TUPME —  Poster Session, Messi Area   (17-Jun-14   16:00—18:00)

Paper	Title	Page
TUPME001	Heat Load, Stress and Reaction Force Studies of a Polarized Positron Production Target for the Future International Linear Collider	1331
	F. Staufenbiel, S. Riemann DESY Zeuthen, Zeuthen, Germany G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany
	The International Linear Collider requires an intense polarized positron beam with yields of about 1014 positrons per second. A polarized positron beam can be produced with a helical undulator passed by the accelerated electron beam to create a high power polarized photon beam. The photon beam penetrates a thin titanium-alloy rotating target wheel of 1m diameter with 500 to 2000 rpm rotation speed and produces polarized positrons. The system should run for 1-2 years without failure. A break down can occur due to the huge heat load in a short time (<1ms). The target design must keep the resulting thermo-mechanical stress below the yield strength and the fatigue limit of the material. FEM ANSYS simulations are used to evaluate the thermo-mechanical stress as well as the vibrations at the bearings of the rotating system. Results are presented with the goal to optimize the target wheel design parameters for a long lifetime.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME001
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TUPME002	An Optimization of Positron Injector of ILC	1334
	M. Kuriki, Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan T. Okugi, M. Satoh, J. Urakawa KEK, Ibaraki, Japan
	Funding: This work is supported by Photon and Quantum Basic Research Coordinated Development Program of MEXT. ILC (International Linear Collider) is a future project of high energy physics. In the current baseline design, positron generation by gamma rays from undulator radiation is assumed. However, this approach is totally new and it is very difficult to demonstrate the system prior to the construction because it requires more than 100 GeV beam as the driver. A conventional positron generation (e-driven) has been proposed as a technical backup option. In this method, the technology is well established, but the issue is to obtain an enough amount of positron with a manageable energy deposition on target. We present a result of a systematic study of capture efficiency defined by DR (Damping Ring) acceptance where the beam emittance is reduced by radiation damping. We performed a start-to-end simulation of the positron source of ILC and found that an enough amount of the positron per bunch is obtained with a manageable energy deposition on the production target.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME002
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TUPME003	Effect of CSR Shielding in the Compact Linear Collider	1337
	J. Esberg, R. Apsimon, A. Latina, D. Schulte CERN, Geneva, Switzerland
	The Drive Beam complex of the Compact LInear Collider must use short bunches with a large charge making beam transport susceptible to unwanted effects of Coherent Synchrotron Radiation emitted in the dipole magnets. We here present the effects of transporting the beam within a limited aperture which decreases the magnitude of the CSR wake. The effect, known as CSR shielding, eases the design of key components of the facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME003
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TUPME004	Lowering the CLIC IP Horizontal Beta Function	1340
	H. Garcia, D. Schulte, R. Tomás CERN, Geneva, Switzerland H. Garcia UPC, Barcelona, Spain
	In order to alleviate the beamstrahlung photon emission, the beams at the CLIC Interaction Point must be flat. We propose to explore this limit reducing the horizontal beta function for CLIC at 500 GeV c.o.m. energy to half of its nominal value. This could increase the photon emission but it also increases luminosity and might allow reducing the bunch charge keeping the same luminosity. This configuration can also be considered for lower energies where beamstrahlung is less critical.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME004
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TUPME005	CLIC FFS Lattice Proposals Combining Local and Non-local Chromaticity Corrections	1343
	O.R. Blanco-García, P. Bambade LAL, Orsay, France R. Tomás CERN, Geneva, Switzerland
	The requirements on the Final Focusing System (FFS) for a new linear collider has lead to lattice designs where chromaticity is corrected either locally or non-locally. Here, alternative proposals of lattice design are presented for the current CLIC 500GeV beam parameters, combining the local chromaticity correction on the vertical plane and non-local correction on the horizontal. The tight tolerance on phase advances and beta functions imposed to obtain -I transformation required to cancel the chromatic terms is relaxed by enlarging the system length and using a more general transformation definition, aiming to obtain better results in tuning simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME005
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TUPME006	Considerations for a QD0 with Hybrid Technology in ILC	1346
	M. Modena, A.V. Aloev, H. Garcia, L. Gatignon, R. Tomás CERN, Geneva, Switzerland
	The baseline design of the QD0 magnet for ILC, the International Linear Collider, is a very compact superconducting quadrupole (coil-dominated magnet). A prototype of this quadrupole is under construction at Brookhaven National Laboratory (USA). In CLIC, the Compact Linear Collider under study at CERN, we are studying another conceptual solution for the QD0. This is due to two main reasons: all the magnets of the Beam Delivery System will need to be stabilized in the nano-meter range and extremely tight alignment tolerances are required. The proposed solution, now baseline for CLIC, is a room temperature hybrid quadrupole based on electromagnetic coils and permanent magnet blocks (iron-dominated magnet). In this paper we present a conceptual design for a hybrid solution studied and adapted also to the ILC project. A special super-ferric solution is proposed to make the cross section compatible with the experiments layout. This design matches the compactness requirement with the advantages of stability and alignment precision, aspects critical also for ILC in order to achieve the design luminosity. Final Focus optics design considerations for this solution are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME006
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TUPME007	Status of CLIC Magnets Studies and R&D	1350
	M. Modena, A.V. Aloev, E. Solodko, P.A. Thonet, A.S. Vorozhtsov CERN, Geneva, Switzerland
	Since 2009 the CERN Magnet Group (CERN-TE-MSC) started R&D activities in order to focalize the most challenging and interesting cases to be studied among the magnets needed for CLIC the Compact Linear Collider. In the last four years several theoretic studies, models and prototypes were realized mainly in two domains: magnets for the Modules, the modular elements that are composing the backbone of the two-beam linac structure of CLIC, and the Machine Detector Interface (MDI) including the Final Focus elements, and the anti-solenoid. In this paper we revise the status for the procured magnets. Among them the Drive Beam Quadrupoles, Main Beam Quadrupoles, Steering Correctors all challenging for the required compactness, performances and production size, and the QD0 final quadrupole and the close SD0 sextupole, challenging for the high performances required in terms of gradients and stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME007
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TUPME008	Status of the CLIC-UK R&D Programme on Design of Key Systems for the Compact Linear Collider	1354
	P. Burrows, R. Ainsworth, T. Aumeyr, D.R. Bett, N. Blaskovic Kraljevic, L.M. Bobb, S.T. Boogert, A. Bosco, G.B. Christian, L. Corner, F.J. Cullinan, M.R. Davis, D. Gamba, P. Karataev, K.O. Kruchinin, A. Lyapin, L.J. Nevay, C. Perry, J. Roberts, J. Snuverink, J.R. Towler JAI, Oxford, United Kingdom R. Ainsworth, T. Aumeyr, S.T. Boogert, A. Bosco, P. Karataev, K.O. Kruchinin, L.J. Nevay, J.R. Towler Royal Holloway, University of London, Surrey, United Kingdom P.K. Ambattu, G. Burt, A.C. Dexter, M. Jenkins, S. Karimian, C. Lingwood, B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom L.M. Bobb, R. Corsini, D. Gamba, A. Grudiev, A. Latina, T. Lefèvre, C. Marrelli, M. Modena, J. Roberts, H. Schmickler, D. Schulte, P.K. Skowroński, J. Snuverink, S. Stapnes, F. Tecker, R. Tomás, R. Wegner, M. Wendt, W. Wuensch CERN, Geneva, Switzerland J.A. Clarke, S.P. Jamison, P.A. McIntosh, B.J.A. Shepherd STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom N.A. Collomb, D.G. Stokes STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom L. Corner Oxford University, Physics Department, Oxford, Oxon, United Kingdom W.A. Gillespie, R. Pan, M.A. Tyrk, D.A. Walsh University of Dundee, Nethergate, Dundee, Scotland, United Kingdom R.M. Jones UMAN, Manchester, United Kingdom
	Six UK institutes are engaged in a collaborative R&D programme with CERN aimed at demonstrating key aspects of technology feasibility for the Compact Linear Collider (CLIC). We give an overview and status of the R&D being done on: 1) Drive-beam components: quadrupole magnets and the beam phase feed-forward prototype. 2) Beam instrumentation: stripline and cavity beam position monitors, an electro-optical longitudinal bunch profile monitor, and laserwire and diffraction and transition radiation monitors for transverse beam-size determination. 3) Beam delivery system and machine-detector interface design, including beam feedback/control systems and crab cavity design and control. 4) RF structure design. In each case, where applicable, we report on the status of prototype systems and performance tests with beam at the CTF3, ATF2 and CesrTA test facilities, including plans for future experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME008
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TUPME009	A Sub-micron Resolution, Wide-band, Stripline BPM System for Driving Bunch-by-bunch Feed-back and Feed-forward Systems at ATF	1358
	G.B. Christian, D.R. Bett, N. Blaskovic Kraljevic, P. Burrowspresenter, M.R. Davis, Y.I. Kim, C. Perry JAI, Oxford, United Kingdom
	A low-latency, sub-micron resolution stripline beam position monitoring (BPM) system has been developed and tested with beam at the KEK Accelerator Test Facility (ATF2), where it has been used as part of a beam stabilisation system. The fast analogue front-end signal processor is based on a single-stage RF down-mixer and a position resolution below 400 nm has been demonstrated for beam intensities of ~1 nC, with single-pass beam. The BPM position data are digitised by fast ADCs on an FPGA-based digital feedback controller, which is used to drive either a pair of kickers local to the BPMs and nominally orthogonal in phase, in closed-loop feedback mode, or a downstream kicker in the ATF2 final focus region, in feedforward mode. The beam jitter is measured downstream of the final focus system with high resolution, low-Q, cavity BPMs, and the relative performance of both systems in stabilising the beam is compared.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME009
