IPAC2015 - List of Keywords (positron)

Paper	Title	Other Keywords	Page
MOPMA022	Numerical Analysis of Parasitic Crossing Compensation with Wires in DAΦNE	luminosity, beam-beam-effects, collider, experiment	589
	A. Valishev Fermilab, Batavia, Illinois, USA C. Milardi, M. Zobov INFN/LNF, Frascati (Roma), Italy D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	Funding: This work was partially supported by the US LARP. The HiLumi LHC Design Study is partially funded by the European Commission Grant Agreement 284404. Current bearing wire compensators were successfully used in the 2005-2006 running of the DAΦNE collider to mitigate the detrimental effects of parasitic beam-beam interactions. A marked improvement of the positron beam lifetime was observed in machine operation with the KLOE detector. In view of the possible application of wire beam-beam compensators for the High Luminosity LHC upgrade, we revisit the DAΦNE experiments. We use an improved model of the accelerator with the goal to validate the modern simulation tools and provide valuable input for the LHC upgrade project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA022
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MOPTY034	Distributed Beam Loss Monitor Based on the Cherenkov Effect in Optical Fiber	electron, radiation, beam-losses, storage-ring	1004
	Yu. Maltseva, F.A. Emanov, A.V. Petrenko, V.G. Prisekin BINP SB RAS, Novosibirsk, Russia F.A. Emanov NSU, Novosibirsk, Russia A.V. Petrenko CERN, Geneva, Switzerland
	A distributed beam loss monitor based on the Cherenkov effect in optical fiber has been implemented for the VEPP5 electron and positron linacs and the 510 MeV damping ring at the Budker INP. The monitor operation is based on detection of the Cherenkov radiation generated in optical fiber by means of relativistic particles created in electromagnetic shower after highly relativistic beam particles (electrons or positrons) hit the vacuum pipe. The main advantage of the distributed monitor compared to local ones is that a long optical fiber section can be used instead of a large number of local beam loss monitors. In our experiments the Cherenkov light was detected by photomultiplier tube (PMT). Timing of PMT signal gives the location of the beam loss. In the experiment with 20 m long optical fiber we achieved 3 m spatial resolution. To improve spatial resolution optimization and selection process of optical fiber and PMT are needed and according to our theoretical estimations 0.5 m spatial resolution can be achieved. We also suggest similar techniques for detection of electron (or positron) losses due to Touschek effect in storage rings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY034
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TUYB1	Progress of SuperKEKB	emittance, electron, gun, linac	1291
	T. Miura, T. Abe, T. Adachi, K. Akai, M. Akemoto, A. Akiyama, D.A. Arakawa, Y. Arakida, Y. Arimoto, M. Arinaga, K. Ebihara, K. Egawa, A. Enomoto, J.W. Flanagan, S. Fukuda, H. Fukuma, Y. Funakoshi, K. Furukawa, T. Furuya, K. Hara, T. Higo, H. Hisamatsu, H. Honma, T. Honma, R. Ichimiya, N. Iida, H. Iinuma, H. Ikeda, M. Ikeda, T. Ishibashi, H. Ishii, M. Iwasaki, A. Kabe, T. Kageyama, H. Kaji, K. Kakihara, S. Kamada, T. Kamitani, S. Kanaeda, K. Kanazawa, H. Katagiri, S. Kato, S. Kazama, M. Kikuchi, T. Kobayashi, H. Koiso, Y. Kojima, M. Kurashina, K. Marutsuka, M. Masuzawa, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, F. Miyahara, K. Mori, T. Mori, A. Morita, Y. Morita, H. Nakai, H. Nakajima, T.T. Nakamura, K. Nakanishi, K. Nakao, H. Nakayama, T. Natsui, M. Nishiwaki, J.-I. Odagiri, Y. Ogawa, K. Ohmi, Y. Ohnishi, S. Ohsawa, Y. Ohsawa, N. Ohuchi, K. Oide, T. Oki, M. Ono, H. Sakai, Y. Sakamoto, S. Sasaki, M. Sato, M. Satoh, K. Shibata, T. Shidara, M. Shirai, A. Shirakawa, M. Suetake, Y. Suetsugu, R. Sugahara, H. Sugimoto, T. Suwada, S. Takasaki, T. Takatomi, T. Takenaka, Y. Takeuchi, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, N. Tokuda, K. Tsuchiya, X. Wang, K. Watanabe, H. Yamaoka, Y. Yano, K. Yokoyama, Ma. Yoshida, M. Yoshida, S.I. Yoshimoto, K. Yoshino, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	This presentation will cover the status of the installation and the injector commissioning status of SuperKEKB. The IR optics and design with very low β^* of less than 1 mm will be discussed.
	Slides TUYB1 [6.588 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUYB1
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TUPWA048	Radiative Cooled Target for the ILC Polarized Positron Source	target, vacuum, photon, radiation	1526
	A. Ushakov University of Hamburg, Hamburg, Germany F. Dietrich, S. Riemann, T. Rublack DESY Zeuthen, Zeuthen, Germany P. Sievers CERN, Geneva, Switzerland
	Funding: Work supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Optimization", contract number 19XL7IC4 The target for the polarized positron source of the future International Linear Collider (ILC) is designed as wheel of 1 m diameter spinning with 2000 revolutions per minute to distribute the heat load. The target system is placed in vacuum since exit windows would not stand the load. In the current ILC design, the positron target is assumed to be water-cooled. Here, as an alternative, radiative cooling of the target has been studied. The energy deposition in the target is the input for ANSYS simulations. They include the temperature evolution as well as the corresponding thermo-mechanical stress in the target components. A principal design is suggested for further consideration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA048
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TUPWA057	DAΦNE LINAC: Beam Diagnostics and Outline of the Last Improvements	linac, klystron, electron, operation	1549
	B. Buonomo, L.G. Foggetta INFN/LNF, Frascati (Roma), Italy
	The LINAC of the DAΦNE complex is in operation since 1996, both as injector of the e⁺ e⁻ phi-factory, and, since 2003, for the extraction of electron beam to the Beam Test Facility. In the last years, many improvements has been developed in different sub-systems of the LINAC, aiming at a wider, tunable range of beam parameters, in particular the pulse time width and the pulse charge. A long term measurement campaign has been recently started to characterize the LINAC performance after that many sub-systems has been overhauled and improved, starting from RF power (i.e. klystron substitution, modulator re-newing, RF driver layout, SLED tuning) as well as the timing system, magnets, cooling, vacuum, control system and energy/position diagnostics. This work reports the latest results on the optimization of the fully consolidated system.
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TUPJE057	Realistic Undulators for Intense Gamma-ray Beams at Future Colliders	undulator, electron, simulation, synchrotron	1756
	A.O. Alrashdi, I.R. Bailey Lancaster University, Lancaster, United Kingdom D. Newton The University of Liverpool, Liverpool, United Kingdom
