IPAC2011 - List of Keywords (positron)

Paper	Title	Other Keywords	Page
MOOCA03	Updates to the International Linear Collider Damping Rings Baseline Design	lattice, damping, electron, cavity	32
	S. Guiducci, M.E. Biagini INFN/LNF, Frascati (Roma), Italy G. Dugan, M.A. Palmer, D. L. Rubin CLASSE, Ithaca, New York, USA J. Gao, D. Wang IHEP Beijing, Beijing, People's Republic of China M.T.F. Pivi, Y. Sun SLAC, Menlo Park, California, USA J. Urakawa KEK, Ibaraki, Japan
	A new baseline design for the International Linear Collider (ILC) damping rings has been adopted which reduces the ring circumference to 3.2 km from 6.4 km. This design change is associated with a revised plan to operate the ILC with one half the beam current originally specified in the ILC Reference Design Report. We describe the new layout and lattice that has been developed for the shorter ring. In addition, we discuss features of the new design that will allow operation at a 10Hz repetition rate which is twice the rate specified for baseline operation. Finally, we examine the implications for restoring operation with the originally specified beam current while maintaining the smaller ring circumference.
	Slides MOOCA03 [2.381 MB]

MOPO017	Latest Performance Results from the FONT5 Intra-train Position and Angle Feedback System at ATF2	feedback, kicker, linear-collider, collider	520
	G.B. Christian, D.R. Bett, M.R. Davis, C. Perry JAI, Oxford, United Kingdom R. Apsimon, P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom B. Constance, A. Gerbershagen CERN, Geneva, Switzerland J. Resta-López IFIC, Valencia, Spain
	A prototype Interaction Point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider, has been designed and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The FONT5 intra-train feedback system aims to stabilize the beam orbit by correcting both the position and angle jitter in the vertical plane on bunch-to-bunch timescales, providing micron-level stability at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. A total system latency as low as approximately 140 ns has been demonstrated.

MOPS007	Interference of CSR Fields in a Curved Waveguide	impedance, damping, storage-ring, wakefield	604
	D.M. Zhou, K. Ohmi KEK, Ibaraki, Japan
	CSR fields generated by a bunched beam passing through a series of bending magnets may interfere with each other due the reflections of outer chamber wall. This kind of multi-bend interference causes sharp peaks and long-range tail in the CSR impedance and wake potentials, respectively. Using a dedicated computer code, CSRZ, we calculated the longitudinal CSR impedance in the SuperKEKB positron damping ring for purpose of demonstration. It was found that multi-bend interference may enhance the CSR fields within a distance comparable to the bunch length, which is typically in the order of several millimeters. A simple instability analysis was performed and it suggested that multi-bend interference might play a role in the single-bunch instabilities of small electron/positron rings.

MOPS057	Beam-beam Interaction under External Force Oscillation	luminosity, simulation, electron, kicker	736
	K. Ohmi KEK, Ibaraki, Japan
	Beam-ion interaction is strongly nonlinear. Response for external oscillation applied to beam shows characteristic feature. Simulations for external frequency scan becomes feasible for the recent computer power. We show the frequency response for beam-ion system in KEK-PF and recent low emittance rings.

MOPS083	Update on Electron Cloud Mitigation Studies at Cesr-TA*	electron, wiggler, resonance, photon	796
	J.R. Calvey, M.G. Billing, J.V. Conway, G. Dugan, S. Greenwald, Y. Li, X. Liu, J.A. Livezey, J. Makita, R.E. Meller, M.A. Palmer, S. Santos, R.M. Schwartz, J.P. Sikora, C.R. Strohman CLASSE, Ithaca, New York, USA S. Calatroni, G. Rumolo CERN, Geneva, Switzerland K. Kanazawa, Y. Suetsugu KEK, Ibaraki, Japan M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the US National Science Foundation (PHY-0734867) and Department of Energy (DE-FC02-08ER41538) Over the course of the past three years, the Cornell Electron Storage Ring (CESR) has been reconfigured to serve as a test facility for next generation particle accelerators. A significant part of this program has been the installation of several diagnostic devices to measure and quantify the electron cloud effect, a potential limiting factor in these machines. In particular, more than 30 Retarding Field Analyzers (RFAs) have been installed in CESR. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. This paper will provide an overview of RFA results obtained at CesrTA over the past year, including measurements taken as function of bunch spacing and wiggler magnetic field. Understanding these results provides a great deal of insight into the behavior of the electron cloud.

MOPS088	Simulation of Electron Cloud Beam Dynamics for CesrTA	emittance, simulation, electron, betatron	808
	K.G. Sonnad, G. Dugan, M.A. Palmer, G. Ramirez, H.A. Williams CLASSE, Ithaca, New York, USA K.R. Butler Cornell University, Ithaca, New York, USA M.T.F. Pivi SLAC, Menlo Park, California, USA
	This presentation provides a comprehensive set of results obtained using the simulation program CMAD. CMAD is being used for studying electron cloud induced beam dynamics issues for CesrTA, which is a test facility for studying physics associated with electron and positron damping rings. In particular, we take a closer look at electron cloud induced effects on positron beams, including head-tail motion, emittance growth and incoherent tune shifts for parameters specific to ongoing experimental studies at CesrTA. The correspondence between simulation and experimental results will also be discussed. Work supported by US Department of Energy grant number DE-FC02-08ER41538 and the National Science Foundation grant number PHY-0734867

MOPZ034	Proton Contamination Studies in the MICE Muon Beam Line	proton, lattice, quadrupole, emittance	871
	S.D. Blot, Y.K. Kim University of Chicago, Chicago, Illinois, USA R.R.M. Fletcher UCR, Riverside, California, USA D.M. Kaplan Illinois Institute of Technology, Chicago, Illinois, USA C.T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	The Muon Ionization Cooling Experiment (MICE) aims to demonstrate transverse beam emittance reduction for a muon beam. To create these muons, a titanium target is dipped into the ISIS proton accelerator at Rutherford Appleton Laboratory (UK) to create pions, which are transported and decay to muons in the MICE beamline. Beam particle identification and triggering is performed using time of flight (ToF) detectors. When running the MICE beamline with positive polarity, protons produced in the target contaminate the muon beam with a sufficiently high rate to saturate the TOF detectors. Polyethylene sheets of varying thicknesses were installed to absorb the proton impurities in the beam. Studies with pion beams at momenta of 140, 200, and 240MeV/c were performed with different proton absorber thicknesses. The results of these studies show good agreement with theoretical range plots and will be presented.