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TUPME010	The Physics Programme of next MICE Step IV	1361
	J.C. Nugent University of Glasgow, Glasgow, United Kingdom V.C. Palladino INFN-Napoli, Napoli, Italy
	Funding: DOE, NSF, STFC, INFN, CHIPP and several others The International Muon Ionization Cooling Experiment is progressing towards a full demonstration of the feasibility of ionization cooling technology decisive for neutrino physics and muon colliders. Step IV should provide the first precise measurements of emittances and first evidence of cooling. The components required for Step IV, including spectrometer solenoids, muon trackers and absorber-FC (focus coil) modules have been assembled with data collection expected in 2015. The physics programme of this Step will be described in detail, with LiH and a few other promising absorber materials of different shapes. Abstract presented by the chair of the speaker bureau of the MICE collaboration, that would next select a MICE member to prepare and present the poster
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TUPME011	The Status of the Construction of MICE Step IV	1364
	P. Snopok IIT, Chicago, Illinois, USA E. Overton Sheffield University, Sheffield, United Kingdom
	Funding: DOE, NSF, STFC, INFN, CHIPP and several others The International Muon Ionization Cooling Experiment will provide the demonstration ionization cooling. The experiment is being built in a series of Steps. Step IV, which consists of a tracking spectrometer upstream and downstream of an absorber/focus-coil (AFC) module will be completed in early in 2015. In this configuration, the emittance of the muon beam upstream and downstream of the absorber will be measured precisely allowing the emittance reduction and the factors that determine the ionization cooling effect to be studied in detail. The AFC module is a 22 liter volume of liquid hydrogen placed inside a superconducting focusing coil. The properties of lithium hydride, and possibly other absorber materials, will also be studied. All the components of Step IV have been manufactured and integration of the experiment in the MICE Hall at the Rutherford Appleton Laboratory is underway. A full study of ionization cooling will be carried out with Step V, which will include a short 201 MHz linac module in which beam transport is achieved with a superconducting “coupling coil”. The status of the preparation of the components of Step V of the experiment will be described briefly.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME011
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TUPME012	The US Muon Accelerator Program	1367
	M.A. Palmer Fermilab, Batavia, Illinois, USA
	Funding: Work supported by US DOE under contract DE-AC02-07CH11359. A directed R&D program is presently underway in the U.S. to evaluate the designs and technologies required to provide muon-based high energy physics (HEP) accelerator capabilities. Such capabilities have the potential to provide unique physics reach for the HEP community. An overview of the status of the designs for the neutrino factory and muon collider applications is provided. Recent progress in the technology R&D program is summarized.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME012
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TUPME013	Thermo-mechanical Tests for the CLIC Two-beam Module Study	1370
	A. Xydou, G. Riddone, A.L. Vamvakaspresenter CERN, Geneva, Switzerland E. Daskalaki NTUA, Athens, Greece
	The luminosity goal of CLIC requires micron level precision with respect to the alignment of the components on its two-meter long modules, composing the two main linacs. The power dissipated inside the module components introduces mechanical deformations affecting their alignment and therefore the resulting machine performance. Several two-beam prototype modules must be assembled to extensively measure their thermo-mechanical behavior under different operation modes. In parallel, the real environmental conditions present in the CLIC tunnel should be studied. The air conditioning and ventilation system providing specified air temperature and flow has been installed in the dedicated laboratory. The power dissipation occurring in the modules is being reproduced by the electrical heaters inserted inside the RF structure mock-ups and the quadrupoles. The efficiency of the cooling systems is being verified and the alignment of module components is monitored. The measurement results will be compared to finite element analysis model and propagated back to engineering design. Finally, simulation of the most possible CLIC machine cycles is accomplished and preliminary results are analysed.
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TUPME014	Development of Six-dimensional Helical Muon Beam Cooling Channel for Muon Colliders	1373
	K. Yonehara Fermilab, Batavia, Illinois, USA
	A six-dimensional (6D) helical muon beam cooling channel (HCC) has been developed for a last decade. The practical HCC lattice parameters were optimized for the cooling performance in theoretical and numerical simulations. The HCC design group has been formed and has begun the machine development to realize the channel. Recent accomplishments and present critical issues are discussed in the presentation.
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TUPME015	Study Cooling Performance in a Helical Cooling Channel for Muon Colliders	1376
	K. Yonehara Fermilab, Batavia, Illinois, USA
	The cooling performance in a six-dimensional helical muon beam cooling channel (HCC) has been studied in various beam lattice parameters. We show that the HCC works with a practical beam parameter.
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TUPME016	Status of the Complete Muon Cooling Channel Design and Simulations	1379
	C.Y. Yoshikawa, C.M. Ankenbrandt, R.P. Johnson, S.A. Kahn, F. Marhauser Muons, Inc, Illinois, USA Y.I. Alexahin, D.V. Neuffer, K. Yonehara Fermilab, Batavia, Illinois, USA Y.S. Derbenev, V.S. Morozov, A.V. Sy JLab, Newport News, Virginia, USA
	Funding: Work supported in part by DOE STTR grant DE-SC 0007634. Muon colliders could provide the most sensitive measurement of the Higgs mass and return the US back to the Energy Frontier. Central to the capabilities of such muon colliders are the cooling channels that provide the extraordinary reduction in emittance required for the precise Higgs mass measurement and increased luminosity for enhanced discovery potential of an Energy Frontier Machine. We present the status of the design and simulation of a complete muon cooling channel that is based on the Helical Cooling Channel (HCC), which operates via continuous emittance exchange to enable the most efficient design.
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TUPME017	Design and Simulation of a Matching System into the Helical Cooling Channel	1382
	C.Y. Yoshikawa MuPlus, Inc., Newport News, Virginia, USA Y.I. Alexahin, D.V. Neuffer, K. Yonehara Fermilab, Batavia, Illinois, USA C.M. Ankenbrandt, R.P. Johnson, S.A. Kahn, F. Marhauser Muons, Inc, Illinois, USA Y.S. Derbenev, V.S. Morozov, A.V. Sy JLab, Newport News, Virginia, USA
	Funding: Work supported in part by DOE STTR grant DE-SC 0007634. Muon colliders could provide the most sensitive measurement of the Higgs mass and return the US back to the Energy Frontier. Central to the capabilities of muon colliders are the cooling channels that provide the extraordinary reduction in emittance required for the precise Higgs mass measurement and increased luminosity for enhanced discovery potential of an Energy Frontier Machine. The Helical Cooling Channel (HCC) is able to achieve such emittance reduction and matching sections within the HCC have been successfully designed in the past with lossless transmission and no emittance growth. However, matching into the HCC from a straight solenoid poses a challenge, since a large emittance beam must cross transition. We elucidate on the challenge and present evaluations of two solutions, along with concepts to integrate the operations of a Charge Separator and match into the HCC.
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TUPME019	Design and Simulation of a High Field - low energy Muon Ionization Cooling Channel	1386
	H. K. Sayed, J.S. Berg, R.B. Palmer, D. Stratakispresenter BNL, Upton, Long Island, New York, USA
	Muon beams are generated with inherited large transverse and longitudinal emittances. In order to achieve low emittance within the short lifetime of the muons, the only feasible cooling scheme is the ionization cooling. In this study we present a design and simulation of a novel ionization cooling channel. The channel operates at a very strong magnetic fields of 25-30 T with low muon beam energy starting from 66 MeV and decreasing gradually. We study the beam dynamics of such low energy beam in high field region inside and between cooling stages. Key design parameters will be presented and in addition the performance and channel requirements of RF cavities and high field magnets will be presented.
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TUPME020	Complete Six-dimensional Muon Cooling Channel for a Muon Collider	1389
	D. Stratakis, J.S. Berg, R.B. Palmer, H. Witte BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We describe a complete 6D rectilinear cooling scheme for use in a Muon Collider. This scheme uses separate 6D cooling channels for the two signs of particle charge. In each, a channel first reduces the emittance of a train of 21 muon bunches until it becomes possible to merge them into a single bunch, one of each sign. The single bunches are then sent through a second rectilinear channel for further cooling towards the requirements of a Muon Collider. We adopt this approach for a new cooling lattice design for the Muon Collider, and for the first time present a end-to-end simulation. We review key parameters such as the required focusing fields, absorber lengths, cavity frequencies and rf gradients. *D. Stratakis et al., Phys. Rev. ST AB 16, 091001 (2013).
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TUPME021	Theoretical Framework to Predict Efficiency of Ionization Cooling Lattices	1392
	D. Stratakis BNL, Upton, Long Island, New York, USA D.V. Neuffer Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Reduction of the 6-dimensional phase-space of a muon beam by 6 orders of magnitude is a key requirement for a Muon Collider. Recently, a 12-stage rectilinear ionization cooling channel has been proposed to achieve that goal. In this paper, we establish the mathematical framework to predict and evaluate the cooling performance of the proposed channel. We predict the system effectiveness, by deriving key lattice parameters such as the lattice quality factor which describes the rate of cooling versus the surviving particles and the longitudinal and effective partition numbers for each stage. Main theoretical findings, such as the equilibrium emittances and effective cooling length, are compared against findings from numerical simulations.
