerland
	The experimental vacuum chambers of the four LHC experiments (ATLAS, CMS, LHCb and ALICE) are mechanically optimized in order to be transparent to particles. In order to grant their mechanical stability and to avoid any overstress, every time there was a request for detector opening or closing and for working in the vicinity of the vacuum chamber, the experimental beam vacuum chambers have been vented to atmospheric pressure. Since the LHC start up a safety procedure has been applied to mechanically secure the four experimental beam pipes during each long technical stop. Ultra-pure neon was used to preserve at best the NEG pumping efficiency. Up to now more than 15 neon injections and pump down have been performed without detecting any reduction of the NEG efficiency. This paper describes the Gas Injection System performances and the main points of the venting and pumping procedure. Details of the experimental beam pipe vacuum recovery and conditioning are presented for each of the four LHC experiments (ATLAS, CMS, LHCb and ALICE).

TUPS018	Observations of Electron Cloud Effects with the LHC Vacuum System	electron, solenoid, simulation, ion	1560
	V. Baglin, G. Bregliozzi, P. Chiggiato, P. Cruikshank, B. Henrist, J.M. Jimenez, G. Lanza CERN, Geneva, Switzerland
	In autumn 2010, during the LHC beam commissioning, electron-cloud effects producing pressure rise in common and single vacuum beam pipes, were observed. To understand the potential limitations for future operation, dedicated machine studies were performed with beams of 50 and 75 ns bunch spacing at energy of 450 GeV. In order to push further the LHC performances, a scrubbing run was held in spring 2011. This paper summarizes the vacuum observations made during these periods. The effects of bunch intensity and different filling schemes on the vacuum levels are discussed. Simulations taking into account the effective pumping speed at the location of the vacuum gauge are introduced. As a consequence, the different vacuum levels observed along the LHC ring could be explained. Finally, the results obtained during the scrubbing run are shown together with an estimation of pressure profiles during the 2011 run.

TUPS019	Synchrotron Radiation in the LHC Vacuum System	photon, dipole, radiation, proton	1563
	V. Baglin, G. Bregliozzi, J.M. Jimenez, G. Lanza CERN, Geneva, Switzerland
	CERN is currently operating the Large Hadron Collider (LHC) with 3.5 TeV per beam. At this energy level, when the protons trajectory is bent, the protons emit synchrotron radiation (SR) with a critical energy of 5.5 eV. Under operation, SR induced molecular desorption is routinely observed in the LHC arcs, long straight sections and experiments. This contribution recalls the SR parameters over the LHC ring for the present and nominal beam parameters. Vacuum observations during energy ramp, after accumulation of dose and along the LHC ring are discussed. Expected pressure profiles and long term behaviours of vacuum levels will be also addressed.

TUPS020	Leak Tightness of LHC Cold Vacuum Systems	cryogenics, superconducting-magnet, controls, proton	1566
	P. Cruikshank, S.D. Claudet, W. Maan, L. Mourier, A. Perrier-Cornet, N. Provot CERN, Geneva, Switzerland
	The cold vacuum systems of the LHC machine have been in operation since 2008. While a number of acceptable helium leaks were known to exist prior to cooldown and have not significantly evolved over the last years, several new leaks have occurred which required immediate repair activities or mitigating solutions to permit operation of the LHC. The LHC vacuum system is described together with a summary and timetable of known air and helium leaks and their impact on the functioning of the cryogenic and vacuum systems. Where leaks have been investigated and repaired, the cause and failure mechanism is described. We elaborate the mitigating solutions that have been implemented to avoid degradation of known leaks and minimize their impact on cryogenic operation and LHC availability, and finally a recall of the consolidation program to be implemented in the next LHC shutdown.

TUPS021	Simulations and Vacuum Tests of a CLIC Accelerating Structure	simulation, cavity, ion, damping	1569
	C. Garion CERN, Geneva, Switzerland
	The Compact LInear Collider, under study, is based on room temperature high gradient structures. The vacuum specificities of these cavities are low conductance, large surface areas and a non-baked system. The main issue is to reach UHV conditions (typically 10^-7 Pa) in a system where the residual vacuum is driven by water outgassing. A finite element model based on an analogy thermal/vacuum has been built to estimate the vacuum profile in an accelerating structure. Vacuum tests are carried out in a dedicated set-up, the vacuum performances of different configurations are presented and compared with the predictions.

TUPS022	MedAustron Beam Vacuum System : From sources to Patient Treatment Rooms	synchrotron, instrumentation, ion, dipole	1572
	J.M. Jimenez, P. Cruikshank, L. Faisandel, W. Maan CERN, Geneva, Switzerland T. Hauser, G. Hulla, P. Landrot, J. Wallner EBG MedAustron, Wr. Neustadt, Austria
	The MedAustron beam vacuum system is a complex system integrating different technical solutions from the source to the patient treatment rooms. The specified vacuum performances combined with the challenging integration issues require technical compromise which will be presented in this poster. The status of the design of the vacuum system will be reviewed and the pending issues will be explained.

TUPS023	Secondary Electron Yield on Cryogenic Surfaces as a Function of Physisorbed Gases	electron, cryogenics, gun, insertion	1575
	A. Kuzucan, H. Neupert, M. Taborelli CERN, Geneva, Switzerland H. Stoeri IAP TUW, Wien, Austria
	Electron cloud is a serious limitation for the operation of particle accelerators with intense positively charged beams. It occurs if the secondary electron yield (SEY) of the beam-pipe surface is sufficiently high to induce an electron multiplication. At low surface temperatures, the SEY is strongly influenced by the nature of the physisorbed gases and by the corresponding surface coverage. These conditions occur in many accelerators operating with superconducting magnets and cold vacuum sections such as the LHC and RHIC. In this work, we investigated the variation of the SEY of copper, aluminium and electro-polished copper as a function of physisorbed N2, CO, CO2, CH4, Kr, C2H6 at cryogenic temperatures. The conditioning by electron bombardment of the surface after the physisorption of H2O on electro polished copper will also be presented. The results of the various gases are compared in order to find a rationale for the behaviour of the secondary electrons for the various adsorbates.

TUPS024	Development of Beryllium Vacuum Chamber Technology for the LHC	electron, collider, controls, background	1578
	R. Veness CERN, Geneva, Switzerland C. Dorn, G. Simmons Materion Electrofusion, Fremont, California, USA
	Beryllium is the material of choice for the beam vacuum chambers around collision points in particle colliders due to a combination of transparency to particles, high specific stiffness and compatibility with ultra-high vacuum. New requirements for these chambers in the LHC experiments have driven the development of new methods for the manufacture of beryllium chambers. This paper reviews the requirements for experimental vacuum chambers. It describes the new beryllium technology adopted for the LHC and experience gained in the manufacture and installation.

TUPS025	Design of a Highly Optimised Vacuum Chamber Support for the LHCb Experiment	radiation, background, interaction-region, collider	1581
	L. Leduc, G. Corti, R. Veness CERN, Geneva, Switzerland
	The beam vacuum chamber in the LHCb experimental area passes through the centre of a large aperture dipole magnet. The vacuum chamber and all its support systems lie in the acceptance of the detector, so must be highly optimised for transparency to particles. As part of the upgrade programme for the LHCb vacuum system, the support system has been re-designed using advanced lightweight materials. In this paper we discuss the physics motivation for the modifications, the criteria for the selection of materials and tests performed to qualify them for the particular environment of a particle physics experiment. We also present the design of the re-optimised support system.

TUPS026	Specification of New Vacuum Chambers for the LHC Experimental Interactions	alignment, impedance, injection, optics	1584
	R. Veness, R.W. Assmann, A. Ball, A. Behrens, C. Bracco, G. Bregliozzi, R. Bruce, H. Burkhardt, G. Corti, M.A. Gallilee, M. Giovannozzi, B. Goddard, D. Mergelkuhl, E. Métral, M. Nessi, W. Riegler, J. Wenninger CERN, Geneva, Switzerland N. Mounet, B. Salvant EPFL, Lausanne, Switzerland
	The apertures for the vacuum chambers at the interaction points inside the LHC experiments are key both to the safe operation of the LHC machine and to obtaining the best physics performance from the experiments. Following the successful startup of the LHC physics programme the ALICE, ATLAS and CMS experiments have launched projects to improve physics performance by adding detector layers closer to the beam. To achieve this they have requested smaller aperture vacuum chambers to be installed. The first periods of LHC operation have yielded much information both on the performance of the LHC and the stability and alignment of the experiments. In this paper, the new information relating to the aperture of these chambers is presented and a summary is made of analysis of parameters required to safely reduce the vacuum chambers apertures for the high-luminosity experiments ATLAS and CMS.

TUPS027	Characterization of Carbon Coatings with Low Secondary Electron Yield	electron, cryogenics, ion, gun	1587
	C. Yin Vallgren, S. Calatroni, P. Costa Pinto, A. Kuzucan, H. Neupert, M. Taborelli CERN, Geneva, Switzerland
	Amorphous carbon (a-C) coatings can reliably be produced with a maximum secondary electron yield (SEY) close to 1 at room temperature. Measurements at low temperature (LHe) are in progress. Analysis by X-ray Photoemission Spectroscopy (XPS) shows a correlation between the lineshape of C1s spectrum in XPS and maximum SEY of the investigated samples. The initial level of oxygen on the surface of the various samples does not seem to be related to the initial maximum SEY value. However, the increase of the SEY with air exposure time on each individual sample is related to the amount of oxygen containing adsorbates. Storage in different environments has been investigated (static vacuum, aluminum foil, dry nitrogen and desiccators) and shows significant differences in the “aging” behavior. Aging is very moderate when storing samples wrapped in aluminum foil in air. Samples which have undergone aging due to inappropriate storage can be recovered nearly to the initial value of the SEY by typical surface treatments as ion bombardment, annealing under vacuum and conditioning by electron beam. However, an enhanced sensitivity to air exposures is observed for most of these curing methods.

TUPS028	Performance of Carbon Coating for Mitigation of Electron Cloud in the SPS	electron, dipole, insertion, extraction	1590
	C. Yin Vallgren, P. Chiggiato, P. Costa Pinto, H. Neupert, G. Rumolo, E.N. Shaposhnikova, M. Taborelli CERN, Geneva, Switzerland
	Amorphous carbon (a-C) coatings have been tested in electron cloud monitors (ECM) in the Super Proton Synchrotron (SPS) and have shown for LHC type beams a reduction of the EC current by a factor 10⁴ compared to stainless steel (SS). This performance has been maintained for more than 2 years under SPS operation conditions. Secondary electron yield (SEY) laboratory data confirm that after 1 year of SPS operation, the coating maintains a SEY below 1. The compatibility of coexisting SS and a-C surfaces has been studied in an ECM having coated and uncoated areas. The results show no degradation of the properties of the a-C areas. The performance of diamond like carbon (DLC) coating has also been studied. DLC shows a less effective reduction of the EC current than a-C, but conditioning is faster than for SS. Three a-C coated dipoles were inserted in the SPS. However, even with no EC detected, the dynamic pressure rise is similar to the one observed in the SS reference dipoles. Measurement in a new ECM equipped with clearing electrodes to verify the relation between pressure signals and intensity of the EC, as well as an improvement of the diagnostics in the dipoles are in progress.

TUPS029	Development of a Feedthrough with Small Reflection for the TPS BPM	impedance, synchrotron, controls	1593
	Huang, Y.T. Huang, C.-C. Chang, C.L. Chen, G.-Y. Hsiung, S-N. Hsu, H.P. Hsueh NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	The TPS BPM feedthrough is a coaxial cable with a structure of a kind for which power loss occurs readily at places at which exists an impedance mismatch. With an impedance equation for a simple coaxial cable combined with a multi-dielectric modification, a model feedthrough with small reflection has been designed. With careful setting of brazing conditions and precise control of the dimensions of devices, a TPS prototypical BPM feedthrough having a reflection coefficient less than 0.05 was manufactured. The eccentricity was constrained within 0.03 mm, and the deviation of measured capacitance of button electrodes was less than 7 %.

TUPS030	Manufacturing and Vacuum Testing of Aluminum Bending Chambers for TPS	ion, photon, synchrotron, electron	1596
	Y.C. Yang, C.K. Chan, C.-C. Chang, C.L. Chen, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu, T.Y. Lee NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) is an aluminum alloy vacuum system with 518.4 m circumference divided into 24 sections. A6061T6 aluminum alloy material is used for TPS bending chambers. Each aluminum bending chamber is component of 2 half plates, about 3.5～4.2 m in length and～0.6 m in width, were oil-free CNC machined, ozone cleaned, and TIG welding in clean room. The deformation < 0.1 mm and leakage rate < 2x10-9mbar. L/s for each welded bending chamber has inspected and achieved. A bending chamber is inspecting the thermal outgassing rate test and ultimate pressure. The manufacturing and vacuum test will be described in this paper.

TUPS031	The Installation of One 14 Meter Cell of TPS Vacuum System	photon, laser, synchrotron, site	1599
	H.P. Hsueh, C.K. Chan, C.H. Chang, C.-C. Chang, C.L. Chen, C.M. Cheng, Y.T. Cheng, G.-Y. Hsiung, S-N. Hsu, I.T. Huang, T.Y. Lee, H.Y. Yan, Y.C. Yang, C.S. huang NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	The construction of a new 3 GeV synchrotron facility, Taiwan Photon Source, is ongoing. The vacuum system has been designed with off-site baking for arc section from sector gate valve to sector gate valve. There is no flange used in this arc section besides the two ends connected to sector gate valves. It is a tedious works for install such long vacuum system with aluminum chambers. In this poster, all the detailed installation procedures will be described. All the precaution inspection procedures for all vacuum components to prevent failed components to be installed will also be described. Every three weeks, one cell will be assembled and stored. Experience is being learned and could be used for the vacuum system of future new accelerator like FEL and others.

TUPS033	Foil Scattering Loss Mitigation by the Additional Collimation System of J-PARC RCS	injection, collimation, septum, scattering	1605
	K. Yamamoto, H. Harada, J. Kamiya, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In the RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. From the beam study, we were certain that these losses were caused by the scattering of the injection and circulating beam at the charge exchange injection foil. In order to mitigate these losses, we started to develop a new collimation system in the H0 branch duct. We presents a overview of this new collimation system.

TUPS038	Design of a Beam Dump for 3 to 100 MeV for the New H⁻ Beam in the CERN Linac4	linac, proton, radiation, ion	1620
	C. Maglioni CERN, Geneva, Switzerland
	In this paper the design of a beam dump for the energy range from 3 to 100 MeV is reported. The dump is developed as temporary dump for the commissioning phase of the Linac4 Project, under construction at CERN, and will be installed in different periods to withstand a beam of different intensities and energies, following the chronological assembly of the linac. The dump design and its functionalities, as well as material choice, criticalities and cooling system are described. Finally, the results from the numerical and analytical thermo-mechanical analyses are reported, while the use of the dump also at 160 MeV is investigated.

TUPS051	Design and Performance of the MICE Target*	target, controls, acceleration, extraction	1644
	C.N. Booth, P. Hodgson, E. Overton, M. Robinson, P.J. Smith Sheffield University, Sheffield, United Kingdom G.J. Barber, K.R. Long Imperial College of Science and Technology, Department of Physics, London, United Kingdom E.G. Capocci, J.S. Tarrant STFC/RAL, Chilton, Didcot, Oxon, United Kingdom B.J.A. Shepherd STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: UK Science and Technology Facilities Council The MICE experiment uses a beam of low energy muons to study ionisation cooling. This beam is derived parasitically from the ISIS synchrotron at the Rutherford Appleton Laboratory. A mechanical drive has been developed which rapidly inserts a small titanium target into the beam after acceleration and before extraction, with minimal disturbance to the circulating protons. One mechanism has operated in ISIS for over half a million pulses, and its performance will be summarised. Upgrades to this design have been tested in parallel with MICE operation; the improvements in performance and reliability will be presented, together with a discussion of further future enhancements.

TUPS058	HiRadMat: A New Irradiation Facility for Material Testing at CERN	proton, target, ion, radiation	1665
	I. Efthymiopoulos, S. Evrard, H. Gaillard, D. Grenier, C. Heßler, M. Meddahi, A. Pardons, C. Theis, P. Trilhe, H. Vincke CERN, Geneva, Switzerland N. Charitonidis EPFL, Lausanne, Switzerland
	HiRadMat (High Irradiation to Materials) is a new facility under construction at CERN designed to provide high-intensity pulsed beams to an irradiation area where material samples as well as accelerator component assemblies can be tested. The facility uses a 440 GeV proton beam extracted from the CERN SPS with a pulse length of 7.2 μs, to a maximum pulse energy of 3.4 MJ. In addition to protons, ion beams with an energy of 173.5 GeV/nucleon and a total pulse energy of 21 kJ can be used. The facility is expected to become operational in autumn 2011. The first tests will include candidate materials and prototype assemblies of LHC collimators foreseen to operate at the ultimate LHC beam powers. Experiments on beam windows and high-power target material options, such as tungsten powder, are also planned. The paper will describe the layout and design parameters for the facility and the way experiments can be operated. Ideas on online and post-irradiation tests and instrumentation will be outlined.

TUPS066	Design of Front End Safety Interlock System for Taiwan Photon Source	controls, photon, radiation, status	1689
	H.Y. Yan, J.-R. Chen, G.-Y. Hsiung, C.K. Kuan, I.C. Sheng, Z.-D. Tsai NSRRC, Hsinchu, Taiwan
	Safety interlock is one of critical subsystems in synchrotron radiation accelerator. A front end (FE) interlock prototype system has been designed, fabricated, and initially tested for Taiwan Photon Source (TPS). TPS FE interlock logic is designed based on that of Taiwan Light Source (TLS), and moderately modified due to the accelerator parameter discrepancy between TPS and TLS. The programmable automation controllers (PAC) have been utilized in FE safety interlock system for their reliability, convenience, processing capability, communication, and stability in user interface. In FE PAC system, touch panels are used as the graphical user interface (GUI) to control and monitor FE components. In addition, with GUI control it is used to beam position monitoring devices as well as confined beam sizes aperture for beam line users. The interlock design such as data acquisition and parameters monitoring for vacuum pressure, flow rate of cooling water, pressure of compressive air, chamber and water temperature, and overall interlock logic are also presented in this paper.

TUPS067	Photon-stimulated Desorption Experiment for a TPS Crotch Absorber	synchrotron, photon, simulation, radiation	1692
	Y.T. Cheng, G.-Y. Hsiung, C.K. Kuan, A. Sheng, H.Y. Yan NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	National Synchrotron Radiation Research Center (NSRRC) is constructing a large third-generation synchrotron accelerator in Taiwan, the so-called Taiwan Photon Source (TPS). This 3-GeV, 500-mA machine will generate high-density bending-magnet radiation, of which 90 % of the power is absorbed by the crotch absorber in the storage ring. To understand better the beam-cleaning and photon-desorption phenomena of a copper crotch absorber, we have performed a PSD (photon-stimulated desorption) test in Taiwan Light Source (TLS) at Beam line 19 (BL19). Some mathematical modelling, experimental designs and results are also presented here.

TUPS079	Construction of a Novel Compact High Voltage Electrostatic Accelerator	high-voltage, target, ion, ion-source	1722
	P. Beasley, O. Heid Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany
	A compact demonstrator system based on a Cockcroft-Walton (or Greinacher) cascade has been successfully built and tested. The concept has been developed using modern materials and a different design philosophy, which in turn can then enable this novel configuration to operate at much higher voltage gradients. This paper explores the progress made over the past 18 months and future plans to utilise the technology to develop one such concept for an energy efficient 10MV, 100μA, tandem proton accelerator, with a <2m2 footprint. The development of such a compact high voltage particle accelerator, with high current capability has the potential to access a wide range of commercial opportunities outside the laboratory.

TUPS082	The LEBT Chopper for the Spiral 2 Project	controls, ion, high-voltage, target	1731
	A.C. Caruso, F. Consoli, G. Gallo, D. Rifuggiato, E. Zappalà INFN/LNS, Catania, Italy M. Di Giacomo GANIL, Caen, France A. Longhitano ALTEK, San Gregorio (CATANIA), Italy
	The Spiral 2 driver uses a slow chopper situated in the common section of the low energy beam transport line to change the beam intensity, to cut off the beam in case of critical loss and to avoid hitting the wheel structure of rotating targets. The device has to work up to 10 kV, 1 kHz repetition frequency rate and its design is based on standard power circuits, custom alarm board and vacuum feed-through. The paper summarizes the design principles and describes the test results of the final device which has been installed on the beam line test bench.

TUPS086	Ultra-high Resolution Observation Device for Carbon Stripper Foil	radiation, monitoring, scattering, proton	1740
	Y. Takeda, Y. Irie, I. Sugai KEK, Ibaraki, Japan
	To observe a growth process of a pinhole on a HBC-foil due to beam irradiation, an up to 10 um of device for ultra-high resolution observation is needed. For the environment where we use the device for observation is so severe as under high radiation and in vacuum, there is no device available for long-time observation. Then, we designed and created a wholly new method based system which enables constant observation by ultra-high resolution even under high radiation environment. We attempted several experiments, compared materials usable under radiation environment, checked up various optical systems which enables high resolution, and finally developed the best method. As a result, we successfully invented an ultra-high resolution observation device available for monitoring an object about 8 meters distant by 8.3um resolution.

TUPS088	Charge Stripping of Uranium-238 Ion Beam with Low-Z Gas Stripper	cyclotron, target, ion, acceleration	1746
	H. Imao RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan N. Fukunishi, A. Goto, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, H. Okuno, T. Watanabe, Y. Yano, S. Yokouchi RIKEN Nishina Center, Wako, Japan
	One of the primary goals of the RIKEN RI beam factory is to generate unprecedented high-power uranium beams (up to tens kW), which yield an enormous breakthrough for exploring new domains of the nuclear chart. The development of reliable and efficient charge stripping scheme for such high-power beams is a key unsolved issue, affecting the overall performance of the heavy ion accelerations. A charge stripper using low-Z (low atomic number Z) gas is an important candidate. Because of the suppression of the electron capture process, the high equilibrium mean charge states for the low-Z gas stripper are expected in conjunction with the intrinsic robustness of the gas. There was, however, no direct experimental data of the charge evolution, because of the difficulty in making massive windowless low-Z gas targets. In the present work, the charge evolution of the 238U beams injected at 10.75 MeV/u were investigated using thick hydrogen and helium gas strippers with huge differential pumping system newly developed. In the energy region of interest, near 10 MeV/u, achievable mean charge states around 65+ with the low-Z gas strippers are far superior to those of the medium-Z ones around 55+.

TUPS092	Research of Thermal Deformation on a Compact Cyclotron CYCHU-10	cavity, cyclotron, impedance, radio-frequency	1753
	K.F. Liu HUST, Wuhan, People's Republic of China
	Nowadays, a cyclotron CYCHU-10 used for PET is under construction in Huazhong University of Science and Technology (HUST) due to the growing demands in medical applications. For space-saving and low energy consumption, the CYCHU-10 was designed compactly and accurately, especially for the RF cavity consists of the valley of the magnetic pole and the dee electrodes installed on the vacuum chamber. The RF system will supply a 10kw power and large part of it will transform into thermal energy. This paper will introduce the thermal deformation of the RF cavity and the main vacuum chamber. Meanwhile the finite elements analysis thermal deformation with ANSYS Products will be present. Finally, the cooling system for the RF cavity will be carefully designed due to the result of thermo analysis and the mechanical tolerance demand in the RF system. Keywords- thermal deformation; mechanical tolerance; FEA;RF power.

TUPS097	In-situ Experiments of Vacuum Discharge using Scanning Electron Microscopes	electron, ion, site, high-voltage	1765
	T. Muranaka, V.G. Ziemann Uppsala University, Uppsala, Sweden T. Blom, K. Leifer Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
	Funding: This work is supported by the 7th European Framework Program EuCARD under grant number 227579 Fundamental understandings of vacuum discharge mechanisms and involving surface damage is an indispensable for CLIC feasibility study. We have been conducting dc experiments inside a Scanning Electron Microscope (SEM) at Uppsala university in order to investigate localised breakdown phenomena. By using a SEM, we achieve the resolution of the electron probe in the few-nm range, which is of great advantage as the surface roughness of the polished accelerating structures is in the same scale. The high accelerating field of 1 GV/m is realised by biasing an electrode with 1 kV set above the sample with a gap of sub μm. Furthermore, a second SEM equipped with a Focused Ion Beam (FIB) is used to modify the topography of sample surfaces thus the geometrical dependence of field emissions and vacuum discharges could be studied. The FIB can be used for the surface damage analysis as well. We have demonstrated subsurface damage observations by using FIB to sputter a rectangular recess into the sample in the breakdown region. Those powerful surface analysis techniques can be productively applied to the study of fatigue in prototype accelerating structures.

TUPS099	A Study of the Surface Quality of High Purity Copper after Heat Treatment	electron, damping, linear-collider, collider	1771
	M. Aicheler, G. Arnau-Izquierdo, S. Atieh, S. Calatroni, S. Lebet, G. Riddone, A. Samoshkin CERN, Geneva, Switzerland
	The manufacturing flow of accelerating structures for the compact linear collider, based on diamond-machined high purity copper components, include several thermal cycles (diffusion bonding, brazing of cooling circuits, baking in vacuum, etc.). The high temperature cycles may be carried out following different schedules and environments (vacuum, reducing hydrogen atmosphere, argon, etc.) and develop peculiar surface topographies which have been the object of extended observations. This study presents and discusses the results of scanning electron microscopy (SEM) and optical microscopy investigations.

TUPS100	Manufacturing the Linac4 PI-mode Structure Prototype at CERN	cavity, linac, alignment, controls	1774
	G. Favre, A. Cherif, A. Dallocchio, J.-M. Geisser, L. Gentini, F. Gerigk, S.J. Mathot, M. Polini, S. Sgobba, T. Tardy, R. Wegner CERN, Geneva, Switzerland
	The PI-Mode Structure (PIMS) of Linac4 consists of 7-cell cavities made from alternating OFE copper discs and rings welded together with electron beam (EB) welding. A full-scale prototype cavity of almost 1.5 m in length has been manufactured, assembled, and tested at CERN to prepare the series production of 12 PIMS cavities as part of an international collaboration. This paper reports on the construction experience including machining operations, EB welding, vacuum brazing, and metrological measurements results.

TUPS103	High Temperature Radio Frequency Loads	simulation, coupling, instrumentation, impedance	1783
	S. Federmann, F. Caspers, A. Grudiev, E. Montesinos, I. Syratchev CERN, Geneva, Switzerland
	In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet with 150 deg C and more than 20 bar has a certain value. Normal RF power loads containing dielectric and sensitive windows usually do not permit going much higher than 50 deg C. Here we present and discuss several design concepts for narrow-band “metal only” RF high power loads. One concept is the application of normal steel corrugated waveguides structures near cutoff .This concept could find practical use above several GHz. Another solution are resonant structures made of normal magnetic steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage the rather high losses of normal steel may also be used in coaxial line geometries with large dimensions.

TUPZ003	Simulation of Electron-cloud Build-Up for the Cold Arcs of the LHC and Comparison with Measured Data	electron, simulation, dipole, injection	1801
	G.H.I. Maury Cuna CINVESTAV, Mérida, Mexico G. Arduini, G. Rumolo, L.J. Tavian, F. Zimmermann CERN, Geneva, Switzerland
	The electron cloud generated by synchrotron radiation or residual gas ionization is a concern for LHC operation and performance. We report the results of simulations studies which examine the electron cloud build-up, at injection energy, 3.5 TeV for various operation parameters In particular we determine the value of the secondary emission yield corresponding to the multipacting threshold, and investigate the electron density, and heat as a function of bunch intensity for dipoles and field-free regions. We also include a comparison between simulations results and measured heat-load data from the LHC scrubbing runs in 2011

TUPZ015	Electron Cloud Parameterization Studies in the LHC	electron, simulation, emittance, beam-losses	1834
	C.O. Domínguez, G. Arduini, V. Baglin, G. Bregliozzi, J.M. Jimenez, E. Métral, G. Rumolo, D. Schulte, F. Zimmermann CERN, Geneva, Switzerland
	During LHC beam commissioning with 150, 75 and 50-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed. The main strategy to combat the LHC electron cloud relies on the surface conditioning arising from the chamber-surface bombardment with cloud electrons. In a standard model, the conditioning state of the beam-pipe surface is characterized by three parameters: 1. the secondary emission yield; 2. the incident electron energy at which the yield is maximum; and 3. the probability of elastic reflection of low-energy primary electrons hitting the chamber wall. Since at the LHC no in-situ secondary-yield measurements are available, we compare the relative local pressure-rise measurements taken for different beam configurations against simulations in which surface parameters are scanned. This benchmark of measurements and these simulations is used to infer the secondary-emission properties of the beam-pipe at different locations around the ring and at various stages of the surface conditioning. In this paper we present the methodology and first results from applying the technique to the LHC.