TUPC005	Evolution of Pressure in Positron Source for Future Linear e⁺e⁻ Collider	target, photon, collider, linear-collider	994
	O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva University of Hamburg, Hamburg, Germany A.F. Hartin, G.A. Moortgat-Pick, S. Riemann, A. Ushakov DESY, Hamburg, Germany A. Schälicke, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE Energy deposition in the conversion targets of positron sources for future linear colliders induces an immense thermal load and create pressure waves in the material. This stress could substantially reduce the lifetime of the target or other target materials impinged by the incident intense photon or electron beam. We have studied the evolution of acoustic pressure waves in target materials based on the parameter assumptions for the International Linear Collider (ILC) baseline source. The fluid model is employed by taking into account the target and the incident photon beam parameters. Initial results of these new simulations are presented and compared with earlier studies. Prospects for further studies are outlined.

TUPC006	Production of Highly Polarized Positron Beams*	polarization, undulator, photon, target	997
	A. Ushakov, O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick University of Hamburg, Hamburg, Germany A.F. Hartin DESY, Hamburg, Germany S. Riemann, A. Schälicke, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE Using of polarized electron and positron beams significantly increases the physics potential of future linear colliders. The generation of an intense and highly polarized positron beam is a challenge. The undulator-based positron source located at the end of electron linac is the baseline source for the International Linear Collider. In case of a 250 GeV drive beam energy, an helical undulator with K = 0.92, an undulator period of 11.5 mm and a titanium alloy target of 0.4 radiation length thickness, the average polarization of the generated positrons is relatively low (about 22 percent). In this contribution, the possibilities of increasing the positron polarization have been considered by adjusting the undulator field and selecting those photons and positrons that yield a highly polarized beam. The detailed simulations have been performed with our developed Geant4-based application PPS-Sim. http://pps-sim.desy.de

TUPC028	Background and Energy Deposition Studies for the CLIC Post-Collision Line*	photon, simulation, radiation, electron	1060
	R. Appleby, M.D. Salt UMAN, Manchester, United Kingdom L.C. Deacon, E. Gschwendtner CERN, Geneva, Switzerland
	The CLIC post-collision line is designed to transport the spent-beam products of collision to their respective dumps, with minimal losses and thus minimal background contributions. With nanometre spot-sizes at TeV energies, large beam-beam effects induce divergence and dispersion of the outgoing beams, with a large production cross-section of Beamstrahlung photons and subsequently coherent pairs. The post-collision line should provide sufficient divergence of the beam to avoid damage to the vacuum exit and dump entrance windows. In this study, the beam losses are investigated, with the production of secondary particles from the interaction with matter simulated. The particle flux leakage from absorbers and dumps is modelled to determine the total energy deposited on magnets of the post-collision line. Finally, both electromagnetic and hadronic backgrounds at the CLIC experiment are considered.

TUPC030	Recommendation for Mitigations of the Electron Cloud Instability in the ILC	electron, vacuum, 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.

TUPC042	First Beam to FACET	linac, electron, controls, vacuum	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.

TUPC053	Superconducting Positron Stacking Ring for CLIC	injection, damping, synchrotron, septum	1117
	F. Zimmermann, L. Rinolfi CERN, Geneva, Switzerland E.V. Bulyak, P. Gladkikh NSC/KIPT, Kharkov, Ukraine T. Omori, J. Urakawa, K. Yokoya KEK, Ibaraki, Japan
	The generation of polarized positrons for future colliders based on Compton storage rings is a promising method. A challenging key ingredient of this method is the necessary quasi-continuous positron injection into a stacking ring. The ordinary methods of multi-turn injection are not appropriate for this purpose, because the required number of injection-turns is a few hundred, and the emittance of the injected positron bunches is large. This paper describes a possible solution based on 5 GeV superconducting stacking ring, where a novel method of the combined longitudinal and transverse injection process is used to stack positrons. The ring dynamic aperture allows to inject the positron beam with normalized emittance up to 2000 micrometers during a few hundred turns. The injection efficiency is larger than 90% in simulation. The number of the injection turns is only limited by the synchrotron radiation power. The ring lattice and the results of injection simulations are presented.

TUPC083	Comparative Studies into 3D Beam Loss Simulations	simulation, photon, beam-losses, electron	1198
	M. Panniello MPI-K, Heidelberg, Germany C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the Helmholtz Association and GSI under contract VH-NG-328. A detailed understanding and monitoring of potential beam loss mechanisms is crucial for every particle accelerator. The main motivation in low energy facilities, such as the Ultra-low energy Storage Ring (USR) at the future Facility of Low energy Antiproton and Ion Research (FLAIR), comes from the very low number of particles available which in such machine ought to be conserved. In High Energy accelerators it is the concern about activation or even physical damage of machine parts which has to be taken into serious account. The CLIC Test Facility (CTF3) at CERN provides an ideal testing ground for studies into novel BLM systems and is well suited for benchmarking the results from numerical simulations in experiments. This contribution summarizes the three-dimensional beam loss pattern as found with the commonly used codes FLUKA and Géant4. The results from these codes are compared and analyzed in detail and used for the identification of optimum beam loss monitor locations.

TUPC153	Study of the Response of Silicon Photomultipliers in Presence of Strong Cross-talk Noise	photon, beam-losses, radiation, heavy-ion	1389
	M. Putignano, A. Intermite The University of Liverpool, Liverpool, United Kingdom M. Putignano, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by STFC, the EU under GA-ITN-215080, the Helmholtz Association and GSI under VH-NG-328. Silicon Photomultipliers (SiPM) are interesting detectors for beam diagnostics applications where they could replace photomultiplier tubes as large dynamic range photon counting devices due to their reduced dimensions and costs, higher photon detection efficiency, immunity to magnetic fields and low operation voltage. Possible applications include longitudinal beam profile measurements by synchrotron light imaging, detection of optical transition radiation for energy spectrum measurements and medical imaging. However, quantitative measurement with SiPMs are jeopardized by the systematic reading error due to Optical Cross-talk (OC), i.e. optical coupling between neighboring diodes in the array. OC results in overestimation of the impinging light level, and reflects the probability of a triggered avalanche creating a photon of suitable energy and direction to fire a second avalanche in another diode. In this paper, we derive a generalized response distribution for SiPM in presence of cross-talk noise, which overcomes the limitations of assumptions currently made in literature and provides a correction of the SiPM response distribution valid for arbitrary large levels of cross-talk.