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TUPME022	Design and Optimization of a Particle Selection System for Muon based Accelerators	1395
	D. Stratakis, J.S. Berg BNL, Upton, Long Island, New York, USA D.V. Neuffer Fermilab, Batavia, Illinois, USA P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In Muon Accelerators muons are produced by impacting high energy protons onto a target to produce pions. The pions decay to muons which are then accelerated. Through this process a significant background of protons and electrons are generated, which may result in heat deposition on superconducting materials and activation of the machine. In this paper we propose a two-step particle selection scheme: a chicane to remove the high momentum particles from the beam and a Beryllium block absorber that reduces momentum of all particles in the beam, resulting in the loss of low momentum protons. We review the design and numerically examine its impact on the performance of the muon front-end.
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TUPME023	Overview of a muon capture section for muon accelerators	1398
	D. Stratakis, J.S. Berg, H. K. Sayed BNL, Upton, Long Island, New York, USA D.V. Neuffer, P. Snopok Fermilab, Batavia, Illinois, USA P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We describe a muon capture section to manipulate the longitudinal and transverse phase-space so that to collect efficiently a muon beam produced from an intense proton source target. We show that this can be achieved by using a set of properly tuned rf cavities that captures the beam into string of bunches and aligns them into nearly equal central energies, and a solenoidal chicane that filters high momentum particles, followed by a proton absorber that reduces the energy of all particles. This work elucidates the key parameters that are needed for successful muon capture, such as the required rf frequencies, rf gradients and focusing field. We discuss the sensitivity in performance against the number of different rf frequencies and accelerating rf gradient.
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TUPME024	A hybrid six-dimensional muon cooling channel with gas filled cavities	1401
	D. Stratakis BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Obtaining the desired micron-scale emittances for a Muon Collider requires transporting the muon beam through long sections of a beam channel containing rf cavities, absorbers, and focusing solenoids. Here we discuss possible implementation of high-pressure gas-filled RF cavities in a 6D ionization cooling channel and some technical issues associated with it. The key idea of our scheme is a hybrid approach that uses high-pressure gas to avoid cavity breakdown, along with discrete LiH absorbers to provide the majority of the energy loss. We show that the channel performs as well as the original vacuum rf channel while potentially avoiding degradation in rf gradient associated with the strong magnetic field in the cooling channel.
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TUPME025	Progress on Low Emittance Tuning for the CLIC Damping Rings	1404
	J. Alabau-Gonzalvo, H. Bartosikpresenter, Y. Papaphilippou CERN, Geneva, Switzerland
	In the frame of the CLIC main Damping Ring a study on the sensitivity of the lattice to different sources of misalignment is presented. The minimum equilibrium emittance is simulated and analytically estimated under dipole and quadrupole rolls, and quadrupole and sextupole vertical offsets. The result of this study establishes alignment tolerances to preserve the vertical emittance below the design value (1 pm·rad). Non-linear dynamics studies have been done to determine the dynamic aperture in the presence of misalignments.
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TUPME026	TMCI Thresholds for LHC Single Bunches in the CERN-SPS and Comparison with Simulations	1407
	H. Bartosik, G. Iadarola, Y. Papaphilippou, G. Rumolo, B. Salvant, C. Zannini CERN, Geneva, Switzerland
	At the beginning of 2013 an extensive measurement campaign was carried out at the SPS in order to determine the Transverse Mode Coupling Instability thresholds of LHC-type bunches in a wide range of intensities and longitudinal emittances. The measurements were performed in two different configurations of machine optics (nominal and low gamma transition) with the goal to characterize the differences in behavior and performance. The purpose of this paper is to describe in detail the measurement procedure and results, as well as the comparison of the experimental data with HEADTAIL simulations based on the latest SPS impedance model. Beside the impedances of the resistive wall, the beam position monitors (BPMs), the RF cavities, and the flanges, an advanced model of the impedance of the kicker magnets is included, which are found to play a major role in the definition of the stability region of the LHC-type bunches in the two optics configurations studied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME026
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TUPME027	Analysis of the Electron Cloud Observations with 25 ns Bunch Spacing at the LHC	1410
	G. Iadarola Naples University Federico II, Science and Technology Pole, Napoli, Italy G. Arduini, V. Baglin, D. Banfi, H. Bartosikpresenter, S.D. Claudet, C.O. Domínguez, J.F. Esteban Müller, G. Iadarola, T. Pieloni, G. Rumolo, E.N. Shaposhnikova, L.J. Tavian, C. Zannini, F. Zimmermann CERN, Geneva, Switzerland
	Electron Cloud (EC) effects have been identified as a major performance limitation for the Large Hadron Collider (LHC) when operating with the nominal bunch spacing of 25 ns. During the LHC Run 1 (2010 - 2013) the luminosity production mainly used beams with 50 ns spacing, while 25 ns beams were only employed for short periods in 2011 and 2012 for test purposes. On these occasions, observables such as pressure rise, heat load in the cold sections as well as clear signatures on bunch-by-bunch emittance blow up, particle loss and energy loss indicated the presence of an EC in a large portion of the LHC. The analysis of the recorded data, together with EC build up simulations, has led to a significant improvement of our understanding of the EC effect in the different components of the LHC. Studies were carried out both at injection energy (450 GeV) and at top energy (4 TeV) aiming at determining the energy dependence of the EC formation and its impact on the quality of the proton beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME027
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TUPME028	Flat Bunches in the LHC	1413
	E.N. Shaposhnikova, T. Argyropoulos, P. Baudrenghien, J.F. Esteban Müller, T. Mastoridis, G. Papotti, B. Salvant, H. Timko CERN, Geneva, Switzerland C.M. Bhat, A.V. Burov Fermilab, Batavia, Illinois, USA
	A high-harmonic RF system that could serve multiple purposes was proposed for the LHC. Possible applications of the second harmonic RF system include beam stabilisation in the longitudinal plane in the absence of wide-band longitudinal feedback and reduction of bunch peak line-density. Apart from other useful features, flat bunches are expected to produce less beam-induced heating at frequencies below 1 GHz, the frequency region critical for some LHC equipment. The latter, however, can also be achieved by de-populating the bunch centre. This was demonstrated during the dedicated machine development session in the LHC using RF phase modulation. In this paper the results of tests with single bunches and nominal LHC beams are presented and the possible use of this technique in LHC operation is discussed.
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TUPME029	Identification of High-frequency Resonant Impedance in the CERN SPS	1416
	E.N. Shaposhnikova, T. Argyropoulos, T. Bohl, J.V. Campelo, F. Caspers, J.F. Esteban Müller, A. Lasheen, B. Salvant, H. Timko CERN, Geneva, Switzerland
	The spectrum of long bunches injected into the ring with RF switched off has been used in the SPS in the past to probe the longitudinal coupling impedance. After a large campaign of shielding of 800 inter-magnet vacuum ports in 1999 - 2001, the microwave instability threshold was significantly increased and the high-frequency spectrum of the beam became practically flat, apart from a prominent peak at around 1.4 GHz. As corresponding high-frequency impedance could potentially lead to microwave instability of high intensity bunches observed now at high energies in the SPS, a search of the source of this impedance was launched. Using a combination of impedance simulations and measurements, vacuum flanges that are present in a large quantity in the machine have been identified as a main source of impedance at this frequency. Particle simulations based on the SPS impedance model, which includes this previously unknown impedance, are able to reproduce the characteristics of the bunch spectrum and amplitude growth rates and hence, confirm that the impedance of the vacuum flanges is responsible for the observed spectral peak.
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TUPME030	The LIGHT Beamline at GSI: Shaping Intense MeV Proton Bunches from a Compact Laser-driven Source	1419
SUSPSNE016	use link to see paper's listing under its alternate paper code
	S. Busold, O. Deppert, M. Roth TU Darmstadt, Darmstadt, Germany V. Bagnoud, A. Blazevic, S. Busold HIJ, Jena, Germany V. Bagnoud, A. Blazevic, S. Busold, D. Schumacher GSI, Darmstadt, Germany C. Brabetz IAP, Frankfurt am Main, Germany F. Kroll TU Dresden, Dresden, Germany F. Kroll Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
	Laser-based proton acceleration as a source of high intensity multi-MeV-range proton bunches became subject of extensive research during the last 15 years and is discussed as potential candidate for various applications. However, their usage often requires special ways of beam shaping first, as the particles are emitted in a wide energy spectrum and with a large divergence angle from the laser matter interaction point. To handle these characteristics, a test stand has been build at GSI Darmstadt, using a pulsed high field solenoid and a radiofrequency cavity to produce intense collimated proton bunches with low energy spread from a TNSA source. In recent experiments, energy compression of an intense proton bunch around 10 MeV central energy to an energy spread of less than 3% could be demonstrated. The particle numbers were in access of 109 protons and the bunch duration was only a few nanoseconds. Even shorter bunches and thus higher particle intensities are possible. This compact laser-driven proton beamline, available now at GSI, will be introduced and latest experimental results presented.
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TUPME031	Radiation Pressure Acceleration and Transport Methods	1422
	P. Schmidt, O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, O. Boine-Frankenheim, I. Hofmann GSI, Darmstadt, Germany I. Hofmann HIJ, Jena, Germany I. Hofmann IAP, Frankfurt am Main, Germany
	Funding: HGS-HIRe for FAIR, HIC for FAIR, Technische Universität Darmstadt, FB 18 TEMF Several projects worldwide such as LIGHT at GSI focus on laser ion acceleration. With the development of new laser systems and advances in the target production a new acceleration mechanism has become of interest: The Radiation Pressure Acceleration (RPA). An ultra short high intense laser pulse hits a very thin foil target and the emerging plasma is ideally accelerated as one piece (light sail regime). The ions reach kinetic energies up to GeV and nearly solid body densities. In this work, the distribution and transport of a RPA plasma is studied. 1D and 2D PIC simulations (software: VSim) are carried out to obtain the phase space distribution of the plasma. The results are compared to fluid models (software: FiPy and USim). A reference model an RPA plasma is obtained which is then used for advanced transport studies. Transport mechanisms (active and passive) are studied, such asμlenses and foil stacks.