TUPZ020	Fill Analysis and Experimental Background Observations in the LHC	background, luminosity, extraction, monitoring	1846
	Y.I. Levinsen, H. Burkhardt, A. Macpherson, M. Pereira, S.X. Roe CERN, Geneva, Switzerland
	Funding: Presenting author funded by the University of Oslo In this work we look at experimental background under different conditions for the early 2011 running. We will discuss the observations in the context of the residual gas pressure, beam halo, and cross-talk between experiments. We have developed a modular fill analysis tool which automatically extracts data and analyses each fill in the LHC. All generated and extracted information is stored for outside use. The tool is applied to aid us in the work presented here.

TUPZ031	Near Beam-gas Backgrounds for LHCb at 3.5 TeV	proton, simulation, background, hadron	1876
	D.R. Brett, R. Appleby UMAN, Manchester, United Kingdom F. Alessio, G. Corti, R. Jacobsson CERN, Geneva, Switzerland M.H. Lieng UNIDO, Dortmund, Germany V. Talanov IHEP Protvino, Protvino, Moscow Region, Russia
	Funding: STFC We consider the machine induced backgrounds for LHCb arising from collisions of the beam with residual gas in the long straight sections of the LHC close to the experiment. We concentrate on the background particle fluxes initiated by inelastic beam-gas interactions with a direct line of sight to the experiment, with the potential impact on the experiment increasing for larger beam currents and changing gas pressures. In this paper we calculate the background rates for parameters foreseen with LHC running in 2011, using realistic residual pressure profiles. We also discuss the effect of using a pressure profile formulated in terms of equivalent hydrogen, through weighting of other residual gases by their cross section, upon the radial fluxes from the machine and the detector response. We present the expected rates and the error introduced through this approximation.

WEOBB03	Electron Bunch Profile Diagnostics in the Few fs Regime using Coherent Smith-Purcell Radiation	radiation, electron, diagnostics, linac	1970
	N. Delerue LAL, Orsay, France R. Bartolini, G. Doucas, K. Pattle, C. Perry, A. Reichold, R. Tovey JAI, Oxford, United Kingdom
	Funding: John Fell Fund, University of Oxford The rapid developments in the field of laser-driven particle acceleration hold the prospect of intense, highly relativistic electron bunches that are only a few fs long. The determination of the temporal profile of such a bunch presents new challenges. The use of a radiative process such as Smith-Purcell radiation (SPR), whereby the beam is made to radiate a small amount of e/m radiation and the temporal profile is then reconstructed from the measured spectral distribution of the radiation, is particularly promising in this respect. We summarize the advantages of SPR and present the design parameters of a forthcoming experiment at the FACET facility at SLAC with bunch lengths of the order of 60fs rms. We also discuss a new approach to the problem of the recovery of the ‘missing phase’, which is essential for the accurate reconstruction of the bunch profile.
	Slides WEOBB03 [4.627 MB]

WEIB04	Accelertor-based Mega-science Projects in China and Their Impact on Economy	linac, ion, electron, radiation	1986
	C. Zhang IHEP Beijing, Beijing, People's Republic of China
	Along with the rapid development of national economy in China, a number of accelerator based mega-science projects were constructed, such as the Beijing Electron-Positron Colliders (BEPC) and its major upgrade project (BEPCII), the Hefei Light Source (HLS), the Heavy Ion Research Facility in Lanzhou (HIRFL) and its Cooling Storage Rings (HIEFL-CSR), the Shanghai Synchrotron Radiation Facility (SSRF) and the Dragon-I induction linac. The Beijing Radioactive Ion Facility (BRIF) and the China Spallation Neutron Source (CSNS) are under construction. In this paper, China’s accelerator projects are briefly reviewed and applications of accelerators are reported. The paper emphasizes spinoff of the accelerator technology developed during R&D and construction of the projects. Collaboration between academia and industry on the projects are described. With some examples, the benefits experienced in the laboratory-industry collaboration and approach of its economic impact are illustrated.
	Slides WEIB04 [14.012 MB]

WEPC050	New Optics for the SOLEIL Storage Ring	optics, injection, coupling, undulator	2124
	P. Brunelle, F. Briquez, A. Loulergue, O. Marcouillé, A. Nadji, L.S. Nadolski, M.-A. Tordeux, J.F. Zhang SOLEIL, Gif-sur-Yvette, France
	SOLEIL, the French 2.75GeV synchrotron light source is delivering photons to 24 beam lines and is presently equipped with 22 insertion devices (ID) including a high field and small gap in-vacuum wiggler. This paper presents the continuous work performed to reduce the strong non linear effects of several IDs. On one side, the ID defaults have been precisely identified using on-beam measurements, and magnetic correction developments are going on, especially for the in-vacuum wiggler and for the 10m long HU640 undulator. On the other side, a new optics has been optimised in terms of beta-functions (at the ID location) and non linear dynamics in order to improve the injection efficiency and the beam lifetime in the presence of IDs. The modified optics has been used daily in operation since November 2010 and ensures a beam lifetime greater than 10h for a 400mA stored beam with the users ID configuration. In parallel, an extensive experimental optimization has been performed to prepare the operation with an additional quadrupole triplet that provides double low vertical beta functions in one long straight section that will accommodate two canted in-vacuum insertion devices. O. Marcouillé et al., IPAC10, p. 3102 (2010). ** A. Loulergue et al., IPAC10, p. 2496 (2010).

WEPC065	Design of a Low Energy Ion Beam Facility*	ion, antiproton, injection, quadrupole	2169
	M.R.F. Siggel-King, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom O. Karamyshev JINR/DLNP, Dubna, Moscow region, Russia G.A. Karamysheva MPI-K, Heidelberg, Germany A.I. Papash JINR, Dubna, Moscow Region, Russia M.R.F. Siggel-King The University of Liverpool, Liverpool, United Kingdom
	Funding: Work supported by STFC, the EU under GA-PITN-215080, the Helmholtz Association and GSI under VH-NG-328. A small electrostatic ring, and associated electrostatic injection beamlines, are being designed and developed. The ring will make possible a variety of experiments using a choice of many types of recirculating ions (e.g., from protons, H-, and antiprotons up to and including large charged biomolecules). A reaction microscope will be incorporated into the ring to enable differential ionization experiments between the recirculating ion beam and gas jet targets. Two injection sections have been designed to cover a variety of ion sources. The facility will be portable to enable it to be moved between facilities and beamlines and it will be unique due to its combination of design elements, flexible beam properties, energy (ca 3-30 keV) and type of circulating particles. In this paper, we give an update on this project.

WEPC106	Touschek Effect at DAΦNE for the New KLOE Run in the Crab-Waist Scheme	background, simulation, scattering, lattice	2262
	M. Boscolo, P. Raimondi INFN/LNF, Frascati (Roma), Italy E. Paoloni University of Pisa and INFN, Pisa, Italy A. Perez INFN-Pisa, Pisa, Italy
	Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11) The innovative crab-waist collision scheme has been recently implemented at DAΦNE for a new KLOE run. This scheme requires special attention to the Touschek effect, both for the lifetime and the machine induced backgrounds into the detector. These two aspects have been handled starting from the same Monte Carlo simulation. The DAΦNE optical model has been tuned to keep the effects of Touschek scattering under control with a trade-off between critical parameters, following the indications given by simulations. Connections between numerical results and lattice modifications are discussed here. Dedicated lifetime measurements have been carried out to validate these studies. Particle losses at the IR have been minimized by means of the same optical knobs, but in addition proper shieldings have been implemented to further decrease their impact on the detector performance. IR distributions of the Touschek particle losses have been tracked from the beam pipe into KLOE for direct comparison of measured and expected backgrounds. Moreover, these studies are carried out with the same software tools used for the SuperB factory design, allowing a direct validation test of this approach.

WEPC108	CSR Impedance for an Ultrarelativistic Beam moving in a Curved Trajectory	impedance, shielding, resonance, radiation	2268
	D.M. Zhou, K. Ohmi, K. Oide KEK, Ibaraki, Japan

Paper

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Other Keywords

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MOXBA01

J-PARC Beam Commissioning Progress

beam-losses, injection, linac, extraction

6

H. Hotchi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The J-PARC is a multi-purpose proton accelerator facility amiming at MW-class output beam power, consisting of a 400 MeV H⁻ linac, a 3-GeV RCS, a 50-GeV MR (Main Ring) and three experimental facilities, the MLF (materials and life science experimental facility), the HD (hadron experimental hall) and the NU (neutrino beam line). The J-PARC beam commissioning started in November 2006 from the linac to the downstream facilities. The current output beam power from the RCS to the MLF users is 210 kW, and the MR delivers 145 kW beam to the NU by fast extraction and a few kW beam to the HD by slow extraction. In this talk, we present a current status of the J-PARC beam commissioning, in which a recent progress in the course of the RCS beam power ramp-up scenario will be described in more detail. This talk will focus on the issues (including beam dynamics), challenges, solutions, and lessons learned during the commissioning and user operation of J-PARC and future plans.

Slides MOXBA01 [2.615 MB]

MOPC004

352.2 MHz HOM Damped Normal Conducting ESRF Cavity: Design and Fabrication

cavity, HOM, coupling, storage-ring

68

V. Serrière, A.K. Bandyopadhyay, D. Boilot, L. Goirand, J. Jacob, B. Ogier, A. Triantafyllou
ESRF, Grenoble, France

Funding: This work, carried out within the framework of the ESRFUP project, has received research funding from the EU Seventh Framework Programme, FP7.
The ongoing ESRF upgrade included an option for an increase of the storage ring current from 200 to 300 mA, which has been tested successfully with the existing RF system. At this current level the HOM tuning of the existing five-cell copper cavities becomes extremely delicate and in view of a future reliable operation in user mode, new HOM free normal conducting cavities were developed at the ESRF. The design is based on the existing BESSY/ALBA cavity. However, several substantial modifications have been implemented and different fabrication processes elaborated to improve the design. Three operational prototypes will be delivered by three manufacturers in the coming months and will be fully tested on the ring. Although the 300 mA option has finally not been retained for the first phase of the ESRF upgrade, the aim is now to validate the new cavity design for a possible later increase in current.

MOPC007

Cold Photocathode RF Gun

cavity, gun, cathode, cryogenics

77

V. Vogel, K. Flöttmann, S. Schreiber
DESY, Hamburg, Germany

Heating and thermal expansion in the normal conductivity RF-photo electron gun, are the main limitations to achieve high accelerating gradient and consequently a low emittance beam. Some pure materials show a significant increase in thermal conductivity with a small coefficient of temperature expansion at temperatures around 20 degrees Kelvin. Possible materials are Molybdenum, Iridium or Tungsten. However, machining of these materials is very difficult. Therefore we propose a simplified shape for an L-band RF gun. We expect to achieve a significant increase in gradient for similar RF powers as used in the present DESY RF-gun. On the other hand, it would also be possible to increase the duty cycle keeping a moderate gradient. In this report we discuss one possible design of an RF-gun using hard metals and present simulations on thermal properties.

MOPC012

Fabrication of the CERN/PSI/ST X-band Accelerating Structures

wakefield, alignment, FEL, coupling

86

M.M. Dehler, A. Citterio, R. Zennaro
PSI, Villigen, Switzerland
S. Atieh, D. Gudkov, S. Lebet, G. Riddone, J. Shi
CERN, Geneva, Switzerland
G. D'Auria, C. Serpico
ELETTRA, Basovizza, Italy

Within a collaboration between CERN, PSI and Sincrotrone Trieste (ST), a multi- purpose X-band accelerating structure has been designed and fabricated, used for high gradients tests in the CLIC structure testing program and in the FEL projects of PSI and ST. The structure has 72 cells with a phase advance of 5 pi/6 and includes upstream and downstream wakefield monitors to measure the beam alignment. The SLAC mode launcher design is used to feed it with RF power. Following the CERN fabrication procedures for high-gradient structure, diffusion bonding and brazing in hydrogen atmosphere is used to assemble the cells. After tuning, a vacuum bakeout is required before the feedthroughs for the wake field monitors are welded in as a last step. We describe the experiences gained in finishing the first two structures out of a series of four and present the results from the RF tuning and low level RF tests.

MOPC015

S-band Vacuum Isolator and Circulator for Injector System of SPring-8 Linac

linac, cavity, insertion, injection

95

T. Taniuchi, H. Hanaki, S. Suzuki
JASRI/SPring-8, Hyogo-ken, Japan
A. Miura, K. Shinohara, S. Tsuruoka
Nihon Koshuha Co. Ltd, Yokohama, Japan

A pressurized sulfur hexafluoride (SF6) waveguide system at an injector section of SPring-8 linac, will be replaced with a vacuum waveguide system in order to renew aged equipments and improve a phase stability. For this renewal, RF isolator and a circulator operated in vacuum, are newly developed. High power RF test for these components were performed and a good result for RF and vacuum characteristics were obtained.

MOPC024

Construction Status of the CPHS RFQ at Tsinghua University

rfq, quadrupole, dipole, cavity

122

Q.Z. Xing, Y.J. Bai, J.C. Cai, C. Cheng, L. Du, T. Du, X. Guan, Q. Qiang, X.W. Wang, Z.F. Xiong, S.Y. Yang, H.Y. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China
J.H. Billen
TechSource, Santa Fe, New Mexico, USA
W.Q. Guan, Y. He, J. Li
NUCTECH, Beijing, People's Republic of China
J. Stovall
CERN, Geneva, Switzerland
L.M. Young
AES, Medford, NY, USA

Funding: Work supported by the “985 Project” of the Ministry of Education of China.
We present, in this paper, the construction status of a Radio Frequency Quadrupole (RFQ) accelerator for the Compact Pulsed Hadron Source (CPHS) at Tsinghua University. The 3-meter-long RFQ will deliver 3 MeV protons to the downstream Drift Tube Linac (DTL) with the peak current of 50 mA, pulse length of 0.5 ms and beam duty factor of 2.5%. The RFQ has been mechanically separated into three sections. A ball-end mill, instead of a forming cutter, is adopted to machine the vane tip due to its varying radius of curvature. The precision of the numerically controlled milling machine has been verified by machining test pieces of aluminum and copper. Fine machining of the vanes was completed in July, 2011. The pre-braze tuning was completed at the beginning of this August.

MOPC030

The C-band Traveling-wave Accelerating Structure for Compact XFEL at SINAP*

linac, controls, impedance, status

133

W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D.C. Tong
TUB, Beijing, People's Republic of China

The R&D of C-band accelerating structure has been launched two years ago at Shanghai Institute of Applied Physics, it will be used for the future compact hard X-ray FEL. The 1st C-band traveling-wave accelerating structure is ready for the high power test now. This structure is the preliminary model for the research of the technology of microwave test and tuning, arts and crafts and high power test. This paper presents the process of fabrication, cold test and tuning results.

MOPC035

Design and Machine Features of 2.2-m C-band Accelerating Structure

cavity, accelerating-gradient, linac, electron

148

C.H. Yi, M.-H. Cho, S.H. Kim, H. Lee
POSTECH, Pohang, Kyungbuk, Republic of Korea
W. Namkung
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work is partly supported by the MEST, Korea and POSTECH BK21 Program. And this work was supported by the Korea Student Aid Foundation (KOSAF) grant funded by the Korea government.
A compact linac system is designed using a longer accelerating column in a C-band linac. It reduces the total number of RF units for the given linac beam energy and results in the cost-effective use of RF powers. For the 10 GeV PAL-XFEL project, a C-band accelerating column of 2.2-m long is investigated, which is 22% longer than 1.8-m for the SACLA at SPring-8. The detailed RF and thermal characteristics are presented by an analytic model.

MOPC037

Engineering Design and Fabrication of X-band Damped Detuned Structure for the CLIC Study

damping, alignment, controls, wakefield

154

V. Soldatov, D. Gudkov, A. Samoshkin
JINR, Dubna, Moscow Region, Russia
S. Atieh, A. D'Elia, A. Grudiev, G. Riddone
CERN, Geneva, Switzerland
R.M. Jones, V.F. Khan
UMAN, Manchester, United Kingdom

A Damped Detuned Structure (DDS), known as CLIC_DDS_A*, has been designed for the Compact Linear Collider (CLIC) study, and is presently under fabrication. The wakefield in DDS structures is damped using a combination of detuning the frequencies of beam-excited higher order modes and by light damping, through slot-coupled manifolds. The broad principles of the design are similar to that used in the NLC/GLC**. This serves as an alternative to the present baseline CLIC design which relies on heavy damping. CLIC_DDS_A is conceived to be tested for its capacity to sustain high gradients at CERN. This structure operates with a 120 degrees phase advance per cell. We report on engineering design and fabrication details of the structure consisting of 24 regular cells plus 2 matching cells at both ends, all diffusion bonded together. This design takes into account practical mechanical engineering issues and is the result of several optimizations since the earlier CLIC_DDS designs.
* V. F. Khan et al., “Recent Progress on a Manifold Damped and Detuned Structure for CLIC”, Proc. of IPAC10, WEPE032, p. 3425 (2010).
** R.M. Jones et al., Phys. Rev. STAB 9, 102001 (2006).

MOPC038

Engineering Design and Fabrication of Tapered Damped X-band Accelerating Structures

damping, wakefield, alignment, HOM

157

A. Solodko, D. Gudkov, A. Samoshkin
JINR, Dubna, Moscow Region, Russia
S. Atieh, A. Grudiev, G. Riddone, M. Taborelli
CERN, Geneva, Switzerland

The accelerating structures (AS) are one of the main components of the Compact LInear Collider (CLIC), under study at CERN. Each AS contains about 30 copper disks, which form the accelerating cavity. A fully featured AS is very challenging and requires several technologies. Different damping methods, waveguides, vacuum manifolds, slots and choke, result in various design configurations. In the CLIC multibunch AS, called TDS (Tapered Damped Structure), each cell is damped by its four waveguides, which are extended by channels machined in dedicated external vacuum manifolds. The manifolds combine few functions such as damping, vacuum pumping and cooling. Silicon carbide absorbers, fixed inside of each manifold, are required for effective damping of High Order Modes. CERN is producing X-band RF structures in close collaboration with a large number of laboratories taking advantage of their large expertise and test facilities. The fabrication includes several steps from the machining to the final assembly, including quality controls. This paper describes the engineering design and fabrication procedure of the X-band AS with damping material, by focusing on few technical solutions.

MOPC041

Cross-Field Multipactor Discharge in the X-Band Cylindrical Cavity

cavity, multipactoring, electron, radiation

166

S.V. Kuzikov, E.V. Ilyakov, I.S. Kulagin, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
D. Lee
NSRRC, Hsinchu, Taiwan

The paper represents the experimental study of one-sided cross-field multipactor discharge in the copper cavity with the operating mode TM01 in external DC magnetic field. It was shown that discharge is very sensible to magnitudes of the external magnetic field and rf fields as well. At proper fields the multipactor discharge can be developed for 15 ns and the electron concentration can be comparable with critical one for the given rf frequency. As a result of discharging, the cavity changes its own resonant frequency and can play a role of a switch which can substitute full transmission by full reflection. Switching parameters could be controlled by DC magnetic field as well as by additional rf radiation at different frequency than operating frequency. The high rf absorption of multipactor discharge also can be used in electrically controlled powerful loads and attenuators.

MOPC042

RF and Accelerating Structure of 12 MeV UPC Race-track Microtron

linac, coupling, microtron, controls

169

Yu.A. Kubyshin, X. Gonzalez Arriola
UPC, Barcelona, Spain
D. Carrillo, L. García-Tabarés, F. Toral
CIEMAT, Madrid, Spain
S.J. Mathot
CERN, Geneva, Switzerland
G. Montoro
EPSC, Castelldefels, Spain
V.I. Shvedunov
MSU, Moscow, Russia

We describe the design and technical characteristics of a C-band SW accelerating structure of a 12 MeV race-track microtron, which is under construction at the Technical University of Catalonia, and its RF system with a 5712 MHz magnetron as a source. Results of cold tests of the accelerating structure, before and after the brazing, and of high-power tests of the RF system at a special stand are reported. The main features of the magnetron frequency stabilization subsystem are also outlined.

MOPC043

Electromagnetic Simulations of the Input Power Couplers for the ESS-Bilbao RFQ

rfq, linac, cavity, radio-frequency

172

O. Gonzalez, I. Bustinduy, N. Garmendia, J.L. Munoz, A. Velez
ESS Bilbao, Bilbao, Spain
F.J. Bermejo
Bilbao, Faculty of Science and Technology, Bilbao, Spain
V. Etxebarria, J. Portilla
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

An input power system is currently being designed at ESS-Bilbao in order to inject the RF power provided by a klystron into the RFQ as part of the linac. In this work, some input power couplers based on a coaxial topology are carefully studied from an electromagnetic point of view. As we will show, the electrical properties of the ceramic window used to ensure the vacuum of the RFQ crucially deteriorates the matching of the devices. To overcome this drawback, a full-wave electromagnetic simulator is used to optimize the coupler dimensions in order to minimize both the return and insertion losses.

MOPC047

RF Design of the Re-buncher Cavities for the LIPAC Deuteron Accelerator

cavity, impedance, linac, beam-transport

184

A. Lara, I. Podadera, F. Toral
CIEMAT, Madrid, Spain

Funding: Work partially supported by Spanish Ministry of Science and Innovation under project ENE2009-11230.
Re-buncher cavities are an essential component of LIPAC (Linear IFMIF Prototype Accelerator), presently being built at Rokkasho (Japan). The deuteron beam exiting from the RFQ (Radio Frequency Quadrupole) structure has to be properly adapted to the superconducting RF (SRF) linac. Re-bunchers are placed in the Medium Energy Beam Transport (MEBT) line and their objective is to longitudinally focus the deuteron beam. IFMIF re-bunchers must provide a 350 kV E0LT at 175 MHz continuous wave (CW). The available length for the re-buncher is limited by the general layout of the MEBT. The high power dissipation derived from the high effective voltage and the short available length is an important design challenge. Four different normal conducting cavity designs were investigated: the pillbox type, double gap coaxial resonators, and multi-gap quarter wave and H resonators. The performance of these cavities was studied with the numerical codes HFSS and ANSYS. The fundamental frequency and field pattern of each re-buncher was investigated in HFSS. This work presents the results of such analyses.

MOPC052

Engineering Design and Fabrication of X-band RF Components

klystron, pick-up, coupling, diagnostics

196

M. Filippova, A. Olyunin, V. Soldatov, A. Solodko
JINR, Dubna, Moscow Region, Russia
S. Atieh, G. Riddone, I. Syratchev
CERN, Geneva, Switzerland

The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.9942 GHz permitting beam independent power production using klystrons for accelerating structure testing. X-band klystron test facilities at 11.424 GHz are operated at SLAC and at KEK, and these facilities are used by CLIC study in the frame of the X-band structure collaboration for testing accelerating structures scaled to that frequency*. Generally RF components are used in the transmission and the transformation of radio frequency signals generated by the power supply. The operating range of the devices accommodates the frequencies from 11.424 to 11.9942 GHz. RF components are needed for the Klystron test stand at CERN, and also for the X-FEL projects at PSI and Sincrotrone Trieste. Currently CERN is ordering tens of these companies to industry. The engineering design of the RF components (high power and compact loads, bi-directional couplers, X-band splitters, hybrids, phase shifters, variable power attenuators) and the main fabrication processes are presented here.
* K.M. Schirm et al., “A 12 GHZ RV Power source for the CLIC study”, Proc. of IPAC’10, THPEB053, p. 3990 (2010).

MOPC055

High Power Test of the First PIMS Cavity for Linac4

cavity, linac, pick-up, klystron

205

F. Gerigk, J.-M. Giguet, P. Ugena Tirado, R. Wegner
CERN, Geneva, Switzerland

The PI-Mode Structure (PIMS) accelerates the Linac4 beam from 100 to 160 MeV. Twelve 7-cell cavities will be installed in the linac, with a gradient of ~4 MV/m and operating at a frequency of 352.2 MHz. A full-power prototype has been constructed at CERN in 2010 and was high- power tested in autumn 2010. Peak power tests at the Linac4 duty cycle and high-average power tests at increased duty cycles were completed successful, so that this prototype will be the first of the 12 cavities to be installed in Linac4. This paper reports on the high-power tests and the conditioning experience.

MOPC056

The Linac4 Power Coupler

cavity, linac, coupling, simulation

208

F. Gerigk, J.-M. Giguet, E. Montesinos, B. Riffaud, P. Ugena Tirado, R. Wegner
CERN, Geneva, Switzerland

Linac4 employs 3 types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell-Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam to 160 MeV. The structures are designed for a peak power of 1 MW per coupler, which consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the wave-guides, and a so-called "coupling T", which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improved with respect to their commonly used design. On the coupler side, the wave-guide short circuit with its matched length has been replaced by a fixed length λ/4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually consists of a ceramic disc and 2 pieces of wave-guides with matching elements, the wave-guide sections could be completely suppressed, so that the window became very compact, lightweight, and much simpler to manufacture. In this paper we present electromagnetic simulations, and tests on first prototypes, which were constructed at CERN.

MOPC073

A Dual-mode Accelerating Cavity to Test RF Breakdown Dependence on RF Magnetic Fields

cavity, simulation, electron, radio-frequency

247

A.D. Yeremian, V.A. Dolgashev, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: * Work Supported by Doe Contract No. DE-AC02-76SF00515
RF Breakdown experiments on short accelerating structures at SLAC have shown that increased rf magnetic fields increase the probability of rf breakdowns. Moreover, the breakdown rate is highly correlated with the peak pulse-heating in soft-copper single-cell standing-wave structures of disk-loaded waveguide type. In these geometries the rf electric and magnetic fields are highly correlated. To separate effects of rf magnetic and electric fields on the rf breakdown rate, we have designed an X-band cavity with a geometry as close to that of a standing-wave accelerator cell as practically possible. This cavity supports two modes: an accelerating TM mode and a TE mode with no-surface-electric field but with a strong magnetic field. The cavity will be constructed and tested at the Accelerator Structure Test Area (ASTA) at SLAC.

MOPC079

Status of the Low Beta 0.07 Cryomodules for SPIRAL2

cavity, cryomodule, LLRF, linac

256

P. Bosland, P. Carbonnier, F. Eozénou, P. Galdemard, O. Piquet
CEA/DSM/IRFU, France
M. Anfreville, C. Madec, L. Maurice
CEA/IRFU, Gif-sur-Yvette, France
P.-E. Bernaudin, R. Ferdinand
GANIL, Caen, France
Y. Gomez-Martinez
LPSC, Grenoble Cedex, France
A. Pérolat
CEA, Gif-sur-Yvette, France

The status of the low beta cryomodules for SPIRAL2, supplied by the Irfu institute of CEA Saclay, is reported in this paper. We summarise in three parts the RF tests performed on the cavities in vertical cryostat, the RF power tests of the qualifying cryomodule performed in 2010 and the RF power tests performed in 2011 on the first cryomodule of the series

MOPC088

Bead-pull Measurement using Phase-Shift Technique in Multi-cell Elliptical Cavity

cavity, linac, controls, monitoring

280

S. Ghosh, A. Mandal, S. Seth, S.S. Som
DAE/VECC, Calcutta, India

The project on the development of high-beta multi-cell elliptical shape superconducting rf linac cavity at around 704 MHz has been funded at VECC, Kolkata, India. A full-scale copper prototype cavity has been designed and fabricated. There are 5 distinct modes exist in the cavity and the accelerating mode is pi-mode in which each cell operates at same frequency with phase difference of 180 degrees between two neighboring cells. A fully automated bead-pull measurement setup has been developed for analyzing these modes and field profile distribution at different modes in such type of linac cavity. A special measurement method inside the cavity using phase-shift technique is proposed in this paper, which describes the development of mechanical setup comprising pulleys and stepper motor–gear arrangement, PC-based control system for precise movement of bead using stepper motor, measurement using VNA, development of software for data acquisition & automation and measurement results for the 5-cell copper prototype cavity.

MOPC092

Effect of Current Densities on Sulfur Generation at Electropolished Niobium Surface

cavity, niobium, cathode, electron

292

P.V. Tyagi
Sokendai, Ibaraki, Japan
H. Hayano, S. Kato, M. Nishiwaki, T. Noguchi, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

We conducted a series of electropolishing (EP) experiments in aged EP acid with high (≈50 mA/cm²) and low (≈30 mA/cm²) current densities on Nb surfaces. The experiments were carried out both for laboratory coupons and a real Nb single cell cavity with six witness samples located at three typical positions (equator, iris and beam pipe). All the samples surface were investigated by XPS (x-ray photoelectron spectroscopy), SEM (scanning electron microscope) and EDX (energy dispersive x-ray spectroscopy). The surface analysis showed the EP with a high current density produced a huge amount sulfate particles at Nb surface whereas the EP with a low current density is very helpful to mitigate sulfate at Nb surface in both the experiments.