TUPO002	High Flux Polarized Gamma Rays Production: First Measurements with a Four-mirror Cavity at the ATF	laser, cavity, electron, damping	1446
	N. Delerue, J. Bonis, I. Chaikovska, R. Chiche, R. Cizeron, M. Cohen, P. Cornebise, R. Flaminio, D. Jehanno, F. Labaye, M. Lacroix, Y. Peinaud, L. Pinard, V. Soskov, A. Variola, Z.F. Zomer LAL, Orsay, France T. Akagi, S. Miyoshi Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan S. Araki, Y. Funahashi, Y. Honda, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan E. Cormier CELIA, Talence, France T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	Funding: ANR, IN2P3 The next generation of e+/e^- colliders will require the production of a very intense flux of gamma rays to allow polarized positrons to be produced in sufficient quantities. To demonstrate that this can be achieved a four-mirror cavity has recently been installed at the Accelerator Test Facility (ATF) at KEK to produce a high flux of polarized gamma rays by inverse Compton scattering. A four-mirror non-planar geometry is used to ensure the polarization of the gamma rays produced. The main mechanical features of the cavity are presented. A fibre amplifier is used to inject about 10W in the high finesse cavity with a gain of 1000. A digital feedback system is used to keep the cavity at the length required for the optimal power enhancement. First preliminary measurements show that on some beam crossings the interactions produce more than 25 photons with an average energy of about 24 MeV. Several upgrades currently in progress are described.

TUPS055	Organizing the ILC Technical Design Documentation	lattice, linear-collider, damping, collider	1656
	L. Hagge, S. Eucker, B. List, N.J. Walker, N. Welle DESY, Hamburg, Germany
	The Global Design Effort (GDE) for the International Linear Collider (ILC) is currently preparing the Technical Design Report (TDR), which will be released at the end of 2012 and will serve as the basis for a decision process. The TDR will be written based on the Technical Design Documentation (TDD), which captures the entire design efforts, results and rationale, including e. g. parameter lists, specifications, CAD models and drawings, cost estimation, simulations and calculations, and summary reports. Formal review meetings help making the documentation complete, correct and consistent. The TDD is stored in an Engineering Data Management System (EDMS), which ensures that it remains accessible beyond the GDE in an organized way and at a well-defined location. The EDMS provides traceability (e. g. from design decisions to corresponding cost estimates), version management and change control. The poster presents the process and tools that were established for the organization of the TDD and provides an overview of the emerging documentation.

WEZA01	Round Beam Collisions at VEPP-2000*	luminosity, lattice, resonance, betatron	1926
	Y.M. Shatunov, D.E. Berkaev, A.N. Kirpotin, I. Koop, A.P. Lysenko, I. Nesterenko, E. Perevedentsev, Yu. A. Rogovsky, A.L. Romanov, P.Yu. Shatunov, D.B. Shwartz, A.N. Skrinsky, I. Zemlyansky BINP SB RAS, Novosibirsk, Russia
	The idea of round beams collision was proposed more than 20 years ago for the Novosibirsk Phi-factory design. It requires equal emittances, equal small fractional tunes, equal beta functions at the IP, no betatron coupling in the collider arcs. A 90° rotation at each passage of the transverse oscillation plane by means of solenoids in the interaction regions provides conservation of the longitudinal component of the angular moment. Thus the transverse motion becomes one-dimensional. Such a scheme helps to eliminate all betatron coupling resonances that are of crucial importance for beam-beam tune shift saturation and lifetime degradation. Only recently, the round beam concept was successfully tested at the electron-positron collider VEPP2000 at the energy of 510 MeV. Despite the low energy a high single bunch luminosity of 10³¹ cm^-2s⁻¹ was achieved together with a maximum tune shift as high as 0.1. At present the work is in progress to increase the energy of the collider to explore the range between 510 MeV and 1 GeV in collision.
	Slides WEZA01 [3.740 MB]

WEOAB02	FACET: The New User Facility at SLAC	electron, plasma, linac, wakefield	1953
	C.I. Clarke, F.-J. Decker, R.A. Erickson, C. Hast, M.J. Hogan, R.H. Iverson, S.Z. Li, Y. Nosochkov, N. Phinney, J. Sheppard, U. Wienands, W. Wittmer, M. Woodley, G. Yocky SLAC, Menlo Park, California, USA A. Seryi JAI, Oxford, United Kingdom
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. FACET (Facility for Advanced Accelerator and Experimental Tests) is a new User Facility at SLAC National Accelerator Laboratory. Its high power electron and positron beams make it a unique facility, ideal for beam-driven Plasma Wakefield Acceleration studies. The first 2 km of the SLAC linac produce 23 GeV, 3.2 nC electron and positron beams with short bunch lengths of 20 um. A final focusing system can produce beam spots 10um wide. User-aided Commissioning took place in summer 2011 and FACET will formally come online in early 2012. We present the User Facility, the current features, planned upgrades and the opportunities for further experiments.
	Slides WEOAB02 [4.772 MB]

WEPC100	Simulation of the Single Bunch Instability due to the Electron Cloud Effect by Tracking with a Pre-computed 2D Wake Matrix*	electron, dipole, simulation, single-bunch	2247
	A. Markoviḱ, G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Supported by DFG Contract Nr. RI 814/20-1. The passage of a positron bunch through an initially homogeneous electron cloud (e-cloud) changes the distribution of the e-cloud in a way that the concentration of electrons in the proximity of the beam axis grows rapidly. The electrons are primarily moving in the transverse plane and are very sensitive on the beam centroid position in that plane. Thus the transverse kick of the e-cloud on the tail particles depends on the centroid position of the head particles of the same bunch. A PIC simulation of the interaction of a positron beam with an e-cloud yields the wake kick from the electrons on the tail particles for a certain offset in the transverse centroid position of the head parts of the bunch. With such a pre-computed 2D wake matrix, for a certain e-cloud density, we investigate the stability of a single bunch by tracking it through the linear optics of the storage ring while at each turn applying the kick from the e-cloud. We examine the positron bunch stability of KEKB-LER and PETRAIII for a certain electron cloud density.

WEPC111	Single Particle Tracking Simulation for Compact Cyclotron*	simulation, cyclotron, cavity, injection	2274
	H.W. Kim, J.-S. Chai, B.N. Lee, Y.S. Lee, K.R. Nam, H.S. Song SKKU, Suwon, Republic of Korea
	Funding: Ministry of Education, Science and Technology, Republic of Korea. Department of Energy Science and School of Information and Communication Engineering of SungKyunKwan University. Low energy compact cyclotrons for Positron emission tomography (PET) are needed for the production of radio-isotope. In the magnet design for those cyclotrons, single particle tracking simulation after the design is important to check the quality of designed magnetic field of the magnet. The study of single particle tracking simulation for cyclotron magnet is shown in this paper. Maximum beam energy of example cyclotron is 9 MeV for proton and pseudo accelerating gap is adapted for the simulation. 3D CAD program CATIA P3 V5 R18 is used for design the magnet and pseudo accelerating gap. All magnetic and electric field calculations had been performed by OPERA-3D TOSCA and the own-made program OPTICY is used for other calculations - phase slip, radial and axial tune.