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TUPME033	Scaling of TNSA-accelerated Proton Beams with Laser Energy and Focal Spot Size	4093
SUSPSNE018	use link to see paper's listing under its alternate paper code
	L. Obst, S. Kraft, J. Metzkes, U. Schramm, K. Zeil Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
	By focusing an ultra-short high-intensity laser pulse on a solid target, pulses of protons and other positively charged ions with energies of several 10 MeV per nucleon are generated. The properties of these particle beams such as their energy and absolute number are highly dependent on experimental conditions like laser and target parameters. In order to achieve principal comparability between different experimental campaigns at the Draco laser system at the Helmholtz-Zentrum Dresden-Rossendorf, a reference setup for the laser ion acceleration experiment was established. A configuration is sought in which proton beams of reproducible characteristics are generated. To ensure a high stability of the proton spectra, the application of longer focal length parabolas (f ~ 1000 mm) will be tested for this setup, according preparatory studies being presented in this paper.
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TUPME034	Transport and Energy Selection of Laser Produced Beams for Medical Research and Multidisciplinary Applications	1425
	M.M. Maggiore INFN/LNL, Legnaro (PD), Italy G.A.P. Cirrone, F. Romano, F. Schillaci, A. Tramontana INFN/LNS, Catania, Italy V. Scuderi ELI-BEAMS, Prague, Czech Republic
	Ion beams produced by the interaction of high-power laser with thin targets are being characterized experimentally around the world in order to get a reasonable amount of particles with low divergence and narrow energy spread for medical and multidisciplinary applications. Several schemes about the energy selection and transport of laser accelerated beams have been considered and tested, however the energy spread of the selected particles remains rather high and the reproducibility has not been yet achieved. In the framework of the ELIMED network, we present a study of a possible layout to capture and transport in an efficient and reproducible way, the beams generated by the laser-target interaction. It consists of a combination of quadrupoles based on permanent magnets placed just downstream the target, coupled with a system composed by a series of 4 dipole magnets of inverted polarity, which provides the final energy selection of the previously focused beam. Such a system will be tested in 2014 at TARANIS facility to select proton beams in the energy range of 4-8 MeV; the main scheme can be scaled for the high energy beam that are expected at ELI-beamlines facility.
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TUPME035	Design Study of the Laser-driven Dielectric Accelerator	1428
	K. Koyama, M. Yoshida KEK, Ibaraki, Japan Y. Matsumura University of Tokyo, Tokyo, Japan S. Otsuki The University of Tokyo, Tokyo, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120. Laser driven dielectric accelerators (LDA) are vigorously studied in order to apply to various fields in recent years. Characteristics of the LDA output such as sub-micron diameter, atto-second bunch and high acceleration field are suitable for in-situ investigating the biological effects of low doses of radiation in a living cell. The output energy of 1 MeV is sufficient for sniping a cell nucleus or DNA. Although the electronic charge in the bunch is in the order of 10 fC, the tightly focused beam enable to cause a local damage in the cell. We have reported optimum structure parameters of dielectric in the nonrelativistic regime. The low acceleration efficiency of slow electrons by short laser pulses is the serious problem. The accelerator length, laser intensity, pulse width, and optical system must be adjusted to design the practical LDA. We present the design principle of the LDA for nonrelativistic electrons and present status of the pumping laser of us.
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TUPME036	Simulation Study on Electron Beam Acceleration using Coherent Cherenkov Radiation	1431
	K. Kan, M. Gohdo, T. Kondoh, K. Norizawa, I. Nozawa, A. Ogata, T. Toigawa, J. Yang, Y. Yoshida ISIR, Osaka, Japan M. Hangyo ILE Osaka, Suita, Japan R. Kuroda, H. Toyokawa AIST, Tsukuba, Ibaraki, Japan
	Beam diagnostics for electron bunch length using spectrum analysis of multimode terahertz (THz) -wave have been studied in ISIR, Osaka University*. The multimode THz-wave was generated by coherent Cherenkov radiation (CCR)** using hollow dielectric tubes and femtosecond/picosecond electron bunches. In this study, numerical calculation of acceleration and deceleration of electron beam using multimode THz-wave was carried out. * K. Kan et al., Appl. Phys. Lett. 99, 231503 (2011). ** A. M. Cook et al., Phys. Rev. Lett. 103, 095003 (2009).
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TUPME037	Development on On-chip Radiation Source using Dielectric Laser Accelerator	1434
SUSPSNE019	use link to see paper's listing under its alternate paper code
	S. Otsuki The University of Tokyo, Tokyo, Japan K. Koyama, M. Yoshida KEK, Ibaraki, Japan Y. Matsumura University of Tokyo, Tokyo, Japan S. Mima RIKEN, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120. One of the state-of-the-art acceleration schemes, where high intensity laser pulses are modulated by dielectric grating structure such as quartz to accelerate charged particles, is dielectric laser acceleration (DLA)*. The difference of our DLA concept from other schemes is installation of a prism: the tilted wave-front in a prism shape refractive medium leads the suitable delay to match the phase advance of the electron beam. We plan to apply this method to build an on-chip radiation source which can hit and damage target elements of the cells. Such an application is useful in radiation biology, i.e., for investigation on bystander effects. The x-rays with small radius and adequate intensity required for this goal can be obtained using sub-micron beams from the small accelerating structure at high repetition rate (such as 50 kHz). In addition, the mass productivity of the DLA based on the consumer-grade laser and the photolithography has advantage compared to the conventional RF accelerator using high power klystrons. We will present field simulation and preliminary experimental results for demonstration on our concept of DLA. * Demonstration of electron acceleration in a laser-driven dielectric microstructure, Nature 2013 ** Laser-Based Acceleration of Nonrelativistic Electrons at a Dielectric Structure, Phys. Rev. 2013
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TUPME038	Wakefield excitation via a metasurface-loaded waveguide	1437
SUSPSNE020	use link to see paper's listing under its alternate paper code
	E. Sharples Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R. Letizia Lancaster University, Lancaster, United Kingdom
	Funding: Work supported by STFC Quota Studentship grant ST/K520133/1 A metallic waveguide loaded with layers of complementary split ring resonator (CSRR) based metasurface is presented for accelerator and coherent source applications. This structure presents left handed behaviour arising from the strong electrical response of CSRRs which form the metasurface and the transverse field confined between the closely positioned metasurface layers. The loaded waveguide structure is known to have a TM-like mode at 5.47GHz suitable for acceleration. In this paper, the results of wakefield simulations are presented and a narrow band excitation identified around the frequency of the TM-like mode, indicating strong coupling between the beam and the field of this mode.
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TUPME039	System Integration of the Demonstration Siemens Electrostatic Accelerator	1440
	H. von Jagwitz-Biegnitz JAI, Oxford, United Kingdom P. Beasley, S. Goßmann-Levchuk, O. Heid Siemens AG, Erlangen, Germany D.C. Faircloth STFC/RAL, Chilton, Didcot, Oxon, United Kingdom R.G. Selway Inspired Engineering Ltd, Climping, United Kingdom
	Siemens has proposed a novel compact DC electrostatic tandem accelerator to produce protons of a few MeV. Siemens is currently building a prototype of the accelerator at the Rutherford Appleton Laboratory. This paper reports on recent progress on the different components of the system as well as the commissioning of the whole machine.
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TUPME040	Drive Beam Break-up Control and Practical Gradient Limitation in Collinear Dielectric Wakefield Accelerators	1443
	C. Li, W. Gaipresenter, J.G. Power, A. Zholents ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA C. Li, C.-X. Tang TUB, Beijing, People's Republic of China
	Dielectric wakefield accelerator (DWA) concept has gained significant attention for the need of the future large scale facilities. For a practical machine, one needs to overcome a major challenge for the DWA that is the efficient energy extraction and stable propagation at the same time for the drive beam. Typically, a slightly off axis beam become unstable in the dielectric channel due to transverse wakefield excitation, that could be controlled if a strong external alternating magnetic focusing channel applied at the same time. However, there is limitation on the practical magnetic field in the focusing channel (typically < 1 Tesla), thus imposing operating point for the DWA. In this article, we explore the operating point of the DWA for various structure frequencies and drive beam charge, particularly on the gradient and total acceleration distance, and provide guidance on the DWA design.
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TUPME041	The Advanced Superconducting Test Accelerator at Fermilab: Science Program	1447
	P. Piot, E.R. Harms, S. Henderson, J.R. Leibfritz, S. Nagaitsev, V.D. Shiltsev, A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: This work is supported by DOE contract DE-AC02-07CH11359 to the Fermi Research Alliance LLC The Advanced Superconducting Test Accelerator (ASTA) currently in commissioning phase at Fermilab is foreseen to support a broad range of beam-based experiments to study fundamental limitations to beam intensity and to develop novel approaches to particle-beam generation, acceleration and manipulation. ASTA incorporates a superconducting radiofrequency (SCRF) linac coupled to a flexible high-brightness photoinjector. The facility also includes a small-circumference storage ring capable of storing electrons or protons. This report summarizes the facility capabilities, and provide an overview of the accelerator-science researches to be enabled.