	The baseline designs for the ILC and CLIC require the production of an intense flux of gamma rays in their positron sources. In the case of CLIC the gamma rays are produced by a Compton backscattering source, but in this paper we concentrate on undulator-based sources as proposed for the ILC. We present the development of a simulation to generate a magnetic field map based on a Fourier analysis of any measured field map. We have used a field map measured from the ILC helical undulator prototype to calculate the typical distribution of field errors, and used them in our calculations to produce simulated field maps. We show that a loss of gamma ray intensity of ~ 8% could be expected, compared to the ideal case. This leads to a similar drop in positron production which can be compensated for by increasing the undulator length.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE057
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TUPMA020	PEPPo: Using a Polarized Electron Beam to Produce Polarized Positrons	electron, target, polarization, solenoid	1878
	A.H. Adeyemi, P.L. Gueye Hampton University, Hampton, Virginia, USA P.A. Adderley, M.M. Ali, H. Areti, J. F. Benesch, L.S. Cardman, J. Clark, S. Covert, C. Cuevas, A. Freyberger, S. Golge, J.M. Grames, P.L. Gueye, J. Hansknecht, P.L. Harrell, C. Hyde, R. Kazimi, Y. Kim, D. Machie, K.L. Mahoney, R.R. Mammei, J.L. McCarter, M.D. McCaughan, M. Poelker, M.L. Stutzman, R. Suleiman, C.-Y. Tsai, D.L. Turner, Y.W. Wang JLab, Newport News, Virginia, USA M.A. Baylac, E. Froidefond, M. Marton, J-F. Muraz, J-S. Real, E. J-M. Voutier LPSC, Grenoble Cedex, France P. Cole, D. Dale, T.A. Forest ISU, Pocatello, Idaho, USA O. Dadoun, A. Variola LAL, Orsay, France D. Dale, Y. Kim IAC, Pocatello, Idaho, USA EF. Fanchini INFN Genova, Genova, Italy S. Golge NCCU, , North Carolina, USA S. Golge, C. Hyde ODU, Norfolk, Virginia, USA J.L. McCarter UVa, Charlottesville, Virginia, USA C.-Y. Tsai Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA A. Variola IN2P3-CNRS, Orsay, France
	Polarized positron beams have been identified as either an essential or a significant ingredient for the experimental program of both the present and next generation of lepton accelerators (JLab, Super KEK B, ILC, CLIC). An experiment demonstrating a new method for producing polarized positrons has been performed at the Continuous Electron Beam Accelerator Facility at Jefferson Lab. The PEPPo (Polarized Electrons for Polarized Positrons) concept relies on the production of polarized e⁻/e⁺ pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high Z conversion target. PEPPo demonstrated the effective transfer of spin-polarization of an 8.2 MeV/c polarized (P~85%) electron beam to positrons produced in varying thickness tungsten production targets, and collected and measured in the range of 3.1 to 6.2 MeV/c. In comparison to other methods this technique reveals a new pathway for producing either high energy or thermal polarized positron beams using a relatively low polarized electron beam energy (~10MeV) .This presentation will describe the PEPPo concept, the motivations of the experiment and high positron polarization achieved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA020
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TUPMA022	CESR Upgrade as a High-Energy, High-Brightness X-Ray Light Source	emittance, electron, lattice, storage-ring	1884
	J.P. Shanks, D. L. Rubin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Research supported by NSF grant DMR-1332208. The Cornell Electron Storage Ring (CESR) operates most of the year as the Cornell High Energy Synchrotron Source (CHESS). CESR was originally designed and operated as an electron/positron collider, circulating high-emittance beams in order to maximize luminosity. Beam lines were developed to extract x-rays from both electron and positron beams. The two beams share a common vacuum chamber, and are electrostatically separated to avoid collisions. The requirement to store counter-rotating beams significantly constrains the storage ring optics, limiting emittance and, beam current, and bunch distributions. The proposed upgrade eliminates two-beam operation in favor of a single optimized on-axis beam. Several new undulator-based beam lines are planned. The horizontal emittance is reduced in steps, first from 90nm to 20nm at 5.3 GeV, and then in a ring-wide upgrade to as low as 300 pm-rad at 6GeV. The low-emittance optics are based on multi-bend achromats with combined function bends. The details of the optics, apertures, and magnet parameters are presented.
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TUPTY003	Study of the Dynamic Response of CLIC Accelerating Structures	alignment, target, operation, monitoring	2000
	E. Daskalaki NTUA, Athens, Greece S. Döbert, M. Duquenne, H. Mainaud Durand, A.L. Vamvakas CERN, Geneva, Switzerland V. Rude ESGT-CNAM, Le Mans, France
	CLIC is a linear electron-positron collider, 48 km long, consisting of more than 20000 repetitive modules. The target beam size of 1 nm dictates very tight alignment tolerances for the accelerating structures (AS). In order to assess the effect of short-term RF power interruptions (breakdowns or failure modes) on the alignment, the dynamic behaviour of the AS was investigated on the prototype two-beam module. On a dedicated experimental setup, the thermal and mechanical time constant (TC) was monitored as a function of ambient temperature, water flow and power. The experimental results showed that the thermal TC ranged between 4 and 11 minutes and presented strong correlation with the cooling water flow. These results were in very good agreement with the theoretical expectations. The displacement dynamics were found to be comparable with the thermal ones. The study indicates that temperature measurement, which is a fast and easy process, can be used as an indicator of the AS displacement. Moreover, it is shown than the transient response can be efficiently controlled through appropriate regulation of the cooling water flow.
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TUPTY008	Commissioning Status and Plan of SuperKEKB Injector Linac	emittance, linac, electron, operation	2013
	M. Satoh, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Iwase, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, S. Kazama, M. Kikuchi, H. Koiso, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, Y. Seimiya, T. Shidara, A. Shirakawa, M. Suetake, H. Sugimoto, T. Suwada, T. Takenaka, M. Tanaka, M. Tawada, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	Toward SuperKEKB project, the injector linac upgrade is ongoing at KEK in order to deliver the low emittance electron/positron beams with the high intensity and small emittance. In the September of 2013, the injector linac commissioning has started. In this presentation, we will describe the commissioning status and plan of SuperKEKB injector linac.
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TUPTY056	Beam-Based Measurements of Long Range Transverse Wakefields in CLIC Main Linac Accelerating Structure	wakefield, electron, linac, experiment	2153
	H. Zha, A. Grudiev, A. Latina, D. Schulte, A. Solodko, W. Wuensch CERN, Geneva, Switzerland E. Adli University of Oslo, Oslo, Norway G. De Michele EPFL, Lausanne, Switzerland G. De Michele PSI, Villigen PSI, Switzerland N. Lipkowitz, G. Yocky SLAC, Menlo Park, California, USA