WEPO026	Advances in the Design of the SuperB Final Doublet	quadrupole, luminosity, collider, controls	2454
	E. Paoloni, N. Carmignani, F. Pilo University of Pisa and INFN, Pisa, Italy S. Bettoni CERN, Geneva, Switzerland M.E. Biagini, P. Raimondi INFN/LNF, Frascati (Roma), Italy F. Bosi INFN-Pisa, Pisa, Italy P. Fabbricatore, S. Farinon, R. Musenich INFN Genova, Genova, Italy M.K. Sullivan SLAC, Menlo Park, California, USA
	SuperB is an asymmetric (6.7 GeV HER, 4.18 GeV LER) e⁺ e− collider operating at the Y(4S) peak with a design peak luminosity of 10³6 Hz/cm² to be built in Italy in the very near future. The design luminosity is almost a factor hundred higher than that of the present generation comparable facilities. To get the design luminosity a novel collision scheme, the so called “large Piwinski angle with crab waist”, has been designed. The scheme requires a short focus final doublet to reduce the vertical beta function down to betay*=0.2 mm at the interaction point (IP). The final doublet will be composed by a set of permanent and superconducting (SC) quadrupoles. The SC quadrupole doublets QD0/QF1 have to be placed as close to the IP as possible. This layout is critical because the space available for the doublets is very small. An advanced design of the quadrupole has been developed, based on the double helical coil concept. The paper discusses the design concept, the construction and the results of test of a model of the superconducting quadrupole based on NbTi technology. Future developments are also presented.

WEPO027	Design Study of Final Focusing Superconducting Magnets for the SuperKEKB	solenoid, focusing, quadrupole, luminosity	2457
	M. Tawada, N. Higashi, M. Iwasaki, H. Koiso, A. Morita, Y. Ohnishi, N. Ohuchi, K. Oide, T. Oki, K. Tsuchiya, H. Yamaoka, Z.G. Zong KEK, Ibaraki, Japan
	For SuperKEKB, which is an upgrade project of KEKB, we are studying the design of the final focus quadrupole magnets for the interaction region. The 7 GeV electrons in the high-energy ring and the 4 GeV positrons in the low-energy ring collide at one IP with a finite crossing angle of 83 mrad. For each beam, the final beam focusing system consists of the superconducting quadrupole-doublets. These quadrupole magnets have to meet specifications described below. (1) Because of the small beam separation between two beam lines, the superconducting magnet is designed with thin coils and the conductor size is required to be minimized. (2) Since the beta functions are so large, a large space with a good field quality is required. (3) These magnets must apply the focusing fields on electrons and positrons, independent each other. The quadrupole magnets in the solenoid field of the particle detector are designed without an iron yoke. Consequently, the reduction of the leakage fields from the adjacent beam lines is a critical issue to achieve large dynamic aperture. In this paper we will report the design of final focusing system.

THYA01	Beam Dynamics in Positron Injector Systems for Next Generation B Factories	emittance, linac, injection, target	2857
	N. Iida, H. Ikeda, T. Kamitani, M. Kikuchi, K. Oide, D.M. Zhou KEK, Ibaraki, Japan
	SuperKEKB, the upgrade plan of KEKB, aims to boost the luminosity up to 8x10³5 /cm²/s. The beam energy of the Low Energy Ring (LER) is 4 GeV for positrons, and that of the High Energy Ring is 7 GeV for electrons. SuperKEKB is designed to produce low emittance beams. The horizontal and vertical emittances of the injection beams are 12.5 nm and 0.9 nm, respectively, which are one or two orders smaller than those of KEKB. The normal and maximum required charges are 4 nC and 8nC, respectively. The positron injector system consists of the source, capture systems, L-band and S-band linacs, collimators, an energy compression system (ECS), a 1.1-GeV damping ring, a bunch compression system (BCS), S-band and C-band linacs, another ECS and a beam transport line into the LER. For the low emittance beam with a huge amount of the positron charge like 8nC, some kinds of issues by the instabilities will be predicted due to such as Coherent Synchrotron Radiation (CSR), beam loading, beam-beam effects, and so on. This paper reports a design of the positron beam injection system for SuperKEKB. In addition, comparisons with SuperB are described.
	Slides THYA01 [7.572 MB]

THPZ008	Strong-strong Simulations for Super B Factories II	simulation, luminosity, resonance, factory	3696
	K. Ohmi KEK, Ibaraki, Japan
	Trials for the strong-strong simulation for study of beam-beam effect in large Piwinski angle (LPA) collision adopted in Super B factories. So far a combination method of particle in cell method and soft-Gaussian model has been used. We now show complete strong-strong simulation for LPA collision scheme. Collisions between many slices of two bunches are evaluated by particle in cell method with shifted Green function.

THPZ010	Beam Background and MDI Design for SuperKEKB/Belle-II	background, luminosity, scattering, radiation	3702
	H. Nakayama, M. Iwasaki, K. Kanazawa, Y. Ohnishi, S. Tanaka, T. Tsuboyama KEK, Tsukuba, Japan H. Nakano Tohoku University, Graduate School of Science, Sendai, Japan
	The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 at^-1before the shutdown in June 2010. We have started upgrading both the accelerator and detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8x10³5 cm^-2s^-1. With the increased luminosity, the beam background will also increase. The development of Machine-Detector Interface (MDI) design is very important to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.

THPZ024	Updated Design of the Italian SuperB Factory Injection System	injection, linac, electron, emittance	3738
	S. Guiducci, M.E. Biagini, R. Boni, M.A. Preger, P. Raimondi INFN/LNF, Frascati (Roma), Italy J. Brossard, O. Dadoun, P. Lepercq, C. Rimbault, A. Variola LAL, Orsay, France A. Chancé CEA, Gif-sur-Yvette, France J.T. Seeman SLAC, Menlo Park, California, USA
	The ultra high luminosity B-factory (SuperB) project of INFN requires a high performance and reliable injection system, providing electrons at 4 GeV and positrons at 7 GeV, to fulfill the very tight requirements of the collider. Due to the short beam lifetime, continuous injection of electrons and positrons in both HER and LER rings is necessary to keep the average luminosity at a high level. An updated version of the injection system, optimized at higher repetition frequency is presented. This scheme includes a polarized electron gun, a positron production scheme with electron/positron conversion at low energy 0.6 GeV, and a 1 GeV damping ring to reduce the injected emittance of the positron beam.