MOPC103

Cryostat for Testing HIE-ISOLDE Superconducting RF Cavities

cavity, cryomodule, cryogenics, niobium

313

O. Capatina, J.P. Brachet, G. Cuccuru, M. Pasini, T. Renaglia, M. Therasse, B. Vullierme
CERN, Geneva, Switzerland

The High Intensity and Energy ISOLDE (HIE-ISOLDE) project is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN [1], with the objective of increasing the energy and the intensity of the delivered radioactive ion beams (RIB). This project aims to fill the request for a more energetic post accelerated beam by means of a new superconducting (SC) linac based on Quarter Wave Resonators (QWRs). A research and development program looking at all different aspects of the SC linac has started in 2008 and continued throughout 2010. In particular the R&D effort has focused on the development of the high β cavity (β = 10.3%), for which it has been decided to adopt the Nb sputtered on Cu substrate technology. Two prototype cavities were manufactured and are undergoing RF cold tests. The pre-series cavity fabrication is under way using 3D forged Cu billets. A single vacuum cryostat was designed and built to test these cavities at liquid helium temperatures. The paper details the main design concepts of the test cryostat as well as the results of the cryogenic behavior of the complete set-up including the cryostat, the RF cavity, the tuner and the main coupler.

MOPC104

HIE-ISOLDE SRF Development Activities at CERN

cavity, cathode, niobium, SRF

316

M. Therasse, O. Brunner, S. Calatroni, J.K. Chambrillon, B. Delaup, M. Pasini
CERN, Geneva, Switzerland

The HIE-ISOLDE project has initiated a new development phase on the SRF domain at CERN. In particular, the HIE-ISOLDE project aims at the construction of the 32 Quarter Wave Resonators (QWRs) using the Nb on Cu sputtering technology. The paper describes the refurbishment of the test infrastructure and the activities from the cavity production to the cold test, including quality assurance procedure for the correct handling of the resonators.

MOPC105

Design of the High Beta Cryomodule for the HIE-ISOLDE Upgrade at CERN

cavity, alignment, cryomodule, target

319

L.R. Williams, A.P. Bouzoud, N. Delruelle, J. Gayde, Y. Leclercq, M. Pasini, J.Ph. G. L. Tock, G. Vandoni
CERN, Geneva, Switzerland

The major upgrade of the energy and intensity of the radioactive ion beams of the existing ISOLDE and REX-ISOLDE facilities at CERN will, in the long term, require downstream of the existing machine, the installation of four high-β and two low-β cryo-modules. The first stage of this upgrade, involving the design, construction, installation and commissioning of two high-β cryo-modules is approved and design work is underway at CERN. The high-β cryo-module houses five high-β superconducting cavities and one superconducting solenoid. As well as providing optimum conditions for physics, where the internal active components must remain aligned within tight tolerances, the cryo-modules need to function under stringent common vacuum and cryogenic conditions. To preserve the RF cavity performance their assembly and sub-system testing will need to be carried out using specifically designed tooling in a class 100 clean-room. We present the determining factors constraining the design of the high-β cryo-module together with the design choices that these factors have imposed.

MOPC114

Design, Fabrication and Testing of Medium-Beta 650 MHz SRF Cavity Prototypes for Project-X

cavity, SRF, linac, electron

343

F. Marhauser, W.A. Clemens, J. Henry, P. Kneisel, R. Martin, R.A. Rimmer, G. Slack, L. Turlington, R.S. Williams
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A new type of superconducting radio frequency (SRF) cavity shape with a shallow equator dome to reduce electron impact energies for suppressing multipacting barriers has been proposed. The shape is in consideration for the first time in the framework of Project-X to design a potential multi-cell cavity candidate for the medium-beta section of the SRF proton CW linac operating at 650 MHz. Rationales covering the design of the multi-cell cavity, the manufacture, post-processing and high power testing of two single-cell prototypes are presented.

MOPC129

Compact Solid State RF-Modules for Direct Drive RF-linacs

linac, impedance, cavity, klystron

382

R. Irsigler, M. Back, R. Baumgartner, O. Heid, T.J.S. Hughes, M. Kaspar, T. Kluge, J. Sirtl, K. Weidner, M. Zerb
Siemens AG, Erlangen, Germany

We present a modular RF power source concept based on solid state RF-modules with novel SiC transistors. The concept offers lower cost, better reliability and reduced maintenance compared to traditional RF-source technology. No circulators are required, which makes the RF-module very compact and reliable. The SiC power transistor has a very low input capacitance and was optimized for low gate resistance to enable fast switching in the VHF range. It delivers a maximum pulsed drain saturation current of 65 A. The transistor provides at 350 V supply voltage and 150 MHz an output power of 5,6 kW at a gain of 15,8 dB. It is essential to avoid high parasitic source inductances at RF and good thermal conductivity is required for operation at high duty cycle. We have built very compact 75 x 90 mm ceramic amplifier modules using a planar interconnect technology (SIPLIT) to connect the bare die transistors to the DCB substrate. The modules have a fully symmetric push-pull topology (circlotron) with four transistors in parallel in each leg. The RF-modules delivered at 150 MHz an impressive RF output power in the range of 40 kW. Further tests at 324 MHz are planned and will be presented.

MOPC134

Multifrequency High Power Microwave Electric-vacuum Devices

electron, klystron, acceleration, cavity

391

K.G. Simonov, A.A. Borisov, A.V. Galdetsky, A.N. Korolev, A.V. Mamontov
ISTOK, Moscow Region, Russia
O.A. Morozov
Research and Production Co. "MAGRATEP", Fryazino, Russia

A new approach for the design of the multifrequency high power microwave vacuum devices is proposed. These devices provide simultaneously some output phased signals with operating frequencies ω, 2 ω, , nω while input frequency is ω. For example, it is possible obtain output power at frequencies ω and 2ω by using of double-gap output resonator tuned on two modes – sinphased mode at 2ω and antiphased mode at frequency ω. It is possible obtain power at four frequencies ω, 2ω, 3ω and 6ω by using of the two double-gap output resonators placed one inside the other. It is possible obtain power at multiple frequencies by using of the special coaxial resonator. A microwave vacuum device has been fabricated in which power was extracted at nine multiple frequencies simultaneously. The output signal has form of pulses with ultrashort duration and superhigh repetition frequency equal to the input signal frequency ω. Multifrequency high power microwave vacuum devices can be used for the development of compact accelerators of charged particles.

MOPC150

High Charge PHIN Photo Injector at CERN with Fast Phase Switching within the Bunch Train for Beam Combination

laser, cathode, gun, bunching

430

M. Divall Csatari, A. Andersson, B. Bolzon, E. Bravin, E. Chevallay, A.E. Dabrowski, S. Döbert, V. Fedosseev, C. Heßler, T. Lefèvre, S. Livesley, R. Losito, O. Mete, M. Olvegård, M. Petrarca, A. Rabiller
CERN, Geneva, Switzerland
A. Drozdy
BUTE, Budapest, Hungary
D. Egger
EPFL, Lausanne, Switzerland

The high charge PHIN photo-injector was developed within the frame of the European CARE program to provide an alternative to the drive beam thermionic gun in CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 sub-trains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the scheme. Stability measurements are presented for the phase-coded system. The paper also discusses the latest 8nC charge production and cathode life-time studies on Cs2Te.

MOPO008

Design and Simulation of the Transverse Feedback Kicker for the HLSⅡ

kicker, impedance, feedback, simulation

496

W.B. Li, P. Lu, B.G. Sun, F.F. Wu, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

In order to suppress the coupled bunch instabilities in the HLSⅡ storage ring, a transverse feedback system is required. The vital component of the system is the kicker that is the feedback actuator. We design a stripline kicker for the HLSⅡ. The horizontal and vertical electrodes are combined in a structure on account of the space limit. In addition to the design issues, this paper focuses on the simulation results for the kicker using the computer codes. By the 2D code POSSION, we calculate and optimize the characteristic impedance of the stripline kicker to match the 50Ω external transmission lines so as to reduce the reflected power. The reflection coefficient and the shunt impedance in the working frequency range are obtained by the 3D code HFSS. The simulation results provide many important supports for the structure design.

MOPO010

Orbit Feedback System for the MAX IV 3 GeV Storage Ring

feedback, power-supply, storage-ring, simulation

499

M. Sjöström, J. Ahlbäck, M.A.G. Johansson, S.C. Leemann, R. Nilsson
MAX-lab, Lund, Sweden

The paper describes the current orbit correction system design for the 3 GeV storage ring at the MAX IV laboratory, a light source facility under construction in Lund, Sweden. The orbit stability requirements for the 3 GeV storage ring are tight at roughly 200 nm vertical position stability in the insertion device (ID) straight sections. To meet this the ring will be equipped with 200 beam position monitors (BPMs) and 380 dipole corrector magnets, 200 in the horizontal and 180 in the vertical plane. The feedback loop solution, one slow orbit feedback (SOFB) loop and one fast orbit feedback (FOFB) loop in fast acquisition mode at 10,000 samples/second, will be presented. The paper will also discuss the various boundary conditions specific to the MAX IV 3 GeV storage ring design, such as a Cu vacuum chamber, and the impact on the corrector design.

MOPO023

Laser-based Alignment System at the KEKB Injector Linac

laser, alignment, linac, injection

529

M. Satoh, N. Iida, T. Suwada
KEK, Ibaraki, Japan
K. Minoshima, S. Telada
AIST, Tsukuba, Japan

A laser-based alignment system is under development at the 500-m-long KEKB injector linac. The original system was designed and constructed more than thirty-years ago, and thus, we are revisiting our alignment system because the previous alignment system has become too obsolete. The new alignment system is again strongly required for the next generation SuperKEKB project. The new laser alignment system is similar to the previous one, which comprises a helium-neon laser and quadrant photodetectors installed in vacuum light pipes. A girder displacement of the accelerating structure can be precisely measured in the direction of the laser-ray trace, where the laser light must stably propagate up to 500-m downstream without any orbital and beam-size fluctuation. We tested the laser-ray propagation and the stability along a 100-m-long beam line under a vacuum condition of 0.1-1 Torr. In this paper, we will report the system description and test results in detail.

MOPO026

Design, Manufacturing and Tests of Closed-loop Quadrupole Mover Prototypes for European XFEL

quadrupole, controls, alignment, feedback

535

J. Munilla, J. Calero, J.M. Cela-Ruiz, L. García-Tabarés, A. Guirao, J.L. Gutiérrez, T. Martínez de Alvaro, E. Molina Marinas, S. Sanz, F. Toral, C. Vazquez
CIEMAT, Madrid, Spain

Funding: Work partially supported by Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009
In this report the development of a quadrupole mover with submicron repeatability is reported, which will be used in the intersections of the Undulator Systems of the European XFEL (EXFEL). It is part of the Spanish in-kind contribution to this facility. The main specifications include submicron repeatability for a 70 kg quadrupole magnet within compact dimensions and a ±1.5 mm stroke in the vertical and horizontal direction. Compact linear actuators based on 5-phase stepping motors have been chosen. Vertical actuator works in a wedge configuration to take mechanical advantage. A closed-loop control system has been developed to achieve this repeatability. For the feedback, one LVDT sensor for each axis was used. Mechanical switches are used to limit movement. In addition, hard-stops are included for emergency. Prototyping stage is done and a serial production of more than 90 devices is expected, so intense work has been done to achieve a reliable industrial production and validation. In this report, results of mechanical measurements including reproducibility, tests of different operation strategies and critical situations will be reported.

MOPS006

Beam Tilt due to Transverse Wakefields for DAΦNE, SuperB, KEKB and SuperKEKB

impedance, closed-orbit, wakefield, collider

601

D.M. Zhou, K. Ohmi
KEK, Ibaraki, Japan
A. Chao
SLAC, Menlo Park, California, USA

When a beam bunch traverses a transverse impedance, the bunch head generates a transverse wakefield that kicks the bunch tail, generating a betatron motion of the tail relative to the head. In a storage ring, in a steady state, this kick to the bunch tail produces a transverse closed orbit (e.g. in the y-direction) of the bunch tail relative to the bunch head, which means the beam now has a y-z tilt. Such beam tilt due to transverse wakefields may cause a loss of luminosity in storage ring colliders or loss of brightness in light sources. In this paper, we present a preliminary study of the beam tilt effect for the colliders DAΦNE, SuperB, KEKB and SuperKEKB.

MOPS017

Simulation Studies of Macro-particles Falling into the LHC Proton Beam

proton, beam-losses, simulation, injection

634

F. Zimmermann, T. Baer, M. Giovannozzi, E.B. Holzer, E. Nebot Del Busto, A. Nordt, M. Sapinski
CERN, Geneva, Switzerland
N. Fuster
Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain
Z. Yang
EPFL, Lausanne, Switzerland

We report updated simulations on the interaction of macro-particles falling from the top of the vacuum chamber into the circulating LHC proton beam. The path and charge state of micron size micro-particles are computed together with the resulting beam losses, which – if high enough - can lead to the local quench of SC magnets. The simulated time evolution of the beam loss is compared with observations in order to constrain some macro-particle parameters. We also discuss the possibility of a "multiple crossing" by the same macro-particle, the effect of a strong dipole field, and the dependence of peak loss rate and loss duration on beam current and on beam size.

MOPS045

Coupling Impedance of Rough Resistive Pipe*

impedance, coupling, resonance, wakefield

700

M. Ivanyan, V.M. Tsakanov
CANDLE, Yerevan, Armenia

A new version of modelling of the surface roughness impact by thin dielectric layer in the round resistive beam pipe is suggested. The calculation method of coupled resistive-roughness impedance is developed.

MOPS049

Study of Ion-induced Instabilities and Transverse Feedback Performance at SOLEIL

ion, feedback, simulation, electron

712

R. Nagaoka, L. Cassinari, M.D. Diop, J.-M. Filhol, M.-P. Level, A. Loulergue, P. Marchand, R. Sreedharan
SOLEIL, Gif-sur-Yvette, France

Experimental studies indicate that the SOLEIL storage ring at its maximum designed current of 500 mA is under a large influence of ions, potentially capable of inducing the so called fast beam-ion instability. To avoid it, the following three conditions have been empirically found effective: A reduced RF voltage, uniform filling and a large vertical chromaticity. While the choice of uniform filling appears contradictory to raising the ion instability threshold, it goes well with lowering of the RF voltage if outgassing due to beam-induced heating of the vacuum components is the primary source of ions. Additional difficulties associated are frequent occurrence of sudden beam blowups despite the presence of transverse feedback, which are large enough to trigger machine interlocks leading to complete beam losses. These blow ups may even take place horizontally inside in-vacuum insertion devices. The present paper reports on the results and findings obtained through experimental and simulation studies carried out on the collective beam dynamics and the transverse feedback performance, which are deeply interlinked, in order to clarify the mechanism of the encountered phenomena.

MOPS056

An Analytical Formula of the Electron Cloud Linear Map Coefficient in a Strong Dipole

electron, dipole, simulation, storage-ring

733

T. Demma
INFN/LNF, Frascati (Roma), Italy
S. Petracca, A. Stabile
U. Sannio, Benevento, Italy
G. Rumolo
CERN, Geneva, Switzerland

Electron cloud effects have been indentified as one of the most serious bottleneck for reaching design performances in presently running and proposed future storage rings. The analysis of these effects is usually performed with very time consuming simulation codes. An alternative analytic approach, based on a cubic map model for the bunch-to-bunch evolution of the electron cloud density, could be useful to determine regions in parameters space compatible with safe machine operations. In this communication we derive a simple approximate formula relating the quadratic coefficient in the electron cloud density map to the parameters relevant for the electron cloud evolution in a strong vertical magnetic field. Results are compared with simulations with particular reference to the LHC dipoles.

MOPS064

Longitudinal Beam Stability and Related Effects at the ALBA Storage Ring

kicker, impedance, resonance, injection

748

T.F. Günzel
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The risk of longitudinal instabilities excited by narrowband and broadband resonator impedance was studied. A campaign for the search of modes trapped in vacuum chamber elements of the ALBA storage ring via electromagnetic simulation was initiated. Several critical vacuum elements in the ring like the vertical scraper, the injection and feedback kickers were identified. The outlets of the injection kicker had to be protected with RF-fingers whereas the scraper only produces dangerous modes in the withdrawn state, both do not pose a real problem. However, the calculated power distribution generated in the feedback kickers could be an obstacle for reaching the nominal current of 400mA. Furthermore, the budget of Z(n)/n of the storage ring was computed and checked on the risk of microwave instability using the Boussard criterion.

MOPS065

Transverse Instability Studies at the ALBA Storage Ring

impedance, single-bunch, kicker, storage-ring

751

T.F. Günzel
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

In the first phase of the ALBA storage ring operation 3 NEG-coated aluminum chambers, 2 in-vacuum undulators and one wiggler chamber will be installed. Under particular consideration of the multilayer character of these chambers and the injection kickers the thresholds of the transverse mode coupled instability(TMCI) were calculated using MOSES*. The thresholds 17.5mA/40.5mA vertical/horizontal leave a rather large operative margin. The detrimental effect of the NEG-coating on the TMCI is relatively limited and on the resistive wall instability is even negligible. As well the thresholds of the head-tail instability were computed as function of chromaticity. Also the incoherent tune shifts generated by the quadrupolar resistive wall wake fields due to the flatness of the vacuum chambers were calculated. The computed results have been compared to first measurements of the storage ring commissioning.
* Y.H.Chin, MOSES 2.0, CERN/LEP-TH/88-05

MOPS070

Electromagnetic Modeling of C Shape Ferrite Loaded Kickers

impedance, kicker, simulation, ion

763

C. Zannini
EPFL, Lausanne, Switzerland
E. Métral, G. Rumolo, B. Salvant, V.G. Vaccaro, C. Zannini
CERN, Geneva, Switzerland

The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of an intensity upgrade of the LHC. In this paper, analytical approach and CST Particle Studio time domain electromagnetic simulations are performed to obtain the longitudinal and transverse impedances/wake potentials of models of ferrite loaded kickers. It turns out that the existing models are not sufficient to characterize correctly these components from the coupling impedance point of view. In particular the results show that below few hundred MHz the real C-structure of the magnet cannot be neglected. Therefore an analytical model was developed and benchmarked with EM simulations to take into account the C-shape of the magnet.

MOPS071

Simulations of the Impedance of the New PS Wire Scanner Tank

simulation, impedance, beam-losses, extraction

766

B. Salvant
EPFL, Lausanne, Switzerland
W. Andreazza, F. Caspers, A. Grudiev, J.F. Herranz Alvarez, E. Métral, G. Rumolo
CERN, Geneva, Switzerland

The CERN PS is equipped with 4 wire scanners. It was identified that the small aperture of the current wire scanner tank causes beam losses and a new tank design was needed. The interaction of the PS bunches with the beam coupling impedance of this new tank may lead to beam degradation and wire damage. This contribution presents impedance studies of the current PS tank as well as the new design in order to assess the need to modify the design and/or install lossy materials plates dedicated to damp higher order cavity modes and reduce the total power deposited by the beam in the tank.

MOPS073

Impedance Calculation for Simple Models of Kickers in the Non-ultrarelativistic Regime

impedance, kicker, coupling, neutron

772

N. Biancacci, N. Mounet, E. Métral, B. Salvant, C. Zannini
CERN, Geneva, Switzerland
N. Biancacci, M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
Q. Qin, N. Wang
IHEP Beijing, Beijing, People's Republic of China

Kicker magnets are usually significant contributors to the beam coupling impedance of particle accelerators. An accurate understanding of their impedance is required in order to correctly assess the machine intensity limitations. The field matching method derived by H. Tsutsui for the longitudinal and transverse dipolar (driving) impedance of simple models of kickers in the ultrarelativistic regime was already extended to the non-ultrarelativistic case, and to the quadrupolar (detuning) impedance in the ultrarelativistic case. This contribution presents the extension to the quadrupolar impedance in the non-ultrarelativistic case, as well as benchmarks with other available methods to compute the impedance. In particular, all the components of the impedances are benchmarked with Tsutsui's model, i.e. in the ultrarelativistic limit, with the model for a flat chamber impedance recently computed by N. Mounet and E. Métral, in the case of finite relativistic gamma, and with CST Particle Studio simulations.

MOPS090

Observation of Beam Ion Instability in SPEAR3

ion, emittance, single-bunch, quadrupole

814

L. Wang, Y. Cai, W.J. Corbett, T.O. Raubenheimer, J.A. Safranek, J.F. Schmerge, J.J. Sebek
SLAC, Menlo Park, California, USA
D. Teytelman
Dimtel, San Jose, USA

Weak vertical coupled bunch instability with oscillation amplitude at μm level has been observed in SPEAR3. The instability becomes stronger when there is a vacuum pressure rise by partially turning off vacuum pumps and it becomes weaker when the vertical beam emittance is increased by turning off the skew quadrupole magnets. These confirmed that the instability was driven by ions in the vacuum. The threshold of the beam ion instability when running with a single bunch train is just under 200 mA. This paper presents the comprehensive observations of the beam ion instability in SPEAR3. The effects of vacuum pressure, beam current, beam filling pattern, chromaticity, beam emittance and bunch-by-bunch feedback are investigated in great detail.pattern, chromaticity, beam emittance and bunch-by-bunch feedback are investigated in great detail.

MOPZ011

An Automated Conditioning System for the MUCOOL Experiments at Fermilab

cavity, controls, pick-up, collider

844

A. Kurup
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The MUCOOL project aims to study RF cavities for the Neutrino Factory and the Muon Collider. The large emittance muon beams in these accelerators require high-gradient RF cavities at low-frequencies and they need to operate in the presence of relatively strong magnetic fields. MUCOOL is conducting a number of tests on 805MHz and 201 MHz cavities in order to develop a technology that can meet all of these requirements. An automated conditioning system was developed for the 805MHz test program for MUCOOL. This system was designed to replicate the logic a human operator would use when conditioning an RF cavity and to provide automated logging of the conditioning process. This paper describes the hardware and software of the system developed.

MOPZ029

Aperture Windows in High-Gradient Cavities for Accelerating Low-Energy Muons

cavity, linac, septum, target

862

S.S. Kurennoy, A.J. Jason, W.M. Tuzel
LANL, Los Alamos, New Mexico, USA

A high-gradient linear accelerator for accelerating low-energy muons and pions in a strong solenoidal magnetic field has been proposed for homeland defense and industrial applications*. The acceleration starts immediately after collection of pions from a target in a solenoidal magnetic field and brings muons to a kinetic energy of about 200 MeV over a distance of the order of 10 m. At this energy, both ionization cooling of the muon beam and its further acceleration become feasible. A normal-conducting linac with external-solenoid focusing can provide the required large beam acceptances. The linac consists of independently fed zero-mode (TM010) RF cavities with wide beam apertures closed by thin conducting windows. The high gradients lead to significant heat deposition on the aperture windows. Here we explore options for the edge-cooled thin windows in the zero-mode cavities. Electromagnetic and thermal-stress computations are complemented by thermal-test experiments to select the best solution for the aperture windows.
* S.S. Kurennoy, A.J. Jason, H. Miyadera, “Large-Acceptance Linac for Accelerating Low-Energy Muons,” Proc. of IPAC10, p. 3518 (2010).

TUZB02

Ultra High Vacuum for High Intensity Proton Accelerators

ion, radiation, proton, radioactivity

971

N. Ogiwara
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In high intensity proton accelerators neutrons, as well as gamma rays, are generated. At the J-PARC synchrotron the cumulative energy dose will be of the order of several-mSv/h over 1 month user operation. In order to minimize the radiation exposure during maintenance, it is necessary to construct a vacuum system with reliable components which have a long life in such a high level of radiation. In addition, in all machines it is necessary to keep the operating pressure of the beam in ultra high vacuum (UHV) to suppress pressure instability. At J-PARC RCS the UHV conditions were realized without baking and the beam operation has been successful to date. General considerations for vacuum systems for high intensity linear and circular accelerators will be provided in the talk.

Slides TUZB02 [3.380 MB]

TUODB01

Progress of the Construction for the TPS Vacuum System

photon, impedance, ion, storage-ring

976

G.-Y. Hsiung, C.K. Chan, C.H. Chang, C.-C. Chang, C.L. Chen, C.M. Cheng, Y.T. Cheng, S-N. Hsu, H.P. Hsueh, I.T. Huang, T.Y. Lee, I.C. Sheng, L.H. Wu, H.Y. Yan, Y.C. Yang, C.S. huang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

Vacuum system for the 3 GeV Taiwan Photon Source (TPS) has been started the construction since 2010. The critical components such as the bellows and gate valves with rf-contact shielding, pulsed magnet kicker ceramic chambers, BPM, crotch absorbers, etc. have been manufactured and tested. Aluminum alloy (Al-) vacuum chambers for the arc-cells have been machined and undergoing the in-house welding. Mass production of the vacuum equipments including the ion gauges, ion pumps, NEG pumps, and gate valves, has been contracted out and partially delivering following the schedule of the cell assembling. Each cell, contains two short Al-straight chambers and two Al-bending chambers, has been started the assembling and on-site welding on the pre-aligned girders in clean room forming an one-piece vacuum vessel about 14 m in length following by the vacuum baking to the ultra-high vacuum. The conceptual design of the vacuum systems for the long straight sections, the concentric booster, and the transport lines, will be addressed. The progress of prototyping development and the status of construction for the TPS vacuum system will be described in this paper.

Slides TUODB01 [35.595 MB]

TUODB02

Extreme High Vacuum System of High Brightness Electron Source for ERL

gun, electron, ion, cathode

979

M. Yamamoto, T. Honda, Y. Honda, T. Miyajima, Y. Saito, Y. Tanimoto, T. Uchiyama
KEK, Ibaraki, Japan
H. Akimichi, H. Yoshida
AIST, Tsukuba, Japan
H. Kurisu
Yamaguchi University, Ube-Shi, Japan

A compact test accelerator for Japan’s future light source based on energy recovery linac (ERL) is under construction in KEK, aiming to demonstrate key technologies such as a high-brightness photocathode DC-gun and superconducting RF cavities. A DC-gun using GaAs-type photocathode which has a negative electron affinity (NEA) surface is employed. The NEA surface plays an indispensable role to extract electrons from conduction band minimum into vacuum. It assures high quantum efficiency of the photocathode and very low intrinsic emittance of the extracted beam. However, the NEA surface is extremely delicate against residual gas in vacuum. In order to extract mA-level beam currents continuously for more than several tens of hours, the pressure should be lower than the order of ·10^-10 Pa to avid the backbombardment of positive ions produced by the collision of accelerated electrons with residual gas molecules in the beam path. Recent achievements in the development of a 500-kV photocathode DC-gun and in the fundamental studies of its extreme high vacuum system will be presented.

Slides TUODB02 [1.606 MB]

TUPC008

CLIC Two-Beam Module for the CLIC Conceptual Design and Related Experimental Program

alignment, linac, quadrupole, RF-structure

1003

A. Samoshkin, D. Gudkov, A. Solodko
JINR, Dubna, Moscow Region, Russia
G. Riddone
CERN, Geneva, Switzerland

The Compact LInear Collider (CLIC), being studied at CERN, involves the design and integration of many different technical systems, tightly bound and influencing each other. For the construction of two main linacs it has been decided to proceed with a modular design, and repetitive two-beam modules of a few types were defined. The modules consist of micro-precision components operating under ultra-high vacuum as required by the beam physics. For the CLIC Conceptual Design Report, the development and system integration is mainly focused on the most complex module type containing the highest number of components and technical systems. For proving the proper functioning of the needed technical systems and confirming their feasibility it has been decided to build four prototype modules and test them without beam. In addition, three modules have to be produced in parallel for tests in the CLIC Experimental Area with beam. This paper is focused on the design of the different technical systems and integration issues of the two-beam module. The experimental program for the prototype modules is also recalled.

TUPC010

Status of the Manufacturing of Accelerating Structures for LINACs

linac, controls, extraction, laser

1009

F.M. Mirapeix, J. Añel, J. Castillo, A. Ortiz
HTS, Mendaro, Spain
X. Aldalur, J. Amores, A. Urzainki
DMP, Mendaro, Spain

Funding: HTS, DMP, ZEHATZ, CERN
Particle accelerators need ongoing development in the state of the art of the field: high-quality manufacturing of accelerating structures, PETS, but also drift tubes, bunchers, high-power couplers, alignment systems, precision test stands, etc. They also require engineering projects in the range of mechatronics, thermodynamics, microwaves, ultra high vacuum, cryogenics, joining techniques, high precision manufacturing, 3D high precision scanning, etc. HTS together with DMP are actually working on all this fronts. In this paper, the actual status of the manufacturing capabilities concerning some accelerating structures will be described.

