NAPAC2016 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOA3IO01	High Energy Coulomb Scattered Electrons Detected in Air Used as the Main Beam Overlap Diagnostics for Tuning the RHIC Electron Lenses	ion, proton, alignment, detector	20
	P. Thieberger, Z. Altinbas, C. Carlson, C. Chasman, M.R. Costanzo, C. Degen, K.A. Drees, W. Fischer, D.M. Gassner, X. Gu, K. Hamdi, J. Hock, Y. Luo, A. Marusic, T.A. Miller, M.G. Minty, C. Montag, A.I. Pikin BNL, Upton, Long Island, New York, USA S.M. White ESRF, Grenoble, France
	Funding: Work supported by Brookhaven Science Associates under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy A new type of electron-ion beam overlap monitor has been developed for the RHIC electron lenses. Low energy electrons acquire high energies in small impact parameter Coulomb scattering collisions with relativistic ions. Such electrons can traverse thin vacuum windows and be conveniently detected in air. Counting rates are maximized to optimize beam overlap. Operational experience with the electron backscattering detectors during the 2015 p-p RHIC run will be presented. Other possible real-time non-invasive beam-diagnostic applications of high energy Coulomb-scattered electrons will be briefly discussed. Most of this material appears in an article by the same authors entitled "High energy Coulomb-scattered electrons for relativistic particle beam diagnostics", Phys. Rev. Accel. Beams 19, 041002 (2016)
	Slides MOA3IO01 [2.164 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOA3IO01
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MOA3CO03	Bunch Shape Monitor Measurements at the LANSCE Linac	ion, linac, target, detector	25
	I.N.D. Draganic, D. Baros, C.M. Fortgang, R.W. Garnett, R.C. McCrady, J.F. O'Hara, L. Rybarcyk, C.E. Taylor, H.A. Watkins LANL, Los Alamos, New Mexico, USA A. Feschenko, V. Gaidash, Yu.V. Kiselev RAS/INR, Moscow, Russia
	Two Bunch Shape Monitors (BSM) [1] have been developed, fabricated and assembled for the first direct longitudinal beam measurements at the Los Alamos Neutron Science Center (LANSCE) linear accelerator (linac). The BSM detectors use different radio frequencies for the deflecting field: first harmonic (201.25 MHz) and second harmonic (402.5 MHz) of fundamental accelerator radio frequency. The first BSM is designed to record the proton beam longitudinal phase distribution after the new RFQ accelerator at a beam energy of 750 keV with phase resolution of 1.0 degree and covering phase range of 180 degree at 201.25 MHz. The second BSM is installed between DTL tanks 3 and 4 of the LANSCE linac in order to scan both H⁺ and H⁻ beams at a beam energy of 73 MeV with a phase resolution up to 0.5 degree in the phase range of 90 degree at 201.25 MHz. Preliminary results of bunch shape measurements for both beams under different beam gates (pulse length of 150 us, 1 Hz repetition rate, etc.) will be presented and compared high performance simulation results (HPSIM) [2]. [1] A. Feschenko, Proc. of RUPAC2012, FRXOR01, Saint Petersburg, Russia, pp. 181 - 185. [2] X. Pang, L. Rybarcyk, and S. Baily, Proc. of HB2014, MOPAB30, East Lansing, MI, USA, pp. 99-102.
	Slides MOA3CO03 [4.942 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOA3CO03
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MOB3IO01	Commissioning of the Phase-I SuperKEKB B-Factory and Update on the Overall Status	ion, vacuum, emittance, coupling	32
	Y. Ohnishi, T. Abe, T. Adachi, K. Akai, Y. Arimoto, K. Egawa, Y. Enomoto, J.W. Flanagan, H. Fukuma, Y. Funakoshi, K. Furukawa, N. Iida, H. Iinuma, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, H. Kaji, T. Kamitani, T. Kawamoto, S. Kazama, M. Kikuchi, T. Kobayashi, K. Kodama, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, S. Nakamura, T.T. Nakamura, H. Nakayama, T. Natsui, M. Nishiwaki, K. Ohmi, T. Oki, S. Sasaki, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, H. Sugimoto, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, S. Uehara, S. Uno, X. Wang, K. Watanabe, Y. Yano, S.I. Yoshimoto, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong KEK, Ibaraki, Japan M.E. Biagini, M. Boscolo, S. Guiducci INFN/LNF, Frascati (Roma), Italy D. El Khechen LAL, Orsay, France
	The SuperKEKB B-Factory at KEK (Japan), after few years of shutdown for the construction and renovation, has finally come to the Phase-1 commissioning of the LER and HER rings, without the final focus system and the Belle II detector. Vacuum scrubbing, optics tuning and beam related background measurements were performed in this phase. Low emittance tuning techniques have also been applied in order to set up the rings for Phase-2 with colliding beams next year. An update of the final focus system construction, as well as the status of the injection system with the new positron damping ring and high current/low emittance electron gun is also presented.