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TUPME042	Planned High-gradient Flat-beam-driven Dielectric Wakefield Experiments at the Fermilab’s Advanced Superconducting Test Accelerator	1451
	F. Lemery, D. Mihalcea, P. Piotpresenter Northern Illinois University, DeKalb, Illinois, USA P. Piotpresenter, J. Zhu Fermilab, Batavia, Illinois, USA J. Zhu CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	In beam driven dielectric wakefield acceleration (DWA), high-gradient short-wavelength accelerating fields are generally achieved by employing dielectric-lined waveguides (DLWs)  with small aperture which constraints the beam sizes. In this paper we investigate the possibility of using a low-energy (50-MeV) flat beams to induce high-gradient wakes in a slab-symmetric DLW. We demonstrate via numerical simulations the possibility to produce axial electric field with peak amplitude close to 0.5 GV/m. Our studies are carried out using the Fermilab's Advanced Superconducting Test Accelerator (ASTA) photoinjector beamline. We finally discuss a possible experiment that could be performed in the ASTA photoinjector and eventually at higher energies.
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TUPME043	Temporal Electron-bunch Shaping from a Photoinjector for Advanced Accelerator Applications	1454
	F. Lemery, P. Piotpresenter Northern Illinois University, DeKalb, Illinois, USA P. Piotpresenter Fermilab, Batavia, Illinois, USA
	Advanced-accelerator applications often require the production of bunches with shaped temporal distributions. An example of sought-after shape is a linearly-ramped current profile that can be improve the transformer ratio in beam-driven acceleration, or produce energy-modulated pulse for, e.g., the subsequent generation of THz radiation. Typically,  such a shaping is achieved by manipulating ultra-relativistic electron bunches. In this contribution we discuss the possibility of shaping the bunch via photoemission and demonstrate using particle-in-cell simulations the production of MeV electron bunches with quasi-ramped current profile.
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TUPME044	Planned High-brightness Channeling Radiation Experiment at Fermilab's Advanced Superconducting Test Accelerator	1457
	B.R. Blomberg, D. Mihalcea, H. Panuganti, P. Piotpresenter Northern Illinois University, DeKalb, Illinois, USA C.A. Brau, B.K. Choi, W.E. Gabella, B.L. Ivanov, M.H. Mendenhall Vanderbilt University, Nashville, Tennessee, USA C.W. Lynn Swarthmore College, Swarthmore, Pennsylvania, USA P. Piotpresenter, T. Sen Fermilab, Batavia, Illinois, USA W.S. Wagner Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
	Funding: Work supported by the DARPA Axis program under contract AXIS N66001-11-1-4196 In this contribution we describe the technical details and experimental setup of our study aimed at producing high-brightness channeling radiation (CR) at Fermilab’s new user facility the Advanced Superconducting Test Accelerator (ASTA). In the ASTA photoinjector area electrons are accelerated up to 40-MeV and focused to a sub-micron spot on a ~40 micron thick carbon diamond, the electrons channel through the crystal and emit CR up to 80-KeV. Our study utilizes ASTA’s long pulse train capabilities and ability to preserve ultra-low emittance, to produce the desired high average brightness.
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TUPME045	Development of a High-Energy Short-pulse 5-μm Parametric Source for Dielectric Laser Acceleration	1460
	G. Xu, I. Jovanovicpresenter, S.F. Wandel Penn State University, University Park, Pennsylvania, USA
	A compact, high-peak-power 5-μm laser source with pulse duration of sub-100 fs has been designed and being constructed for pumping a dielectric photonic structure to produce an acceleration gradient of order GV/m in dielectric laser acceleration. Breakdown of dielectric structure induced by multiphoton ionization can be mitigated by adopting long wavelength driver laser. Since the dielectric structure scales with the laser wavelength, fabrication tolerances for dielectric structure are relaxed as well. The 5-μm laser source is based on two cascaded optical parametric amplifiers (OPA): a 2-μm BBO OPA with a mixed phase matching scheme is used as a pump source, and a type-I phase-matched ZGP OPA is designed to produce sub-mJ, <100 fs 5-μm laser pulses. The two-stage 2-μm OPA is pumped by a Ti:sapphire amplifier and produces pulse energy of ~2.2 mJ with a pulse duration of 42 fs (~6 optical cycles), and excellent pulse stability and beam quality. Preliminary result of ~50 μJ pulse energy at 5-μm is demonstrated by using single-stage ZGP OPA, and an improved two-stage OPA scheme for production of higher pulse energy at 5-μm is under development.
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TUPME046	3-D Particle-in-cell Simulations for Quasi-phase Matched Direct Laser Electron Acceleration in Density-modulated Plasma Waveguides	1463
	M.W. Lin The Pennsylvania State University, University Park, Pennsylvania, USA I. Jovanovicpresenter Penn State University, University Park, Pennsylvania, USA
	Funding: This work is supported by the Defense Threat Reduction Agency through contract HDTRA1-10-1-0034. Quasi-phase matched (QPM) direct laser acceleration (DLA) of electrons can be realized with guided, radially polarized laser pulses in density-modulated plasma waveguides*,**. A 3-D particle-in-cell (PIC) simulation model has been developed to study the scheme in which an electron bunch from a laser wakefield accelerator (LWFA) is injected into a plasma waveguide for the second-stage DLA to higher energies. In addition to being driven directly by the laser field, the electrons also experience the laser pondermotive force and the electrostatic force from the excited plasma waves. The results lead to better understanding of the interactions between the electron bunch, the laser pulse and the background plasma. Selected bunch lengths, bunch sizes and time delays with respect to the laser pulse are assigned for the injected electrons in a series of simulations. The energy spectrum and emittance of the accelerated electron bunch vary depending on those initial conditions, and they can be chosen to optimize the DLA performance. * P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000). ** M. -W. Lin and I. Jovanovic, Phys. Plasmas 19, 113104 (2012).
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TUPME047	SINBAD - A Proposal for a Dedicated Accelerator Research Facility at DESY	1466
	R.W. Aßmann, C. Behrens, R. Brinkmann, U. Dorda, K. Flöttmann, B. Foster, J. Grebenyuk, I. Hartl, M. Hüning, Y.C. Nie, J. Osterhoff, A. Rühl, H. Schlarb, B. Schmidt DESY, Hamburg, Germany M. Groß, B. Marchetti, F. Stephan DESY Zeuthen, Zeuthen, Germany F.J. Grüner, B. Hidding, A.R. Maier Uni HH, Hamburg, Germany F.X. Kärtner, B. Zeitler CFEL, Hamburg, Germany A.-S. Müller, M. Schuh KIT, Karlsruhe, Germany
	A new, dedicated accelerator research facility SINBAD (Short INnovative Bunches and Accelerators at DESY) is proposed. This facility is aimed at promoting two major goals: (1) Short electron bunches for ultra-fast science. (2) Construction of a plasma accelerator module with useable beam quality. Research and development on these topics is presently ongoing at various places at DESY, as add-on experiments at operational facilities. The two research goals are intimately connected: short bunches and precise femtosecond timing are requirements for developing a plasma accelerator module. The scientific case of a dedicated facility for accelerator research at DESY is discussed. Further options are mentioned, like the use of a 1 GeV beam from Linac2 for FEL studies and the setup of an attosecond radiation source with advanced technology. The presently planned conversion of the DORIS storage ring and its central halls into the SINBAD facility is described. The available space will allow setting up several independent experiments with a cost-effective use of the same infrastructure. National and international contributions and proposals can be envisaged.
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TUPME048	Injection of a LWFA Electron Bunch in a PWFA Driven by a Self-modulated-proton-bunch	1470
	P. Muggli MPI, Muenchen, Germany L.D. Amorim IST, Lisboa, Portugal S. Karsch MPQ, Garching, Munich, Germany N.C. Lopes, J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	The AWAKE experiment recently approved at CERN will study the acceleration of an externally injected electron bunch in a plasma wakefield accelerator (PWFA) driven by a self-modulated proton bunch. We study the possibility of injecting a bunch created by a laser-driven plasma wakefield accelerator (LWFA). We consider a first plasma source used for self-modulation of the drive bunch and a gas discharge source for acceleration of the collinearly injected bunch. The LWFA produces an electron bunch very short when compared to the PWFA wavelength and with relatively large current, possibly allowing for loading of the wakefields. Short length and high current lead to a small final energy spread. Co-linear injection preserves the incoming bunch quality and insures trapping and acceleration of the whole bunch. The energy of the LWFA electron bunch can easily exceed the trapping energy and can be produced over only a few millimeters gas-jet plasma driven by a laser of relatively modest power by today’s standards. We explore the parameter space suitable for this injection scheme that is more compact, simpler to implement and more suitable for injection in the mm-size accelerator structure.
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TUPME049	Hosing Suppression in the Self-modulated Wakefield Accelerator	1473
	J. Vieira IPFN, Lisbon, Portugal W.B. Mori UCLA, Los Angeles, California, USA P. Mugglipresenter MPI, Muenchen, Germany
	Funding: FCT-Portugal contract no EXPL/FIS-PLA/0834/1012; European Research Council contract no ERC-2010-AdG Grant 267841; by DOE contract no DE-SC0008491, DE-SC0008316, and DE-FG02- 92-ER40727. The proton driven plasma wakefield accelerator (PDPWFA) uses short LHC proton (p+) bunches (shorter than the plasma wavelength) as drivers for strongly non-linear plasma waves. Simulations showed that the PDPWFA could be used to accelerate electrons to 600 GeVs in 600 m long plasmas*. Currently available p+ bunches are much longer than the plasma wavelength, being ideal to excite intese wakefields through the self-modulation instability (SMI). An experiment is being prepared at CERN to demonstrate SMI of p+ bunches. In addition, lepton SMI experiments are also being prepared at SLAC, DESY-PITZ and RAL. The hosing instability (HI) is a competing instability that may lead to beam breakup, and needs to be controlled over the long propagation distances required for SMI growth and saturation. In this work we show that the HI can be suppressed after SMI saturation in the linear wakefield excitation regime. SMI saturation before beam-break up can be achieved by seeding SMI, and as long as the initial bunch centroid displacements are within the initial bunch transverse size. The HI suppression occurs via a plasma analogue of the BNS damping in conventional accelerators. * A. Caldwell et al, Nat. Physics Nat. Phys. 5, 363 (2009).