	The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures in the main linac. Every accelerating structure cell has four waveguides, terminated with individual RF loads, to damp the unwanted long-range transverse wakefields, in order to maintain beam stability in multi-bunch operation. In order to experimentally verify the calculated suppression of the wakefields, a prototype structure has been built and installed in FACET test facility at SLAC. The results of the measurements of the wakefields in the prototype structure by means of positron and electron bunches are presented.
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TUPTY072	A New ILC Positron Source Target System Using Sliding Contact Cooling	target, vacuum, radiation, undulator	2196
	W. Gai, D.S. Doran, R.A. Erck, G.R. Fenske, V.J. Guarino, W. Liu ANL, Argonne, Illinois, USA
	The R&D of the baseline positron source target for ILC is still ongoing after TDR due to the uncertainty of rotating vacuum seal and water cooling system of the fast spinning target wheel. Different institutes around the globe have proposed different approaches to tackle this issue. A spinning target wheel system with sliding contact cooling has been proposed by ANL. The proposed system eliminated the needs of rotating vacuum seal by using magnet bearings and vacuum compatible motor driven solid spinning wheel target. The energy deposited from positron production process is taken away via sliding cooling pads sliding against the spinning wheel. Details about this new target system are presented in this paper.
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TUPTY079	Initial Modeling of Electron Cloud Buildup in the Final-focus Quadrupole Magnets of the SuperKEKB Positron Ring	electron, photon, quadrupole, vacuum	2218
	J.A. Crittenden Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: US National Science Foundation contracts PHY-0734867, PHY-1002467, and PHY-1068662, US Department of Energy contract DE-FC02-08ER41538 and the Japan/US Cooperation Program We present modeling results for electron cloud buildup in the final-focus quadrupole magnet nearest the interaction point in the SuperKEKB positron storage ring. The calculations employ as input recently obtained estimates of synchrotron radiation absorption rates on the vacuum chamber wall including the effect of photon scattering. While the effect both adds to and subtracts from photoelectron production at the points in the ring where unscattered photons strike the wall, it also produces cloud in the other regions. Results for beam-pipe-averaged and beam-averaged cloud densities are presented, as are estimates for the contribution to the fractional vertical coherent tune shift. The effect of the strong magnetic fields is studied and the dependence on the vacuum chamber surface secondary yield characteristics is considered. Cloud buildup is modeled with a 2D particle-in-cell macroparticle tracking code validated using recent measurements of electron trapping in a quadrupole magnet at the Cornell Electron Storage Ring Test Accelerator.
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TUPTY080	Synchrotron Radiation Analysis of the SuperKEKB Positron Storage Ring	photon, scattering, electron, vacuum	2222
	J.A. Crittenden, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA T. Ishibashi, Y. Suetsugu KEK, Ibaraki, Japan
	Funding: US National Science Foundation contracts PHY-0734867, PHY-1002467, and PHY-1068662, US Department of Energy contract DE-FC02-08ER41538 and the Japan/US Cooperation Program. We report on modeling results for synchrotron radiation absorption in the SuperKEKB positron storage ring vacuum chamber including the effects of photon scattering on the interior walls. A detailed model of the geometry of the inner vacuum chamber profile has been developed and used as input to a photon tracking code. Particular emphasis is placed on the photon absorption rates in the electron-positron interaction region.
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WEXB2	Measurement and Analysis of Electron Cloud Induced Emittance Growth at CesrTA	electron, simulation, emittance, feedback	2390
	K.G. Sonnad, L.Y. Bartnik, M.G. Billing, G. Dugan, M.J. Forster Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.W. Flanagan, K. Ohmi KEK, Ibaraki, Japan R. Holtzapple, K.E. McArdle, M.I. Miller CalPoly, San Luis Obispo, California, USA L. Pentecost Colgate University, Hamilton, New York, USA M.T.F. Pivi EBG MedAustron, Wr. Neustadt, Austria S. Tucker Cal Poly, San Luis Obispo, California, USA
	CesrTA is a test accelerator facility at Cornell University that has been configured to study physics associated with electron and positron damping rings. Electron cloud effects is a concern for positron beams for such damping rings. The presentation will give an overview of recent measurements and simulation results for CesrTA. The measurement conditions were set up in order to study single bunch phenomena by observing a "Witness bunch" behind a train of positron bunches. The beam size and the turn by turn spectra were obeserved for the witness bunch under different conditions. Simulations were performed under similar conditions using the program CMAD.
	Slides WEXB2 [2.263 MB]
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WEBB3	Lattice and its Related Beam Dynamics Issues in the CEPC Storage Ring	lattice, quadrupole, electron, factory	2469
	H. Geng, S. Bai, Z. Duan, Y.M. Peng, Q. Qin, D. Wang, Y. Wang, G. Xu, Y. Yue, Y. Zhang IHEP, Beijing, People's Republic of China W. Chou Fermilab, Batavia, Illinois, USA
	The institute of High Energy Physics has proposed an electron positron collider ring with a circumference of 50-100km to study the Higgs boson. Since the proposal was made, the lattice design for CEPC has been carried out and a preliminary conceptual design report has been written at the end of 2014. In this paper, we will describe the philosophy and results of our lattice design. The procedure of dynamic aperture optimization will be shown. A specific issue for CEPC, the pretzel orbit, which has been found distorting the linear lattice for a considerable amount, will be examined. The ways that we are trying to correct the pretzel orbit effect and the result will be shown. We will also discuss the saw tooth effect on the linear lattice and dynamic aperture of the ring.
	Slides WEBB3 [2.599 MB]
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WEPWA008	Measuring the Self-modulation Instability of Electron and Positron Bunches in Plasmas	plasma, electron, cavity, radiation	2506