	Slides MOB3IO01 [10.375 MB]
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MOB3CO03	RHIC Au-Au Operation at 100 GeV in Run16	ion, operation, cavity, luminosity	42
	X. Gu, J.G. Alessi, E.N. Beebe, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, W. Fischer, C.J. Gardner, D.M. Gassner, Y. Hao, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, P.F. Ingrassia, J.P. Jamilkowski, J.S. Laster, V. Litvinenko, C. Liu, Y. Luo, M. Mapes, G.J. Marr, A. Marusic, G.T. McIntyre, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, I. Pinayev, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, J.E. Tuozzolo, G. Wang, Q. Wu, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang BNL, Upton, Long Island, New York, USA
	In order to achieve higher instantaneous and integrated luminosities, the average Au bunch intensity in RHIC has been increased by 30% compared to the preceding Au run. This increase was accomplished by merging bunches in the RHIC injector AGS. Luminosity leveling for one of the two interaction points (IP) with collisions was realized by continuous control of the vertical beam separation. Parallel to RHIC physics operation, the electron beam commissioning of a novel cooling technique with potential application in eRHIC, Coherent electron Cooling as a proof of principle (CeCPoP), was carried out. In addition, a 56 MHz superconducting RF cavity was commissioned and made operational. In this paper we will focus on the RHIC performance during the 2016 Au-Au run.
	Slides MOB3CO03 [2.173 MB]
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MOB4IO02	ERL-Ring and Ring-Ring Designs for the eRHIC Electron-Ion Collider	ion, luminosity, proton, linac	64
	V. Ptitsyn BNL, Upton, Long Island, New York, USA
	An overview of the eRHIC project.
	Slides MOB4IO02 [6.001 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOB4IO02
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MOPOB39	A 600 Volt Multi-Stage, High Repetition Rate GaN FET Switch	ion, linac, ECR, operation	152
	G.W. Saewert, D. Frolov, H. Pfeffer Fermilab, Batavia, Illinois, USA
	Using recently available GaN FETs, a 600 Volt three-stage, multi-FET switch has been developed having 2 nanosecond rise time driving a 200 Ω load with the potential of approaching 30 MHz average switching rates. Possible applications include driving particle beam choppers kicking bunch-by-bunch and beam deflectors where the rise time needs to be custom tailored. This paper reports on the engineering issues addressed, the design approach taken and some performance results of this switch.
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MOPOB53	Simulation of Ping-Pong Multipactor with Continuous Electron Seeding	ion, simulation, multipactoring, resonance	181
	M. Siddiqi, R.A. Kishek UMD, College Park, Maryland, USA
	Funding: National Science Foundation grant No. PHY1535519 Multipactor is a discharge induced by the impact of electrons on a surface due to radio-frequency (RF) electromagnetic fields and secondary electron emission (SEE). Depending on the impact energy and RF phase of the incident electron, a growth in the electron density is possible. Multipactor can lead to device breakdown in many applications, such as particle accelerator structures and rf systems, satellite communication equipment, and microwave components. Multipactor can also be a precursor for electron cloud effects. Due to the critical need to mitigate multipactor, a more comprehensive theory has been introduced that views multipactor as a global effect that can be analyzed through the concepts of iterative maps and nonlinear dynamics . In order to test this novel approach, multipactor is simulated in a parallel-plate waveguide using the WARP particle-in-cell code. Different parameters are varied in the simulation to determine the conditions that add to multipactor growth, such as geometry dimensions, electron seeding scenarios, and an applied DC electric field. These computational results and their implications on the further development of this theory will be presented. R.A. Kishek, Physics of Plasmas 20, 056702 (2013).