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TUPME050	Electron Bunch Self-modulation in Long Plasmas at SLAC FACET	1476
	P. Muggli MPI, Muenchen, Germany E. Adli, V.K.B. Olsen University of Oslo, Oslo, Norway L.D. Amorim IST, Lisboa, Portugal S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos SLAC, Menlo Park, California, USA C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi UCLA, Los Angeles, California, USA N.C. Lopes, J. Vieira Instituto Superior Tecnico, Lisbon, Portugal O. Reimann MPI-P, München, Germany
	Funding: This work performed in part under DOE Contract DE-AC02-76SF00515. We study the physics of self-modulation instability (SMI) of long, when compared to the wake wavelength, electron and positron bunches in pre-formed plasmas at SLAC-FACET. Self-modulation is the result of the action of focusing/defocusing transverse wakefields on the bunch radius. Self-modulation leads to observables such as overall defocusing of the bunch, periodic modulation of the bunch radius at the wake period and multi-GeV energy gain/loss by drive bunch particles. Defocusing is observed from OTR images, radial self-modulation from CTR spectra and interferometric traces and energy gain/loss from energy spectra with sub-GeV resolution. The plasma density is varied by changing the vapor density ionized by a laser/axicon system. The bunch length, radius and charge can also be varied. The SMI can be seeded using a notch collimator system. Numerical simulations indicate that seeding the SMI mitigates the hose instability. Hose instability can also be seeded, for example by using the RF deflecting cavity to impart a tilt to the incoming bunch axis. The overall experimental plan as well as the latest experimental results obtained with electron bunches will be presented.
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TUPME051	Self-Injection by Trapping of Plasma Electrons Oscillating in Rising Density Gradient at Vacuum-Plasma Interface	1479
	A. A. Sahai, T.C. Katsouleas Duke ECE, Durham, North Carolina, USA P. Mugglipresenter MPI-P, München, Germany
	Funding: DE-SC0010012, NSF-PHY-0936278 We model the trapping of plasma electrons within the density structures excited by a propagating energy source in a rising plasma density gradient. Rising density gradient leads to spatially contiguous coupled up-chirped plasmons (d{ω2pe(x)}/{dx}>0). Therefore phase mixing between plasmons can lead to trapping until the plasmon field is high enough such that e- trajectories returning towards a longer wavelength see a trapping potential. Rising plasma density gradients are ubiquitous for confining the plasma within sources at the vacuum-plasma interfaces. Therefore trapping of plasma-e- in a rising ramp is important for acceleration diagnostics and to understand the energy dissipation from the excited plasmon train [1]. Down-ramp in density [2][3] has been used for plasma-e- trapping within the first bucket behind the driver. Here, in rising density gradient the trapping does not occur in the first plasmon bucket but in subsequent plasmon buckets behind the driver. Trapping reduces the Hamiltonian of each bucket where e- are trapped, so it is a wakefield-decay probe. Preliminary computational results for beam and laser-driven wakefield are shown. 1.Sahai, A. A. et.al.,Proc of IPAC2013, MOPAC10, Oct2013 2.Suk, H. et.al.,Phys. Rev.Lett. 86 2001 10.1103/PhysRevLett.86.1011 3.Dawson, J, Phys Rev 113 1959 10.1103/PhysRev.113.383
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TUPME052	Enhanced Laser Ion Acceleration based on Near-Critical Density Plasma Lens	1483
SUSPSNE023	use link to see paper's listing under its alternate paper code
	Y.X. Geng, J.E. Chen, L.R.F. Li, Y.H. Li, Q. Liao, C. Lin, L.H.Y. Lu, Y.R. Lu, H. Wang, X.Q. Yan, Z.X. Yuan, S. Zhao, W.B. Zhao, Y.Y. Zhao, K. Zhu, B.Y. Zou PKU, Beijing, People's Republic of China
	The laser prepulse has large effect on ion acceleration driven by high power laser pulse. Recently, simulations show that with proper prepulse parameters, a near critical density pre-plasma can be generated in the front target. When the main laser pulse propagating in this pre-plasma, it can experience transverse Self-focusing, longitudinal profile steepening and prepluse cleaning at the same time, meaning its quality is spontaneously improved by this “plasma lens”.The effects can greatly improve the energy coupling efficiency of laser pulse into accelerated ions. A 3mJ Ti-Sapphire laser system has been built at PKU in order to experimentally study the pre-pulse effect on a solid target. Fluid simulation show that, after hundreds of picoseconds radiated with this laser pulse, the pre-plasma in front of the target will expand to near critical density with tens of micron scale length, which is suitable as a plasma lens to improve the ion acceleration. A laser interferometer system is built to measure the scale length and density evolution of plasma and the optimum condition of the pre-plasma has been searched using both Aluminum target and home-made DLC target. H.Y.Wang et al, Laser shaping of a relativistic intense, short Gaussian pulse by a plasma lens, PRL, 107,265002, 2011
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TUPME053	Study of the Energy Modulated Electron Cyclotron Resonance Ion Source for the Coupled RFQ-SFRFQ Cavity	1486
	W.L. Xia, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.R. Lupresenter, S.X. Peng, Z. Wang, X.Q. Yan, J. Zhao, K. Zhu PKU, Beijing, People's Republic of China
	The coupled RFQ and SFRFQ cavity has been manufactured and tested recently. According to the beam dynamic design, the input He+ beam within 120° phase width is designed for the cavity to achieve over 98% transmission efficiency. An energy modulated electron cyclotron resonance (ECR) ion source was proposed and simulated. To achieve the 1% energy modulation on the 30keV direct current (DC) beam, two simplified RF power feeding structures for beam bunching were studied. The simulations show positive results as well as the bunched beam is achieved by the energy modulated ECR ion source.
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TUPME054	Influence of a Vacuum Gap on a Bunch Wakefield in a Circular Waveguide Filled up with Dielectric	1489
	T.Yu. Alekhina, A.V. Tyukhtin, V.V. Vorobevpresenter Saint-Petersburg State University, Saint-Petersburg, Russia
	Analysis of electromagnetic field of a particle bunch intersecting several boundaries in a dielectric waveguide is important for the wakefield acceleration technique and other problems of accelerator physics. In previous works we investigated the case of a single boundary in a waveguide*. Now we study the electromagnetic field of the bunch moving in a dielectric circular waveguide and crossing a vacuum cavity. The main attention is given to the case when wakefield (Cherenkov radiation) is generated in dielectric. The behavior of the total field depending on distance and time is explored numerically. Analytical estimations are made as well. Influence of the vacuum gap on the wakefield is considered for different lengths of the gap. It is clarified conditions when the vacuum gap does not practically influence on the wakefield. It is noted that the quasi monochromatic wave (the Cherenkov transition radiation) generated in the vacuum region can be used for restoration of the field in the area after the gap. This effect can be achieved for some optimal parameters of the problem. * T.Yu. Alekhina, A.V. Tyukhtin, Phys. Rev. ST-AB, v.15, 091302 (2012); T.Yu. Alekhina, A.V. Tyukhtin, Phys. Rev. ST-AB, v.16, 081301 (2013).
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TUPME055	Room-temperature Burst-mode GHz and THz Pulse-train Photoinjector	1492
SUSPSNE022	use link to see paper's listing under its alternate paper code
	F.H. Chao, C.H. Chen, K.Y. Huang, Y.-C. Huang, Y.C. Wang, M.H. Wu NTHU, Hsinchu, Taiwan P.J. Chou NSRRC, Hsinchu, Taiwan
	A photoinjector usually generates an electron pulse with few ps pulse duration repeating at 10-100 Hz. The low-pulse rate limits the data rate in a number of applications. Although high-repetition-rate operation is possible from a superconducting accelerator, the high cost and complexity of a superconducting system prevent it from being widely used. In this paper, we present our study toward a burst-mode GHz/THz pulse train photoinjector operating at room temperature. For the GHz operation mode, we self-develop a driver laser system, generating tens of laser pulses at 2.856 GHz in an adjustable 5-10 ns temporal envelope repeating at 10 Hz. Upon illuminating the photocathode with the driver laser, our S-band photoinjector (supported by Tsing Hua University, Beijing) is to generate a GHz electron pulse train with the same temporal structure as that of the driver laser pulses. For the THz operation mode, we illuminate the photocathode with two lasers, one being a typical UV gun-driver laser at 260 nm and the other being a mid-infrared laser at 100 THz. The UV laser induces photoemission and the infrared laser gates the emission current at 100 THz by virtue of the Schottky effect.
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TUPME056	Improving Ion and Electron Beam Characteristics within LA³NET	1495
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289191. Lasers are widely used at accelerator and light source facilities for beam generation, acceleration and optimization. Research within LA³NET focuses on laser-based particle sources (photo injectors and laser ion sources), laser acceleration, and laser-based beam diagnostics. This project was recently selected as a ‘success story’ by the European Commission for its research achievements. This paper presents selected numerical and experimental results. From HZDR results of electron transport simulations in their new SRF gun II cavity, super-conductive solenoid and downstream accelerators are shown. The results from optimization studies into asymmetric grating structures obtained at the University of Liverpool are also presented, along with initial results from studies into novel diagnostics for high intensity proton beams at CERN and low energy electron beams at KIT. Finally, the events organized by the consortium to date and future plans are summarized.