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MOOCA03

Updates to the International Linear Collider Damping Rings Baseline Design

lattice, damping, electron, cavity

32

S. Guiducci, M.E. Biagini
INFN/LNF, Frascati (Roma), Italy
G. Dugan, M.A. Palmer, D. L. Rubin
CLASSE, Ithaca, New York, USA
J. Gao, D. Wang
IHEP Beijing, Beijing, People's Republic of China
M.T.F. Pivi, Y. Sun
SLAC, Menlo Park, California, USA
J. Urakawa
KEK, Ibaraki, Japan

A new baseline design for the International Linear Collider (ILC) damping rings has been adopted which reduces the ring circumference to 3.2 km from 6.4 km. This design change is associated with a revised plan to operate the ILC with one half the beam current originally specified in the ILC Reference Design Report. We describe the new layout and lattice that has been developed for the shorter ring. In addition, we discuss features of the new design that will allow operation at a 10Hz repetition rate which is twice the rate specified for baseline operation. Finally, we examine the implications for restoring operation with the originally specified beam current while maintaining the smaller ring circumference.

Slides MOOCA03 [2.381 MB]

MOPO017

Latest Performance Results from the FONT5 Intra-train Position and Angle Feedback System at ATF2

feedback, kicker, linear-collider, collider

520

G.B. Christian, D.R. Bett, M.R. Davis, C. Perry
JAI, Oxford, United Kingdom
R. Apsimon, P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
B. Constance, A. Gerbershagen
CERN, Geneva, Switzerland
J. Resta-López
IFIC, Valencia, Spain

A prototype Interaction Point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider, has been designed and tested on the extraction line of the KEK Accelerator Test Facility (ATF). The FONT5 intra-train feedback system aims to stabilize the beam orbit by correcting both the position and angle jitter in the vertical plane on bunch-to-bunch timescales, providing micron-level stability at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. A total system latency as low as approximately 140 ns has been demonstrated.

MOPS007

Interference of CSR Fields in a Curved Waveguide

impedance, damping, storage-ring, wakefield

604

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

CSR fields generated by a bunched beam passing through a series of bending magnets may interfere with each other due the reflections of outer chamber wall. This kind of multi-bend interference causes sharp peaks and long-range tail in the CSR impedance and wake potentials, respectively. Using a dedicated computer code, CSRZ, we calculated the longitudinal CSR impedance in the SuperKEKB positron damping ring for purpose of demonstration. It was found that multi-bend interference may enhance the CSR fields within a distance comparable to the bunch length, which is typically in the order of several millimeters. A simple instability analysis was performed and it suggested that multi-bend interference might play a role in the single-bunch instabilities of small electron/positron rings.

MOPS057

Beam-beam Interaction under External Force Oscillation

luminosity, simulation, electron, kicker

736

K. Ohmi
KEK, Ibaraki, Japan

Beam-ion interaction is strongly nonlinear. Response for external oscillation applied to beam shows characteristic feature. Simulations for external frequency scan becomes feasible for the recent computer power. We show the frequency response for beam-ion system in KEK-PF and recent low emittance rings.

MOPS083

Update on Electron Cloud Mitigation Studies at Cesr-TA*

electron, wiggler, resonance, photon

796

J.R. Calvey, M.G. Billing, J.V. Conway, G. Dugan, S. Greenwald, Y. Li, X. Liu, J.A. Livezey, J. Makita, R.E. Meller, M.A. Palmer, S. Santos, R.M. Schwartz, J.P. Sikora, C.R. Strohman
CLASSE, Ithaca, New York, USA
S. Calatroni, G. Rumolo
CERN, Geneva, Switzerland
K. Kanazawa, Y. Suetsugu
KEK, Ibaraki, Japan
M.T.F. Pivi, L. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the US National Science Foundation (PHY-0734867) and Department of Energy (DE-FC02-08ER41538)
Over the course of the past three years, the Cornell Electron Storage Ring (CESR) has been reconfigured to serve as a test facility for next generation particle accelerators. A significant part of this program has been the installation of several diagnostic devices to measure and quantify the electron cloud effect, a potential limiting factor in these machines. In particular, more than 30 Retarding Field Analyzers (RFAs) have been installed in CESR. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. This paper will provide an overview of RFA results obtained at CesrTA over the past year, including measurements taken as function of bunch spacing and wiggler magnetic field. Understanding these results provides a great deal of insight into the behavior of the electron cloud.

MOPS088

Simulation of Electron Cloud Beam Dynamics for CesrTA

emittance, simulation, electron, betatron

808

K.G. Sonnad, G. Dugan, M.A. Palmer, G. Ramirez, H.A. Williams
CLASSE, Ithaca, New York, USA
K.R. Butler
Cornell University, Ithaca, New York, USA
M.T.F. Pivi
SLAC, Menlo Park, California, USA

This presentation provides a comprehensive set of results obtained using the simulation program CMAD. CMAD is being used for studying electron cloud induced beam dynamics issues for CesrTA, which is a test facility for studying physics associated with electron and positron damping rings. In particular, we take a closer look at electron cloud induced effects on positron beams, including head-tail motion, emittance growth and incoherent tune shifts for parameters specific to ongoing experimental studies at CesrTA. The correspondence between simulation and experimental results will also be discussed.
Work supported by US Department of Energy grant number DE-FC02-08ER41538
and the National Science Foundation grant number PHY-0734867

MOPZ034

Proton Contamination Studies in the MICE Muon Beam Line

proton, lattice, quadrupole, emittance

871

S.D. Blot, Y.K. Kim
University of Chicago, Chicago, Illinois, USA
R.R.M. Fletcher
UCR, Riverside, California, USA
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA
C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

The Muon Ionization Cooling Experiment (MICE) aims to demonstrate transverse beam emittance reduction for a muon beam. To create these muons, a titanium target is dipped into the ISIS proton accelerator at Rutherford Appleton Laboratory (UK) to create pions, which are transported and decay to muons in the MICE beamline. Beam particle identification and triggering is performed using time of flight (ToF) detectors. When running the MICE beamline with positive polarity, protons produced in the target contaminate the muon beam with a sufficiently high rate to saturate the TOF detectors. Polyethylene sheets of varying thicknesses were installed to absorb the proton impurities in the beam. Studies with pion beams at momenta of 140, 200, and 240MeV/c were performed with different proton absorber thicknesses. The results of these studies show good agreement with theoretical range plots and will be presented.