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MOPOB56	Frequency Domain Simulations of Rf Cavity Structures and Coupler Designs for Co-Linear X-Band Energy Booster (CXEB) with ACE3P	ion, cavity, GUI, simulation	191
	T. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA
	Due to their higher intrinsic shunt impedance X-band accelerating structures offer significant gradients with relatively modest input powers, and this can lead to more compact light sources. At the Colorado State University Accelerator Laboratory (CSUAL) we would like to adapt this technology to our 1.3-GHz, L-band accelerator system using a passively driven 11.7 GHz traveling wave X-band configuration that capitalizes on the high shunt impedances achievable in X-band accelerating structures in order to increase our overall beam energy in a manner that does not require investment in an expensive, custom, high-power X-band klystron system. Here we provide the frequency domain simulation results using the ACE3P Electromagnetic Suite's OMEGA3P and S3P for our proposed Co-linear X-band Energy Booster (CXEB) system that will allow us to achieve our goal of reaching the maximum practical net potential across the X-band accelerating structures while driven solely by the beam from the L-band system.
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MOPOB68	A New Method for Grain Texture Manipulation in Post-Deposition Niobium Films	ion, laser, niobium, controls	221
	J. Musson, K. Macha, H.L. Phillips JLab, Newport News, Virginia, USA W. Cao, H. Elsayed-Ali ODU, Norfolk, Virginia, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Old Dominion University Niobium films are frequently grown using forms of energetic condensation, with modest substrate temperatures to control grain structure. As an alternative, energetic deposition onto a cold substrate results in a dense amorphous film, with a much larger energy density than the re-crystallized state. Re-crystallization is then performed using a pulsed UV (HIPPO) laser, with minimal damage to the substrate. In addition, a graded interface between the substrate and Nb film is created during the early stages of energetic deposition. Experimental approach and apparatus are described.
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MOPOB76	Field Emission Dark Current Simulation for eRHIC ERL Cavities	ion, cavity, SRF, simulation	235
	C. Xu, I. Ben-Zvi, Y. Hao, V. Ptitsyn, K.S. Smith, B. P. Xiao, W. Xu BNL, Upton, Long Island, New York, USA
	The eRHIC project will be a electron and proton collider proposed in BNL. These high repetition rates will require Super-Conducting Radio-Frequency cavities with fundamental frequency of 650MHZ for high current applications. Each with a string of two of those cavities. The strong electromagnetic fields in the SRF cavities will extract electrons from the cavity walls and will accelerate those. Most dark current will be deposited locally, although some electrons may reach several neighbour cyromodules, thereby gaining substantial energy before they hit a collimator or other aperture. Simulation of these effects is therefore crucial for the design of the machine. Track3P code was used to simulate field-emission electrons from different SRF cavities setup to optimize the field emission dark current characterizes.
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TUB1CO02	Operating Synchrotron Light Sources with a High Gain Free Electron Laser	ion, FEL, undulator, emittance	259
	S. Di Mitri, M. Cornacchia Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The peak current required by a high gain free electron laser (FEL) is not deemed to be compatible with the multi-bunch filling pattern of synchrotrons. We show that this problem can be overcome by virtue of magnetic bunch length compression in a ring section and that, after lasing, the beam returns to equilibrium conditions without beam quality disruption. As a consequence of bunch length compression, the peak current stimulates a high gain FEL emission, while the large energy spread makes the beam less sensitive to the FEL heating and to the microwave instability. The beam large energy spread is matched to the FEL energy bandwidth through a transverse gradient undulator. Feasibility of lasing at 25 nm is shown for the Elettra synchrotron light source (SLS) at 1 GeV. Viable scenarios for the upgrade of existing or planned SLSs to the new hybrid insertion devices-plus-FEL operational mode are discussed, while ensuring little impact on the standard beamlines functionality. S. Di Mitri and M. Cornacchia, NJP 17 (2015) 113006
	Slides TUB1CO02 [2.353 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB1CO02
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TUA2IO01	AWAKE - A Proton Driven Plasma Wakefield Acceleration Experiment at CERN	ion, plasma, proton, wakefield	266
	A. Caldwell MPI-P, München, Germany
	It is the aim of the AWAKE project at CERN to demonstrate the acceleration of electrons in the wake created by a proton beam passing through plasma. The proton beam will be modulated as a result of the transverse two-stream instability into a series ofμbunches that will then drive strong wakefields. The wakefields will then be used to accelerate electrons with GV/m strength fields. The AWAKE experiment is currently being commissioned and first data taking is expected this year. The status of the experimental program is described as well as first thoughts on future steps.