TUPC011

Striplines for CLIC Pre-Damping and Damping Rings*

impedance, kicker, damping, extraction

1012

C. Belver-Aguilar, A. Faus-Golfe
IFIC, Valencia, Spain
M.J. Barnes, G. Rumolo
CERN, Geneva, Switzerland
F. Toral
CIEMAT, Madrid, Spain
C. Zannini
EPFL, Lausanne, Switzerland

The Compact Linear Collider (CLIC) study explores the scheme for an electron-positron collider with high luminosity and a nominal center-of-mass energy of 3 TeV: CLIC would complement LHC physics in the multi-TeV range. The CLIC design relies on the presence of Pre-Damping Rings (PDR) and Damping Rings (DR) to achieve, through synchrotron radiation, the very low emittance needed to fulfil the luminosity requirements. The specifications for the kicker systems are very challenging and include very low beam coupling impedance and excellent field homogeneity: striplines have been chosen for the kicker elements. Analytical calculations have been carried out to determine the effect of tapering upon the high frequency beam coupling impedance. In addition detailed numerical modeling of the field homogeneity has been performed and the sensitivity of the homogeneity to various parameters, including stripline cross-section, has been studied. This paper presents the main conclusions of the beam impedance calculations and field homogeneity predictions.

TUPC018

Progress on Modelling of the Thermo-Mechanical Behavior of the CLIC Two-Beam Module

RF-structure, simulation, linac, collider

1033

R.J. Raatikainen, K. Osterberg
HIP, University of Helsinki, Finland
T.O. Niinikoski, G. Riddone
CERN, Geneva, Switzerland

The luminosity goal of the CLIC collider, currently under study, imposes micrometer mechanical stability of the 2-m long two-beam modules, the shortest repetitive elements of the main linacs. These modules will be exposed to variable high power dissipation during operation resulting in mechanical distortions in and between module components. The stability of the CLIC module will be tested in laboratory conditions at CERN in a full-scale prototype module. In this paper, the FEA model developed for CLIC prototype module is described. The thermal and structural results for the new module configuration are presented considering the thermo-mechanical behavior of the CLIC collider in its primary operation modes. These results will be compared to the laboratory measurements to be done during 2011 and 2012 with the full-scale prototype module. The experimental results will allow for better understanding of the module behaviour and they will be propagated back to the present thermo-mechanical model.

TUPC030

Recommendation for Mitigations of the Electron Cloud Instability in the ILC

electron, positron, emittance, quadrupole

1063

M.T.F. Pivi, L. Wang
SLAC, Menlo Park, California, USA
L.E. Boon, K.C. Harkay
ANL, Argonne, USA
J.A. Crittenden, G. Dugan, M.A. Palmer
CLASSE, Ithaca, New York, USA
T. Demma, S. Guiducci
INFN/LNF, Frascati (Roma), Italy
M.A. Furman
LBNL, Berkeley, California, USA
K. Ohmi, K. Shibata, Y. Suetsugu, J. Urakawa
KEK, Ibaraki, Japan
C. Yin Vallgren
Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden

Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515.
Electron cloud has been identified as one of the highest priority issues for the ILC Damping Rings (DR). A working group has evaluated the electron cloud effect and instability, and mitigation solutions for the electron cloud formation. Working group deliverables include recommendations for the baseline and alternate solutions for the electron cloud mitigation in various regions of the ILC Positron DR, which is presently assumed to be the 3.2km design. Detailed studies of a range of mitigation options including coatings, clearing electrodes, grooves and novel concepts, were carried out over the previous several years by nearly 50 researchers, and the results of the studies form the basis for the recommendation. The assessments of the benefits or risks associated with the various options were based on a systematic ranking scheme. The recommendations are the result of the working group discussions held at numerous meetings and during a dedicated workshop. The mitigation choices will be also presented in a more detailed report later in 2012. In addition, a number of items requiring further investigation were identified and studies will be carried out at CesrTA and other institutions.

TUPC041

Self-consistent Time-dependent Quasi-3D Model of Multipactor in Dielectric-loaded Accelerating Structures

space-charge, electron, multipactoring, plasma

1090

O.V. Sinitsyn, T.M. Antonsen, G.S. Nusinovich
UMD, College Park, Maryland, USA

Funding: This work is supported by the Office of High Energy Physics of the US Department of Energy.
Multipactor (MP) manifests itself as a rapid growth of the number of secondary electrons emitted from a solid surface in the presence of the RF field under vacuum conditions. The secondary electrons appear as the result of surface impacts of energetic primary electrons accelerated by the RF field. MP occurs in various microwave and RF systems and usually severely degrades their performance. Therefore, theoretical and experimental studies of MP are of great interest to researchers working in related areas of physics and engineering. In this paper we study MP in dielectric-loaded accelerating (DLA) structures. We started our work with the development of a self-consistent time-dependent 2D model of MP in such structures*. To benchmark that model, we compared its results with available experimental data**. The comparison showed good agreement between theory and experiment for DLA structures of larger diameter, however for structures of smaller diameter a significant discrepancy was observed. Therefore, we decided to develop a new quasi-3D model of MP that would allow us to take into account the effects ignored in our 2D studies. Results of our 3D analysis are presented in this paper.
* O. V. Sinitsyn, G. S. Nusinovich and T. M. Antonsen, Jr., Phys. Plasmas, 16, 073102 (2009).
** O. V. Sinitsyn, G. S. Nusinovich and T. M. Antonsen, Jr., AIP Conf. Proc., 1299, 302 (2010).

TUPC042

First Beam to FACET

linac, electron, positron, controls

1093

R.A. Erickson, C.I. Clarke, W.S. Colocho, F.-J. Decker, M.J. Hogan, S. Kalsi, N. Lipkowitz, J. Nelson, N. Phinney, P. Schuh, J. Sheppard, H. Smith, T.J. Smith, M. Stanek, J.L. Turner, J. Warren, S.P. Weathersby, U. Wienands, W. Wittmer, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy contract DE-AC02-76SF00515.
The SLAC 3km linear electron accelerator has been reconfigured to provide a beam of electrons to the new FACET facility while simultaneously providing an electron beam to the Linac Coherent Light Source (LCLS). FACET is a new experimental facility constructed in the linac tunnel that can transport, compress, and focus electron bunches to support a variety of accelerator R&D experiments. In this paper, we describe our first experiences with the operation of the linac for this new facility.

TUPC043

SEM Field Emission Probe Surface Science Study

cathode, electron, gun, laser

1096

L. Laurent, R.E. Kirby, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work is supported by Department of Energy Contract No. DE-AC03- 76SF00515.
After decades of rf breakdown research, a common acknowledgement among researchers is that a better understanding of what is happening on the surface at a microscopic level needs to be the impetus for future studies. We are designing and fabricating an electron microscope-based high-electric-field current-emission probe to study topographic material features which will enable us to better understand and further advance the technology of high-brightness photocathode rf guns and enable the study of high gradient phenomena. The SEM field emission probe will provide an important diagnostic tool allowing cathodes and high gradient surfaces to be evaluated before and after testing and will help identify and understand the relationship between high field emission locations and vacuum breakdown, non-uniform emission, surface cracking, hotspots, etc. The preliminary results and 2012 goals will be presented.

TUPC050

Impedance Effects in the CLIC Damping Rings

impedance, wiggler, damping, simulation

1111

E. Koukovini, K.S.B. Li, N. Mounet, G. Rumolo, B. Salvant
CERN, Geneva, Switzerland

Due to the unprecedented brilliance of the beams, the performance of the Compact Linear Collider (CLIC) damping rings is affected by collective effects. Single bunch instability thresholds based on a broad-band resonator model and the associated coherent tune shifts have been evaluated with the HEADTAIL code. Simulations performed for positive and negative values of chromaticity proved that higher order bunch modes can be potentially dangerous for the beam stability. This study also includes the effects of high frequency resistive wall impedance due to different coatings applied on the chambers of the wigglers for e-cloud mitigation and/or ultra-low vacuum pressure. The impact of the resistive-wall wake fields on the transverse impedance budget is finally discussed.

TUPC070

SAFARI, an Optimized Beam Stop Device for High Intensity Beams at the SPIRAL2 Facility

linac, beam-transport, neutron, beam-losses

1162

E. Schibler
IN2P3 IPNL, Villeurbanne, France
L. Perrot
IPN, Orsay, France

The SPIRAL2 facility at GANIL-Caen is now in its construction phase, with a project group including the participation of many French laboratories (CNRS, CEA) and international partners. The facility will be able to produce various accelerated beams at high intensities: 40 MeV Deuterons, 33 MeV Protons with intensity until 5mA and heavy ions with A/Q=3 up to 14.5MeV/u until 1mA current. We will present the final status of the 200kW beam stop located in the high energy beam transport lines. From the beam characteristics (HEBT line up to beam stop) and activation constraints, we studied and developed a complete design of a new high efficiency Beam Stop that has been nicknamed SAFARI (Système Arrêt Faisceau Adapté Rayons Intenses - Optimized Beam Stop Device for High Intensity Beams). Special focus will be done on the adequacy between beam dynamic and thermo-mechanical behavior. The Beam Stop shape marries to the beam characteristics in order to smooth for the best power density and improve thermo-mechanical behavior under nominal and critical beams. Optimization by various fluids studies and calculations led us to a new high efficiency counter-current water cooling system.

TUPC084

Performance of the Scintillation Profile Monitor in the COSY Synchrotron

synchrotron, proton, electron, target

1201

V. Kamerdzhiev, J. Dietrich, K. Reimers
FZJ, Jülich, Germany

Residual gas scintillation is used for measuring profile of the proton beam circulating in the COSY synchrotron. The problem of low rate of scintillation events detected by a multichannel photomultiplier is coped with by injecting small amounts of pure nitrogen into the SPM vacuum chamber. This leads to a temporary local pressure bump of no more than an order of magnitude. A commercially available piezo-electric dosing valve allows good control over the amplitude and duration of the pressure bump. Since the average pressure in the machine is hardly changed, the method is fully compatible with experiment operation. This approach offers a robust and inexpensive way to measure the beam profile. The design of the SPM is discussed. The latest measurement results and comparison to the ionization profile monitor data is presented.

TUPC085

Observation of Microwave Radiation using Low-cost Detectors at the ANKA Storage Ring

radiation, synchrotron, storage-ring, optics

1203

V. Judin, N. Hiller, A. Hofmann, E. Huttel, B. Kehrer, M. Klein, S. Marsching, A.-S. Müller, M.J. Nasse, N.J. Smale
KIT, Karlsruhe, Germany
F. Caspers
CERN, Geneva, Switzerland
P. Peier
PSI, Villigen, Switzerland

Funding: Work supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320
Synchrotron light sources emit Coherent Synchrotron Radiation (CSR) for wavelengths longer than or equal to the bunch length. At most storage rings CSR cannot be observed because the waveguide cuts off radiation with long wavelengths. There are different approaches for shifting the CSR to shorter wavelengths that can propagate through the beam pipe, e.g.: The accelerator optics can be optimized for a low momentum compaction factor, thus reducing the bunch length. Alternatively, laser slicing can modulate substructures on long bunches. Both techniques extend the CSR spectrum to shorter wavelengths, so that CSR is emitted at wavelengths above the waveguide cut off. Usually fast detectors, like superconducting bolometer detector systems or Schottky barrier diodes, are used for observation of dynamic processes in accelerator physics. In this paper, we present observations of microwave radiation at ANKA using an alternative detector, a LNB (Low Noise Block) system. These devices are usually used in standard TV-SAT-receivers and are very cheap. We determined the time response of LNBs to be below 100 ns. The sensitivity of LNBs is optimized to detect very low intensity "noise-like" signals.

TUPC088

An Ionization Profile Monitor for the Determination of the FLASH and PITZ Beam Parameters

electron, photon, diagnostics, ion

1212

J. Mießner, H.-J. Grabosch, M. Markert, R. Sternberger
DESY Zeuthen, Zeuthen, Germany
A. Hofmann
KIT, Karlsruhe, Germany
K.I. Tiedtke
DESY, Hamburg, Germany

To operate FLASH (Free-electron LASer at Hamburg) successfully, accurate measurements of the photon beam parameters, like position and profile, are essential. The development of a specific Ionization Profile Monitor (IPM) is one contribution to the photon beam diagnostics, and currently one horizontal and one vertical oriented IPM are installed at FLASH. The working principle of the IPM is based on the detection of ions generated by interactions of the photon beam with the residual gas, which is always present in the beam line. An essential advantage of this method is that the beam is not influenced by the IPM, so it is possible to analyze the beam parameters without beam destruction. Moreover, the monitor is able to determine the relative position and the spatial profile of the beam with the precision of a few um. In this poster, the design and first measurements with the IPM taken at FLASH are presented. A good measuring accuracy of the IPM is obtained. Moreover, first results of measurements at PITZ (PhotoInjector Testfacility at Zeuthen) are given for one vertical oriented IPM with a up to 25 MeV electron beam.

TUPC092

Transverse C-band Deflecting Structure for Longitudinal Phase Space Diagnostics in the XFEL/SPring-8 “SACLA”

laser, coupling, diagnostics, emittance

1221

H. Ego
RIKEN/SPring-8, Hyogo, Japan
T. Hashirano, S. Miura
MHI, Hiroshima, Japan
H. Maesaka, Y. Otake
RIKEN Spring-8 Harima, Hyogo, Japan
T. Sakurai
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

In SPring-8, the 8 GeV compact XFEL “SACLA” is under commissioning. A single bunch of electrons is compressed down to about 30 fs for brilliant SASE X-ray lasing. It is an important key of stable lasing to investigate the longitudinal phase space and the sliced emittance of a lasing part of the bunch by using a transverse RF deflector. We developed a high gradient C-band deflecting structure operated at 5712 MHz for the bunch diagnosis with a resolution of femtosecond regime at a limited space in the SACLA. The backward travelling-wave of the HEM11-5pi/6 mode is excited in the cylindrical structure periodically loaded with racetrack-shaped irises. The featuring irises suppress rotation of the deflection plane and generate strong cell-to-cell coupling for stable resonance. Two 1.8m-long structures were fabricated and installed in the SACLA. They successfully generated a deflection voltage over 40 MV and pitched the bunch at the zero-crossing RF phase. In this paper, we present the details of the fabrication and the deflecting performance of the structures applied to the diagnosis.

TUPC097

Status of Cold Cavity Beam Position Monitor for STF

cavity, linac, cryomodule, coupling

1236

E.-S. Kim, A. Heo
KNU, Deagu, Republic of Korea
H. Hayano
KEK, Ibaraki, Japan

Cold cavity BPM was developed to meet high position resolution and bunch to bunch measurement time. It is designed based on re-entrant cavity and has Low-Q to achieve short signal decay time in L-band frequency with large aperture as 78mm. The beam test was performed to demonstrate position resolution at ATF main linac, which is operating with 1.6nC bunch charge, while BPM will be installed inside the ILC cyomodule with 3.2nC spacing 369ns like as ILC at STF. Stripline BPMs, ML2P and ML3P installed upstream and downstream of the BPM’s location respectively were used to predict its position. Reference cavity was optimized to use for synchronous detection. We had achieved ~340nm position resolution since position resolution was estimated due to limitation of system with noise, namely in case of ideal state. We will present configuration of beam test, procedure to measure position resolution and the result on the test. Furthermore, new design will be introduced to improve signal intensity and have heavy coupling.

TUPC099

New Measurements of Proton Beam Extinction at J-PARC

proton, injection, secondary-beams, linac

1242

K. Yoshimura, Y. Hori, Y. Igarashi, S. Mihara, H. Nishiguchi, Y. Sato, M. Shimamoto, Y. Takeda, M. Uota
KEK, Ibaraki, Japan
M. Aoki, S. Hikida, H. Nakai
Osaka University, Osaka, Japan
Y. Hashimoto
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Proton beam extinction, defined as a residual to primary ratio of beam intensity, is one of the most important parameters to realize the future muon electron conversion experiment (COMET) proposed at J-PARC. To achieve the required extinction level of 10^-9, we started measuring extinction at main ring (MR) as its first step. According to the various measurements done at the different positions, empty RF buckets of RCS, which were considered to be swept away by the RF chopper, contained about 10^-7 ~ 10^-5 of the main beam pulse due to chopper inefficiency. We have developed a new beam monitor with improved performance for further studies at the abort line. In addition, we have started new measurements at the Hadron experimental hall by using slow-extracted beam. In this paper, we present recent results and future prospect of beam extinction measurements.

TUPC121

Development of MCP Based Photon Detectors for the European XFEL

photon, radiation, FEL, background

1299

E. Syresin, M.N. Kapishin
JINR, Dubna, Moscow Region, Russia
O.I. Brovko, A.V. Shabunov
JINR/VBLHEP, Moscow, Russia
W. Freund, J. Grünert, H. Sinn
European XFEL GmbH, Hamburg, Germany
M.V. Yurkov
DESY, Hamburg, Germany

To provide successful operation of SASE XFEL the radiation detectors should operate in wide dynamic range from the level of spontaneous emission to the saturation level, in wide wavelength range from 0.05 nm to 0.16 nm for SASE1 and SASE2 and from 0.4 nm to 4.4 nm for SASE3. High relative accuracy of measurements is crucial for detection of a signature of lasing, tuning of amplification process, and characterization of statistical properties of the radiation. The XFEL radiation detector based on micro-channel plates (MCP) meets these requirements. Two types of the photon detector are used for measurements of the pulse radiation energy and the image of the photon beam. The dynamic range of photon pulse energies is between 1 nJ and 10 mJ. This applies to spontaneous and FEL radiation. The relative accuracy of pulse energy measurements is better than 1%. The visualization of a single bunch in a train, or average image over the full train will perform by the MCP imager at a spatial resolution of 30 μm.

TUPC129

A Beam Position System for Hadrontherapy Facilities

electron, photon, controls, proton

1323

A. Faus-Golfe, C. Belver-Aguilar, C. Blanch Gutierrez, J.J. García-Garrigós
IFIC, Valencia, Spain
E. Benveniste, M. Haguenauer, P. Poilleux
LLR, Palaiseau, France

Funding: MICINN-FPA:AIC10-D-000518
Essential parts of the needed instrumentation for the beam control in the Hadrontherapy accelerators are the Beam Position Monitors (BPM). The measurement of the beam position in Hadronterapy accelerators become more important at the secondary transport lines towards the patient room where this parameter must be completely determined. The BPM described in this paper is a new type of BPM based on four scintillating fibers coupled to four photodiodes to detect the light produced by the fibers when intercepting the beam. We present here the study of the different photodiodes able to read the light emitted by the scintillating fiber, the tests performed in order to find the most suitable photodiode to measure the beam position from the variations in the beam current, the mechanical design and the corresponding acquisition electronics.

TUPC133

Instrumentation for the 12 GHz Stand-alone Test-stand to Test CLIC Acceleration Structures

electron, laser, diagnostics, ion

1335

M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden
J.W. Kovermann
CERN, Geneva, Switzerland

Vacuum breakdown is one of the primary limitations in the design and construction of high energy accelerators operating with warm accelerating structures (ACS) such as CLIC linear collider because the mechanisms that cause the breakdown are still a mystery. The ongoing experimental work is trying to benchmark the theoretical models focusing on the physics of vacuum breakdown which is responsible for the observed discharges. The CLIC collaboration is preparing a dedicated 12 GHz test-stand to observe the characteristics of the RF discharges and their eroding effects on the ACS. The instrumentation for the test-stand must be versatile and allow for the conditioning of the ACS with measurements of the breakdown rates at different power levels as well as detection of the dark current and light emission directly relevant to breakdown physics. For that purpose we are developing 2 novel instruments. A pepper-pot chamber with an external magnetic spectrometer for measurement of the spatial and energy distributions of the electrons emitted from the ACS and an optical laser system for probing the ACS to observe the effect of a discharge on the transmitted light.

TUPC147

A Micro-Channel Plate Based Gas Ionization Profile Monitor with Shaping Field Electrodes for the ISIS H⁻ Injector

ion, controls, radiation, beam-losses

1371

P.G. Barnes, G.M. Cross, B.S. Drumm, S.A. Fisher, S.J. Payne, A. Pertica, C.C. Wilcox
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Beam profile measurements within the ISIS H⁻ injector line are achieved using destructive devices such as moving wire scanners. To avoid damage to the wires, measurements are made with the injector operating on reduced power. This paper reports the development of a Micro-Channel Plate based profile monitor which allows beam measurements to be made under normal operating conditions. The monitor produces profiles by measuring the +ion current resulting from the interaction of the H⁻ beam with the surrounding residual gas. The 32 channel Micro-Channel Plate is mounted on a rotating arm to enable it to be positioned parallel to the beam for calibration (all channels then measure the same +ion current) and perpendicular to the beam for profile measurements. A 15kV drift field is used together with field shaping electrodes to ensure a flat electric field gradient across the monitor, thereby minimising distortion of the profile due to the electric field. This paper details all aspects of the design and construction of this profile monitor. Beam profiles are compared to previous wire scanner results. Shaping field upgrades are discussed to improve the longitudinal field shape.

TUPC163

Experimental Results from Test Measurements with the USR Beam Position Monitoring System

pick-up, simulation, storage-ring, alignment

1416

J. Harasimowicz, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J. Harasimowicz, I. Takov
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported by STFC, the EU under GA-ITN-215080, the Helmholtz Association and GSI under VH-NG-328.
A diagonal-cut capacitive pick-up (PU) was optimised for monitoring slow (v < 0.025c), long (~1 m) bunches consisting of only about 10⁶ antiprotons at the future Ultra-low energy Storage Ring (USR). Ultra-low noise (0.5 nV/Hz⁰.5) FET pre-amplifiers are used to allow detection of the weak signals generated in the PU plates. The amplified signals are then digitized by a 16-bit, 200 MS/s ADC and processed in a digital manner. The following contribution presents the beam monitoring system as it was tested with a stretched-wire method and compares the measurements with the results from 3D electromagnetic simulations.

TUPC178

Charge Lifetime Study of K2CsSb Photocathode Inside a Jlab DC High Voltage Gun

laser, cathode, gun, high-voltage

1443

R.R. Mammei, M. Poelker, R. Suleiman
JLAB, Newport News, Virginia, USA
J.L. McCarter
UVa, Charlottesville, Virginia, USA
T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE
Two photocathodes are frequently considered for generating high average current electron beams and/or beams with high brightness for current and future accelerator applications: GaAs:Cs and K2CsSb. Each photocathode has advantages and disadvantages, and need to demonstrate performance at “production” accelerator facilities. To this end a K2CsSb photocathode was manufactured at Brookhaven National Lab and delivered to Jefferson Lab within a compact vacuum apparatus at pressure ~ 5x10^-11 Torr. This photocathode was installed inside a dc high voltage photogun biased at voltages up to 200 kV, and illuminated with laser light at 440 or 532 nm, to generate beams up to 20 mA. Photocathode charge lifetime measurements indicate that under some conditions this cathode has exceptionally high charge lifetime, without measurable QE decay, even from the center of the photocathode where operation using GaAs photocathodes is precluded due to ion bombardment. These studies also suggest a complex QE decay mechanism likely related to chemistry and localized heating via the laser beam.

TUPO029

Status of the BERLinPro Optics Design

emittance, linac, optics, electron

1500

A.N. Matveenko, M. Abo-Bakr, A.V. Bondarenko, A. Jankowiak, J. Knobloch, B.C. Kuske, Y. Petenev
HZB, Berlin, Germany

Following funding approval late 2010, Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a high-current (100 mA) low emittance beam (1 mm•mrad normalized), as required for future ERL-based synchrotron light sources. Given the flexibility ERLs provides, a short bunch operation mode will also be investigated. Current optics was designed to allow of low emittance and short bunch operation modes. Optics is flexible to suppress BBU and minimize CSR effects. Estimation of impact of ion accumulation, wake fields, halo and chromatic aberrations is given. Requirements for beam diagnostic system, alignment accuracy and power supply stability are investigated.

TUPS001

Upgrade of the ESRF Vacuum System

storage-ring, controls, cathode, synchrotron

1515

M. Hahn, J.C. Biasci, H.P. Marques, A. Meunier
ESRF, Grenoble, France

The upgrade program of the ESRF concerns in terms of electron storage ring vacuum chambers mainly the insertion device (ID) sectors. Here the length available for the production of intense synchrotron light is being increased from five to six or even seven meters. The presence of canted ID sectors where two independent synchrotron light beams will be produced in the same straight section requires new quadrupole chambers compatible with the new geometry. A number of long insertion device vacuum chambers for the new ID sectors has already been produced by ESRF and coated with non-evaporable getter (NEG) material, a new generation of in vacuum undulators for the extended ID sections are under preparation. This paper outlines the status of the modification of the vacuum system and informs about consequences for the ESRF NEG coating activity and some recent improvements of the vacuum measurement and control system.

TUPS002

Photodesorption Measurements at ESRF D31

radiation, synchrotron, synchrotron-radiation, electron

1518

H.P. Marques, G. Debut, M. Hahn
ESRF, Grenoble, France

Since 1998 exists at ESRF a dedicated beamline for photodesorption measurement from vacuum chambers - D31. The original goal of this installation was to study the wall pumping effect. When exposed to synchrotron radiation surfaces exhibit strong outgassing of the adsorbed gas layer despite UHV conditions. Long term outgassing leads to the depletion of the adsorbed layer and produces a very clean surface which turns the walls of the vacuum chamber into an active pumping surface. The desorption mechanisms can be described by the long standing models of Knotek-Feibelman (KF) and Menzel-Gomer-Redhead – (MGR) which are themselves encompassed under the name of Desorption Induced by Electronic Transitions (DIET). In these models the surface itself plays a fundamental role in the desorption mechanism. At D31 have been tested chambers of stainless steel, aluminum and copper, with or without coatings (e.g. NEG, copper), designed by ESRF and other institutes like ALBA, CERN, ELETTRA and Soleil. Here we review some of the results obtained and outline the future plans of D31.

TUPS003

Upgrade of the ESRF RGA System

controls, diagnostics, monitoring, survey

1521

A. Meunier, M. Hahn, I. Parat, J.L. Pons
ESRF, Grenoble, France

In the frame of the ESRF upgrade program, the Residual Gas Analyzer (RGA) system has been reviewed. A campaign of RGA refurbishment has been started recently giving more reliability and accuracy on partial pressure vacuum control. Based on new technologies and our operating experience, new RGA monitoring application and diagnostic tools have been developed. This paper outlines the evolution of the actual RGA system focusing on the controlled hardware installation description, on software and user interface developments. The continuous follow up of a defined number of partial pressure measurements using different dynamic control modes will be described.

TUPS004

Enhanced High-voltage Holding under Vacuum by Field Induced Adsorption of Gas on Metal Surfaces

high-voltage, electron, cathode, plasma

1524

A. Simonin, L. Christin, L. Doceul, F. Faisse, F. Villecroze, H. de Esch
CEA, St Paul Lez Durance, France

*The energy of future neutral beam injector heating systems of fusion power plants ranges from 1 to 2 MeV. The beam line and the reactor chamber are under vacuum, while all the electrical components (power supplies) are connected to the injector via a long pressured (SF6) high-voltage (1-2 MV) transmission line. The bushing is a key component that ensures the barrier between the transmission line and the injector under vacuum; the design of this component is very challenging as it faces several stringent constraints due to the nuclear environment, in which high-voltage holding, mechanical stresses, and radiations are combined. Moreover, it is a high-voltage feed-through that allows supply of the accelerator electrodes with electrical power, active water cooling, and gas. In this paper, a new high-voltage bushing concept based on experimental findings previously obtained in the laboratory is presented. The main advantages of the concept is a reduction of the electron field emission under vacuum, which is an issue for conventional bushings, a reduction in size, and mechanical simplification of the device resulting in cost reduction and greater reliability."

TUPS007

Construction and Test of a Cryocatcher Prototype for SIS100*

ion, heavy-ion, controls, beam-losses

1527

L.H.J. Bozyk, D.H.H. Hoffmann
TU Darmstadt, Darmstadt, Germany
H. Kollmus, P.J. Spiller, M. Wengenroth
GSI, Darmstadt, Germany

Funding: EU-FP-7 project COLMAT, FIAS
The main accelerator, SIS100, of the FAIR-facility will provide heavy ion beams of highest intensities. Ionization beam loss is the most important loss mechanism at operation with high intensity, intermediate charge state heavy ions. A special synchrotron design has been developed for SIS100, aiming for hundred percent control of ionization beam loss by means of a dedicated cold ion catcher system. To suppress dynamic vacuum effects, the cryo catcher system shall also provide a significantly reduced effective desorption yield. The construction and tests of a prototype cryo ion catcher is a workpackage of the EU-FP-7 project COLMAT. A prototype test setup including cryostat has been constructed, manufactured and tested at GSI under realistic conditions with heavy ion beams of the of the heavy ion synchrotron SIS18. The design and results are presented.