TUPC005

Evolution of Pressure in Positron Source for Future Linear e⁺e⁻ Collider

target, photon, collider, linear-collider

994

O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva
University of Hamburg, Hamburg, Germany
A.F. Hartin, G.A. Moortgat-Pick, S. Riemann, A. Ushakov
DESY, Hamburg, Germany
A. Schälicke, F. Staufenbiel
DESY Zeuthen, Zeuthen, Germany

Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
Energy deposition in the conversion targets of positron sources for future linear colliders induces an immense thermal load and create pressure waves in the material. This stress could substantially reduce the lifetime of the target or other target materials impinged by the incident intense photon or electron beam. We have studied the evolution of acoustic pressure waves in target materials based on the parameter assumptions for the International Linear Collider (ILC) baseline source. The fluid model is employed by taking into account the target and the incident photon beam parameters. Initial results of these new simulations are presented and compared with earlier studies. Prospects for further studies are outlined.

TUPC006

Production of Highly Polarized Positron Beams*

polarization, undulator, photon, target

997

A. Ushakov, O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick
University of Hamburg, Hamburg, Germany
A.F. Hartin
DESY, Hamburg, Germany
S. Riemann, A. Schälicke, F. Staufenbiel
DESY Zeuthen, Zeuthen, Germany

Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
Using of polarized electron and positron beams significantly increases the physics potential of future linear colliders. The generation of an intense and highly polarized positron beam is a challenge. The undulator-based positron source located at the end of electron linac is the baseline source for the International Linear Collider. In case of a 250 GeV drive beam energy, an helical undulator with K = 0.92, an undulator period of 11.5 mm and a titanium alloy target of 0.4 radiation length thickness, the average polarization of the generated positrons is relatively low (about 22 percent). In this contribution, the possibilities of increasing the positron polarization have been considered by adjusting the undulator field and selecting those photons and positrons that yield a highly polarized beam. The detailed simulations have been performed with our developed Geant4-based application PPS-Sim*.
* http://pps-sim.desy.de

TUPC028

Background and Energy Deposition Studies for the CLIC Post-Collision Line*

photon, simulation, radiation, electron

1060

R. Appleby, M.D. Salt
UMAN, Manchester, United Kingdom
L.C. Deacon, E. Gschwendtner
CERN, Geneva, Switzerland

The CLIC post-collision line is designed to transport the spent-beam products of collision to their respective dumps, with minimal losses and thus minimal background contributions. With nanometre spot-sizes at TeV energies, large beam-beam effects induce divergence and dispersion of the outgoing beams, with a large production cross-section of Beamstrahlung photons and subsequently coherent pairs. The post-collision line should provide sufficient divergence of the beam to avoid damage to the vacuum exit and dump entrance windows. In this study, the beam losses are investigated, with the production of secondary particles from the interaction with matter simulated. The particle flux leakage from absorbers and dumps is modelled to determine the total energy deposited on magnets of the post-collision line. Finally, both electromagnetic and hadronic backgrounds at the CLIC experiment are considered.

TUPC030

Recommendation for Mitigations of the Electron Cloud Instability in the ILC

electron, vacuum, 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.

TUPC042

First Beam to FACET

linac, electron, controls, vacuum

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.

TUPC053

Superconducting Positron Stacking Ring for CLIC

injection, damping, synchrotron, septum

1117

F. Zimmermann, L. Rinolfi
CERN, Geneva, Switzerland
E.V. Bulyak, P. Gladkikh
NSC/KIPT, Kharkov, Ukraine
T. Omori, J. Urakawa, K. Yokoya
KEK, Ibaraki, Japan

The generation of polarized positrons for future colliders based on Compton storage rings is a promising method. A challenging key ingredient of this method is the necessary quasi-continuous positron injection into a stacking ring. The ordinary methods of multi-turn injection are not appropriate for this purpose, because the required number of injection-turns is a few hundred, and the emittance of the injected positron bunches is large. This paper describes a possible solution based on 5 GeV superconducting stacking ring, where a novel method of the combined longitudinal and transverse injection process is used to stack positrons. The ring dynamic aperture allows to inject the positron beam with normalized emittance up to 2000 micrometers during a few hundred turns. The injection efficiency is larger than 90% in simulation. The number of the injection turns is only limited by the synchrotron radiation power. The ring lattice and the results of injection simulations are presented.

TUPC083

Comparative Studies into 3D Beam Loss Simulations

simulation, photon, beam-losses, electron

1198

M. Panniello
MPI-K, Heidelberg, Germany
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by the Helmholtz Association and GSI under contract VH-NG-328.
A detailed understanding and monitoring of potential beam loss mechanisms is crucial for every particle accelerator. The main motivation in low energy facilities, such as the Ultra-low energy Storage Ring (USR) at the future Facility of Low energy Antiproton and Ion Research (FLAIR), comes from the very low number of particles available which in such machine ought to be conserved. In High Energy accelerators it is the concern about activation or even physical damage of machine parts which has to be taken into serious account. The CLIC Test Facility (CTF3) at CERN provides an ideal testing ground for studies into novel BLM systems and is well suited for benchmarking the results from numerical simulations in experiments. This contribution summarizes the three-dimensional beam loss pattern as found with the commonly used codes FLUKA and Géant4. The results from these codes are compared and analyzed in detail and used for the identification of optimum beam loss monitor locations.

TUPC153

Study of the Response of Silicon Photomultipliers in Presence of Strong Cross-talk Noise

photon, beam-losses, radiation, heavy-ion

1389

M. Putignano, A. Intermite
The University of Liverpool, Liverpool, United Kingdom
M. Putignano, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by STFC, the EU under GA-ITN-215080, the Helmholtz Association and GSI under VH-NG-328.
Silicon Photomultipliers (SiPM) are interesting detectors for beam diagnostics applications where they could replace photomultiplier tubes as large dynamic range photon counting devices due to their reduced dimensions and costs, higher photon detection efficiency, immunity to magnetic fields and low operation voltage. Possible applications include longitudinal beam profile measurements by synchrotron light imaging, detection of optical transition radiation for energy spectrum measurements and medical imaging. However, quantitative measurement with SiPMs are jeopardized by the systematic reading error due to Optical Cross-talk (OC), i.e. optical coupling between neighboring diodes in the array. OC results in overestimation of the impinging light level, and reflects the probability of a triggered avalanche creating a photon of suitable energy and direction to fire a second avalanche in another diode. In this paper, we derive a generalized response distribution for SiPM in presence of cross-talk noise, which overcomes the limitations of assumptions currently made in literature and provides a correction of the SiPM response distribution valid for arbitrary large levels of cross-talk.