	Slides TUA2IO01 [24.428 MB]
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TUB2IO02	Advanced Concepts for Seeded FELs	ion, FEL, controls, laser	284
	E. Ferrari, E. Allaria Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The use of an external laser to seed an electron beam at the beginning of the Free Electron Laser process has been proposed as a way to improve temporal coherence of modern short wavelength FELs. More recent studies and experiments have shown that electron beam manipulation through interaction with a seed laser can be exploited for tailoring FEL properties to specific users requests. Recently, experiment for phase control, multi-color emission and coherent control have been reported.
	Slides TUB2IO02 [15.975 MB]
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TUB2CO04	Corrugated Structure Insertion to Extend SASE Bandwidth Up to 3% at the European XFEL	ion, radiation, undulator, FEL	293
	I. Zagorodnov, G. Feng, T. Limberg DESY, Hamburg, Germany
	The usage of x-ray free electron laser (XFEL) in femtosecond nanocrystallography involves sequential illumination of many small crystals of arbitrary orientation. Hence a wide radiation bandwidth could be useful in order to obtain and to index a larger number of Bragg peaks used for determination of crystal orientation. Considering the baseline configuration of the European XFEL in Hamburg, and based on beam dynamics simulations, we demonstrate here that usage of corrugated structures allows for a considerable increase in radiation bandwidth. It allows for data collection with a 3% bandwidth, a few micrjoule radiation pulse energy, a few fs pulse duration, and a photon energy 4.1 keV.
	Slides TUB2CO04 [5.848 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB2CO04
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TUPOA04	Study on THz Imaging by Using the Coherent Cherenkov Radiation	ion, radiation, experiment, detector	296
	M. Nishida, M. Brameld, M. Washio Waseda University, Tokyo, Japan R. Kuroda, Y. Taira AIST, Tsukuba, Ibaraki, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
	THz frequency is a special electromagnetic wave which is categorized between a radio wave and a light wave. It can pass through the various materials like a radio wave and can be transported with optical components like a light wave. Thus, it's suitable for imaging application of materials. At Waseda University, it's possible to generate a high-quality electron beam using Cs-Te photocathode RF-Gun and the electron beam is applied to several application researches. As an application of this electron beam, we generate a coherent Cherenkov radiation, and succeed in observing a high power THz light. The successful results of high power THz radiation encourage us to perform the THz imaging with transmission and reflection imaging using some materials, cross-section imaging using a simple material. On studying the THz imaging, it is necessary to clarify the spatial resolution. So, we tried to evaluate the spatial resolution in our device. Furthermore, our target is to get the three-dimensional THz images. We will introduce the CT technique in order to obtain the clear cross-section image. In this conference, we report the recent results of the THz imaging and future prospective.
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TUPOA05	Development of a Fiber Laser for Improving the Pulse Radiolysis System	ion, laser, radiation, gun	299
	Y. Saito, S.Y. Soeta, M. Washio Waseda University, Tokyo, Japan Y. Hosaka, K. Sakaue RISE, Tokyo, Japan
	When material is irradiated by the ionizing radiation, short-lived and highly reactive substance intermediate active species are made and then react with substances. The chemical reaction is determined by intermediate active species in early process. Proving the behavior of intermediate active species is important for understanding and controlling radiation chemical reaction. In Waseda university we been developing a Pulse Radiolysis System, a method to measure the behavior of intermediate species, for radiation chemical analysis with RF electron gun. Currently we are developing a Supercontinuum ray(SC ray)as a probe ray to improve Pulse Radiolysis System. We have introduced a SC ray using Yb fiver laser and PCF(Photonic Crystal Fiber). But this type of prove light isn't stable enough in the visible light region. Therefore we started to study Er fiber laser oscillator as new prove ray source. We have succeeded to oscillate a Er fs laser pulse, second harmonic generation and measurement of hydrated electron in ns time resolution. In this presentation we will report current research about generation of SC ray, Er fiber laser system and dose rate effect against the hydrated electron.