	P. Muggli, O. Reimann MPI-P, München, Germany E. Adli, V.K.B. Olsen University of Oslo, Oslo, Norway J. Allen, S.J. Gessner, S.Z. Green, M.J. Hogan, M.D. Litos, B.D. O'Shea, V. Yakimenko SLAC, Menlo Park, California, USA L.D. Amorim IST, Lisboa, Portugal G. Andonian, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi, O. Williams UCLA, Los Angeles, California, USA N.C. Lopes, L.O. Silva, J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	The self-modulation instability (SMI) * can be used to transform a long, charged particle bunch into a train of periodically spaced shorter bunches. The SMI occurs in a plasma when the plasma wake period is much shorter than the bunch length. The train of short bunches can then resonantly drive wakefields to much larger amplitude that the long bunch can. The SMI will be used in the AWAKE experiment at CERN, where the wakefields will be driven by a high-energy (400GeV) proton bunch. However, most of the SMI physics can be tested with the electron and positron bunches available at SLAC-FACET. * In this case, the bunch is ~10 plasma wavelengths long, but can drive wakefields in the GV/m range. FACET has a meter-long plasma **** and is well equipped in terms of diagnostic for SMI detection: optical transition radiation for transverse bunch profile measurements, coherent transition radiation interferometry for radial modulation period measurements and energy spectrometer for energy loss and gain measurement of the drive bunch particles. The latest experimental results will be presented. * N. Kumar et al., PRL 104, 255003 (2010) AWAKE Collaboration, PPCF 56 084013 (2014) * J. Vieira et al., PoP 19, 063105 (2012) **** S.Z. Green et al., PPCF 56, 084011 (2014)
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WEPWA017	An Optimization of ILC Positron Source for Electron-Driven Scheme	electron, target, beam-loading, linac	2529
	Y. Seimiya, M. Kuriki, M. Urano HU/AdSM, Higashi-Hiroshima, Japan S. Kashiwagi Tohoku University, School of Science, Sendai, Japan T. Okugi, T. Omori, M. Satoh, J. Urakawa KEK, Ibaraki, Japan T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	International Linear Collider is a future accelerator to find new physics behind the electroweak symmetry breaking by precise measurements of Higgs sector, Top quark, and so on. ILC has capacities to reveal new phenomena beyond Standard model, such as Supersymmetry particles and dark matters. In current design of positron source, undulator scheme is adapted as a baseline. In the scheme, positrons are generated from gamma rays through pair-creation process in Ti-alloy target. Generations of the gamma rays by the undulator radiation requires more than 130 GeV electrons. Therefore, a system demonstration of the scheme is practically difficult prior to the real construction. Consequently, it is desirable to prepare a technical backup of this undulator scheme. We study an optimization of positron source based on the conventional electron-driven scheme for ILC. In this scheme, positron beam is generated by several GeV electron beam impinging on W-Re target. Although heavy heat load and destruction of the target is a potential problem, it can be relaxed by stretching the effective pulse length to 60 ms instead of 1 ms, by a dedicated electron linac for the positron production. In this report, a start-to-end simulation of the electron-driven ILC positron source is performed. Beam-loading effect caused by multi-bunch acceleration in the standing wave RF cavity is also considered.
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WEPWA021	A New DC Muon Beam Line at RCNP, Osaka University	solenoid, proton, target, quadrupole	2537
	Y. Matsumoto, Y. Kohno, Y. Kuno, Y. Nakazawa, H. Sakamoto, A. Sato Osaka University, Osaka, Japan M. Fukuda, K. Hatanaka, Y. Kawashima, S. Morinobu, K. Takahisa, H. Ueda RCNP, Osaka, Japan M. Ieiri, M. Minakawa KEK, Tsukuba, Japan
	A new DC muon beam line has been constructed at RCNP, Osaka University. The MuSIC, which has the highest muon production efficiency using superconducting solenoidal magnets, has successfully demonstrated to provide a 2x10⁸ [mu+/sec/micro A]. In 2014, the solenoid solenoidal magnets of the MuSIC were extended by a new beam line with normal conducting magnets. The new beamline consists of beam slits, quadrupole magnets, bending magnets and a spin rotator. This new beamline is designed for muon experiments such as μSR experiments and muonic X-ray measurements. In order to study the performance of the beams provided by the beamline , a beam test will be performed in December 2014. In this paper, I will present about a detail design of MuSIC including the new beamline and result of the beam test.
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WEPJE001	Optimal Positron-Beam Excited Plasma Wakefields in Hollow and Ion-Wake Channels	plasma, electron, wakefield, ion	2674
	A. A. Sahai, T.C. Katsouleas Duke ECE, Durham, North Carolina, USA
	Funding: DE-SC-0010012, NSF-PHY-0936278 A positron-beam interacting with the plasma electrons drives radial suck-in, in contrast to an electron-beam driven blow-out in the over-dense regime, n_b>n₀. In a homogeneous plasma, the electrons are radially sucked-in from all the different radii. The electrons collapsing from different radii do not simultaneously compress on-axis driving weak fields. A hollow-channel allows electrons from its channel-radius to collapse simultaneously exciting coherent fields . We analyze the optimal channel radius. Additionally, the low ion density in the hollow allows a larger region with focusing phase. We have shown the formation of an ion-wake channel behind a blow-out electron bubble-wake. Here we explore positron acceleration in the over-dense regime comparing an optimal hollow-plasma channel to the ion-wake channel . The condition for optimal hollow-channel radius is also compared. We also address the effects of a non-ideal ion-wake channel on positron-beam excited fields. S Lee, T Katsouleas, Phys. Rev. E, vol 64, 045501(R) (2001) ** A A Sahai, T Katsouleas, Non-linear ion-wake excitation by ultra relativistic electron wakefields, in review (http://arxiv.org/pdf/1504.03735v1.pdf)
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WEPMN003	The Magnetic Measurement for Low Magnetic Field Stability of Dipole Magnet for CEPC	collimation, dipole, collider, electron	2917
	Z. Zhang, F.S. Chen, H. Geng, B. Yin IHEP, Beijing, People's Republic of China
	The CEPC (China Electron-Positron Collider) project is in the pre-research stage. When the beam energy of booster is 120 GeV, the magnetic field of deflection magnet is 640 G. In order to save funds for scientific research, we are ready to select the injection energy for 6 GeV, this corresponds to a magnetic field about 32 G. In such a low magnetic field, the effects of earth's magnetic field and ambient temperature variations cannot be ignored. In this paper, first written the collection procedures for magnetic field value and ambient temperature values by Labview software, then used a one-dimensional probe to measure the background magnetic field for three directions (Bx, By, Bz) and the value of the ambient temperature values, the time of data collection for each direction are more than 24 hours (every minute collecting a set of values). Finally, plus the different currents (3A, 6A.. 15A) to the dipole magnet, the time of measured and the data collected by over 24 hours. Based on the results of the analysis of large amounts of data, summarized and analyzed the effect of Earth's magnetic field and ambient temperature for dipole magnet in a low magnetic field.
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MOPMA022