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TUPME057	Optimization of Accelerators and Light Sources within oPAC	1499
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485. The optimization of particle accelerators and light sources by combining studies into beam physics, instrumentation, numerical simulations and accelerator control systems is the aim of the EU-funded oPAC project. With a budget of more than 6 M€, oPAC is one of the largest training networks ever funded by the EU and currently trains more than 20 Marie Curie Fellows. This paper presents selected research highlights, including optimization studies into the CERN Proton Synchrotron (PS), measurement and correction of linear and nonlinear optics distortions in the ALBA synchrotron (Spain), perturbation measurements of a cavity Schottky noise detector at GSI (Germany) and R&D into device control data base tool at COSYLAB (Slovenia). Moreover, a summary of past and future oPAC events is also given.
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TUPME058	The Argonne Wakefield Accelerator (AWA): Commissioning and Operation	1503
	M.E. Conde, S.P. Antipov, D.S. Doran, W. Gai, C.-J. Jing, C. Li, W. Liu, J.G. Power, J.Q. Qiu, J.H. Shao, C. Whiteford, E.E. Wisniewski ANL, Argonne, Illinois, USA S.P. Antipov, C.-J. Jing, J.Q. Qiu Euclid TechLabs, LLC, Solon, Ohio, USA S. Cao IMP, Lanzhou, People's Republic of China C. Li, J.H. Shao TUB, Beijing, People's Republic of China E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357. The commissioning of the upgraded AWA facility is well underway. The new L-band electron gun has been fully commissioned and has been successfully operated with its Cesium Telluride photocathode at a gradient of 80 MV/m. Single bunches of up to 100 nC, and bunch trains of four bunches with up to 80 nC per bunch have been generated. The six new accelerating cavities (L-band, seven cells, pi mode) have been RF conditioned to 12 MW or more; their operation at 10 MW brings the beam energy up to 75 MeV. Measurements of the beam parameters are presently underway, and the use of this intense beam to drive high gradient wakefields will soon follow. One of the main goals of the facility is to generate RF pulses with GW power levels, corresponding to accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure.
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TUPME059	Longitudinal Bunch Shaping with a Double Dogleg based Emittance Exchange Beam Line	1506
	G. Ha, M.E. Condepresenter, W. Gai, C.-J. Jing, K.-J. Kim, J.G. Power, A. Zholents ANL, Argonne, Illinois, USA M.-H. Cho, G. Ha, W. Namkung POSTECH, Pohang, Kyungbuk, Republic of Korea C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: Work supported by High Energy Physics, Office of Science, US DOE. A new program is under development at Argonne National Laboratory (ANL) to use an emittance exchange (EEX) beamline to produce longitudinally shaped electron bunches. While the ultimate goal is to generate triangular shapes for high transformer ratio wakefield acceleration we are also exploring, in general, the capability of the double dogleg EEX beamline to control the bunch shape. We are studying effects that degrade the quality of the longitudinal current profile including: non-uniform particle distribution, emittance, the deflecting cavity thick-lens effect, 2nd order effects, space charge effects and coherent synchrotron radiation effects. We will present the double dogleg EEX beamline layout and the diagnostic design as well as give a progress report on the experimental status of the program.
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TUPME060	Simulation Analysis on Micro-Bunched Density Modulation from a Slit-Masked Chicane	1509
	Y.-M. Shin, P. Piot, C.R. Prokop Northern Illinois University, DeKalb, Illinois, USA D.R. Broemmelsiek, E.R. Harmspresenter, A.H. Lumpkin, J. Ruan, J.C.T. Thangaraj Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the DOE contract No. DEAC02-07CH11359 to the Fermi Research Alliance LLC. Pre-bunching a beam at a resonance condition with an accelerating structure vastly improves performance of beam-driven accelerators and undulators since it enhances a beam-wave coupling. We plan to test a slit-mask micro-buncher at the chicane of Fermilab-ASTA 50 MeV beamline in the effort of advanced accelerator research. With the chicane design parameters (bending angle (alpha) of 18 degree, R56 ~ - 0.18 m, and bending radius of ~ 0.78 m), analytic model showed that a slit-mask with W (period) = 900 um and a (aperture width) = 300 um (30 % transparency) generates 100 um spaced micro-bunches with 5 ~ 6 % correlated energy spread. Two kinds of combined beamline simulation, CST-PS+Impact-Z and Elegant+Shower, including space charge and CSR effects, showed that a 900 um spaced, 300 um wide slits placed in the middle of chicane splits 20 pC – 1 nC bunches into ~ 100 um spaced micro-bunches. It is possible that a further optimization of mask design creates sub-100 fs micro-bunches, which is currently under development. *[1] NIM A 375, 597 (1996) [2] PRL 101, 054801 (2008) [3] Y.-E Sun, P. R. G. Piot, FEMILAB-CONF-08-408-APC ** ASTA: Advanced Superconducting Test Accelerator
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TUPME061	Ultra-High Gradient Beam-Driven Channeling Acceleration in Hollow Crystalline Media	1512
	Y.-M. Shin, T. Xu Northern Illinois University, DeKalb, Illinois, USA G. Flanagan Muons, Inc, Illinois, USA E.R. Harmspresenter, J. Ruan, V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	Since the recent discovery of the Higgs boson particle, there is an increasing demand in Energy Frontier to develop new technology for a TeV/m range of acceleration gradient. The density of charge carriers, ~ 1024 – 1029 m-3, of crystals is significantly higher than that of a plasma gas, and correspondingly in principle wakefield gradients of up to 0.1 - 10 TV/m are possible. Our simulations (VORPAL and CST-PIC) with Fermilab-ASTA* beam parameters showed that micro-bunched beam gains energy up to ~ 70 MeV along the 100 um long channel under the resonant coupling condition of the plasma wavelength, ~ 10 um. Also, with lowering a charge, electron bunches channeling through a high-density plasma medium have higher energy gain in a hollow channel than in a uniformly filled cylinder, which might be attribute to lower scattering ratios of the tunnel structure. The numerical analysis implied that synthetic crystalline plasma media (e.g. carbon nanotubes) have potential to mitigate constraint of bunch charges required for beam-driven acceleration in high density plasma media. The channeling acceleration** will be tested at the ASTA facility, once fully commissioned. * ASTA: Advanced Superconducting Test Accelerator ** [1] T. Tajima and M. Cavenago, PRL 59, 13(1987) [2] P. Chen and R. Noble, SLAC-PUB-7402(1998) [3] V.Shiltsev, Physics Uspekhi 55, 965(2012)
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TUPME064	Laser-driven Acceleration with External Injection at SINBAD	1515
	J. Grebenyuk, R.W. Aßmann, U. Dorda, B. Marchetti DESY, Hamburg, Germany
	One of the important milestones to make plasma acceleration a realistic technology for user-applications is demonstration of bunch acceleration inside a plasma wake with minimal degradation of its quality. This can be achieved by external injection of beams into a plasma accelerator. SINBAD is a proposed dedicated accelerator research and development facility at DESY where amongst other topics laser-driven wakefield acceleration with external injection of ultra-short bunches will be exploited. To minimise energy-spread growth the bunch should occupy a small fraction of the plasma wavelength. In addition it has to be longitudinally synchronised with the laser driver to high accuracy. To avoid emittance growth the beam Twiss parameters have to be matched to the intrinsic beta-function of the plasma. To facilitate matching and synchronisation, acceleration at low plasma densities can be advantageous. We present a preparatory feasibility study for future plasma experiments at SINBAD using simulations with the particle-in-cell code OSIRIS. Field-gradient scaling laws are presented together with parameter scans of externally injected bunch, such as its injection phase, charge and length.
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TUPME069	Proton Electron Accelerator at CERN	1519
	R. Tarkeshian MPI, Muenchen, Germany
	AWAKE is a proton driven plasma-wakefield acceleration at CERN*, that uses long proton bunches ~ 400 ps from the SPS. In a dense plasma, a long proton bunch is subject toμbunching at plasma period due to the self-modulation instability, SMI**. The self-modulated proton bunch generates large amplitude charge separation through resonant wakefield excitation. Numerical simulations show that when seeded the SMI can grow and saturate over ~4 m in a plasma with density in the (1-10) *1014/cc range. Seeding also allows for deterministic injection of witness bunches in the focusing and accelerating phase of the wakefields. The SPS proton bunch carrying kJ of energy is a unique driver for generation of ~ GeV/m wakefields through 10’s of meters of plasma. The side-injected electrons ~15 MeV can reach GeV energies. The AWAKE experimental layout, the physics of self-modulation, simulation results, plasma source under study, diagnostics plan for bunch modulation measurement using transverse coherent transition radiation***, and phasing of the witness bunch respect to the wave and synchronisation with diagnostics will be presented.**** *A. Caldwel, et. al, Nature Physics 5, 2009 **N. Kumar, A. Pukhov, PRL, 104, 2010 ***O. Reimann, R. Tarkeshian, Proc. of IBIC, 2013 **** The work is submitted on behalf of AWAKE collaboration.