TUPS008

The Gas Attenuator Vacuum System of FERMI@Elettra

photon, radiation, FEL, electron

1530

L. Rumiz, D. Cocco, C. Fava, S. Gerusina, R. Gobessi, E. Mazzucco, F. Zudini
ELETTRA, Basovizza, Italy
M. Zangrando
IOM-CNR, Trieste, Italy

The FERMI@Elettra Free Electron Laser aims to produce a coherent light in the EUV-soft X-ray range employing High Gain Harmonic Generation (HGHG) schemes. The ultrafast, high intensity pulses are delivered to the experimental stations by means of a section called PADReS (Photon Analysis Delivery and Reduction System). Since several experiments need to reduce the FEL radiation intensity without changing the machine parameters, PADReS provides an integrated system to measure and reduce it up to 4 orders of magnitude. It is composed by a windowless gas-filled cell, a gas injection system, a differential pumping system, and the intensity monitors. The gas cell can be filled up to 0.15 mbar of nitrogen and the differential pumping system can keep up over 6 orders of magnitude. The pressure is finely regulated in the ·10^-5 mbar range in the intensity monitor vacuum chamber, almost independently from the gas cell pressure level. The general layout and the performance of the differential pumping system prototype are presented.

TUPS010

A Novel Approach in UHV Pumping of Accelerators: the NEXTorr® Pump

ion, insertion, insertion-device, synchrotron

1536

P. Manini, A. Bonucci, L. Caruso, A. Conte, F. Siviero, L. Viale
SAES Getters S.p.A., Lainate, Italy

In spite of the large dimensions of accelerators, like synchrotrons or colliders, the space available for mounting UHV pumps is getting smaller, due to design constraints, service equipments, conductances, magnets, various instrumentations. This poses challenges to traditional UHV pump designs which are called to provide more pumping performances in smaller spaces. A radically new approach is here presented which can mitigate this issue. In this approach Non Evaporable Getter (NEG) and ion pumping technologies are properly combined and integrated in one single device, called NEXTorr®, having a unique design. In this pump, the getter cartridge acts as the main UHV pumping element, leaving to a small sputter ion pump the ancillary task of removing noble gases and methane, not pumped by the NEG. This design allows achieving large pumping speed in a very small package as well as delivering interesting pumping synergies. Main features of this new pump, including pumping tests, and example of applications will be reported, with a special focus to accelerators and high energy physics systems. Its impact in the design of vacuum systems for accelerators will also be discussed.

TUPS011

Use of NEG Pumps to Ensure Long Term Performances of High Quantum Efficiency Photocathodes

ion, cathode, photon, gun

1539

L. Monaco, P.M. Michelato, D. Sertore
INFN/LASA, Segrate (MI), Italy
P. Manini, F. Siviero
SAES Getters S.p.A., Lainate, Italy

Laser triggered photo-cathodes are key components of the electron sources of 4th generation light machines. However, they are very sensitive to the vacuum level and its composition. Photo-cathodes are usually prepared in UHV chamber and then transferred, keeping the extreme vacuum condition, to the operation sites. Since transportation/storage may last from several days to weeks, retaining UHV conditions is a fundamental task to the photocathode usage. In this paper the results obtained using a novel pumping approach are given. This approach is based on coupling a 20 l.s⁻¹ ion getter pump with a Capacitorr® D100 Non Evaporable Getter (NEG) pump. Pressure of 2x10-11 mbar was achieved with the NEG pump after 2 days bake-out, as compared to 8x10-10 mbar achieved with the ion pump alone, after 7 days bake-out. Such pressure values were retained even in absence of power, due to the ability of the NEG to remove gases by chemical reaction. Long term monitoring of cathodes QEs was also carried out at different photon wavelengths over more than 6 months, showing no degradation of the photo-emissive film properties.

TUPS012

The Present Status of Vacuum System of XFEL in SPring-8

shielding, electron, undulator, laser

1542

T. Bizen
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Hasegawa
RIKEN/SPring-8, Hyogo, Japan

The vacuum component assembly and installation were completed by February in 2011. The total length of the vacuum system is about 630 m. A 455 sputter ion pumps and a 10⁸ NEG cartridge pumps generate vacuum. The average pressures are on the order of ·10^-7 Pa or less. The flange developed for C-band waveguide shows high reliability of vacuum seal.

TUPS013

Development of the H0 Dump Branch Duct for the Additional Collimation System in J-PARC RCS

septum, shielding, collimation, beam-losses

1545

M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

For the new collimation system in the J-PARC RCS, we have the H0 branch duct installed at the dump septum magnet remodeled. This new branch duct is made of the two kinds of the stainless steels as follows; austenitic stainless steel, SUS316L and ferritic stainless steel, SUS430. In order to research on the property of the SUS430, test ducts were made in various heat-treating condition. In this presentation, we report the design of the new H0 branch duct and the study results with the test ducts.

TUPS014

Vacuum Performance Simulation of C-band Accelerating Structures

cavity, linac, simulation, free-electron-laser

1548

H. Lee, M.-H. Cho, S.H. Kim, C.H. Yi
POSTECH, Pohang, Kyungbuk, Republic of Korea
W. Namkung, C.D. Park
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work is partly supported by the MEST and POSTECH Physics BK21 program.
A C-band accelerating structure has a higher accelerating gradient than that of the S-band structure. It provides a good advantage of a shorter machine length. In order to effectively use RF power and for cost reduction, the accelerating structure should be as long as possible. We propose a 2.2-m long structure compared to 1.8-m at SACLA (SPring-8 Angstrom Compact free electron LAser). However, a longer accelerating structure has worse vacuum performance than a shorter accelerating structure. Thus, the vacuum conductance of 2.2-m long structure has to be checked. We calculate vacuum performance of the accelerating structure by 1-D analytical method and 3-D finite element method (FEM). It is shown that the vacuum performance for the 2.2-m long accelerating structure is safe enough for the XFEL LINAC.

TUPS015

ALBA Storage Ring Vacuum System Commissioning

storage-ring, photon, cavity, synchrotron

1551

E. Al-dmour, D. Einfeld
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The ALBA booster and storage ring vacuum system installation has been done in 2009, followed by the installation of the RF cavities and the booster to storage transfer line in 2010. Early 2011, the first phase of insertion devices (ID) installation took place, with three narrow gap NEG coated vacuum chambers have been installed, for the use of two Apple-II undulators and one conventional wiggler. On 8th of March 2011, the storage ring commissioning started and it was marked with the achievement of the first turn in the storage ring on the 9th of March and on the 1st of April 2011, 100 mA of beam current has been accumulated. During this period the vacuum system conditioning took place with very good performance. The base pressure without beam was 4·10^-10 mbar and the average pressure with 100 mA was 7.7·10^-9 mbar. The results of the conditioning together with the latest developments are introduced.

TUPS016

Vacuum System Design for the MAX IV 3 GeV Ring

storage-ring, synchrotron, lattice, radiation

1554

E. Al-dmour, D. Einfeld, J. Pasquaud, M. Quispe
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
J. Ahlbäck, M.J. Grabski, P.F. Tavares
MAX-lab, Lund, Sweden

We describe the conceptual design of the vacuum system of the 3 GeV electron storage ring in the MAX IV facility currently under construction in Lund, Sweden. The standard vacuum chambers are for the most part a cylindrical copper tube with 11 mm inner radius whereas stainless steel will be used at selected locations for beam position monitors, bellows and corrector vacuum chambers. In order to cope with the low vacuum conductance, distributed pumping will be provided through NEG coating of all chambers, including those in dipole magnets making MAX IV the first storage ring to be fully NEG coated. We present the mechanical and thermal design of these chambers and discuss the challenges involved in extracting insertion device radiation as well as coping with the heat load from both IDs and bending magnets in a machine with large bending radius, narrow chambers and tight mechanical tolerance requirements.

TUPS017

The LHC Experimental Beam Pipe Neon Venting, Pumping and Conditioning

injection, ion, monitoring, shielding

1557

V. Baglin, G. Bregliozzi, D. Calegari, J.M. Jimenez, G. Lanza, G. Schneider
CERN, Geneva, Switzerland

The experimental vacuum chambers of the four LHC experiments (ATLAS, CMS, LHCb and ALICE) are mechanically optimized in order to be transparent to particles. In order to grant their mechanical stability and to avoid any overstress, every time there was a request for detector opening or closing and for working in the vicinity of the vacuum chamber, the experimental beam vacuum chambers have been vented to atmospheric pressure. Since the LHC start up a safety procedure has been applied to mechanically secure the four experimental beam pipes during each long technical stop. Ultra-pure neon was used to preserve at best the NEG pumping efficiency. Up to now more than 15 neon injections and pump down have been performed without detecting any reduction of the NEG efficiency. This paper describes the Gas Injection System performances and the main points of the venting and pumping procedure. Details of the experimental beam pipe vacuum recovery and conditioning are presented for each of the four LHC experiments (ATLAS, CMS, LHCb and ALICE).

TUPS018

Observations of Electron Cloud Effects with the LHC Vacuum System

electron, solenoid, simulation, ion

1560

V. Baglin, G. Bregliozzi, P. Chiggiato, P. Cruikshank, B. Henrist, J.M. Jimenez, G. Lanza
CERN, Geneva, Switzerland

In autumn 2010, during the LHC beam commissioning, electron-cloud effects producing pressure rise in common and single vacuum beam pipes, were observed. To understand the potential limitations for future operation, dedicated machine studies were performed with beams of 50 and 75 ns bunch spacing at energy of 450 GeV. In order to push further the LHC performances, a scrubbing run was held in spring 2011. This paper summarizes the vacuum observations made during these periods. The effects of bunch intensity and different filling schemes on the vacuum levels are discussed. Simulations taking into account the effective pumping speed at the location of the vacuum gauge are introduced. As a consequence, the different vacuum levels observed along the LHC ring could be explained. Finally, the results obtained during the scrubbing run are shown together with an estimation of pressure profiles during the 2011 run.

TUPS019

Synchrotron Radiation in the LHC Vacuum System

photon, dipole, radiation, proton

1563

V. Baglin, G. Bregliozzi, J.M. Jimenez, G. Lanza
CERN, Geneva, Switzerland

CERN is currently operating the Large Hadron Collider (LHC) with 3.5 TeV per beam. At this energy level, when the protons trajectory is bent, the protons emit synchrotron radiation (SR) with a critical energy of 5.5 eV. Under operation, SR induced molecular desorption is routinely observed in the LHC arcs, long straight sections and experiments. This contribution recalls the SR parameters over the LHC ring for the present and nominal beam parameters. Vacuum observations during energy ramp, after accumulation of dose and along the LHC ring are discussed. Expected pressure profiles and long term behaviours of vacuum levels will be also addressed.

TUPS020

Leak Tightness of LHC Cold Vacuum Systems

cryogenics, superconducting-magnet, controls, proton

1566

P. Cruikshank, S.D. Claudet, W. Maan, L. Mourier, A. Perrier-Cornet, N. Provot
CERN, Geneva, Switzerland

The cold vacuum systems of the LHC machine have been in operation since 2008. While a number of acceptable helium leaks were known to exist prior to cooldown and have not significantly evolved over the last years, several new leaks have occurred which required immediate repair activities or mitigating solutions to permit operation of the LHC. The LHC vacuum system is described together with a summary and timetable of known air and helium leaks and their impact on the functioning of the cryogenic and vacuum systems. Where leaks have been investigated and repaired, the cause and failure mechanism is described. We elaborate the mitigating solutions that have been implemented to avoid degradation of known leaks and minimize their impact on cryogenic operation and LHC availability, and finally a recall of the consolidation program to be implemented in the next LHC shutdown.

TUPS021

Simulations and Vacuum Tests of a CLIC Accelerating Structure

simulation, cavity, ion, damping

1569

C. Garion
CERN, Geneva, Switzerland

The Compact LInear Collider, under study, is based on room temperature high gradient structures. The vacuum specificities of these cavities are low conductance, large surface areas and a non-baked system. The main issue is to reach UHV conditions (typically 10^-7 Pa) in a system where the residual vacuum is driven by water outgassing. A finite element model based on an analogy thermal/vacuum has been built to estimate the vacuum profile in an accelerating structure. Vacuum tests are carried out in a dedicated set-up, the vacuum performances of different configurations are presented and compared with the predictions.

TUPS022

MedAustron Beam Vacuum System : From sources to Patient Treatment Rooms

synchrotron, instrumentation, ion, dipole

1572

J.M. Jimenez, P. Cruikshank, L. Faisandel, W. Maan
CERN, Geneva, Switzerland
T. Hauser, G. Hulla, P. Landrot, J. Wallner
EBG MedAustron, Wr. Neustadt, Austria

The MedAustron beam vacuum system is a complex system integrating different technical solutions from the source to the patient treatment rooms. The specified vacuum performances combined with the challenging integration issues require technical compromise which will be presented in this poster. The status of the design of the vacuum system will be reviewed and the pending issues will be explained.

TUPS023

Secondary Electron Yield on Cryogenic Surfaces as a Function of Physisorbed Gases

electron, cryogenics, gun, insertion

1575

A. Kuzucan, H. Neupert, M. Taborelli
CERN, Geneva, Switzerland
H. Stoeri
IAP TUW, Wien, Austria

Electron cloud is a serious limitation for the operation of particle accelerators with intense positively charged beams. It occurs if the secondary electron yield (SEY) of the beam-pipe surface is sufficiently high to induce an electron multiplication. At low surface temperatures, the SEY is strongly influenced by the nature of the physisorbed gases and by the corresponding surface coverage. These conditions occur in many accelerators operating with superconducting magnets and cold vacuum sections such as the LHC and RHIC. In this work, we investigated the variation of the SEY of copper, aluminium and electro-polished copper as a function of physisorbed N2, CO, CO2, CH4, Kr, C2H6 at cryogenic temperatures. The conditioning by electron bombardment of the surface after the physisorption of H2O on electro polished copper will also be presented. The results of the various gases are compared in order to find a rationale for the behaviour of the secondary electrons for the various adsorbates.

TUPS024

Development of Beryllium Vacuum Chamber Technology for the LHC

electron, collider, controls, background

1578

R. Veness
CERN, Geneva, Switzerland
C. Dorn, G. Simmons
Materion Electrofusion, Fremont, California, USA

Beryllium is the material of choice for the beam vacuum chambers around collision points in particle colliders due to a combination of transparency to particles, high specific stiffness and compatibility with ultra-high vacuum. New requirements for these chambers in the LHC experiments have driven the development of new methods for the manufacture of beryllium chambers. This paper reviews the requirements for experimental vacuum chambers. It describes the new beryllium technology adopted for the LHC and experience gained in the manufacture and installation.

TUPS025

Design of a Highly Optimised Vacuum Chamber Support for the LHCb Experiment

radiation, background, interaction-region, collider

1581

L. Leduc, G. Corti, R. Veness
CERN, Geneva, Switzerland

The beam vacuum chamber in the LHCb experimental area passes through the centre of a large aperture dipole magnet. The vacuum chamber and all its support systems lie in the acceptance of the detector, so must be highly optimised for transparency to particles. As part of the upgrade programme for the LHCb vacuum system, the support system has been re-designed using advanced lightweight materials. In this paper we discuss the physics motivation for the modifications, the criteria for the selection of materials and tests performed to qualify them for the particular environment of a particle physics experiment. We also present the design of the re-optimised support system.

TUPS026

Specification of New Vacuum Chambers for the LHC Experimental Interactions

alignment, impedance, injection, optics

1584

R. Veness, R.W. Assmann, A. Ball, A. Behrens, C. Bracco, G. Bregliozzi, R. Bruce, H. Burkhardt, G. Corti, M.A. Gallilee, M. Giovannozzi, B. Goddard, D. Mergelkuhl, E. Métral, M. Nessi, W. Riegler, J. Wenninger
CERN, Geneva, Switzerland
N. Mounet, B. Salvant
EPFL, Lausanne, Switzerland

The apertures for the vacuum chambers at the interaction points inside the LHC experiments are key both to the safe operation of the LHC machine and to obtaining the best physics performance from the experiments. Following the successful startup of the LHC physics programme the ALICE, ATLAS and CMS experiments have launched projects to improve physics performance by adding detector layers closer to the beam. To achieve this they have requested smaller aperture vacuum chambers to be installed. The first periods of LHC operation have yielded much information both on the performance of the LHC and the stability and alignment of the experiments. In this paper, the new information relating to the aperture of these chambers is presented and a summary is made of analysis of parameters required to safely reduce the vacuum chambers apertures for the high-luminosity experiments ATLAS and CMS.

TUPS027

Characterization of Carbon Coatings with Low Secondary Electron Yield

electron, cryogenics, ion, gun

1587

C. Yin Vallgren, S. Calatroni, P. Costa Pinto, A. Kuzucan, H. Neupert, M. Taborelli
CERN, Geneva, Switzerland

Amorphous carbon (a-C) coatings can reliably be produced with a maximum secondary electron yield (SEY) close to 1 at room temperature. Measurements at low temperature (LHe) are in progress. Analysis by X-ray Photoemission Spectroscopy (XPS) shows a correlation between the lineshape of C1s spectrum in XPS and maximum SEY of the investigated samples. The initial level of oxygen on the surface of the various samples does not seem to be related to the initial maximum SEY value. However, the increase of the SEY with air exposure time on each individual sample is related to the amount of oxygen containing adsorbates. Storage in different environments has been investigated (static vacuum, aluminum foil, dry nitrogen and desiccators) and shows significant differences in the “aging” behavior. Aging is very moderate when storing samples wrapped in aluminum foil in air. Samples which have undergone aging due to inappropriate storage can be recovered nearly to the initial value of the SEY by typical surface treatments as ion bombardment, annealing under vacuum and conditioning by electron beam. However, an enhanced sensitivity to air exposures is observed for most of these curing methods.

TUPS028

Performance of Carbon Coating for Mitigation of Electron Cloud in the SPS

electron, dipole, insertion, extraction

1590

C. Yin Vallgren, P. Chiggiato, P. Costa Pinto, H. Neupert, G. Rumolo, E.N. Shaposhnikova, M. Taborelli
CERN, Geneva, Switzerland

Amorphous carbon (a-C) coatings have been tested in electron cloud monitors (ECM) in the Super Proton Synchrotron (SPS) and have shown for LHC type beams a reduction of the EC current by a factor 10⁴ compared to stainless steel (SS). This performance has been maintained for more than 2 years under SPS operation conditions. Secondary electron yield (SEY) laboratory data confirm that after 1 year of SPS operation, the coating maintains a SEY below 1. The compatibility of coexisting SS and a-C surfaces has been studied in an ECM having coated and uncoated areas. The results show no degradation of the properties of the a-C areas. The performance of diamond like carbon (DLC) coating has also been studied. DLC shows a less effective reduction of the EC current than a-C, but conditioning is faster than for SS. Three a-C coated dipoles were inserted in the SPS. However, even with no EC detected, the dynamic pressure rise is similar to the one observed in the SS reference dipoles. Measurement in a new ECM equipped with clearing electrodes to verify the relation between pressure signals and intensity of the EC, as well as an improvement of the diagnostics in the dipoles are in progress.

TUPS029

Development of a Feedthrough with Small Reflection for the TPS BPM

impedance, synchrotron, controls

1593

Huang, Y.T. Huang, C.-C. Chang, C.L. Chen, G.-Y. Hsiung, S-N. Hsu, H.P. Hsueh
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The TPS BPM feedthrough is a coaxial cable with a structure of a kind for which power loss occurs readily at places at which exists an impedance mismatch. With an impedance equation for a simple coaxial cable combined with a multi-dielectric modification, a model feedthrough with small reflection has been designed. With careful setting of brazing conditions and precise control of the dimensions of devices, a TPS prototypical BPM feedthrough having a reflection coefficient less than 0.05 was manufactured. The eccentricity was constrained within 0.03 mm, and the deviation of measured capacitance of button electrodes was less than 7 %.

TUPS030

Manufacturing and Vacuum Testing of Aluminum Bending Chambers for TPS

ion, photon, synchrotron, electron

1596

Y.C. Yang, C.K. Chan, C.-C. Chang, C.L. Chen, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu, T.Y. Lee
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is an aluminum alloy vacuum system with 518.4 m circumference divided into 24 sections. A6061T6 aluminum alloy material is used for TPS bending chambers. Each aluminum bending chamber is component of 2 half plates, about 3.5～4.2 m in length and～0.6 m in width, were oil-free CNC machined, ozone cleaned, and TIG welding in clean room. The deformation < 0.1 mm and leakage rate < 2x10-9mbar. L/s for each welded bending chamber has inspected and achieved. A bending chamber is inspecting the thermal outgassing rate test and ultimate pressure. The manufacturing and vacuum test will be described in this paper.

TUPS031

The Installation of One 14 Meter Cell of TPS Vacuum System

photon, laser, synchrotron, site

1599

H.P. Hsueh, C.K. Chan, C.H. Chang, C.-C. Chang, C.L. Chen, C.M. Cheng, Y.T. Cheng, G.-Y. Hsiung, S-N. Hsu, I.T. Huang, T.Y. Lee, H.Y. Yan, Y.C. Yang, C.S. huang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The construction of a new 3 GeV synchrotron facility, Taiwan Photon Source, is ongoing. The vacuum system has been designed with off-site baking for arc section from sector gate valve to sector gate valve. There is no flange used in this arc section besides the two ends connected to sector gate valves. It is a tedious works for install such long vacuum system with aluminum chambers. In this poster, all the detailed installation procedures will be described. All the precaution inspection procedures for all vacuum components to prevent failed components to be installed will also be described. Every three weeks, one cell will be assembled and stored. Experience is being learned and could be used for the vacuum system of future new accelerator like FEL and others.

TUPS033

Foil Scattering Loss Mitigation by the Additional Collimation System of J-PARC RCS

injection, collimation, septum, scattering

1605

K. Yamamoto, H. Harada, J. Kamiya, Y. Yamazaki, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In the RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. From the beam study, we were certain that these losses were caused by the scattering of the injection and circulating beam at the charge exchange injection foil. In order to mitigate these losses, we started to develop a new collimation system in the H0 branch duct. We presents a overview of this new collimation system.

TUPS038

Design of a Beam Dump for 3 to 100 MeV for the New H⁻ Beam in the CERN Linac4

linac, proton, radiation, ion

1620

C. Maglioni
CERN, Geneva, Switzerland

In this paper the design of a beam dump for the energy range from 3 to 100 MeV is reported. The dump is developed as temporary dump for the commissioning phase of the Linac4 Project, under construction at CERN, and will be installed in different periods to withstand a beam of different intensities and energies, following the chronological assembly of the linac. The dump design and its functionalities, as well as material choice, criticalities and cooling system are described. Finally, the results from the numerical and analytical thermo-mechanical analyses are reported, while the use of the dump also at 160 MeV is investigated.

TUPS051

Design and Performance of the MICE Target*

target, controls, acceleration, extraction

1644

C.N. Booth, P. Hodgson, E. Overton, M. Robinson, P.J. Smith
Sheffield University, Sheffield, United Kingdom
G.J. Barber, K.R. Long
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
E.G. Capocci, J.S. Tarrant
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
B.J.A. Shepherd
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: UK Science and Technology Facilities Council
The MICE experiment uses a beam of low energy muons to study ionisation cooling. This beam is derived parasitically from the ISIS synchrotron at the Rutherford Appleton Laboratory. A mechanical drive has been developed which rapidly inserts a small titanium target into the beam after acceleration and before extraction, with minimal disturbance to the circulating protons. One mechanism has operated in ISIS for over half a million pulses, and its performance will be summarised. Upgrades to this design have been tested in parallel with MICE operation; the improvements in performance and reliability will be presented, together with a discussion of further future enhancements.

TUPS058

HiRadMat: A New Irradiation Facility for Material Testing at CERN

proton, target, ion, radiation

1665

I. Efthymiopoulos, S. Evrard, H. Gaillard, D. Grenier, C. Heßler, M. Meddahi, A. Pardons, C. Theis, P. Trilhe, H. Vincke
CERN, Geneva, Switzerland
N. Charitonidis
EPFL, Lausanne, Switzerland

HiRadMat (High Irradiation to Materials) is a new facility under construction at CERN designed to provide high-intensity pulsed beams to an irradiation area where material samples as well as accelerator component assemblies can be tested. The facility uses a 440 GeV proton beam extracted from the CERN SPS with a pulse length of 7.2 μs, to a maximum pulse energy of 3.4 MJ. In addition to protons, ion beams with an energy of 173.5 GeV/nucleon and a total pulse energy of 21 kJ can be used. The facility is expected to become operational in autumn 2011. The first tests will include candidate materials and prototype assemblies of LHC collimators foreseen to operate at the ultimate LHC beam powers. Experiments on beam windows and high-power target material options, such as tungsten powder, are also planned. The paper will describe the layout and design parameters for the facility and the way experiments can be operated. Ideas on online and post-irradiation tests and instrumentation will be outlined.

TUPS066

Design of Front End Safety Interlock System for Taiwan Photon Source

controls, photon, radiation, status

1689

H.Y. Yan, J.-R. Chen, G.-Y. Hsiung, C.K. Kuan, I.C. Sheng, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

Safety interlock is one of critical subsystems in synchrotron radiation accelerator. A front end (FE) interlock prototype system has been designed, fabricated, and initially tested for Taiwan Photon Source (TPS). TPS FE interlock logic is designed based on that of Taiwan Light Source (TLS), and moderately modified due to the accelerator parameter discrepancy between TPS and TLS. The programmable automation controllers (PAC) have been utilized in FE safety interlock system for their reliability, convenience, processing capability, communication, and stability in user interface. In FE PAC system, touch panels are used as the graphical user interface (GUI) to control and monitor FE components. In addition, with GUI control it is used to beam position monitoring devices as well as confined beam sizes aperture for beam line users. The interlock design such as data acquisition and parameters monitoring for vacuum pressure, flow rate of cooling water, pressure of compressive air, chamber and water temperature, and overall interlock logic are also presented in this paper.

TUPS067

Photon-stimulated Desorption Experiment for a TPS Crotch Absorber

synchrotron, photon, simulation, radiation

1692

Y.T. Cheng, G.-Y. Hsiung, C.K. Kuan, A. Sheng, H.Y. Yan
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

National Synchrotron Radiation Research Center (NSRRC) is constructing a large third-generation synchrotron accelerator in Taiwan, the so-called Taiwan Photon Source (TPS). This 3-GeV, 500-mA machine will generate high-density bending-magnet radiation, of which 90 % of the power is absorbed by the crotch absorber in the storage ring. To understand better the beam-cleaning and photon-desorption phenomena of a copper crotch absorber, we have performed a PSD (photon-stimulated desorption) test in Taiwan Light Source (TLS) at Beam line 19 (BL19). Some mathematical modelling, experimental designs and results are also presented here.

TUPS079

Construction of a Novel Compact High Voltage Electrostatic Accelerator

high-voltage, target, ion, ion-source

1722

P. Beasley, O. Heid
Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany

A compact demonstrator system based on a Cockcroft-Walton (or Greinacher) cascade has been successfully built and tested. The concept has been developed using modern materials and a different design philosophy, which in turn can then enable this novel configuration to operate at much higher voltage gradients. This paper explores the progress made over the past 18 months and future plans to utilise the technology to develop one such concept for an energy efficient 10MV, 100μA, tandem proton accelerator, with a <2m2 footprint. The development of such a compact high voltage particle accelerator, with high current capability has the potential to access a wide range of commercial opportunities outside the laboratory.

TUPS082

The LEBT Chopper for the Spiral 2 Project

controls, ion, high-voltage, target

1731

A.C. Caruso, F. Consoli, G. Gallo, D. Rifuggiato, E. Zappalà
INFN/LNS, Catania, Italy
M. Di Giacomo
GANIL, Caen, France
A. Longhitano
ALTEK, San Gregorio (CATANIA), Italy

The Spiral 2 driver uses a slow chopper situated in the common section of the low energy beam transport line to change the beam intensity, to cut off the beam in case of critical loss and to avoid hitting the wheel structure of rotating targets. The device has to work up to 10 kV, 1 kHz repetition frequency rate and its design is based on standard power circuits, custom alarm board and vacuum feed-through. The paper summarizes the design principles and describes the test results of the final device which has been installed on the beam line test bench.

TUPS086

Ultra-high Resolution Observation Device for Carbon Stripper Foil

radiation, monitoring, scattering, proton

1740

Y. Takeda, Y. Irie, I. Sugai
KEK, Ibaraki, Japan

To observe a growth process of a pinhole on a HBC-foil due to beam irradiation, an up to 10 um of device for ultra-high resolution observation is needed. For the environment where we use the device for observation is so severe as under high radiation and in vacuum, there is no device available for long-time observation. Then, we designed and created a wholly new method based system which enables constant observation by ultra-high resolution even under high radiation environment. We attempted several experiments, compared materials usable under radiation environment, checked up various optical systems which enables high resolution, and finally developed the best method. As a result, we successfully invented an ultra-high resolution observation device available for monitoring an object about 8 meters distant by 8.3um resolution.