Numerical Analysis of Parasitic Crossing Compensation with Wires in DAΦNE

luminosity, beam-beam-effects, collider, experiment

589

A. Valishev
Fermilab, Batavia, Illinois, USA
C. Milardi, M. Zobov
INFN/LNF, Frascati (Roma), Italy
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: This work was partially supported by the US LARP. The HiLumi LHC Design Study is partially funded by the European Commission Grant Agreement 284404.
Current bearing wire compensators were successfully used in the 2005-2006 running of the DAΦNE collider to mitigate the detrimental effects of parasitic beam-beam interactions. A marked improvement of the positron beam lifetime was observed in machine operation with the KLOE detector. In view of the possible application of wire beam-beam compensators for the High Luminosity LHC upgrade, we revisit the DAΦNE experiments. We use an improved model of the accelerator with the goal to validate the modern simulation tools and provide valuable input for the LHC upgrade project.

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MOPTY034

Distributed Beam Loss Monitor Based on the Cherenkov Effect in Optical Fiber

electron, radiation, beam-losses, storage-ring

1004

Yu. Maltseva, F.A. Emanov, A.V. Petrenko, V.G. Prisekin
BINP SB RAS, Novosibirsk, Russia
F.A. Emanov
NSU, Novosibirsk, Russia
A.V. Petrenko
CERN, Geneva, Switzerland

A distributed beam loss monitor based on the Cherenkov effect in optical fiber has been implemented for the VEPP5 electron and positron linacs and the 510 MeV damping ring at the Budker INP. The monitor operation is based on detection of the Cherenkov radiation generated in optical fiber by means of relativistic particles created in electromagnetic shower after highly relativistic beam particles (electrons or positrons) hit the vacuum pipe. The main advantage of the distributed monitor compared to local ones is that a long optical fiber section can be used instead of a large number of local beam loss monitors. In our experiments the Cherenkov light was detected by photomultiplier tube (PMT). Timing of PMT signal gives the location of the beam loss. In the experiment with 20 m long optical fiber we achieved 3 m spatial resolution. To improve spatial resolution optimization and selection process of optical fiber and PMT are needed and according to our theoretical estimations 0.5 m spatial resolution can be achieved. We also suggest similar techniques for detection of electron (or positron) losses due to Touschek effect in storage rings.

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TUYB1

Progress of SuperKEKB

emittance, electron, gun, linac

1291

T. Miura, T. Abe, T. Adachi, K. Akai, M. Akemoto, A. Akiyama, D.A. Arakawa, Y. Arakida, Y. Arimoto, M. Arinaga, K. Ebihara, K. Egawa, A. Enomoto, J.W. Flanagan, S. Fukuda, H. Fukuma, Y. Funakoshi, K. Furukawa, T. Furuya, K. Hara, T. Higo, H. Hisamatsu, H. Honma, T. Honma, R. Ichimiya, N. Iida, H. Iinuma, H. Ikeda, M. Ikeda, T. Ishibashi, H. Ishii, M. Iwasaki, A. Kabe, T. Kageyama, H. Kaji, K. Kakihara, S. Kamada, T. Kamitani, S. Kanaeda, K. Kanazawa, H. Katagiri, S. Kato, S. Kazama, M. Kikuchi, T. Kobayashi, H. Koiso, Y. Kojima, M. Kurashina, K. Marutsuka, M. Masuzawa, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, F. Miyahara, K. Mori, T. Mori, A. Morita, Y. Morita, H. Nakai, H. Nakajima, T.T. Nakamura, K. Nakanishi, K. Nakao, H. Nakayama, T. Natsui, M. Nishiwaki, J.-I. Odagiri, Y. Ogawa, K. Ohmi, Y. Ohnishi, S. Ohsawa, Y. Ohsawa, N. Ohuchi, K. Oide, T. Oki, M. Ono, H. Sakai, Y. Sakamoto, S. Sasaki, M. Sato, M. Satoh, K. Shibata, T. Shidara, M. Shirai, A. Shirakawa, M. Suetake, Y. Suetsugu, R. Sugahara, H. Sugimoto, T. Suwada, S. Takasaki, T. Takatomi, T. Takenaka, Y. Takeuchi, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, N. Tokuda, K. Tsuchiya, X. Wang, K. Watanabe, H. Yamaoka, Y. Yano, K. Yokoyama, Ma. Yoshida, M. Yoshida, S.I. Yoshimoto, K. Yoshino, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

This presentation will cover the status of the installation and the injector commissioning status of SuperKEKB. The IR optics and design with very low β^* of less than 1 mm will be discussed.

Slides TUYB1 [6.588 MB]

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TUPWA048

Radiative Cooled Target for the ILC Polarized Positron Source

target, vacuum, photon, radiation

1526

A. Ushakov
University of Hamburg, Hamburg, Germany
F. Dietrich, S. Riemann, T. Rublack
DESY Zeuthen, Zeuthen, Germany
P. Sievers
CERN, Geneva, Switzerland

Funding: Work supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Optimization", contract number 19XL7IC4
The target for the polarized positron source of the future International Linear Collider (ILC) is designed as wheel of 1 m diameter spinning with 2000 revolutions per minute to distribute the heat load. The target system is placed in vacuum since exit windows would not stand the load. In the current ILC design, the positron target is assumed to be water-cooled. Here, as an alternative, radiative cooling of the target has been studied. The energy deposition in the target is the input for ANSYS simulations. They include the temperature evolution as well as the corresponding thermo-mechanical stress in the target components. A principal design is suggested for further consideration.

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TUPWA057

DAΦNE LINAC: Beam Diagnostics and Outline of the Last Improvements

linac, klystron, electron, operation

1549

B. Buonomo, L.G. Foggetta
INFN/LNF, Frascati (Roma), Italy

The LINAC of the DAΦNE complex is in operation since 1996, both as injector of the e⁺ e⁻ phi-factory, and, since 2003, for the extraction of electron beam to the Beam Test Facility. In the last years, many improvements has been developed in different sub-systems of the LINAC, aiming at a wider, tunable range of beam parameters, in particular the pulse time width and the pulse charge. A long term measurement campaign has been recently started to characterize the LINAC performance after that many sub-systems has been overhauled and improved, starting from RF power (i.e. klystron substitution, modulator re-newing, RF driver layout, SLED tuning) as well as the timing system, magnets, cooling, vacuum, control system and energy/position diagnostics. This work reports the latest results on the optimization of the fully consolidated system.

