07 Accelerator Technology
T14 Vacuum Technology

Paper	Title	Page
TUZB02	Ultra High Vacuum for High Intensity Proton Accelerators	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	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	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]
TUPS001	Upgrade of the ESRF Vacuum System	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	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	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	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*	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	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.
TUPS009	SEY of Al Samples from the Dipole Chamber of PETRA III at DESY	1533
	D. R. Grosso, R. Cimino, M. Commisso INFN/LNF, Frascati (Roma), Italy R. Flammini CNR-IMIP, Monterotondo Stazione RM, Italy R. Larciprete ISM-CNR, Rome, Italy R. Wanzenberg DESY, Hamburg, Germany
	At the synchrotron radiation facility PETRA III, tune spectra have been measured with some characteristics which are typically observed at other storage rings in connection with electron cloud effects. For some bunch filling patterns, an increase of the vertical emittance has been observed. To estimate such effects with the available e-cloud simulation codes, the detailed knowledge of the SEY (Secondary Electron Yield) of the Al chamber, is required. To the purpose, representative PETRA III Al samples, were studied in detail at the INFN-LNF Surface Science Laboratory. XPS (X-ray photoelectron spectroscopy) and SEY measurements were performed as a function of electron and argon ion conditioning. The SEY of the as received samples shows a maximum value of δmax ≅ 2.8. Electron conditioning at 500 eV kinetic energy, reduces the SEY to values between δmax ≅ 1.8 to 1.4 (depending on the actual sample analyzed). The XPS characterization of the sample surface, after several cycles of argon ion sputtering, shows clearly that the SEY variation is closely related to the oxidation state of the Al sample, reaching a δmax value as low as 1.3 for our cleanest surface.
TUPS010	A Novel Approach in UHV Pumping of Accelerators: the NEXTorr® Pump	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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	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.
TUPS030	Manufacturing and Vacuum Testing of Aluminum Bending Chambers for TPS	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	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.