TUPS088

Charge Stripping of Uranium-238 Ion Beam with Low-Z Gas Stripper

cyclotron, target, ion, acceleration

1746

H. Imao
RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
N. Fukunishi, A. Goto, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, H. Okuno, T. Watanabe, Y. Yano, S. Yokouchi
RIKEN Nishina Center, Wako, Japan

One of the primary goals of the RIKEN RI beam factory is to generate unprecedented high-power uranium beams (up to tens kW), which yield an enormous breakthrough for exploring new domains of the nuclear chart. The development of reliable and efficient charge stripping scheme for such high-power beams is a key unsolved issue, affecting the overall performance of the heavy ion accelerations. A charge stripper using low-Z (low atomic number Z) gas is an important candidate. Because of the suppression of the electron capture process, the high equilibrium mean charge states for the low-Z gas stripper are expected in conjunction with the intrinsic robustness of the gas. There was, however, no direct experimental data of the charge evolution, because of the difficulty in making massive windowless low-Z gas targets. In the present work, the charge evolution of the 238U beams injected at 10.75 MeV/u were investigated using thick hydrogen and helium gas strippers with huge differential pumping system newly developed. In the energy region of interest, near 10 MeV/u, achievable mean charge states around 65+ with the low-Z gas strippers are far superior to those of the medium-Z ones around 55+.

TUPS092

Research of Thermal Deformation on a Compact Cyclotron CYCHU-10

cavity, cyclotron, impedance, radio-frequency

1753

K.F. Liu
HUST, Wuhan, People's Republic of China

Nowadays, a cyclotron CYCHU-10 used for PET is under construction in Huazhong University of Science and Technology (HUST) due to the growing demands in medical applications. For space-saving and low energy consumption, the CYCHU-10 was designed compactly and accurately, especially for the RF cavity consists of the valley of the magnetic pole and the dee electrodes installed on the vacuum chamber. The RF system will supply a 10kw power and large part of it will transform into thermal energy. This paper will introduce the thermal deformation of the RF cavity and the main vacuum chamber. Meanwhile the finite elements analysis thermal deformation with ANSYS Products will be present. Finally, the cooling system for the RF cavity will be carefully designed due to the result of thermo analysis and the mechanical tolerance demand in the RF system. Keywords- thermal deformation; mechanical tolerance; FEA;RF power.

TUPS097

In-situ Experiments of Vacuum Discharge using Scanning Electron Microscopes

electron, ion, site, high-voltage

1765

T. Muranaka, V.G. Ziemann
Uppsala University, Uppsala, Sweden
T. Blom, K. Leifer
Uppsala University, Department of Engineering Sciences, Uppsala, Sweden

Funding: This work is supported by the 7th European Framework Program EuCARD under grant number 227579
Fundamental understandings of vacuum discharge mechanisms and involving surface damage is an indispensable for CLIC feasibility study. We have been conducting dc experiments inside a Scanning Electron Microscope (SEM) at Uppsala university in order to investigate localised breakdown phenomena. By using a SEM, we achieve the resolution of the electron probe in the few-nm range, which is of great advantage as the surface roughness of the polished accelerating structures is in the same scale. The high accelerating field of 1 GV/m is realised by biasing an electrode with 1 kV set above the sample with a gap of sub μm. Furthermore, a second SEM equipped with a Focused Ion Beam (FIB) is used to modify the topography of sample surfaces thus the geometrical dependence of field emissions and vacuum discharges could be studied. The FIB can be used for the surface damage analysis as well. We have demonstrated subsurface damage observations by using FIB to sputter a rectangular recess into the sample in the breakdown region. Those powerful surface analysis techniques can be productively applied to the study of fatigue in prototype accelerating structures.

TUPS099

A Study of the Surface Quality of High Purity Copper after Heat Treatment

electron, damping, linear-collider, collider

1771

M. Aicheler, G. Arnau-Izquierdo, S. Atieh, S. Calatroni, S. Lebet, G. Riddone, A. Samoshkin
CERN, Geneva, Switzerland

The manufacturing flow of accelerating structures for the compact linear collider, based on diamond-machined high purity copper components, include several thermal cycles (diffusion bonding, brazing of cooling circuits, baking in vacuum, etc.). The high temperature cycles may be carried out following different schedules and environments (vacuum, reducing hydrogen atmosphere, argon, etc.) and develop peculiar surface topographies which have been the object of extended observations. This study presents and discusses the results of scanning electron microscopy (SEM) and optical microscopy investigations.

TUPS100

Manufacturing the Linac4 PI-mode Structure Prototype at CERN

cavity, linac, alignment, controls

1774

G. Favre, A. Cherif, A. Dallocchio, J.-M. Geisser, L. Gentini, F. Gerigk, S.J. Mathot, M. Polini, S. Sgobba, T. Tardy, R. Wegner
CERN, Geneva, Switzerland

The PI-Mode Structure (PIMS) of Linac4 consists of 7-cell cavities made from alternating OFE copper discs and rings welded together with electron beam (EB) welding. A full-scale prototype cavity of almost 1.5 m in length has been manufactured, assembled, and tested at CERN to prepare the series production of 12 PIMS cavities as part of an international collaboration. This paper reports on the construction experience including machining operations, EB welding, vacuum brazing, and metrological measurements results.

TUPS103

High Temperature Radio Frequency Loads

simulation, coupling, instrumentation, impedance

1783

S. Federmann, F. Caspers, A. Grudiev, E. Montesinos, I. Syratchev
CERN, Geneva, Switzerland

In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet with 150 deg C and more than 20 bar has a certain value. Normal RF power loads containing dielectric and sensitive windows usually do not permit going much higher than 50 deg C. Here we present and discuss several design concepts for narrow-band “metal only” RF high power loads. One concept is the application of normal steel corrugated waveguides structures near cutoff .This concept could find practical use above several GHz. Another solution are resonant structures made of normal magnetic steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage the rather high losses of normal steel may also be used in coaxial line geometries with large dimensions.

TUPZ003

Simulation of Electron-cloud Build-Up for the Cold Arcs of the LHC and Comparison with Measured Data

electron, simulation, dipole, injection

1801

G.H.I. Maury Cuna
CINVESTAV, Mérida, Mexico
G. Arduini, G. Rumolo, L.J. Tavian, F. Zimmermann
CERN, Geneva, Switzerland

The electron cloud generated by synchrotron radiation or residual gas ionization is a concern for LHC operation and performance. We report the results of simulations studies which examine the electron cloud build-up, at injection energy, 3.5 TeV for various operation parameters In particular we determine the value of the secondary emission yield corresponding to the multipacting threshold, and investigate the electron density, and heat as a function of bunch intensity for dipoles and field-free regions. We also include a comparison between simulations results and measured heat-load data from the LHC scrubbing runs in 2011

TUPZ015

Electron Cloud Parameterization Studies in the LHC

electron, simulation, emittance, beam-losses

1834

C.O. Domínguez, G. Arduini, V. Baglin, G. Bregliozzi, J.M. Jimenez, E. Métral, G. Rumolo, D. Schulte, F. Zimmermann
CERN, Geneva, Switzerland

During LHC beam commissioning with 150, 75 and 50-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed. The main strategy to combat the LHC electron cloud relies on the surface conditioning arising from the chamber-surface bombardment with cloud electrons. In a standard model, the conditioning state of the beam-pipe surface is characterized by three parameters: 1. the secondary emission yield; 2. the incident electron energy at which the yield is maximum; and 3. the probability of elastic reflection of low-energy primary electrons hitting the chamber wall. Since at the LHC no in-situ secondary-yield measurements are available, we compare the relative local pressure-rise measurements taken for different beam configurations against simulations in which surface parameters are scanned. This benchmark of measurements and these simulations is used to infer the secondary-emission properties of the beam-pipe at different locations around the ring and at various stages of the surface conditioning. In this paper we present the methodology and first results from applying the technique to the LHC.

TUPZ020

Fill Analysis and Experimental Background Observations in the LHC

background, luminosity, extraction, monitoring

1846

Y.I. Levinsen, H. Burkhardt, A. Macpherson, M. Pereira, S.X. Roe
CERN, Geneva, Switzerland

Funding: Presenting author funded by the University of Oslo
In this work we look at experimental background under different conditions for the early 2011 running. We will discuss the observations in the context of the residual gas pressure, beam halo, and cross-talk between experiments. We have developed a modular fill analysis tool which automatically extracts data and analyses each fill in the LHC. All generated and extracted information is stored for outside use. The tool is applied to aid us in the work presented here.

TUPZ031

Near Beam-gas Backgrounds for LHCb at 3.5 TeV

proton, simulation, background, hadron

1876

D.R. Brett, R. Appleby
UMAN, Manchester, United Kingdom
F. Alessio, G. Corti, R. Jacobsson
CERN, Geneva, Switzerland
M.H. Lieng
UNIDO, Dortmund, Germany
V. Talanov
IHEP Protvino, Protvino, Moscow Region, Russia

Funding: STFC
We consider the machine induced backgrounds for LHCb arising from collisions of the beam with residual gas in the long straight sections of the LHC close to the experiment. We concentrate on the background particle fluxes initiated by inelastic beam-gas interactions with a direct line of sight to the experiment, with the potential impact on the experiment increasing for larger beam currents and changing gas pressures. In this paper we calculate the background rates for parameters foreseen with LHC running in 2011, using realistic residual pressure profiles. We also discuss the effect of using a pressure profile formulated in terms of equivalent hydrogen, through weighting of other residual gases by their cross section, upon the radial fluxes from the machine and the detector response. We present the expected rates and the error introduced through this approximation.

WEOBB03

Electron Bunch Profile Diagnostics in the Few fs Regime using Coherent Smith-Purcell Radiation

radiation, electron, diagnostics, linac

1970

N. Delerue
LAL, Orsay, France
R. Bartolini, G. Doucas, K. Pattle, C. Perry, A. Reichold, R. Tovey
JAI, Oxford, United Kingdom

Funding: John Fell Fund, University of Oxford
The rapid developments in the field of laser-driven particle acceleration hold the prospect of intense, highly relativistic electron bunches that are only a few fs long. The determination of the temporal profile of such a bunch presents new challenges. The use of a radiative process such as Smith-Purcell radiation (SPR), whereby the beam is made to radiate a small amount of e/m radiation and the temporal profile is then reconstructed from the measured spectral distribution of the radiation, is particularly promising in this respect. We summarize the advantages of SPR and present the design parameters of a forthcoming experiment at the FACET facility at SLAC with bunch lengths of the order of 60fs rms. We also discuss a new approach to the problem of the recovery of the ‘missing phase’, which is essential for the accurate reconstruction of the bunch profile.

Slides WEOBB03 [4.627 MB]

WEIB04

Accelertor-based Mega-science Projects in China and Their Impact on Economy

linac, ion, electron, radiation

1986

C. Zhang
IHEP Beijing, Beijing, People's Republic of China

Along with the rapid development of national economy in China, a number of accelerator based mega-science projects were constructed, such as the Beijing Electron-Positron Colliders (BEPC) and its major upgrade project (BEPCII), the Hefei Light Source (HLS), the Heavy Ion Research Facility in Lanzhou (HIRFL) and its Cooling Storage Rings (HIEFL-CSR), the Shanghai Synchrotron Radiation Facility (SSRF) and the Dragon-I induction linac. The Beijing Radioactive Ion Facility (BRIF) and the China Spallation Neutron Source (CSNS) are under construction. In this paper, China’s accelerator projects are briefly reviewed and applications of accelerators are reported. The paper emphasizes spinoff of the accelerator technology developed during R&D and construction of the projects. Collaboration between academia and industry on the projects are described. With some examples, the benefits experienced in the laboratory-industry collaboration and approach of its economic impact are illustrated.

Slides WEIB04 [14.012 MB]

WEPC050

New Optics for the SOLEIL Storage Ring

optics, injection, coupling, undulator

2124

P. Brunelle, F. Briquez, A. Loulergue, O. Marcouillé, A. Nadji, L.S. Nadolski, M.-A. Tordeux, J.F. Zhang
SOLEIL, Gif-sur-Yvette, France

SOLEIL, the French 2.75GeV synchrotron light source is delivering photons to 24 beam lines and is presently equipped with 22 insertion devices (ID) including a high field and small gap in-vacuum wiggler*. This paper presents the continuous work performed to reduce the strong non linear effects of several IDs. On one side, the ID defaults have been precisely identified using on-beam measurements, and magnetic correction developments are going on, especially for the in-vacuum wiggler and for the 10m long HU640 undulator. On the other side, a new optics has been optimised in terms of beta-functions (at the ID location) and non linear dynamics in order to improve the injection efficiency and the beam lifetime in the presence of IDs. The modified optics has been used daily in operation since November 2010 and ensures a beam lifetime greater than 10h for a 400mA stored beam with the users ID configuration. In parallel, an extensive experimental optimization has been performed to prepare the operation with an additional quadrupole triplet that provides double low vertical beta functions in one long straight section that will accommodate two canted in-vacuum insertion devices**.
* O. Marcouillé et al., IPAC10, p. 3102 (2010).
** A. Loulergue et al., IPAC10, p. 2496 (2010).

WEPC065

Design of a Low Energy Ion Beam Facility*

ion, antiproton, injection, quadrupole

2169

M.R.F. Siggel-King, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
O. Karamyshev
JINR/DLNP, Dubna, Moscow region, Russia
G.A. Karamysheva
MPI-K, Heidelberg, Germany
A.I. Papash
JINR, Dubna, Moscow Region, Russia
M.R.F. Siggel-King
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported by STFC, the EU under GA-PITN-215080, the Helmholtz Association and GSI under VH-NG-328.
A small electrostatic ring, and associated electrostatic injection beamlines, are being designed and developed. The ring will make possible a variety of experiments using a choice of many types of recirculating ions (e.g., from protons, H-, and antiprotons up to and including large charged biomolecules). A reaction microscope will be incorporated into the ring to enable differential ionization experiments between the recirculating ion beam and gas jet targets. Two injection sections have been designed to cover a variety of ion sources. The facility will be portable to enable it to be moved between facilities and beamlines and it will be unique due to its combination of design elements, flexible beam properties, energy (ca 3-30 keV) and type of circulating particles. In this paper, we give an update on this project.

WEPC106

Touschek Effect at DAΦNE for the New KLOE Run in the Crab-Waist Scheme

background, simulation, scattering, lattice

2262

M. Boscolo, P. Raimondi
INFN/LNF, Frascati (Roma), Italy
E. Paoloni
University of Pisa and INFN, Pisa, Italy
A. Perez
INFN-Pisa, Pisa, Italy

Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11)
The innovative crab-waist collision scheme has been recently implemented at DAΦNE for a new KLOE run. This scheme requires special attention to the Touschek effect, both for the lifetime and the machine induced backgrounds into the detector. These two aspects have been handled starting from the same Monte Carlo simulation. The DAΦNE optical model has been tuned to keep the effects of Touschek scattering under control with a trade-off between critical parameters, following the indications given by simulations. Connections between numerical results and lattice modifications are discussed here. Dedicated lifetime measurements have been carried out to validate these studies. Particle losses at the IR have been minimized by means of the same optical knobs, but in addition proper shieldings have been implemented to further decrease their impact on the detector performance. IR distributions of the Touschek particle losses have been tracked from the beam pipe into KLOE for direct comparison of measured and expected backgrounds. Moreover, these studies are carried out with the same software tools used for the SuperB factory design, allowing a direct validation test of this approach.

WEPC108

CSR Impedance for an Ultrarelativistic Beam moving in a Curved Trajectory

impedance, shielding, resonance, radiation

2268

D.M. Zhou, K. Ohmi, K. Oide
KEK, Ibaraki, Japan

A dedicated computer code, CSRZ, has been developed to calculate the coherent synchrotron radiation (CSR) impedance for an ultrarelativistic beam moving in a curved trajectory. Following the pioneering work of T. Agoh and K. Yokoya*, the code solves the parabolic equation in the frequency domain in a curvilinear coordinate system. The beam is assumed to move along a vacuum chamber which has a uniform rectangular cross section but with variable bending radius. Using this code, we did investigations in calculating the longitudinal CSR impedance of a single and a series of bending magnets. The calculation results indicate that the shielding effect due to outer chamber wall can be well explained by a simple optical approximation model at high frequencies. The CSR fields reflected by the outer wall may interfere with each other in a long bending magnet and lead to sharp narrow peaks in the CSR impedance.
* T. Agoh and K. Yokoya, Phys. Rev. ST Accel. Beams, 7(5):054403 (2004).

WEPC132

Simulations of Surface Effects and Electron Emission from Diamond-Amplifier Cathodes

electron, simulation, scattering, cathode

2307

D.A. Dimitrov, R. Busby, J.R. Cary, D.N. Smithe
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi
Stony Brook University, Stony Brook, USA
X. Chang, T. Rao, J. Smedley, Q. Wu
BNL, Upton, Long Island, New York, USA
E. Wang
PKU/IHIP, Beijing, People's Republic of China

Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grants DE-SC0004431 (Tech-X Corp.), DE-AC02-98CH10886 (BNL), and DE-SC0005713 (Stony Brook University).
Emission of electrons in diamond experiments based on the promising diamond-amplifier concept* was recently demonstrated**. Transmission mode experiments have shown the potential to realize over two orders of magnitude charge amplification. However, the recent emission experiments indicate that surface effects should be understood in detail to build cathodes with optimal properties. We have made progress in understanding secondary electron generation and charge transport in diamond with models we implemented in the VORPAL particle-in-cell computational framework. We will introduce models that we have been implementing for surface effects (band bending and electron affinity), charge trapping, and electron emission from diamond. Then, we will present results from 3D VORPAL diamond-vacuum simulations with the integrated capabilities on generating electrons and holes, initiated by energetic primary electrons, charge transport, and then emission of electrons from diamond into vacuum. Finally, we will discuss simulation results on the dependence of the electron emission on diamond surface properties.
* I. Ben-Zvi et al., Secondary emission enhanced photoinjector, C-AD Accel. Phys. Rep. C-A/AP/149, BNL (2004).
** X. Chang et al., Phys. Rev. Lett. 10⁵, 164801 (2010).

WEPC135

Recent Developments in Modeling Time-resolved Shielded-pickup Measurements of Electron Cloud Buildup at CESRTA

electron, radiation, pick-up, photon

2313

J.A. Crittenden, Y. Li, X. Liu, M.A. Palmer, J.P. Sikora
CLASSE, Ithaca, New York, USA
R.P. Badman
Syracuse University, Syracuse, USA
S. Calatroni, G. Rumolo
CERN, Geneva, Switzerland
S. Kato
KEK, Ibaraki, Japan

Funding: Work supported by the U.S. National Science Foundation PHY-0734867, PHY-1002467 and the U.S. Department of Energy DE-FC02-08ER41538
The Cornell Electron Storage Ring Test Accelerator program includes investigations into the mitigation of electron cloud buildup using a variety of techniques in custom vacuum chambers. The CESR ring accommodates two such chambers equipped with BPM-style pickup detectors shielded against the direct beam-induced signal. The signals provide time-resolved information on cloud development. Results for diamond-like carbon, amorphous carbon, and TiN coatings have been compared to those for an uncoated aluminum chamber. Here we report on extensions to the ECLOUD modeling code which refine its description of a variety of new types of in situ vacuum chamber comparisons. Our results highlight the sensitivity afforded by these measurements to the modeled photoelectron production and secondary yield parameters. We draw conclusions comparing the photoelectron and secondary yield properties of the various vacuum chamber coatings, including conditioning effects as a function of synchrotron radiation dose. We find substantial conditioning effects in both the quantum efficiency for producing photoelectrons and in the secondary yield.

WEPC141

Application of the SYNRAD3D Photon-Tracking Model to Shielded Pickup Measurements of Electron Cloud Buildup at CesrTA

photon, scattering, electron, simulation

2319

L.E. Boon
Purdue University, West Lafayette, Indiana, USA
J.A. Crittenden, T. Ishibashi
CLASSE, Ithaca, New York, USA
K.C. Harkay
ANL, Argonne, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
We present calculations of synchrotron radiation photon reflection in the vacuum chamber at the Cornell Electron Storage Ring Test Accelerator (CesrTA), applying them as input to the electron cloud buildup code ECLOUD to model time-resolved local measurements with shielded pickup detectors. The recently developed SYNRAD3D photon-tracking code employs a reflection model based on data from the Center for X-Ray Optics at LBNL. This study investigates the dependence of electron cloud buildup on the azimuthal position and kinetic energy distribution of photoelectron production on the vacuum chamber wall.

WEPC144

Beam Monitor Deformation by Tohoku Earthquake and its Recovery Project

cavity, linac, DTL, impedance

2328

A. Miura, K. Hasegawa, H. Oguri, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
Z. Igarashi, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan

On March 11, 2011, the biggest earthquake occurred at Tohoku and North Kanto area in Japan. This earthquake and related ones have attacked J-PARC accelerators and caused the big damage. As for the linac beam monitors, some commissioning tools which were installed in the linac had damage and the air leakage was observed. In the first step of the recovery work, we checked the damage and put the emergency treatment for vacuum of the cavities. All beam monitors were observed, the leak from the vacuum devices was tested and the conduction of the signal cables was measured to compare the previous performance. In the next step, we started to order the new devices which should be replaced and to obtain the calibration data. We found the leakage from the phase monitors. The earthquake caused the crack and deformation at the welded points between the metallic parts and ceramic parts. And a wire of the profile monitor was broken while the beam position monitors have no damage. We are continuing this recovery work ongoingly.

WEPC146

Design and Implementation of Distributed Control System for PEFP 100-MeV Proton Accelerator*

controls, EPICS, proton, monitoring

2334

Y.-G. Song, Y.-S. Cho, J.-H. Jang, H.-J. Kwon
KAERI, Daejon, Republic of Korea

Funding: This work is supported by the Ministry of Education, Science and Technology of the Korean Government.
The Proton Engineering Frontier Project (PEFP) has been developing the control system for 100-MeV proton accelerator. The PEFP control system should be designed to fit control conditions based on networked and distributed real-time system composed of several sub-systems such as machine control, diagnostic control, timing, and interlock. In order to implement the distributed control system, the Experimental Physics and Industrial Control System (EPICS) has been chosen as the middleware of PEFP control system. The EPICS software provides a distributed architecture that supports a wide range of solution such as independent programming tool, operator interface tool, database and web-based archiving tools. In this paper, we will present the details of the design and implementation issues of the PEFP control system.

WEPC152

Android Based Mobile Monitoring System for EPICS Networks: Vacuum System Application*

controls, EPICS, monitoring, ion-source

2337

I. Badillo, I. Arredondo, M. Eguiraun, J. Feuchtwanger, G. Harper
ESS-Bilbao, Zamudio, Spain
J. Jugo
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

Funding: The present work is supported by the Basque Government and Spanish Ministry of Science and Innovation.
When cabling is not really needed for performance reasons, wireless monitoring is a good choice for large scientific facilities like particle accelerators, due to the quick implementation. There are several wireless flavors: ZigBee, WiFi etc. depending on requirements of specific application. In this work, a wireless monitoring system for EPICS based on an Android device is presented. The task is to monitor the vacuum control system of ISHN project at ESSBilbao, where control system variables are acquired over the network and published in a mobile device. This allows the operator to check process variables everywhere the signal spreads. In this approach, a Python based server is continuously getting EPICS variables via CA protocol and sending them through a WiFi network using ICE middleware, a toolkit oriented to develop distributed applications. Finally, the mobile device reads and shows the data to the operator. The security of the communication is ensured by a limited WiFi signal spread, following the same idea as in NFC for larger distances. With this approach, local monitoring and control applications are easily implemented, useful in starting up and maintenance stages.

WEPC164

First Operation of a Fiber Beam Loss Monitor at the SACLA FEL

undulator, beam-losses, electron, radiation

2367

X.-M. Maréchal, T. Itoga
JASRI/SPring-8, Sayo-gun, Japan
Y. Asano
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

A fiber-based Cerenkov beam loss monitor (CBLM) has been developed as a quick and long-range detection tool for radiation safety at the X-ray FEL SACLA (SPring-8 angstrom compact free electron laser) to minimize electron beam losses. Based on tests carried out at the 250 MeV SPring-8 Compact SASE Source facility, large core (400 μm), long (>120 m) multimode fibers were selected and installed in the undulator section of SACLA. We report on the first few months of operation of the CBLM. During the commissioning of the X-FEL, the CBLM has performed effectively, with a detection limit below 10 pC per pulse across the 110 meters of the in-vacuum undulators, and with a position accuracy of less than 2 m. Experimental results are presented along with detailed numerical studies including the geometry of in-vacuum insertion devices, and discussed.

WEPC169

BPM System Interlock for Machine Protection at SOLEIL

photon, undulator, power-supply, electron

2379

J.-C. Denard, C. Herbeaux, M. Labat, V. Leroux, A. Loulergue, J.L. Marlats
SOLEIL, Gif-sur-Yvette, France

SOLEIL, a third generation light source, has its Beam Position Monitors (BPM) processed by the LIBERA electronics built by Instrumentation Technologies. This electronics initiated and specified by SOLEIL features a fast hardware interlock output for machine protection. Although interlocks are available in both horizontal and vertical planes, it was initially thought that only the vertical interlocks would be useful. Actually, the high photon beam power densities (up to 1kW/mm2) generated by the in-vacuum undulators could damage vacuum chamber elements in case of corrector power supply failures in horizontal or vertical plane. Crotch absorbers, XBPMs and their upstream absorbers were designed on the basis that they will be protected with interlock thresholds not tighter than ±1mm. This approach was also applied for specifying the apertures of the XBPMs and of their upstream absorbers. More recently tracking simulation has shown that the crotch absorber apertures downstream the new canted undulators needed special attention.

WEPC174

A Failure Catalogue for the LHC

monitoring, extraction, beam-losses, injection

2394

S. Wagner, R. Schmidt, B. Todd, J.A. Uythoven, M. Zerlauth
CERN, Geneva, Switzerland

The LHC, with a stored energy of more than 360 MJ per beam, requires a complex machine protection system to prevent equipment damage. The system was designed based on a large number of possible failures in the subsystems and operational phases of the LHC. This led to a mixed system with active and passive protection. The active part monitors many thousand parameters (such as beam losses, temperatures in superconducting magnets, power converter currents, etc.) and triggers a beam dump in case a failure is detected. The passive part includes protection elements like collimators and beam absorbers to ensure the prevention of damage in case of single turn beam losses (e.g. during beam transfer and injection). So far, the knowledge of the possible failures is distributed over the different teams involved in the design, construction and operation of the LHC. A newly started project aims at bringing together this knowledge in a common failure catalogue. The chosen approach in addition is expected to allow for the identification of failures that might not have been considered yet or that require further measures. This paper introduces the approach and presents the first experience.

WEPO006

Suppression of Leakage Fields from DC Magnets in J-PARC 3 GeV RCS

shielding, beam-losses, extraction, septum

2412

M. Yoshimoto, H. Harada, N. Hayashi, H. Hotchi, M. Kinsho, P.K. Saha, K. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In the J-PARC 3 GeV RCS, we found that DC leakage fields from the extraction beam line significantly affected the beam. For this issue, we installed additional shields and got the 40% reduction of the DC leakage field. Thus the circulating beam loss was successfully reduced. In this presentation, we report the detail of the shield structure and the results of the beam studies.

WEPO013

Septum and Kicker Magnets for the ALBA Booster and Storage Ring

kicker, injection, booster, storage-ring

2421

M. Pont, R. Nunez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
E. Huttel
KIT, Karlsruhe, Germany

At the ALBA Synchrotron light source 6 kicker and 3 septa magnets are installed for beam injection and extraction. A 100 MeV beam coming from the linac is injected on axis into the Booster. The full energy (3 GeV) beam is extracted from the booster and injected into the Storage Ring, where 4 kicker magnets bring the stored beam close to the septa. All septa are direct driven out-of-vacuum magnets with C shape iron laminated yoke. The magnets are excited by a full sine approx. 300 μs pulse length; the nominal field is 0.15/0.84/0.9 T (booster injection/extraction/storage-ring-injection). The stray field seen by the stored beam is less than 1 μT. The booster kicker magnets are in-vacuum magnets with C-ferrite yoke. The magnets are excited by a 0.4 μs flat top pulse; the nominal field is 0.03/0.04 T (booster injection/extraction). The storage ring kickers have a C-ferrite yoke and a 0.4 μm Ti coated ceramic vacuum chamber. The excitation is done by 6 μs half sine; the nominal field is 0.13 T. The paper will present the design of the elements and their magnetic characteristics. First results of their behaviour during commissioning will also be discussed.

WEPO022

Tightening the Tolerance Budget of Core Fabrication to Achieve Higher Magnet Performance

sextupole, dipole, quadrupole, scattering

2448

N. Li, A. Madur
LBNL, Berkeley, California, USA
J. Jin
SINAP, Shanghai, People's Republic of China

Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231.
Traditionally, laminated cores of AC magnets have been always built by the laminations that are produced by a punching die. There are 5 links in the tolerance chain when a magnet core is built by this procedure: 1. Error of punching die; 2. Error of lamination punching; 3. Error of half core stacking; 4. Error of core assembly; and 5. Error of magnet re-assembling during the installation in the accelerator. As time goes on, the Lattice physicists call for more and more ever higher magnet performance, which makes the required magnet field quality almost impossible achieve by traditional core fabrication procedures. It is the goal of this paper to describe a relatively new procedure that was first used by Buckley System Ltd, NZ and is being used at SINAP, China for ALS combined function sextupole core fabrication. The advantage of this new procedure and the fabrication issues related to this procedure will be described in this paper.