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TUPME073	A Novel Laser Ionized Rb Plasma Source for Plasma Wakefield Accelerators	1522
	E. Öz, F. Batsch, P. Muggli MPI-P, München, Germany
	Funding: AWAKE collaboration A proton driven plasma wakefield accelerator* is to be conducted at CERN by the AWAKE collaboration. Externally injected electrons are accelerated in a large gradient (~GeV/m) wakefield. The large gradient is achieved by resonant formation of the wakefield by a train of micro-bunches. Transverse modulation of a long (~12 cm) proton bunch by the self modulation instability** creates these plasma wavelength size (~1 mm) micro-bunches. This resonant mechanism brings a strict requirement on the plasma density uniformity, namely % 0.2, in order for the injected electron bunch to remain in the accelerating and focusing phase of the wakefields. We describe the plasma source*** that satisfies this requirement during the beam plasma interaction. Rb vapor with ~1015 cm-3 density is confined in a 10 m long 4 cm diameter, stainless-steel tube which is heated to ~200 Co by an oil heat exchanger. The access to the source during interaction is provided by custom built fast valves. The vapor is fully tunnel ionized (first e-) by a laser forming a 2 mm diameter plasma channel. * http://awake.web.cern.ch/awake/ ** http://link.aps.org/doi/10.1103/PhysRevLett.104.255003 *** http://dx.doi.org/10.1016/j.nima.2013.10.093
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TUPME074	First Experiences with the PITZ Plasma Cell for Electron Beam Self-modulation Studies	1525
	M. Groß, A. Donat, J.D. Good, M. Khojoyan, G. Koss, M. Krasilnikov, R. Schütze, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany R. Brinkmann DESY, Hamburg, Germany F.J. Grüner, G. Pathak Uni HH, Hamburg, Germany P. Muggli, E. Öz MPI-P, München, Germany D. Richter HZB, Berlin, Germany C.B. Schroeder LBNL, Berkeley, California, USA
	The self-modulation of long particle beams in a plasma has recently gained interest in light of the ongoing preparation for the plasma wakefield acceleration experiment of the AWAKE collaboration at CERN. Instrumental to the experiment is the self-modulation of a proton beam to generate bunches short enough for producing high acceleration fields. As electron bunches are easier to handle and the underlying physics is identical, it is judicious to first gain insight into the experimental conditions of the self-modulation of long particle beams in plasma by using electron bunches before progressing to the experiment with proton bunches. The experimental demonstration of self-modulation of an electron bunch is in preparation at the Photo Injector Test facility at DESY, location Zeuthen (PITZ). In this contribution the fabrication and first experimental tests towards a Lithium plasma cell are highlighted. The distinctive feature of this plasma cell is the addition of side ports for insertion of the ionization laser beam and for diagnostics purposes.
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TUPME075	Simulations on Laser Wakefield Generation in a Parabolic Magnetic-plasma Channel	1528
	D.N. Gupta, M. Singhpresenter University of Delhi, Delhi, India D. Jang, H. Suk APRI-GIST, Gwangju, Republic of Korea B.S. Sharma Kota University, Rajasthan, India
	To utilize the laser-plasma channel for laser wakefield acceleration, we have studied the non-paraxial theory of nonlinear propagation of ultra-intense relativistic Gaussian laser pulse in a preformed spatially tapered magneto-plasma channel having a parabolic density profile. A three-dimensional envelope equation for the laser field is derived, which includes the non-paraxial and applied magnetic field effects. An analytical expression for the wakefield is derived and analyzed the results with the help of particle-in-cell (PIC) simulations. It is shown that wakefield structures and the phase of axial component of the wakefield depend on applied external magnetic field. This aspect of theoretical observation can be used in the production of highly collimated mono-energetic x-rays.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME075
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TUPME076	Numerical modeling of the E-209 self-modulation experiment at SLAC - FACET	1531
	L.D. Amorim, L.O. Silva, J. Vieira IPFN, Lisbon, Portugal P. Mugglipresenter MPI, Muenchen, Germany
	The E-209 experiment currently running at SLAC- FACET used a long electron bunch (∼ 5 times the plasma wavelength) to drive plasma wakefields through the self- modulation instability. In this work we present and analyze numerical simulation results performed with the particle-in- cell (PIC) code OSIRIS. The results show that SMI saturates after 5cm of propagation in the plasma and that the maxi- mum acceleration wakefields, 15 − 20GV/m, are sustained over a 1m long plasma. Electron bunch energy loss of 4GeV was observed in the simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME076
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TUPME077	The Challenge of Interfacing the Primary Beam Lines for the AWAKE Project at CERN	1534
	C. Bracco, B. Goddard, E. Gschwendtner, M. Meddahi, A.V. Petrenko CERN, Geneva, Switzerland P. Muggli MPI, Muenchen, Germany F.M. Velotti EPFL, Lausanne, Switzerland
	The Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) at CERN foresees the simultaneous operation of a proton, a laser and an electron beam. The first stage of the experiment will consist in proving the self-modulation, in the plasma, of a long proton bunch into micro-bunches. The success of this experiment requires an almost perfect concentricity of the proton and laser beams, over the full length of the plasma cell. The complexity of integrating the laser into the proton beam line and fulfilling the strict requirements in terms of pointing precision of the proton beam at the plasma cell are described. The second stage of the experiment foresees also the injection of electron bunches to probe the accelerating wakefields driven by the proton beam. Studies were performed to evaluate the possibility of injecting the electron beam parallel and with an offset to the proton beam axis. This option would imply that protons and electrons will have to share the last few meters of a common beam line. Issues and possible solutions for this case are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME077
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TUPME078	Electron Injection Studies for the AWAKE Experiment at CERN	1537
	A.V. Petrenko, C. Bracco, E. Gschwendtner CERN, Geneva, Switzerland K.V. Lotov NSU, Novosibirsk, Russia K.V. Lotov BINP SB RAS, Novosibirsk, Russia P. Muggli MPI, Muenchen, Germany
	The AWAKE experiment recently approved at CERN will use the self-modulation instability (SMI) of long (12 cm), relativistic (400 GeV/c) proton bunches in dense plasmas to drive wakefields with accelerating gradients at the GV/m level. These accelerating gradients will be probed by externally injected electrons. In order to preserve the plasma uniformity required for the SMI the first experiments will use on-axis injection of a low energy 10-20 MeV electron beam collinearly with the proton beam. In this article we describe the physics of electron injection into the proton driven SMI wakefields. Requirements on the injected electron beam are determined and the final accelerated beam parameters are obtained via numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME078
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TUPME079	A Spectrometer for Proton Driven Plasma Wakefield Accelerated Electrons at AWAKE	1540
	S. Jolly, L.C. Deacon, J.A. Goodhand, S.R. Mandry, M. Wing UCL, London, United Kingdom S.R. Mandry MPI, Muenchen, Germany
	The AWAKE experiment is to be constructed at the CERN Neutrinos to Gran Sasso facility (CNGS). This will be the first experiment to demonstrate electron acceleration by use of a proton driven plasma wakefield. The 400 GeV proton beam from the CERN SPS will excite a wakefield in a plasma cell several metres in length. To observe the plasma wakefield, electrons of a few MeV will be injected into the wakefield following the head of the proton beam. Simulations indicate that electrons will be accelerated to GeV energies by the plasma wakefield. The AWAKE spectrometer is intended to measure both the peak energy and energy spread of these accelerated electrons. The baseline design makes use of a single dipole magnet to separate the electrons from the proton beam. The dispersed electron beam then impacts on a scintillator screen: the resulting scintillation light is collected and recorded by an intensified CCD camera. The design of the spectrometer is detailed with a focus on the scintillator screen. Results of simulations to optimise the scintillator are presented, including studies of the standard GadOx scintillators commonly used for imaging electrons in plasma wakefield experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME079
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TUPME081	Plasma Wakefield Acceleration at CLARA PARS	1544
SUSPSNE025	use link to see paper's listing under its alternate paper code
	K. Hanahoe, Ö. Mete, G.X. Xia UMAN, Manchester, United Kingdom D. Angal-Kalinin, J.A. Clarke, J.K. Jones, J.W. McKenzie, B.L. Militsyn, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D. Angal-Kalinin, J.A. Clarke, J.K. Jones, J.W. McKenzie, Y. Wei, C.P. Welsch, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom B. Hidding USTRAT/SUPA, Glasgow, United Kingdom J.D.A. Smith TXUK, Warrington, United Kingdom Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	PARS is a proposed Plasma Accelerator Research Station using the planned CLARA (Compact Linear Accelerator for Research and Applications) electron linear accelerator at Daresbury Laboratory in the UK. In this paper, two- dimensional particle-in-cell simulations based on realistic CLARA beam parameters are presented. The results show that an accelerating gradient of 2.0 GV/m can be achieved over an accelerating length of at least 13 cm. Preliminary simulation results for a two bunch scheme show an energy gain of 70% over a length of 13 cm, giving an average accelerating gradient of 1.2 GeV/m.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME081
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TUPME084	On the Frequency Choice for the eRHIC SRF Linac	1547
	S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn, W. Xu BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, V. Litvinenko, V. Ptitsyn Stony Brook University, Stony Brook, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. eRHIC is a future electron-hadron collider proposed at BNL. It will collide high-intensity hadron beams from one of the existing rings of RHIC with a 50-mA electron beam from a multi-pass 10-GeV superconducting RF (SRF) Energy Recovery Linac (ERL). A novel approach to the multi-pass ERL utilizing a non-scaling FFAG was recently proposed. It has many advantages over the previous designs including significant cost savings. The current design has 11 passes in two FFAG rings. To mitigate various beam dynamics effects, it was proposed to lower RF frequency of the SRF linac from 704 MHz used in the previous design. In this paper we consider different effects driving the frequency choice of the SRF ERL and present our arguments for choosing lower RF frequency.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME084
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