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TUPJE057

Realistic Undulators for Intense Gamma-ray Beams at Future Colliders

undulator, electron, simulation, synchrotron

1756

A.O. Alrashdi, I.R. Bailey
Lancaster University, Lancaster, United Kingdom
D. Newton
The University of Liverpool, Liverpool, United Kingdom

The baseline designs for the ILC and CLIC require the production of an intense flux of gamma rays in their positron sources. In the case of CLIC the gamma rays are produced by a Compton backscattering source, but in this paper we concentrate on undulator-based sources as proposed for the ILC. We present the development of a simulation to generate a magnetic field map based on a Fourier analysis of any measured field map. We have used a field map measured from the ILC helical undulator prototype to calculate the typical distribution of field errors, and used them in our calculations to produce simulated field maps. We show that a loss of gamma ray intensity of ~ 8% could be expected, compared to the ideal case. This leads to a similar drop in positron production which can be compensated for by increasing the undulator length.

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TUPMA020

PEPPo: Using a Polarized Electron Beam to Produce Polarized Positrons

electron, target, polarization, solenoid

1878

A.H. Adeyemi, P.L. Gueye
Hampton University, Hampton, Virginia, USA
P.A. Adderley, M.M. Ali, H. Areti, J. F. Benesch, L.S. Cardman, J. Clark, S. Covert, C. Cuevas, A. Freyberger, S. Golge, J.M. Grames, P.L. Gueye, J. Hansknecht, P.L. Harrell, C. Hyde, R. Kazimi, Y. Kim, D. Machie, K.L. Mahoney, R.R. Mammei, J.L. McCarter, M.D. McCaughan, M. Poelker, M.L. Stutzman, R. Suleiman, C.-Y. Tsai, D.L. Turner, Y.W. Wang
JLab, Newport News, Virginia, USA
M.A. Baylac, E. Froidefond, M. Marton, J-F. Muraz, J-S. Real, E. J-M. Voutier
LPSC, Grenoble Cedex, France
P. Cole, D. Dale, T.A. Forest
ISU, Pocatello, Idaho, USA
O. Dadoun, A. Variola
LAL, Orsay, France
D. Dale, Y. Kim
IAC, Pocatello, Idaho, USA
EF. Fanchini
INFN Genova, Genova, Italy
S. Golge
NCCU, , North Carolina, USA
S. Golge, C. Hyde
ODU, Norfolk, Virginia, USA
J.L. McCarter
UVa, Charlottesville, Virginia, USA
C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
A. Variola
IN2P3-CNRS, Orsay, France

Polarized positron beams have been identified as either an essential or a significant ingredient for the experimental program of both the present and next generation of lepton accelerators (JLab, Super KEK B, ILC, CLIC). An experiment demonstrating a new method for producing polarized positrons has been performed at the Continuous Electron Beam Accelerator Facility at Jefferson Lab. The PEPPo (Polarized Electrons for Polarized Positrons) concept relies on the production of polarized e⁻/e⁺ pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high Z conversion target. PEPPo demonstrated the effective transfer of spin-polarization of an 8.2 MeV/c polarized (P~85%) electron beam to positrons produced in varying thickness tungsten production targets, and collected and measured in the range of 3.1 to 6.2 MeV/c. In comparison to other methods this technique reveals a new pathway for producing either high energy or thermal polarized positron beams using a relatively low polarized electron beam energy (~10MeV) .This presentation will describe the PEPPo concept, the motivations of the experiment and high positron polarization achieved.

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TUPMA022

CESR Upgrade as a High-Energy, High-Brightness X-Ray Light Source

emittance, electron, lattice, storage-ring

1884

J.P. Shanks, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Research supported by NSF grant DMR-1332208.
The Cornell Electron Storage Ring (CESR) operates most of the year as the Cornell High Energy Synchrotron Source (CHESS). CESR was originally designed and operated as an electron/positron collider, circulating high-emittance beams in order to maximize luminosity. Beam lines were developed to extract x-rays from both electron and positron beams. The two beams share a common vacuum chamber, and are electrostatically separated to avoid collisions. The requirement to store counter-rotating beams significantly constrains the storage ring optics, limiting emittance and, beam current, and bunch distributions. The proposed upgrade eliminates two-beam operation in favor of a single optimized on-axis beam. Several new undulator-based beam lines are planned. The horizontal emittance is reduced in steps, first from 90nm to 20nm at 5.3 GeV, and then in a ring-wide upgrade to as low as 300 pm-rad at 6GeV. The low-emittance optics are based on multi-bend achromats with combined function bends. The details of the optics, apertures, and magnet parameters are presented.

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TUPTY003

Study of the Dynamic Response of CLIC Accelerating Structures

alignment, target, operation, monitoring

2000

E. Daskalaki
NTUA, Athens, Greece
S. Döbert, M. Duquenne, H. Mainaud Durand, A.L. Vamvakas
CERN, Geneva, Switzerland
V. Rude
ESGT-CNAM, Le Mans, France

CLIC is a linear electron-positron collider, 48 km long, consisting of more than 20000 repetitive modules. The target beam size of 1 nm dictates very tight alignment tolerances for the accelerating structures (AS). In order to assess the effect of short-term RF power interruptions (breakdowns or failure modes) on the alignment, the dynamic behaviour of the AS was investigated on the prototype two-beam module. On a dedicated experimental setup, the thermal and mechanical time constant (TC) was monitored as a function of ambient temperature, water flow and power. The experimental results showed that the thermal TC ranged between 4 and 11 minutes and presented strong correlation with the cooling water flow. These results were in very good agreement with the theoretical expectations. The displacement dynamics were found to be comparable with the thermal ones. The study indicates that temperature measurement, which is a fast and easy process, can be used as an indicator of the AS displacement. Moreover, it is shown than the transient response can be efficiently controlled through appropriate regulation of the cooling water flow.

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TUPTY008

Commissioning Status and Plan of SuperKEKB Injector Linac

emittance, linac, electron, operation

2013

M. Satoh, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Iwase, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, S. Kazama, M. Kikuchi, H. Koiso, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, Y. Seimiya, T. Shidara, A. Shirakawa, M. Suetake, H. Sugimoto, T. Suwada, T. Takenaka, M. Tanaka, M. Tawada, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

Toward SuperKEKB project, the injector linac upgrade is ongoing at KEK in order to deliver the low emittance electron/positron beams with the high intensity and small emittance. In the September of 2013, the injector linac commissioning has started. In this presentation, we will describe the commissioning status and plan of SuperKEKB injector linac.