TUPO002

High Flux Polarized Gamma Rays Production: First Measurements with a Four-mirror Cavity at the ATF

laser, cavity, electron, damping

1446

N. Delerue, J. Bonis, I. Chaikovska, R. Chiche, R. Cizeron, M. Cohen, P. Cornebise, R. Flaminio, D. Jehanno, F. Labaye, M. Lacroix, Y. Peinaud, L. Pinard, V. Soskov, A. Variola, Z.F. Zomer
LAL, Orsay, France
T. Akagi, S. Miyoshi
Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan
S. Araki, Y. Funahashi, Y. Honda, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
E. Cormier
CELIA, Talence, France
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

Funding: ANR, IN2P3
The next generation of e+/e^- colliders will require the production of a very intense flux of gamma rays to allow polarized positrons to be produced in sufficient quantities. To demonstrate that this can be achieved a four-mirror cavity has recently been installed at the Accelerator Test Facility (ATF) at KEK to produce a high flux of polarized gamma rays by inverse Compton scattering. A four-mirror non-planar geometry is used to ensure the polarization of the gamma rays produced. The main mechanical features of the cavity are presented. A fibre amplifier is used to inject about 10W in the high finesse cavity with a gain of 1000. A digital feedback system is used to keep the cavity at the length required for the optimal power enhancement. First preliminary measurements show that on some beam crossings the interactions produce more than 25 photons with an average energy of about 24 MeV. Several upgrades currently in progress are described.

TUPS055

Organizing the ILC Technical Design Documentation

lattice, linear-collider, damping, collider

1656

L. Hagge, S. Eucker, B. List, N.J. Walker, N. Welle
DESY, Hamburg, Germany

The Global Design Effort (GDE) for the International Linear Collider (ILC) is currently preparing the Technical Design Report (TDR), which will be released at the end of 2012 and will serve as the basis for a decision process. The TDR will be written based on the Technical Design Documentation (TDD), which captures the entire design efforts, results and rationale, including e. g. parameter lists, specifications, CAD models and drawings, cost estimation, simulations and calculations, and summary reports. Formal review meetings help making the documentation complete, correct and consistent. The TDD is stored in an Engineering Data Management System (EDMS), which ensures that it remains accessible beyond the GDE in an organized way and at a well-defined location. The EDMS provides traceability (e. g. from design decisions to corresponding cost estimates), version management and change control. The poster presents the process and tools that were established for the organization of the TDD and provides an overview of the emerging documentation.

WEZA01

Round Beam Collisions at VEPP-2000*

luminosity, lattice, resonance, betatron

1926

Y.M. Shatunov, D.E. Berkaev, A.N. Kirpotin, I. Koop, A.P. Lysenko, I. Nesterenko, E. Perevedentsev, Yu. A. Rogovsky, A.L. Romanov, P.Yu. Shatunov, D.B. Shwartz, A.N. Skrinsky, I. Zemlyansky
BINP SB RAS, Novosibirsk, Russia

The idea of round beams collision was proposed more than 20 years ago for the Novosibirsk Phi-factory design. It requires equal emittances, equal small fractional tunes, equal beta functions at the IP, no betatron coupling in the collider arcs. A 90° rotation at each passage of the transverse oscillation plane by means of solenoids in the interaction regions provides conservation of the longitudinal component of the angular moment. Thus the transverse motion becomes one-dimensional. Such a scheme helps to eliminate all betatron coupling resonances that are of crucial importance for beam-beam tune shift saturation and lifetime degradation. Only recently, the round beam concept was successfully tested at the electron-positron collider VEPP2000 at the energy of 510 MeV. Despite the low energy a high single bunch luminosity of 10³¹ cm^-2s⁻¹ was achieved together with a maximum tune shift as high as 0.1. At present the work is in progress to increase the energy of the collider to explore the range between 510 MeV and 1 GeV in collision.

Slides WEZA01 [3.740 MB]

WEOAB02

FACET: The New User Facility at SLAC

electron, plasma, linac, wakefield

1953

C.I. Clarke, F.-J. Decker, R.A. Erickson, C. Hast, M.J. Hogan, R.H. Iverson, S.Z. Li, Y. Nosochkov, N. Phinney, J. Sheppard, U. Wienands, W. Wittmer, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA
A. Seryi
JAI, Oxford, United Kingdom

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET (Facility for Advanced Accelerator and Experimental Tests) is a new User Facility at SLAC National Accelerator Laboratory. Its high power electron and positron beams make it a unique facility, ideal for beam-driven Plasma Wakefield Acceleration studies. The first 2 km of the SLAC linac produce 23 GeV, 3.2 nC electron and positron beams with short bunch lengths of 20 um. A final focusing system can produce beam spots 10um wide. User-aided Commissioning took place in summer 2011 and FACET will formally come online in early 2012. We present the User Facility, the current features, planned upgrades and the opportunities for further experiments.

Slides WEOAB02 [4.772 MB]

WEPC100

Simulation of the Single Bunch Instability due to the Electron Cloud Effect by Tracking with a Pre-computed 2D Wake Matrix*

electron, dipole, simulation, single-bunch

2247

A. Markoviḱ, G. Pöplau, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Supported by DFG Contract Nr. RI 814/20-1.
The passage of a positron bunch through an initially homogeneous electron cloud (e-cloud) changes the distribution of the e-cloud in a way that the concentration of electrons in the proximity of the beam axis grows rapidly. The electrons are primarily moving in the transverse plane and are very sensitive on the beam centroid position in that plane. Thus the transverse kick of the e-cloud on the tail particles depends on the centroid position of the head particles of the same bunch. A PIC simulation of the interaction of a positron beam with an e-cloud yields the wake kick from the electrons on the tail particles for a certain offset in the transverse centroid position of the head parts of the bunch. With such a pre-computed 2D wake matrix, for a certain e-cloud density, we investigate the stability of a single bunch by tracking it through the linear optics of the storage ring while at each turn applying the kick from the e-cloud. We examine the positron bunch stability of KEKB-LER and PETRAIII for a certain electron cloud density.

WEPC111

Single Particle Tracking Simulation for Compact Cyclotron*

simulation, cyclotron, cavity, injection

2274

H.W. Kim, J.-S. Chai, B.N. Lee, Y.S. Lee, K.R. Nam, H.S. Song
SKKU, Suwon, Republic of Korea

Funding: Ministry of Education, Science and Technology, Republic of Korea. Department of Energy Science and School of Information and Communication Engineering of SungKyunKwan University.
Low energy compact cyclotrons for Positron emission tomography (PET) are needed for the production of radio-isotope. In the magnet design for those cyclotrons, single particle tracking simulation after the design is important to check the quality of designed magnetic field of the magnet. The study of single particle tracking simulation for cyclotron magnet is shown in this paper. Maximum beam energy of example cyclotron is 9 MeV for proton and pseudo accelerating gap is adapted for the simulation. 3D CAD program CATIA P3 V5 R18 is used for design the magnet and pseudo accelerating gap. All magnetic and electric field calculations had been performed by OPERA-3D TOSCA and the own-made program OPTICY is used for other calculations - phase slip, radial and axial tune.