WEPO030

Fabrication and Testing of the First Magnet Package Prototype for the SRF Linac of LIPAc

solenoid, cavity, linac, SRF

2463

S. Sanz, J. Calero, F.M. De Aragon, J.L. Gutiérrez, I. Moya, I. Podadera, F. Toral, J.G.S. de la Gama
CIEMAT, Madrid, Spain
N. Bazin, P. Bosland, P. Bredy, N. Grouas, P. Hardy, V.M. Hennion, J. Migne, F. Orsini, B. Renard
CEA/DSM/IRFU, France
G. Disset, J. Relland
CEA, Gif-sur-Yvette, France
H. Jenhani
CEA/IRFU, Gif-sur-Yvette, France
E.N. Zaplatin
FZJ, Jülich, Germany

Funding: Work partially supported by Spanish Ministry of Science and Innovation under project AIC10-A-000441 and ENE2009-11230.
The IFMIF-EVEDA accelerator will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. The SRF Linac design is based on superconducting Half Wave Resonators (HWR) cavities operating at 4.4 K. Due to space charge associated to the high intensity beam, a short, but strong, superconducting focusing magnet package is necessary between cavities. The selected configuration has been a superconducting NbTi solenoid acting as a magnetic lens and a concentric outer solenoid in antiparallel configuration to reduce the dangerous stray field on the cavities. The selected arrangement for the steerers is a pair of parallel racetrack coils for each vertical and horizontal axis. This paper describes the manufacturing techniques of the different coils, and the test realized in warm and cold conditions, with special attention to the training test of the main solenoid, as the nominal working point in the load line is very high (86.2%).

WEPO035

Thermal Performance of the S1-Global Cryomodule for ILC

cavity, cryomodule, radiation, linac

2472

N. Ohuchi, M. Akemoto, S. Fukuda, K. Hara, H. Hayano, N. Higashi, E. Kako, Y. Kojima, Y. Kondo, T. Matsumoto, S. Michizono, T. Miura, H. Nakai, H. Nakajima, K. Nakanishi, S. Noguchi, T. Saeki, M. Satoh, T. Shidara, T. Shishido, T. Takenaka, A. Terashima, N. Toge, K. Tsuchiya, K. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, K. Yokoya
KEK, Ibaraki, Japan
T.T. Arkan, S. Barbanotti, H. Carter, M.S. Champion, A. Hocker, R.D. Kephart, J.S. Kerby, D.V. Mitchell, T.J. Peterson, Y.M. Pischalnikov, M.C. Ross
Fermilab, Batavia, USA
A. Bosotti, C. Pagani, R. Paparella, P. Pierini
INFN/LASA, Segrate (MI), Italy
D. Kostin, L. Lilje, A. Matheisen, W.-D. Möller, N.J. Walker, H. Weise
DESY, Hamburg, Germany

The S1-Global program is the international research collaboration among INFN, FNAL, DESY, SLAC and KEK as one of the GDE R&D for construction of ILC. The S1-Global cryomodule consists of two half-size cryomodules of 6 meter. One was designed by IFNF, and it contained two FNAL cavities and two DESY cavities. The associated components, like input couplers and RF cables, were same as the TTF-III cryomodule. The other was designed by KEK, and the thermal design was based on the TTF-III cryomodule. This cryomodule contains four KEK cavities with the associated components which were designed by KEK. For characterizing the thermal performances of two cryomodules, the static heat load and the temperature profiles of the cold components were measured. The temperature profiles of the components were compared between two cryomodules and the static heat load was evaluated with the design values of the cryomodules. The dynamic losses of the DESY, FNAL and two KEK cavities at their maximum operative gradients were measured and, with the measured losses, Q values were calculated. In this paper, we will make the summary of the thermal measurements of the S1-Global cryomodule.

WEPS013

Results of the Nuclotron Upgrade Program

ion, power-supply, heavy-ion, acceleration

2508

A.V. Eliseev, N.N. Agapov, A.V. Alfeev, V. Andreev, V. Batin, D.E. Donets, E.D. Donets, E.E. Donets, E.V. Gorbachev, A. Govorov, V. Karpinsky, V.D. Kekelidze, H.G. Khodzhibagiyan, A. Kirichenko, A.D. Kovalenko, O.S. Kozlov, N.I. Lebedev, I.N. Meshkov, V.A. Mikhailov, V. Monchinsky, S. Romanov, T.V. Rukoyatkina, A.O. Sidorin, I. Slepnev, V. Slepnev, A.V. Smirnov, A. Sorin, G.V. Trubnikov, B. Vasilishin
JINR, Dubna, Moscow Region, Russia
O.I. Brovko, A.V. Butenko, N.V. Semin, V. Volkov
JINR/VBLHEP, Moscow, Russia

The Nuclotron upgrade – the Nuclotron-M project, which had been started in 2007, involved the modernization of almost all of the accelerator systems, using beam time during seven runs devoted to testing newly installed equipment. Following the project goals, in March 2010 Xe ions were accelerated to about 1.5 GeV/u. In December 2010, the stable and safe operation of the magnetic system was achieved with a main field of 2 T. The successful completion of the project paves the way for further development of the Nuclotron-based Ion Collider fAcility (NICA).

WEPS034

A CW RFQ Prototype

rfq, simulation, impedance, linac

2559

U. Bartz, A. Schempp
IAP, Frankfurt am Main, Germany

A short RFQ prototype was built for RF-tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. HF-simulations with CST Microwave Studio and measurements were done. The cw-tests with 20 kW/m RF-power and simulations of thermal effects with ALGOR were finished successfully. The optimization of some details of the HF design is on focus now. First results and the status of the project will be presented.

WEPS048

Dependence of Beam Loss on Vacuum Pressure Level in J-PARC Linac

beam-losses, linac, ion, collimation

2598

G.H. Wei
KEK/JAEA, Ibaraki-Ken, Japan
K. Hirano, T. Maruta, A. Miura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

In J-PARC linac, a 181-MeV negative hydrogen beam is supported to a succeeding 3-GeV synchrotron with normal operation power at 100-300 kW. During operation, a beam loss in the straight section of the beam transport line immediately after the linac exit is found. The residual radiation level reaches 0.3 mSv/h on the surface of the vacuum chamber several hours after the beam shutdown with the linac beam power of 12 kW. We suppose that the residual gas scattering of negative hydrogen ions generates neutral hydrogen atoms and they give rise to the beam loss by hitting the vacuum chamber wall. To confirm this speculation, the vacuum pressure level in the linac had been changed in order to find the dependence of the beam loss on it. After data analysis, we found the relationship between beam loss amplitude, which was attained from beam loss signal, and vacuum pressure was linear. Corresponding deduction and simulation has been down according to the residual gas components in linac chamber. In this paper, we present the experimental result and some simulations in this study.

WEPS058

The Medium Energy Beam Transport Line (MEBT) of IFMIF/EVEDA LIPAc

rfq, cavity, SRF, quadrupole

2628

I. Podadera, J.C. Calvo, J.M. Carmona, A. Ibarra, D. Iglesias, A. Lara, C. Oliver, F. Toral
CIEMAT, Madrid, Spain

Funding: Work partially supported by Spanish Ministry of Science and Innovation under project AIC10-A-000441 and ENE2009-11230.
The IFMIF-EVEDA Linear IFMIF Prototype Accelerator (LIPAc)will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. The acceleration of the beam will be carried out in two stages. An RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac made of a chain of eight Half Wave Resonators bring the particles to the final energy. Between both stages, a Medium Energy Beam Transport line (MEBT) is in charge of transporting and matching the beam between the RFQ and the SRF. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities surrounding the doublet handle the longitudinal dynamics. Two movable collimators are also included to purify the beam optics coming out the RFQ and avoid losses in the SRF. From the inputs of the beam dynamics group, CIEMAT is in charge of designing, manufacturing and integrating all the components of the beamline. In this contribution, the MEBT subsystem will be described and the main objectives and issues for each component will be discussed.

WEPS076

Straight Scaling FFAG

linac, emittance, closed-orbit, instrumentation

2682

J.-B. Lagrange, Y. Ishi, Y. Kuriyama, Y. Mori, T. Planche, B. Qin, T. Uesugi, E. Yamakawa
KURRI, Osaka, Japan
K. Okabe
University of Fukui, Faculty of Engineering, Fukui, Japan
A. Sardet, R. Wasef
LPSC, Grenoble Cedex, France

Recent developments in scaling fixed field alternating gradient (FFAG) accelerators have opened new ways for lattice design, with straight sections, and insertions like dispersion suppressors. An experiment to study straight sections and dispersion suppressors is under progress at KURRI.

WEPS092

High Energy Beam Line Design of the 600MeV, 4 mA Proton Linac for the MYRRHA Facility

target, dipole, proton, linac

2721

H. Saugnac
IPN, Orsay, France

The general goal of the CDT project is to design a FAst Spectrum Transmutation Experimental Facility (FASTEF) able to demonstrate efficient transmutation and associated technology through a system working in subcritical and/or critical mode. A superconducting LINAC, part of the MYRRHA facility, will produce a 600 MeV, 4 mA proton beam and transport it to the spalation target located inside the reactor core. On this paper we focus on the final beam line design and describe optic simulations, beam instrumentation, integration inside the reactor building, mechanical and vacuum aspects as well as a preliminary design of the 2.4 MW beam dump located at the end of the accelerator tunnel.

WEPS094

Dynamic Vacuum Stability in SIS100

ion, extraction, cryogenics, beam-losses

2724

P. Puppel, U. Ratzinger
IAP, Frankfurt am Main, Germany
P.J. Spiller
GSI, Darmstadt, Germany

SIS100 is the main synchrotron of the FAIR project. It is designed to accelerate high intensity intermediate charge state uranium beams from 200 MeV/u up to 2.7 GeV/u. Intermediate charge state heavy ions are exposed to a high probability of charge exchange due to collisions with residual gas molecules. Since the charge exchange process changes the magnetic rigidity, the involved ions are lost behind dispersive elements, and an energy-dependent gas desorption takes place. The StrahlSim code has been used to predict the stability of the residual gas pressure in SIS100 under beam loss driven dynamic conditions. The results show, that a stable operation at highest U²⁸⁺ intensities is possible, under the constraint that the vacuum chambers of the ion catcher system are cold enough to pump hydrogen. Furthermore, in order to determine the load to the cryogenic system, the average beam energy deposition onto the ion catcher system has been calculated.

WEPS095

Status of J-PARC Accelerator Facilities after the Great East Japan Earthquake

linac, status, DTL, neutron

2727

K. Hasegawa, M. Kinsho, H. Oguri
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Koseki
KEK, Tokai, Ibaraki, Japan

J-PARC was heavily affected by the March 11 Great East Japan Earthquake. When the earthquake struck, we had a beam study operation of the linac and the machine immediately stopped. Fortunately, we had no effects of tsunami that happened nearby and no one was injured. We can see subsidence at many places; about 1.5m over the wide area at the entrance of the linac building, about 50cm over the area of 1m x 10m at the main ring building, etc. Underground water is coming into the linac and the main ring tunnels. The water level at the linac reached a depth of 10 cm, but pumping with a diesel generator successfully saved from further flooding. At the RCS, the circulating road went wavy and the yard area for electricity and water devices was heavily distorted. Therefore, a high voltage power is not available on the date of abstract submission. We are investigating damages of each facility and also we are trying to estimate the beam restoration. The current status of the J-PARC accelerator facilities after the earthquake will be presented.

WEPZ012

Influence of Transition Radiation on Formation of a Bunch Wakefield in a Circular Waveguide

radiation, wakefield, plasma, acceleration

2793

T.Yu. Alekhina, A.V. Tyukhtin
Saint-Petersburg State University, Saint-Petersburg, Russia

Funding: The Education Agency of Russian Federation.
Investigation of a field of a particle bunch in a waveguide loaded with a dielectric is important for the wakefield acceleration (WFA) technique and other problems in the accelerator physics. One of subjects of investigation in this area consists in analysis of transition radiation generated by the bunch flying into (out of) the dielectric structure. This radiation can be both destructive (for WFA) and useful (for diagnostics of bunch or material). We investigate the total field of small bunch crossing a boundary between two dielectrics in the waveguide. It includes a “forced” field and a “free” one. The “forced” field is the field of the charge in the unbounded waveguide (it can contain the wakefield). The “free” field is connected with influence of the boundary (it includes transition radiation). Two cases are analyzed in detail: the bunch flies from vacuum into dielectric and from dielectric into vacuum. The behavior of the field depending on distance and time is explored analytically and numerically. Some interesting physical effects are noted. As well, we make a comparison with the case of intersection between vacuum and cold plasma.

THOBA01

Electron Cloud Observations in LHC

electron, injection, emittance, simulation

2862

G. Rumolo, G. Arduini, V. Baglin, H. Bartosik, P. Baudrenghien, N. Biancacci, G. Bregliozzi, S.D. Claudet, R. De Maria, J. Esteban Muller, M. Favier, C. Hansen, W. Höfle, J.M. Jimenez, V. Kain, E. Koukovini, G. Lanza, K.S.B. Li, G.H.I. Maury Cuna, E. Métral, G. Papotti, T. Pieloni, F. Roncarolo, B. Salvant, E.N. Shaposhnikova, R.J. Steinhagen, L.J. Tavian, D. Valuch, W. Venturini Delsolaro, F. Zimmermann
CERN, Geneva, Switzerland
C.M. Bhat
Fermilab, Batavia, USA
U. Iriso
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
N. Mounet, C. Zannini
EPFL, Lausanne, Switzerland

Operation of LHC with bunch trains different spacings has revealed the formation of an electron cloud inside the machine. The main observations of electron cloud build-up are the pressure rise measured at the vacuum gauges in the warm regions, as well as the increase of the beam screen temperature in the cold regions due to an additional heat load. The effects of the electron cloud were also visible as a strong instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity and/or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with existing models will be presented. The efficiency of scrubbing and scrubbing strategies to improve the machine running performance will be also briefly discussed.

Slides THOBA01 [2.911 MB]

THPC003

Installation of the ASTRID2 Synchrotron Light Source

extraction, kicker, dipole, cavity

2909

J.S. Nielsen, N. Hertel, S.P. Møller
ISA, Aarhus, Denmark

ASTRID2 is the new 10 nm UV and soft x-ray light source being built at Aarhus University, to replace the aging source ASTRID. ASTRID2 is now in the middle of its installation. An update of the design will be presented. Almost all components have now been acquired and received. Several choices and solutions of hardware will be described, and future commissioning plans outlined. Commissioning is expected to take place in the winter 2011/2012.

THPC008

Touschek Lifetime and Momentum Acceptance Measurements for ESRF

emittance, scattering, synchrotron, electron

2921

B. Nash, F. Ewald, L. Farvacque, J. Jacob, E. Plouviez, J.-L. Revol, K.B. Scheidt
ESRF, Grenoble, France

The Touschek lifetime of a synchrotron results from electrons scattering off one another within the bunch and subsequently being lost. We have measured the Touschek lifetime for the major operating modes of the ESRF as a function of RF voltages. This includes multibunch and few bunch filling patterns with correspondingly different chromaticity values. Through calibration of the RF voltage and measurement of the other beam parameters such as bunch length and vertical emittance, we may understand the momentum acceptance in the regime where this is determined by non-linear dynamics effects.

THPC009

Performance and Upgrade of the ESRF Light Source

emittance, undulator, cavity, storage-ring

2924

J.-L. Revol, J.C. Biasci, J-F. B. Bouteille, J. Chavanne, F. Ewald, L. Farvacque, A. Franchi, G. Gautier, L. Goirand, M. Hahn, L. Hardy, J. Jacob, J.M. Koch, M.L. Langlois, G. Lebec, J.M. Mercier, T.P. Perron, E. Plouviez, K.B. Scheidt, V. Serrière
ESRF, Grenoble, France

The European Synchrotron Radiation Facility (ESRF) is now fully engaged in a large Upgrade Programme of its infrastructure, beamlines and X ray source. In this context, a first set of 10 insertion device straight sections are being lengthened from five to six metres; a number of them will be operated with canted undulators. The insertion devices are themselves subject to an ambitious development programme to fulfil the scientific requirements. The Radio Frequency system upgrade has started with the replacement of the booster klystron-based transmitter by high power solid state amplifiers, and the development of HOM damped cavities operating at room temperature. A completely new DC-AC orbit stabilization system using 224 BPMs and 96 orbit steerers is currently being commissioned. The upgrade is conducted while keeping, and even improving, routine performance for the user service. In particular the recent installation of new skew quadrupole power supplies allows routine operation with ultra low vertical emittance. This paper reports on the present operation performance of the source, highlighting recent developments and those still to come.

THPC010

Recent Developments at the Metrology Light Source

quadrupole, injection, feedback, synchrotron

2927

J. Feikes, T. Birke, O. Dressler, D.B. Engel, F. Falkenstern, B. Franksen, A. Heugel, H.-G. Hoberg, F. Hoffmann, J. Kuszynski, J. Rahn, M. Ries, P.O. Schmid, T. Schneegans, D. Schüler, G. Wüstefeld
HZB, Berlin, Germany
K.B. Bürkmann-Gehrlein, V. Dürr, H.G. Glass, G. Schindhelm
BESSY GmbH, Berlin, Germany
R. Klein
PTB, Berlin, Germany

The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, owns the electron storage ring Metrology Light Source (MLS) which was built and is operated by the Helmholtz-Zentrum Berlin [1, 2]. The MLS has been in regular user operation since April 2008 and supports synchrotron-radiation-based metrology and technological developments in the IR, UV, VUV and EUV spectral range. Here we report on recent progress to develop the MLS into a reliable, flexible and stable user facility.

THPC034

Post-earthquake Recovery of PF Ring and PF-AR

injection, survey, alignment, storage-ring

2984

T. Honda, T. Aoto, S. Asaoka, K. Endo, K. Haga, K. Harada, Y. Honda, M. Izawa, Y. Kobayashi, A. Mishina, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, T. Ozaki, C.O. Pak, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, K. Satoh, M. Shimada, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, M. Yamamoto
KEK, Ibaraki, Japan

When the unprecedented scale of earthquake occurred in Japan on the afternoon of March 11, 2011, PF ring and PF-AR, two synchrotron light sources in KEK, also suffered various damages. At PF ring, a formed bellows in a wall current monitor was broken, and atmospheric air rushed into the beam duct. At PF-AR, which is installed in the underground tunnel, the alignment of the ring magnets seemed to be disordered to an order of ten mm. At both rings, a lot of electronics racks and toolboxes in the control rooms or in the experimental halls were tilted or tipped over. It was extremely fortunate that the user operation had just been stopped on the morning of that day, and all the gate valves in the rings and to the beam lines had already been closed for the scheduled shutdown. A wide area blackout took place at the big earthquake, and the electric power for the accelerator was interrupted over the next two weeks because of temporal shortage of the electricity in the eastern part of Japan. In April, we could start detailed investigation of machine damages and repair works towards recommissioning of the rings before the summer and resumption of the user operations in the autumn.

THPC043

Status of SESAME Project

booster, EPICS, controls, quadrupole

2999

A. Nadji
SESAME, Amman, Jordan

This paper reports on the progress which has been made on the construction of the SESAME accelerator complex. The construction of the shielding wall has been finished on March 2011. According to plan, the preparation works and tenders of the conventional facilities have been launched such as the cooling system, electrical distribution systems, PSS system and so on. The commissioning of the Microtron at full energy and the installation of the booster are the next millstones to accomplish. The booster upgrade plan has started which consists of replacing all bending magnets vacuum chamber with new one, BPM Libera Electronics, new control system based on EPICS, new timing system, new electronics for tune measurement. The site acceptance test of the new power supplies of the booster with their tracking electronics is planned to take place in July 2011. The magnet system of the storage ring has been reviewed and the manufacturing tendering is foreseen before the end of 2011.

THPC044

Operation and Performance Upgrade of the Soleil Storage Ring

undulator, storage-ring, photon, feedback

3002

A. Nadji, P. Brunelle, M.-E. Couprie, J.-C. Denard, J.-M. Filhol, J.-F. Lamarre, P. Lebasque, A. Loulergue, P. Marchand, L.S. Nadolski, R. Nagaoka, M.-A. Tordeux
SOLEIL, Gif-sur-Yvette, France

SOLEIL delivers photons to 24 beamlines. Up to 22 very diverse insertion devices (IDs) are now installed on the storage ring, and 4 more will come by summer 2011, including a Cryogenic undulator and an electromagnetic/permanent magnet helical undulator, both designed and built at SOLEIL. Work is continuing on beam dynamics and magnetic corrections to reduce the nonlinear effects of all these IDs. A new optics incorporating an additional quadrupole triplet in one long straight section has been successfully tested and will be put in operation by fall 2011. A new coupling correction will also be implemented to maintain the ratio of the vertical to the horizontal emittances at 1% for any IDs configuration. The electron beam orbit stability has been significantly improved reaching a residual noise of 300 nm RMS. Photon LIBERA modules of X-BPM located on the bends, will be integrated soon in the orbit feedback loops. 4905 hours have been delivered in 2010 to the beamlines with an availability of 96.3%. The user operation with the maximum current of 500 mA is foreseen to start by fall 2011, after the completion of the radiation safety tests of the beamlines.

THPC055

Front Ends at ALBA

photon, radiation, synchrotron, undulator

3017

J. Marcos, J. Campmany, D. Einfeld, J. Pasquaud
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3GeV 3rd generation synchrotron radiation source built nearby Barcelona currently under commissioning phase. This paper describes the design and installation of the set of 10 Front Ends that have been manufactured and assembled for day-one operation of the facility. This initial set includes 8 Front Ends devoted to transmit the photons generated by both Insertion Device or Bending Magnet sources to experimental Beamlines, and 2 additional Front Ends for electron beam-diagnostics purposes. The design of each individual Front End has been adapted in order to meet the aperture and power load requirements posed by both the characteristics of the photon sources and the needs of the Beamline users. At the same time, an effort has been made in order to keep a suitable degree of standardization among the components of different Front Ends. With this aim a modular design approach has been adopted. The general layout of the Front Ends as well as the design and function of their main components is described. Finally, a brief summary of their performance during the commissioning period is presented.

THPC058

The MAX IV Synchrotron Light Source

linac, emittance, lattice, storage-ring

3026

M. Eriksson, J. Ahlbäck, Å. Andersson, M.A.G. Johansson, D. Kumbaro, S.C. Leemann, F. Lindau, L.-J. Lindgren, L. Malmgren, J.H. Modéer, R. Nilsson, M. Sjöström, J. Tagger, P.F. Tavares, S. Thorin, E.J. Wallén, S. Werin
MAX-lab, Lund, Sweden
B. Anderberg
AMACC, Uppsala, Sweden
L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada

The MAX IV synchrotron radiation facility is currently being constructed in Lund, Sweden. It consists of a 3 GeV linac injector and 2 storage rings operated at 1.5 and 3 GeV respectively. The linac injector will also be used for the generation of short X-ray pulses. The three machines mentioned above will be descibed with some emphasis on the effort to create a very small emittance in the 3 GeV ring. Some unconventional technical solutions will also be presented.

THPC063

A 2.9 Tesla Room Temperature Superbend Magnet for the Swiss Light Source at PSI

storage-ring, power-supply, dipole, synchrotron

3038

A.L. Gabard, D. George, M. Negrazus, L. Rivkin, V. Vrankovic
PSI, Villigen, Switzerland
Y. Kolokolnikov, P. Vobly
BINP SB RAS, Novosibirsk, Russia

The Swiss Light Source (SLS) at the Paul Scherrer Institute (PSI) in Villigen, Switzerland, is a 3rd generation synchrotron light source. With an energy of 2.4 GeV, it provides high brightness photon beams for research in materials science, biology and chemistry. The SLS storage ring contains 36 room temperature bending magnets, all of which produce light for experimental use; at the design energy of 2.4 GeV, they have a maximum magnetic field of 1.4 Tesla. Light is produced along the entire bending arc but can only be transferred to the external experimental facilities from selected short portions of the beam path. In cooperation with the Budker Institute for Nuclear Physics (BINP) in Novosibirsk, Russia, three of these magnets were replaced with new room temperature magnets with short regions of high magnetic field up to 2.9 Tesla. This enabled the production of intense light beams at shorter wavelengths than from the existing magnets. The critical energy of the 2.9 T magnet is 11.1 keV, compared to the 5.4 keV of the normal bend. This paper describes the design, including the multiple restraints, together with the measurement and commissioning of these so-called superbends.

THPC068

CSR and THz Emission Measurements at the Diamond Light Source

radiation, electron, bunching, dipole

3050

R. Bartolini, G. Cinque, G. Rehm, C.A. Thomas
Diamond, Oxfordshire, United Kingdom
I.P.S. Martin
JAI, Oxford, United Kingdom

After the successful implementation of the low alpha optics at Diamond we have started a characterisation of coherent THz emission with the aim of classifying the rich phenomenology of stable and bursting emission and to devise the best operational mode for potential THz users. In conjunction with the Diamond IR beamline B22, THz spectral data were acquired simultaneously with Schottky diode signals in the mm-wave region of the spectrum. We also report the results of comparison with numerical simulations made with the aim of reproducing the measured THz emission spectra and gaining further understanding on the mechanisms of the instability.

THPC071

Study of the Possibility of Implementing a Superbend in the Diamond Light Source

dipole, radiation, magnet-design, photon

3059

R.P. Walker, N.P. Hammond, J. Kay, S.P. Mhaskar, B. Singh
Diamond, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

We report on recent studies of the feasibility and impact of replacing one of the regular 1.4 T bending magnets in Diamond with a normal conducting 3 T "Superbend" in order to enhance the hard X-ray output for a possible future beamline. We describe the preliminary magnet design, the engineering implications and the effect on beam dynamics, including the additional constraints that arise from implementing a superbend in a DBA lattice, as compared to the more common application in a TBA lattice.

THPC116

Surface Analysis of a Degraded NEA-GaAs Photocathode by Temperature Programmed Desorption Technique

cathode, electron, quadrupole, ion

3158

H. Iijima, M. Kuriki, Y.M. Masumoto
HU/AdSM, Higashi-Hiroshima, Japan

A GaAs photocathode activated the surface to negative electron affinity (NEA) is an important device for high-average-current electron accelerators, such as a next-generation light source based on an energy recovery linac. It is well known that the quantum efficiency of the NEA-GaAs photocathode is decaying with time elapsing, even if the electron beam is not extracted. The degradation is mainly caused by adsorption of residual gases in a vacuum chamber. Previously a few investigators reported that the quantum efficiency of the photocathode was rapidly degraded by water or carbon dioxide vapor. In order to analyze such surface states, we have measured desorption of gases from the degraded NEA-GaAs photocathode by using of temperature programmed desorption (TPD) technique with a quadrupole mass spectrometer. The desorption peaks of hydrogen, carbon oxide and carbon dioxide from the degraded NEA surface were observed, while that of water was not observed.

THPC117

Analysis Quantum Efficiency Spectrum of NEA-GaAs Photocathode

electron, cathode, brightness, linac

3161

Y.M. Masumoto, H. Iijima, M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan

ERL is a future project of synchrotron light source with high brightness and partial coherence. ERL is based on super conducting linear accelerator providing the high brightness electron beam to insertion devices continuously. One of the most difficult technical challenge is the electron source for ERL. A photo-cathode DC biased gun is assumed, but several issues should be solved. One of the issue is the operational lifetime of cathode material, NEA GaAs. NEA stands for Negative electron affinity made by artificial treatment on clean GaAs surface. Emission from the cathode is decreased in time and extracted beam current. In order to research the phenomena, the surface potential is studied by measuring the QE　(Quantum Efficiency) spectrum. Observing temporal evolution of QE, we found that the photon energy threshold did not change during the decay. The spectrum shape was changed suggesting that the surface potential barrier becomes thicker.

THPC121

Design and Cold Tests of a Prototype photocathode RF Gun for Shanghai SXFEL Facility

gun, cathode, coupling, emittance

3170

H.J. Qian, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, X.H. Liu, X. H. Lu, C.-X. Tang
TUB, Beijing, People's Republic of China

A soft X-ray (~9 nm) FEL (SXFEL) facility is going to be constructed in Shanghai, China, which requires high charge (>500 pC) electron beam with low transverse emittance (<1.5 mm-mrad) at photoinjector exit. One of the keys to achieve a low emittance with high charge is high gradient on the photocathode, so an S-band photocathode RF gun modified from BNL type gun is designed, which aims running 100 MV/m peak gradient at 10 Hz. By changing the cathode seal technique, removing the insertion RF tuner, and reducing the peak surface field, RF breakdown possibility is reduced. Besides, RF pulse width is also considered to be reduced to lower the RF breakdown possibility. Since zero mode and multipole field degrades the beam emittance, they are also suppressed in the new gun design. Design details and cold testing results are presented in this paper.