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TUPTY056

Beam-Based Measurements of Long Range Transverse Wakefields in CLIC Main Linac Accelerating Structure

wakefield, electron, linac, experiment

2153

H. Zha, A. Grudiev, A. Latina, D. Schulte, A. Solodko, W. Wuensch
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway
G. De Michele
EPFL, Lausanne, Switzerland
G. De Michele
PSI, Villigen PSI, Switzerland
N. Lipkowitz, G. Yocky
SLAC, Menlo Park, California, USA

The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures in the main linac. Every accelerating structure cell has four waveguides, terminated with individual RF loads, to damp the unwanted long-range transverse wakefields, in order to maintain beam stability in multi-bunch operation. In order to experimentally verify the calculated suppression of the wakefields, a prototype structure has been built and installed in FACET test facility at SLAC. The results of the measurements of the wakefields in the prototype structure by means of positron and electron bunches are presented.

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TUPTY072

A New ILC Positron Source Target System Using Sliding Contact Cooling

target, vacuum, radiation, undulator

2196

W. Gai, D.S. Doran, R.A. Erck, G.R. Fenske, V.J. Guarino, W. Liu
ANL, Argonne, Illinois, USA

The R&D of the baseline positron source target for ILC is still ongoing after TDR due to the uncertainty of rotating vacuum seal and water cooling system of the fast spinning target wheel. Different institutes around the globe have proposed different approaches to tackle this issue. A spinning target wheel system with sliding contact cooling has been proposed by ANL. The proposed system eliminated the needs of rotating vacuum seal by using magnet bearings and vacuum compatible motor driven solid spinning wheel target. The energy deposited from positron production process is taken away via sliding cooling pads sliding against the spinning wheel. Details about this new target system are presented in this paper.

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TUPTY079

Initial Modeling of Electron Cloud Buildup in the Final-focus Quadrupole Magnets of the SuperKEKB Positron Ring

electron, photon, quadrupole, vacuum

2218

J.A. Crittenden
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: US National Science Foundation contracts PHY-0734867, PHY-1002467, and PHY-1068662, US Department of Energy contract DE-FC02-08ER41538 and the Japan/US Cooperation Program
We present modeling results for electron cloud buildup in the final-focus quadrupole magnet nearest the interaction point in the SuperKEKB positron storage ring. The calculations employ as input recently obtained estimates of synchrotron radiation absorption rates on the vacuum chamber wall including the effect of photon scattering. While the effect both adds to and subtracts from photoelectron production at the points in the ring where unscattered photons strike the wall, it also produces cloud in the other regions. Results for beam-pipe-averaged and beam-averaged cloud densities are presented, as are estimates for the contribution to the fractional vertical coherent tune shift. The effect of the strong magnetic fields is studied and the dependence on the vacuum chamber surface secondary yield characteristics is considered. Cloud buildup is modeled with a 2D particle-in-cell macroparticle tracking code validated using recent measurements of electron trapping in a quadrupole magnet at the Cornell Electron Storage Ring Test Accelerator.

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TUPTY080

Synchrotron Radiation Analysis of the SuperKEKB Positron Storage Ring

photon, scattering, electron, vacuum

2222

J.A. Crittenden, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T. Ishibashi, Y. Suetsugu
KEK, Ibaraki, Japan

Funding: US National Science Foundation contracts PHY-0734867, PHY-1002467, and PHY-1068662, US Department of Energy contract DE-FC02-08ER41538 and the Japan/US Cooperation Program.
We report on modeling results for synchrotron radiation absorption in the SuperKEKB positron storage ring vacuum chamber including the effects of photon scattering on the interior walls. A detailed model of the geometry of the inner vacuum chamber profile has been developed and used as input to a photon tracking code. Particular emphasis is placed on the photon absorption rates in the electron-positron interaction region.

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WEXB2

Measurement and Analysis of Electron Cloud Induced Emittance Growth at CesrTA

electron, simulation, emittance, feedback

2390

K.G. Sonnad, L.Y. Bartnik, M.G. Billing, G. Dugan, M.J. Forster
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.W. Flanagan, K. Ohmi
KEK, Ibaraki, Japan
R. Holtzapple, K.E. McArdle, M.I. Miller
CalPoly, San Luis Obispo, California, USA
L. Pentecost
Colgate University, Hamilton, New York, USA
M.T.F. Pivi
EBG MedAustron, Wr. Neustadt, Austria
S. Tucker
Cal Poly, San Luis Obispo, California, USA

CesrTA is a test accelerator facility at Cornell University that has been configured to study physics associated with electron and positron damping rings. Electron cloud effects is a concern for positron beams for such damping rings. The presentation will give an overview of recent measurements and simulation results for CesrTA. The measurement conditions were set up in order to study single bunch phenomena by observing a "Witness bunch" behind a train of positron bunches. The beam size and the turn by turn spectra were obeserved for the witness bunch under different conditions. Simulations were performed under similar conditions using the program CMAD.

Slides WEXB2 [2.263 MB]

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WEBB3

Lattice and its Related Beam Dynamics Issues in the CEPC Storage Ring

lattice, quadrupole, electron, factory

2469

H. Geng, S. Bai, Z. Duan, Y.M. Peng, Q. Qin, D. Wang, Y. Wang, G. Xu, Y. Yue, Y. Zhang
IHEP, Beijing, People's Republic of China
W. Chou
Fermilab, Batavia, Illinois, USA

The institute of High Energy Physics has proposed an electron positron collider ring with a circumference of 50-100km to study the Higgs boson. Since the proposal was made, the lattice design for CEPC has been carried out and a preliminary conceptual design report has been written at the end of 2014. In this paper, we will describe the philosophy and results of our lattice design. The procedure of dynamic aperture optimization will be shown. A specific issue for CEPC, the pretzel orbit, which has been found distorting the linear lattice for a considerable amount, will be examined. The ways that we are trying to correct the pretzel orbit effect and the result will be shown. We will also discuss the saw tooth effect on the linear lattice and dynamic aperture of the ring.