WEPO026

Advances in the Design of the SuperB Final Doublet

quadrupole, luminosity, collider, controls

2454

E. Paoloni, N. Carmignani, F. Pilo
University of Pisa and INFN, Pisa, Italy
S. Bettoni
CERN, Geneva, Switzerland
M.E. Biagini, P. Raimondi
INFN/LNF, Frascati (Roma), Italy
F. Bosi
INFN-Pisa, Pisa, Italy
P. Fabbricatore, S. Farinon, R. Musenich
INFN Genova, Genova, Italy
M.K. Sullivan
SLAC, Menlo Park, California, USA

SuperB is an asymmetric (6.7 GeV HER, 4.18 GeV LER) e⁺ e− collider operating at the Y(4S) peak with a design peak luminosity of 10³6 Hz/cm² to be built in Italy in the very near future. The design luminosity is almost a factor hundred higher than that of the present generation comparable facilities. To get the design luminosity a novel collision scheme, the so called “large Piwinski angle with crab waist”, has been designed. The scheme requires a short focus final doublet to reduce the vertical beta function down to betay*=0.2 mm at the interaction point (IP). The final doublet will be composed by a set of permanent and superconducting (SC) quadrupoles. The SC quadrupole doublets QD0/QF1 have to be placed as close to the IP as possible. This layout is critical because the space available for the doublets is very small. An advanced design of the quadrupole has been developed, based on the double helical coil concept. The paper discusses the design concept, the construction and the results of test of a model of the superconducting quadrupole based on NbTi technology. Future developments are also presented.

WEPO027

Design Study of Final Focusing Superconducting Magnets for the SuperKEKB

solenoid, focusing, quadrupole, luminosity

2457

M. Tawada, N. Higashi, M. Iwasaki, H. Koiso, A. Morita, Y. Ohnishi, N. Ohuchi, K. Oide, T. Oki, K. Tsuchiya, H. Yamaoka, Z.G. Zong
KEK, Ibaraki, Japan

For SuperKEKB, which is an upgrade project of KEKB, we are studying the design of the final focus quadrupole magnets for the interaction region. The 7 GeV electrons in the high-energy ring and the 4 GeV positrons in the low-energy ring collide at one IP with a finite crossing angle of 83 mrad. For each beam, the final beam focusing system consists of the superconducting quadrupole-doublets. These quadrupole magnets have to meet specifications described below. (1) Because of the small beam separation between two beam lines, the superconducting magnet is designed with thin coils and the conductor size is required to be minimized. (2) Since the beta functions are so large, a large space with a good field quality is required. (3) These magnets must apply the focusing fields on electrons and positrons, independent each other. The quadrupole magnets in the solenoid field of the particle detector are designed without an iron yoke. Consequently, the reduction of the leakage fields from the adjacent beam lines is a critical issue to achieve large dynamic aperture. In this paper we will report the design of final focusing system.

THYA01

Beam Dynamics in Positron Injector Systems for Next Generation B Factories

emittance, linac, injection, target

2857

N. Iida, H. Ikeda, T. Kamitani, M. Kikuchi, K. Oide, D.M. Zhou
KEK, Ibaraki, Japan

SuperKEKB, the upgrade plan of KEKB, aims to boost the luminosity up to 8x10³5 /cm²/s. The beam energy of the Low Energy Ring (LER) is 4 GeV for positrons, and that of the High Energy Ring is 7 GeV for electrons. SuperKEKB is designed to produce low emittance beams. The horizontal and vertical emittances of the injection beams are 12.5 nm and 0.9 nm, respectively, which are one or two orders smaller than those of KEKB. The normal and maximum required charges are 4 nC and 8nC, respectively. The positron injector system consists of the source, capture systems, L-band and S-band linacs, collimators, an energy compression system (ECS), a 1.1-GeV damping ring, a bunch compression system (BCS), S-band and C-band linacs, another ECS and a beam transport line into the LER. For the low emittance beam with a huge amount of the positron charge like 8nC, some kinds of issues by the instabilities will be predicted due to such as Coherent Synchrotron Radiation (CSR), beam loading, beam-beam effects, and so on. This paper reports a design of the positron beam injection system for SuperKEKB. In addition, comparisons with SuperB are described.

Slides THYA01 [7.572 MB]

THPZ008

Strong-strong Simulations for Super B Factories II

simulation, luminosity, resonance, factory

3696

K. Ohmi
KEK, Ibaraki, Japan

Trials for the strong-strong simulation for study of beam-beam effect in large Piwinski angle (LPA) collision adopted in Super B factories. So far a combination method of particle in cell method and soft-Gaussian model has been used. We now show complete strong-strong simulation for LPA collision scheme. Collisions between many slices of two bunches are evaluated by particle in cell method with shifted Green function.

THPZ010

Beam Background and MDI Design for SuperKEKB/Belle-II

background, luminosity, scattering, radiation

3702

H. Nakayama, M. Iwasaki, K. Kanazawa, Y. Ohnishi, S. Tanaka, T. Tsuboyama
KEK, Tsukuba, Japan
H. Nakano
Tohoku University, Graduate School of Science, Sendai, Japan

The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 at^-1before the shutdown in June 2010. We have started upgrading both the accelerator and detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8x10³5 cm^-2s^-1. With the increased luminosity, the beam background will also increase. The development of Machine-Detector Interface (MDI) design is very important to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.

THPZ024

Updated Design of the Italian SuperB Factory Injection System

injection, linac, electron, emittance

3738

S. Guiducci, M.E. Biagini, R. Boni, M.A. Preger, P. Raimondi
INFN/LNF, Frascati (Roma), Italy
J. Brossard, O. Dadoun, P. Lepercq, C. Rimbault, A. Variola
LAL, Orsay, France
A. Chancé
CEA, Gif-sur-Yvette, France
J.T. Seeman
SLAC, Menlo Park, California, USA

The ultra high luminosity B-factory (SuperB) project of INFN requires a high performance and reliable injection system, providing electrons at 4 GeV and positrons at 7 GeV, to fulfill the very tight requirements of the collider. Due to the short beam lifetime, continuous injection of electrons and positrons in both HER and LER rings is necessary to keep the average luminosity at a high level. An updated version of the injection system, optimized at higher repetition frequency is presented. This scheme includes a polarized electron gun, a positron production scheme with electron/positron conversion at low energy 0.6 GeV, and a 1 GeV damping ring to reduce the injected emittance of the positron beam.