THPC129

Gallium Arsenide Photocathode Research at Daresbury Laboratory

cathode, electron, laser, gun

3185

L.B. Jones, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.J. Cash
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
N. Chanlek
UMAN, Manchester, United Kingdom

Significant effort has been expended over several years by ASTeC to optimise procedures for preparing GaAs photocathodes for use as high-current electron sources in accelerators. Having established robust chemical and thermal cleaning processes, and carried out lifetime studies on activated photocathodes by deliberately poisoning them*, we present data showing high levels of Quantum Efficiency (QE) for heterostructure photocathodes when activated with Cs-O and Cs-NF3 procedures. We will show that the use of NF3 delivers higher QE, and conveys greater control in that the final QE level can be set more accurately using NF3 than with O. We plan to carry out further experiments on GaAs photocathodes to measure the 2-D energy distribution of the emitted electrons at both room and cryogenic temperatures. We are constructing a retarding-field electron calorimeter which will measure current as a function of retarding voltage. From this, we will establish the 2-D energy distribution in the electron beam, permitting a comparison of these figures for photocathodes at room and low temperatures. The goal is to create an ultra-bright electron source for use with particle accelerators.
* Proc IPAC ’10, TUPEC018, 1752-1754

THPC136

High Efficiency Visible Photocathode Development

cathode, synchrotron, laser, diagnostics

3206

J. Smedley, K. Mueller, T. Rao
BNL, Upton, Long Island, New York, USA
K. Attenkofer, S.W. Lee
ANL, Argonne, USA
I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Oses
Stony Brook University, Stony Brook, USA
H.A. Padmore, T. Vecchione
LBNL, Berkeley, California, USA

Alkali antimonide cathodes are critical both for high average current photoinjectors for energy recovery linacs and for high quantum efficiency photodetectors. These cathodes have historically been plagued by extreme vacuum sensitivity, non-reproducibility and poor lifetime. We report on ongoing efforts to improve the performance of alkali antimonides (principally K2CsSb). Cathodes have been fabricated which have a QE of 7% at 532 nm. The films are much more resistant to oxygen and water exposure than previously thought, with a 50% yield lifetime of 20 hrs at 2 pBar partial pressure of water. Several analysis techniques have been employed in this study, including in-situ x-ray diffraction during growth to measure grain size and texture, measurement of transverse momentum distribution of the emitted electrons, and measurement of the stoichiometry of the films via x-ray fluorescence. An extensive study of the growth parameters, including both transparent and metallic substrates, sputtered and evaporated films, variation of growth time and temperatures and post-growth annealing processes, is currently underway.

THPC140

Design, Tuning and Results of the Pulsed Magnetic Systems for the Beam Injection in the SOLEIL Storage Ring Operated in ‘Transparent’ Top Up Mode

septum, kicker, injection, storage-ring

3215

P. Lebasque, R. Ben El Fekih, M. Bol, J. Da Silva Castro, A. Hardy, C. Herbeaux, J.-P. Lavieville, A. Loulergue, J.L. Marlats, D. Muller, G. Renaud, J.P. Ricaud
SOLEIL, Gif-sur-Yvette, France

From the beginning, the SOLEIL Storage Ring was designed to operate in Top Up injection mode. So all equipments involved have been specified to generate as small as possible beam perturbations of the stored beam during the electron beam injection. This concerns many aspects of the design and realization of the injection pulsed magnets (kickers and septa), their vacuum chambers, pulsed power supplies and timing electronics. Despite quite satisfactory results of pulsed magnetic measurements in labs, a still too large perturbation was observed on the e^- beam orbit during the Storage Ring commissioning. Therefore a strong work of systematic measurements, analysis of each phenomena, tuning or modification of each device was led until reaching rather good and acceptable performances. This paper will present the results obtained. At this stage, the Storage Ring beam orbit is sufficiently stable in Top Up injection mode so that it is almost transparent to the 24 beam lines, even for the most sensitive ones. After a summary of the main significant topics, we present the developments foreseen to further improve the performances and make a new step towards a “perfect” Top Up injection.

THPC147

TPS SR Kicker Prototype Installation Status*

kicker, injection, storage-ring, high-voltage

3230

Y.-H. Liu, C.K. Chan, C.-S. Chen, Y.L. Chu, K.H. Hsu, H.P. Hsueh, C.K. Kuan, C.Y. Kuo, C.-S. Yang
NSRRC, Hsinchu, Taiwan

The purpose of this paper is to illustrate the installation sequence of TPS SR kicker. Because of adding the rotation function in row direction, the position of every component of kicker must be very precise. The kicker magnet and EMI enclosure were fastened on the rotation motor plate which could rotate ±3.0 mrad. The ceramic chamber remain fixed on the bottom plate in order to let the bellow stress free during rotation. After installation, the inductance measurement and the high voltage breakdown test were also tested. The experimental results showed the good uniformity and reached the expected request. The field mapping and EMI prevention schemes will be tested in the future.

THPC149

Development of PrFeB Cryogenic Undulator (CPMU) at SOLEIL

undulator, cryogenics, permanent-magnet, storage-ring

3233

C. Benabderrahmane, P. Berteaud, N. Béchu, L. Chapuis, M.-E. Couprie, J.P. Daguerre, J.-M. Filhol, C. Herbeaux, A. Lestrade, M. Louvet, J.L. Marlats, K. Tavakoli, M. Valléau, D. Zerbib
SOLEIL, Gif-sur-Yvette, France

A R&D programme for the construction of a 2 m long 18 mm period CPMU is under progress at SOLEIL. The cryogenic undulator will provide photons in the region of 1.4 to 30 keV. It will be installed in the next few months on the long straight section (SDL13) of the storage ring, and could be used later on to produce photons for the NANOSCOPIUM beamline. The use of PrFeB which features a 1.35 T remanence (Br) at room temperature enables to increase the peak magnetic field at 5.5 mm minimum gap, from 1.04 T at room temperature to 1.15 T at a cryogenic temperature of 77 K. Praseodymium was chosen instead of Neodymium magnetic material, because it is more resistant against the appearance of the Spin Reorientation Transition. Different corrections were performed first at room temperature to adjust the phase error, the electron trajectory and to reduce the multipolar components. The mounting inside the vacuum chamber enables the fitting of a dedicated magnetic measurement bench to check the magnetic performance of the undulator at low temperature. The results of the magnetic measurements at low temperature and the comparison with the measurement at room temperature are reported.

THPC150

Review of Insertion Device Dedicated to HIgh Energy Photons at SOLEIL

undulator, photon, brightness, insertion

3236

O. Marcouillé, C. Benabderrahmane, P. Berteaud, F. Briquez, L. Chapuis, M.-E. Couprie, T.K. El Ajjouri, F. Marteau, M. Valléau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France

Producing high energy photons between 10 keV and 70 keV is a challenging topic in a medium energy storage ring. It requires up-to-date measurement techniques and specific Insertion Device (ID) technologies to produce high magnetic fields and short periods. SOLEIL (2.75 GeV) has designed and built eight conventional in-vacuum hybrid undulators operating at high radiation harmonics and also one small gap multipole wiggler to produce high magnetic field. The construction has been progressively improved by the choice of new magnetic materials of better quality and higher magnetization, additional correction techniques and mechanical changes. A 2-m long full scale cryogenic undulator made of PrFeB and vanadium permendur has been built, measured, corrected and is to be tested on the beam. An additional wiggler dedicated for Slicing experiments has been designed. The required magnetic field is high enough to also consider the ID as a good candidate for the production of hard X-ray photons. This paper presents the ID dedicated for the high energy photons and their spectral performances.

THPC152

Measurements of SOLEIL Insertion Devices using Pulsed Wire Method

insertion, undulator, insertion-device, wiggler

3242

M. Valléau, C. Benabderrahmane, M.-E. Couprie, O. Marcouillé, F. Marteau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France

SOLEIL permanent magnets insertion devices are usually measured with a Hall probe in order to evaluate the electron angular deflexion, their deviation and the optical phase error, a figure of merit related to the quality of the insertion device radiation. A pulsed wire bench is developed at SOLEIL for reducing the measurement time of an undulator and for providing a measurement method without lateral access. A current pulse injected in a stretched wire inside the magnetic field area generates acoustic wave. The wire motion is detected by optical sensors whose signals are proportional to the local integral value. The signal-to-noise ratio of this method is often reduced due to several effects such as electronic noise, external and wire vibrations. However, following some hardware optimization it was possible to increase it up to almost 26 dB, making the method accurate and reproducible in order to realize efficient corrections. Measurements of first and second integral performed with Pulse wire, with Hall probe and with the electron beam are compared on three different types of insertions: an U18 in-vacuum cryogenic undulator, a HU60 APPLE-II undulator and a WSV50 in-vacuum wiggler.

THPC159

Factory Acceptance Test of COLDDIAG: A Cold Vacuum Chamber for Diagnostics

electron, diagnostics, synchrotron, factory

3263

S. Gerstl, T. Baumbach, S. Casalbuoni, A.W. Grau, M. Hagelstein, T. Holubek, D. Saez de Jauregui
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
V. Baglin
CERN, Geneva, Switzerland
C. Boffo, G. Sikler
BNG, Würzburg, Germany
T.W. Bradshaw
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
R. Cimino, M. Commisso, A. Mostacci, B. Spataro
INFN/LNF, Frascati (Roma), Italy
J.A. Clarke, R.M. Jones, D.J. Scott
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M.P. Cox, J.C. Schouten
Diamond, Oxfordshire, United Kingdom
I.R.R. Shinton
UMAN, Manchester, United Kingdom
E.J. Wallén
MAX-lab, Lund, Sweden
R. Weigel
Max-Planck Institute for Metal Research, Stuttgart, Germany

Superconductive insertion devices (IDs) have higher fields for a given gap and period length compared with the state-of-the-art technology of permanent magnet IDs. One of the still open issues for the development of superconductive insertion devices is the understanding of the heat intake from the electron beam. With the aim of measuring the beam heat load to a cold bore and the hope to gain a deeper understanding in the underlying mechanisms, a cold vacuum chamber for diagnostics was built. It is equipped with the following instrumentation: retarding field analyzers to measure the electron flux, temperature sensors to measure the beam heat load, pressure gauges, and mass spectrometers to measure the gas content. The flexibility of the engineering design will allow the installation of the cryostat in different synchrotron light sources. The installation in the storage ring of the Diamond Light Source is foreseen in November 2011. Here we report about the technical design of this device, the factory acceptance test and the planned measurements with electron beam.

THPC162

Possible Application of NbTi Wire with Artificial Pinning Centres for Insertion Devices

undulator, brilliance, insertion, insertion-device

3272

T. Holubek, S. Casalbuoni, S. Gerstl, A.W. Grau, D. Saez de Jauregui
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
M. Klaeser, T. Schneider
FZ Karlsruhe, Karlsruhe, Germany
L. Motowidlo
SupraMagnetics, Inc., Plantsville, USA

Superconductive insertion devices (IDs) allow higher fields for a given gap and period length compared to the classical permanent magnet IDs. This technological concept permits to increase the brilliance and/or the photon energy. The working horse for superconducting magnets are multifilament NbTi wires, which are nowadays also used for superconducting insertion devices. Even higher magnetic fields can be reached by using a conductor with enhanced critical current density. Here, we propose a possible application for superconducting undulators, wound with NbTi wire with artificial pinning centres, developed by SupraMagnetics, Inc. We report the critical current characteristic, Jc(B), of short wire measured in a liquid helium bath, and the load-line of a racetrack coil, designed to simulate the field configuration on the conductor as in a superconducting undulator. Based on the measured load-line we report the simulations of the magnetic field on axis and of the spectrum in a third generation light source of a possible undulator wound with a wire having similar properties of the measured one.

THPC166

Design Consideration of New Insertion Devices of Hefei Light Source

undulator, photon, radiation, insertion

3284

Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China

To meet the requirements of users for higher brilliance and good transverse coherence VUV and soft X-ray synchrotron radiation, Hefei Light Source(HLS) will be upgraded. After upgrade HLS will have smaller beam emittance and install more insertion devices. In this paper the design considerations of new insertion devices are reported, they include one elliptically polarizing undulator, one quasi-periodic undulator, one in-vacuum undulator and one wiggler.

THPC167

The Design of Dual Canted In-vacuum Undulators at SSRF

undulator, radiation, ion, synchrotron

3287

X. Hu, L. Yin, Q.G. Zhou
SINAP, Shanghai, People's Republic of China

Funding: National foundation for scientific infrastructure, Development and Reform Commission of China.
Five new beamlines are under design and construction at SSRF to supply the synchrotron radiation for the structural biology research in the protein project. Two in-vacuum undulators with canted angle of 6mrad are arranged in a 6.5m long straight section in order to keep the potential to accommodate more beamlines for the future. Limited by the length of the straight section and the angle between two beamlines, the layout design in the straight section is rather difficult to satisfy the required photon flux to the beamline and keep the normal design of the undulator. Many main components will be redesigned in this section on the base of existing ones, including in-vacuum undulator, correction magnet, RF bellows, photon absorbers and so on. In this paper the layout design and the modified design for some key components are described.

THPC171

Performance of ID at ALBA

wiggler, undulator, storage-ring, insertion

3299

J. Campmany, J. Marcos, V. Massana
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The new synchrotron light source ALBA is currently being commissioned along with the first phase of beamlines. Up to 6 beamlines are using light produced by Insertion Devices. There are up to four types of IDs: 2 Apple-II undulators (EU62 and EU71) operating at low energies, one conventional wiggler (MPW80) operating in the range of 2 – 20 keV, two in-vacuum undulators (IVU21) operating in the range 5 – 30 keV and a superconducting wiggler (SCW30) operating in the range of 40 keV. Installation of the IDs has been done in two steps. First, the out-vacuum devices (EU62, EU71 and MPW80) have been mechanically installed. Initial commissioning of Storage Ring has been done with their gaps opened to maximum value. Then, their gap has been closed to study the effect in the beam dynamics. In the second step, the in-vacuum devices (both IVU21 and the SCW30) have been installed and tested. In this paper we present the first results and performances of the insertion devices obtained both in Site Acceptance Test and during the first months of commissioning with beam.

THPC172

Superconducting 119-pole Wiggler for ALBA Light Source

wiggler, electron, site, radiation

3302

N.A. Mezentsev, S.V. Khrushchev, V.K. Lev, E.G. Miginsky, V.A. Shkaruba, V.M. Syrovatin, V.M. Tsukanov, A.A. Volkov
BINP SB RAS, Novosibirsk, Russia
J. Campmany, D. Einfeld
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

Budker INP of Siberian Branch of the Russian Academy of Science has designed, manufactured and tested 119-pole superconducting wiggler for ALBA CELLS light source. The period length and maximal field of the wiggler are 30 mm 2.2 Ò correspondingly. Pole gap and vertical aperture for electron beam are 12.6 mm and 8.5 mm, accordingly. The wiggler magnetic structure closely comes nearer to undulator structure as K-value is about 6. The wiggler cryostat is bath cryostat type with use of cryocoolers which provide zero liquid helium consumption for long period. In June, 2010 the wiggler has been successfully tested on ALBA site. Test results of the wiggler including magnetic measurement, quench training, cryogenic system behavior for various mode of operation are presented.

THPC176

Progress in Insertion Devices for TPS in Phase I

undulator, insertion, insertion-device, photon

3314

C.H. Chang, C.-H. Chang, J.C. Huang, C.-S. Hwang, C.K. Yang
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) with beam energy 3 GeV and beam current 500 mA is a third-generation synchrotron radiation facility of medium energy. In the initial commissioning stage of TPS, the machine will be equipped with ten insertion devices (ID) and serve seven beamlines in phase I. Of these, three long straight sections configured as a double-minimum betay function lattice design with minimized beam influence of emittance are used for the installation of a pair of insertion devices in a straight section, two undulators of APPLE-II type and four in-vacuum undulators (IU), to produce great brilliance and coherent X-rays with great flux. The details of these insertion devices are explained herein.

THPC178

Superconducting Planar Undulator Development in the UK

undulator, cryogenics, cryomodule, radiation

3320

J.A. Clarke, D.J. Scott, B.J.A. Shepherd
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V. Bayliss, T.W. Bradshaw, A.J. Brummitt, G.W. Burton, M.J.D. Courthold, M.J. Hills, S.R. Watson, M.L. Woodward
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Superconducting undulators promise higher peak fields on axis than any other technology but they are still not a mainstream solution for 3rd or 4th generation light sources. A team within the UK is developing the design of a short period, narrow aperture, superconducting undulator that is planned to be installed and tested in the Diamond Light Source (DLS) in 2014. This paper will describe the main parameters of the undulator and the key design choices that have been made. Recent progress is then described in the areas of magnet modelling, mechanical design, cryogenic design, and prototyping. Finally, the next steps are described.

THPO023

Ageing of Airix Accelerating Units

controls, pulsed-power, monitoring, high-voltage

3391

A. Georges, H. Dzitko, B. Gouin, M. Mouillet
CEA, Arpajon, France

Airix is a linear accelerator producing a 60ns, 2kA, 19MeV electron beam. It has been operated in a single shot mode by the “Commissariat à l’Energie Atomique et aux Energies Alternatives” (CEA) for flash X-ray radiography purposes for 10 years. Its modular architecture increases the beam energy by quarter of a megavolt step: each cell delivers a 75ns impulsion of 250kV amplitude. Our aim is to guarantee a minimum lifetime for the cells and their pulse driver. To achieve it, we are operating a test-bed at a moderately low repetition rate (a couple of pulses per minute) for tens of thousands of pulses. Afterwards, we will run a series of both non-destructive and destructive analysis to identify the most stressed parts, and, if necessary, the means of increasing the cell lifetime. This paper describes the test-bed: a pair of cells and its driver, and the first results of these ageing tests.

THPO024

Development of a Non-Linear Kicker System to Facilitate a New Injection Scheme for the BESSY II Storage Ring

kicker, injection, storage-ring, impedance

3394

O. Dressler, T. Atkinson, M. Dirsat, P. Kuske
HZB, Berlin, Germany
H. Rast
DELTA, Dortmund, Germany

Top-Up injections without noticeable motion of the stored beam is a challenge. The common method of beam accumulation with a local bump formed by four independent pulsed dipole kicker magnets usually causes beam oscillations. The matching of the four independent kicker systems regarding pulse jitters and shapes is technologically limited. Afterward the beam excitation was reduced more when two kicker magnets on each side of the septum were powered in series by one pulser unit. An even more promising approach is to adopt an alternative injection method deploying a single non-linear kicker magnet with zero Bx,y-field in the center and an off-axis maximum, By, which is horizontally displaced by 10^-12 mm. There the injected beam gets kicked and looses half of its transverse momentum. Such a magnet was designed and built as a short in-vacuum magnet with a small vertical gap height. For first beam tests the kicker was placed in the second straight section after the injection point, and the 1.5 μs pulse was designed to deflect the 1.72 GeV beam by 1 mrad. In this paper, the calculations of the magnetic fields, the mechanical design as well as the electrical pulser circuit are described.
*New injection scheme using a pulsed quadrupole magnet in electron storage rings, Kentaro Harada, PHYSICAL REVIEW SPECIAL TOPICS - AB 10, 123501 (2007)

THPO033

Calculation of Metallization Resistivity and Thickness for MedAustron Kicker Systems

simulation, kicker, status, proton

3412

M.J. Barnes
CERN, Geneva, Switzerland
T. Kramer, T. Stadlbauer
EBG MedAustron, Wr. Neustadt, Austria

The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and ions for both cancer therapy and research. Different types of kicker magnets will be used in the facility. The kicker magnets are outside machine vacuum: each kicker magnet has a ceramic beam chamber whose inner surface is metallized. The resistivity and thickness of the metallization are chosen such that the induced eddy currents, resulting from the pulsed kicker magnetic field, do not unduly affect the rise/fall times or homogeneity of the magnetic field. A comparison of an analytical calculation and measurement is reported for the effect of metallization of the ceramic beam chamber of an existing kicker system at CERN. For a MedAustron kicker the result of an analytical calculation is compared with predictions from electromagnetic simulations: conclusions concerning the metallization of the ceramic beam chambers, for the MedAustron kicker magnets, are presented.

THPO034

Optimization of a Dual One-turn Coils Kicker Magnet System

kicker, extraction, synchrotron, monitoring

3415

K.L. Tsai, C.-T. Chen, C.-S. Fann, S.Y. Hsu, Y.D. Li, K.-K. Lin, K.-B. Liu, H.M. Shih, Y.S. Wong
NSRRC, Hsinchu, Taiwan

Optimization of a dual one-turn coils configuration for fast kicker magnet system is presented in this report. Emphasis has been made on the: 1) optimization of various possible coils arrangement restricted by the existing available hardware; and 2) synchronization between pulsed currents delivering on the respective upper and lower coils. In the consideration of coils arrangement, good field region is utilized as the guiding parameter while adjusting fixture gap between the coils. As for coil currents timing optimization, fast rise-time and pulse shape preservation are used for practical implementation purpose. Both numerical analysis and experimental data will be presented and discussed.

THPO036

Final Layout and Test Results of the Disconnect Switch for ALS Storage Ring RF System Power Supply

high-voltage, power-supply, klystron, fibre-optics

3421

S. Kwiatkowski, K.M. Baptiste, J. Julian, M.E. Kennedy
LBNL, Berkeley, California, USA
J. Miszczak
SLCJ, Warsaw, Poland

Funding: Work supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Science and Engineering Division, of the Department of Energy under contract No. DE-AC02-05CH11231.
ALS is the 1.9 GeV third generation synchrotron light source which has been operating since 1993 at Berkeley National Lab. The new RF system, which is now under construction will use two TH 2161B 300kW klystrons to power two single cell RF cavities. In the new design the existing conventional crow-bar klystron protection system will be replaced with the fast disconnect switch. The switch consist 24 high voltage IGBTs connected in series, equipped with static and dynamic balancing systems. The main advantage of using this new technology is faster action and virtually no stress for the components of the high voltage power supply. This paper will show the final lay-out and the test results of the production unit.

THPS049

Feasibility Study of a CERN PS Injection at 2 GeV

injection, optics, kicker, septum

3535

J. Borburgh, S. Aumon, W. Bartmann, S.S. Gilardoni, B. Goddard, L. Sermeus, R.R. Steerenberg
CERN, Geneva, Switzerland

In the framework of the potential CERN PS Booster (PSB) energy upgrade, a study was initiated to look into the possibilities and constraints to inject protons into the PS at kinetic energies up to 2 GeV, for LHC type beams and other (high intensity) beams. This paper highlights the identified bottlenecks and potential solutions and addresses the resulting requirements for the hardware in the transfer line and injection region of the PS. In conjunction with the proposed upgrade of the PSB-PS transfer line hardware the optics can be changed for different cycles. Optics solutions optimized for the different requirements of LHC type and other beams are presented.

THPS060

RAM Methodology and Activities for IFMIF Engineering Design

target, neutron, controls, rfq

3565

J.M. Arroyo, A. Ibarra, J. Molla
CIEMAT, Madrid, Spain
J. Abal, E. Bargalló, J. Dies, C. Tapia
UPC, Barcelona, Spain

IFMIF will be an accelerator-based neutron source to test fusion candidate materials. The Engineering Validation and Engineering Design Activities of IFMIF are aimed to deliver the complete engineering design file of this major facility. Achieving a high level of availability and reliability is a key point for IFMIF mission. A goal of 70% of operational availability has been established. In order to fulfill the availability requirements, RAM has to be considered during the engineering design phase. This paper summarizes the methodology developed and the proposed process aimed at including RAM in the design of IFMIF, as well as the activities performed in this framework. Overall RAM specifications have been defined for IFMIF project. RAM methodology dealing with RAM design guidelines, reliability database and RAM modelization has been developed. As a first step for the iterative process of RAM analysis of IFMIF design, a fault tree model based on a new reliability database has been performed with Risk Spectrum®. The result is a first assessment of the availability and first allocation of RAM requirements.

THPS079

Vacuum-insulation Tandem Accelerator for Boron Neutron Capture Therapy

neutron, target, proton, tandem-accelerator

3615

S.Yu. Taskaev, V.I. Aleynik, A. Burdakov, A.A. Ivanov, A.S. Kuznetsov, A.N. Makarov, I.N. Sorokin
BINP SB RAS, Novosibirsk, Russia

Novel powerful electrostatic vacuum-insulation tandem accelerator had been proposed* and created at BINP. A 2 MeV 3 mA dc proton beam is obtained. Neutrons are generated by 7Li(p,n)7Be reaction in the near threshold mode**. Epithermal neutron flux is formed for the development of Boron Neutron Capture Therapy (BNCT) of malignant tumors. In this report results on proton beam obtaining, neutron flux generation and in vitro investigation are presented and discussed. This accelerator based neutron source looks like a prototype of compact inexpensive epithermal neutron source for the spread of BNCT. Plans on BNCT realization are declared. Also the facility is used for the development of nuclear resonance absorption technique for nitrogen detection, and for the investigation of neutronless fusion. First, 9.17-MeV gamma rays are generated by 13C(p,gamma)14N reaction at 1.76 MeV protons***. Second, we are ready to measure alfa particles energy spectrum of p+11B reaction.
* Bayanov et al., NIM A 413 (1998) 397-426.
** Kuznetsov et al., Technical Physics Letters 35/8 (2009) 1-6.
*** Kuznetsov et al., NIM A 606 (2009) 238-242.

THPS081

Design Choices of the MedAustron Nozzles and Proton Gantry based on Modeling of Particle Scattering

scattering, proton, dipole, optics

3621

M. Palm
CERN, Geneva, Switzerland
M. Benedikt, A. Fabich
EBG MedAustron, Wr. Neustadt, Austria
M. Palm
ATI, Wien, Austria

MedAustron, the Austrian hadron therapy center is currently under construction. Irradiations will be performed using active scanning with a proton or carbon ion pencil beam which is subject to scattering in vacuum windows, beam monitors and air gap. For applications where sharp lateral beam penumbras are required in order to spare critical organs from unwanted dose, scattering should be minimal. A semi-empirical scattering model has been established to evaluate beam size growth at the patient due to upstream scattering. Major design choices for proton gantry and nozzle based on the scattering calculations are presented.

THPS094

New Approaches in High Power RFQ Technology

rfq, linac, resonance, RF-structure

3654

A. Bechtold, J.M. Maus, G. Ritter
NTG Neue Technologien GmbH & Co KG, Gelnhausen, Germany

There is a clear tendency for the utilization of continuous wave c.w. high power RFQs in a huge variety of applications like nuclear waste transmutation or material research. They can serve as injectors for the production of secondary particles like neutrons or rare isotopes and can be applied for post acceleration of the latter ones. These RF-structures have to withstand an enormous amount of RF-power dissipated on the surfaces (up to several 10s kW per meter) and the associated thermal load. NTG Company gained lots of experience especially in the field of 4-rod c.w. RFQ design. Most recent developments to handle such high RF-power dissipation shall be reported.

THPS095

Q-factor of an Open Resonator for a Compact Soft X-ray Source based on Thomson Scattering of Stimulated Coherent Diffraction Radiation

cavity, radiation, electron, scattering

3657

A.S. Aryshev, S. Araki, M.K. Fukuda, J. Urakawa
KEK, Ibaraki, Japan
V. Karataev
JAI, Egham, Surrey, United Kingdom
G.A. Naumenko
Tomsk Polytechnic University, Nuclear Physics Institute, Tomsk, Russia
A. Potylitsyn, L.G. Sukhikh, D. Verigin
TPU, Tomsk, Russia
K. Sakaue
RISE, Tokyo, Japan

High-brightness and reliable sources in the VUV and the soft X-ray region may be used for numerous applications in such areas as medicine, biology, biochemistry, material science, etc. We have proposed a new approach to produce the intense beams of X-rays in the range of eV based on Thomson scattering of Coherent Diffraction Radiation (CDR) on a 43 MeV electron beam. CDR is generated when a charged particle moves in the vicinity of an obstacle. The radiation is coherent when its wavelength is comparable to or longer than the bunch length. The CDR waves are generated in an opened resonator formed by two mirrors. In this report the status of the experiment, the first CDR measurements at the multibunch beam of the LUCX facility and general hardware design will be reported.

THPZ021

Effect of Coherent Synchrotron Radiation at the SuperKEKB Damping Ring

emittance, damping, linac, wakefield

3732

H. Ikeda, T. Abe, M. Kikuchi, K. Oide, K. Shibata, M. Tobiyama, D.M. Zhou
KEK, Ibaraki, Japan

The longitudinal wake field dominated by the CSR is important at the SuperKEKB damping ring. The peak of the CSR wake field is 100 times higher than those of the vacuum chamber components. We calculated the CSR effect for different vacuum chamber cross-sections, and adopted one which reduced longitudinal instability.