Slides WEBB3 [2.599 MB]

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WEPWA008

Measuring the Self-modulation Instability of Electron and Positron Bunches in Plasmas

plasma, electron, cavity, radiation

2506

P. Muggli, O. Reimann
MPI-P, München, Germany
E. Adli, V.K.B. Olsen
University of Oslo, Oslo, Norway
J. Allen, S.J. Gessner, S.Z. Green, M.J. Hogan, M.D. Litos, B.D. O'Shea, V. Yakimenko
SLAC, Menlo Park, California, USA
L.D. Amorim
IST, Lisboa, Portugal
G. Andonian, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi, O. Williams
UCLA, Los Angeles, California, USA
N.C. Lopes, L.O. Silva, J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

The self-modulation instability (SMI) * can be used to transform a long, charged particle bunch into a train of periodically spaced shorter bunches. The SMI occurs in a plasma when the plasma wake period is much shorter than the bunch length. The train of short bunches can then resonantly drive wakefields to much larger amplitude that the long bunch can. The SMI will be used in the AWAKE experiment at CERN, where the wakefields will be driven by a high-energy (400GeV) proton bunch. ** However, most of the SMI physics can be tested with the electron and positron bunches available at SLAC-FACET. *** In this case, the bunch is ~10 plasma wavelengths long, but can drive wakefields in the GV/m range. FACET has a meter-long plasma **** and is well equipped in terms of diagnostic for SMI detection: optical transition radiation for transverse bunch profile measurements, coherent transition radiation interferometry for radial modulation period measurements and energy spectrometer for energy loss and gain measurement of the drive bunch particles. The latest experimental results will be presented.
* N. Kumar et al., PRL 104, 255003 (2010)
** AWAKE Collaboration, PPCF 56 084013 (2014)
*** J. Vieira et al., PoP 19, 063105 (2012)
**** S.Z. Green et al., PPCF 56, 084011 (2014)

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WEPWA017

An Optimization of ILC Positron Source for Electron-Driven Scheme

electron, target, beam-loading, linac

2529

Y. Seimiya, M. Kuriki, M. Urano
HU/AdSM, Higashi-Hiroshima, Japan
S. Kashiwagi
Tohoku University, School of Science, Sendai, Japan
T. Okugi, T. Omori, M. Satoh, J. Urakawa
KEK, Ibaraki, Japan
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

International Linear Collider is a future accelerator to find new physics behind the electroweak symmetry breaking by precise measurements of Higgs sector, Top quark, and so on. ILC has capacities to reveal new phenomena beyond Standard model, such as Supersymmetry particles and dark matters. In current design of positron source, undulator scheme is adapted as a baseline. In the scheme, positrons are generated from gamma rays through pair-creation process in Ti-alloy target. Generations of the gamma rays by the undulator radiation requires more than 130 GeV electrons. Therefore, a system demonstration of the scheme is practically difficult prior to the real construction. Consequently, it is desirable to prepare a technical backup of this undulator scheme. We study an optimization of positron source based on the conventional electron-driven scheme for ILC. In this scheme, positron beam is generated by several GeV electron beam impinging on W-Re target. Although heavy heat load and destruction of the target is a potential problem, it can be relaxed by stretching the effective pulse length to 60 ms instead of 1 ms, by a dedicated electron linac for the positron production. In this report, a start-to-end simulation of the electron-driven ILC positron source is performed. Beam-loading effect caused by multi-bunch acceleration in the standing wave RF cavity is also considered.

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WEPWA021

A New DC Muon Beam Line at RCNP, Osaka University

solenoid, proton, target, quadrupole

2537

Y. Matsumoto, Y. Kohno, Y. Kuno, Y. Nakazawa, H. Sakamoto, A. Sato
Osaka University, Osaka, Japan
M. Fukuda, K. Hatanaka, Y. Kawashima, S. Morinobu, K. Takahisa, H. Ueda
RCNP, Osaka, Japan
M. Ieiri, M. Minakawa
KEK, Tsukuba, Japan

A new DC muon beam line has been constructed at RCNP, Osaka University. The MuSIC, which has the highest muon production efficiency using superconducting solenoidal magnets, has successfully demonstrated to provide a 2x10⁸ [mu+/sec/micro A]. In 2014, the solenoid solenoidal magnets of the MuSIC were extended by a new beam line with normal conducting magnets. The new beamline consists of beam slits, quadrupole magnets, bending magnets and a spin rotator. This new beamline is designed for muon experiments such as μSR experiments and muonic X-ray measurements. In order to study the performance of the beams provided by the beamline , a beam test will be performed in December 2014. In this paper, I will present about a detail design of MuSIC including the new beamline and result of the beam test.

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WEPJE001

Optimal Positron-Beam Excited Plasma Wakefields in Hollow and Ion-Wake Channels

plasma, electron, wakefield, ion

2674

A. A. Sahai, T.C. Katsouleas
Duke ECE, Durham, North Carolina, USA

Funding: DE-SC-0010012, NSF-PHY-0936278
A positron-beam interacting with the plasma electrons drives radial suck-in, in contrast to an electron-beam driven blow-out in the over-dense regime, n_b>n₀. In a homogeneous plasma, the electrons are radially sucked-in from all the different radii. The electrons collapsing from different radii do not simultaneously compress on-axis driving weak fields. A hollow-channel allows electrons from its channel-radius to collapse simultaneously exciting coherent fields *. We analyze the optimal channel radius. Additionally, the low ion density in the hollow allows a larger region with focusing phase. We have shown the formation of an ion-wake channel behind a blow-out electron bubble-wake. Here we explore positron acceleration in the over-dense regime comparing an optimal hollow-plasma channel to the ion-wake channel **. The condition for optimal hollow-channel radius is also compared. We also address the effects of a non-ideal ion-wake channel on positron-beam excited fields.
* S Lee, T Katsouleas, Phys. Rev. E, vol 64, 045501(R) (2001)
** A A Sahai, T Katsouleas, Non-linear ion-wake excitation by ultra relativistic electron wakefields, in review (http://arxiv.org/pdf/1504.03735v1.pdf)

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WEPMN003

The Magnetic Measurement for Low Magnetic Field Stability of Dipole Magnet for CEPC

collimation, dipole, collider, electron

2917

Z. Zhang, F.S. Chen, H. Geng, B. Yin
IHEP, Beijing, People's Republic of China

The CEPC (China Electron-Positron Collider) project is in the pre-research stage. When the beam energy of booster is 120 GeV, the magnetic field of deflection magnet is 640 G. In order to save funds for scientific research, we are ready to select the injection energy for 6 GeV, this corresponds to a magnetic field about 32 G. In such a low magnetic field, the effects of earth's magnetic field and ambient temperature variations cannot be ignored. In this paper, first written the collection procedures for magnetic field value and ambient temperature values by Labview software, then used a one-dimensional probe to measure the background magnetic field for three directions (Bx, By, Bz) and the value of the ambient temperature values, the time of data collection for each direction are more than 24 hours (every minute collecting a set of values). Finally, plus the different currents (3A, 6A.. 15A) to the dipole magnet, the time of measured and the data collected by over 24 hours. Based on the results of the analysis of large amounts of data, summarized and analyzed the effect of Earth's magnetic field and ambient temperature for dipole magnet in a low magnetic field.

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