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TUPOA13	First Test Run for High Density Material Imaging Experiment Using Relativistic Electron Beam at the Argonne Wakefield Accelerator	ion, target, experiment, diagnostics	311
	Y.R. Wang AAI/ANL, Argonne, Illinois, USA S. Cao, X.K. Shen, Z.M. Zhang, Q.T. Zhao IMP/CAS, Lanzhou, People's Republic of China M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford, E.E. Wisniewski ANL, Argonne, Illinois, USA
	A test facility, AWA, has been commissioned and in operation since last year. It can provide beam of several bunches in a train of nano-seconds and 10s of nC with energy up to 70 MeV. In addition, the AWA can accommodate various beamlines for experiments. One of the proposed experiments is to use the AWA beam as a diagnostics for time resolved high density material, typically a target with high Z and time dependent, imaging experiments. When electron beam scatters after passing through the target, and the angular and energy distribution of beam will depend on the density and thickness of the target. A small aperture is used to collimate the scattered electron beam for off axis particles, and the target image will be detected by imaging plate. By measuring the scatted angle and energy at the imaging plate would yield information of the target. In this paper, we report on the AWA electron imaging (EI) system setup, which consist of a target, imaging optics and drift transport. The AWA EI beam line was installed on June, 2016 and the first test run was performed on August, 2016. This work will have implication on the high energy density physics and even future nuclear fusion studies.
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TUPOA19	50-MeV Run of the IOTA/FAST Electron Accelerator	ion, gun, emittance, cavity	326
	D.R. Edstrom, C.M. Baffes, C.I. Briegel, D.R. Broemmelsiek, K. Carlson, B.E. Chase, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, B.J. Fellenz, E.R. Harms, M.J. Kucera, J.R. Leibfritz, A.H. Lumpkin, D.J. Nicklaus, E. Prebys, P.S. Prieto, J. Reid, A.L. Romanov, J. Ruan, J.K. Santucci, T. Sen, V.D. Shiltsev, Y.-M. Shin, G. Stancari, J.C.T. Thangaraj, R.M. Thurman-Keup, A. Valishev, A. Warner, S.J. Wesseln Fermilab, Batavia, Illinois, USA A.T. Green Northern Illinois Univerity, DeKalb, Illinois, USA A. Halavanau, D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA J. Hyun Sokendai, Ibaraki, Japan P. Kobak BYU-I, Rexburg, USA W.D. Rush KU, Lawrence, Kansas, USA
	Funding: Supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. The low-energy section of the photoinjector-based electron linear accelerator at the Fermilab Accelerator Science & Technology (FAST) facility was recently commissioned to an energy of 50 MeV. This linear accelerator relies primarily upon pulsed SRF acceleration and an optional bunch compressor to produce a stable beam within a large operational regime in terms of bunch charge, total average charge, bunch length, and beam energy. Various instrumentation was used to characterize fundamental properties of the electron beam including the intensity, stability, emittance, and bunch length. While much of this instrumentation was commissioned in a 20 MeV running period prior, some (including a new Martin-Puplett interferometer) was in development or pending installation at that time. All instrumentation has since been recommissioned over the wide operational range of beam energies up to 50 MeV, intensities up to 4 nC/pulse, and bunch structures from ~1 ps to more than 50 ps in length.
	Poster TUPOA19 [4.636 MB]
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TUPOA25	Initial Demonstration of 9-MHz Framing Camera Rates on the FAST Drive Laser Pulse Trains*	ion, laser, optics, radiation	333
	A.H. Lumpkin, D.R. Edstrom, J. Ruan Fermilab, Batavia, Illinois, USA
	Funding: * Work at Fermilab supported by Fermi Research Alliance, LLC under Contract No. DE-AC02- 07CH11359 with the United States Department of Energy. Although beam centroid information at the MHz-micropulse-repetition rate has routinely been achieved at various facilities with rf BPMS, the challenge of recording beam size information at that rate is more daunting. The Integrable Optics Test Accelerator (IOTA) ring being planned at Fermilab has ~8 MHz revolution rates. To simulate the IOTA synchrotron radiation source temporal structure, we have used the UV component of the drive laser of the Fermilab Accelerator Science and Technology (FAST) Facility. This laser is normally set at 3 MHz, but has also been run at 9 MHz. We have configured our Hamamatsu C5680 streak camera in a framing camera mode using a slow vertical sweep plugin unit with the dual axis horizontal sweep unit. A two-dimensional array of images sampled at the MHz rate can then be displayed on the streak tube phosphor and recorded by the CCD readout camera at up to 10 Hz. As an example, by using the 10 microsecond vertical sweep with the 100 microsecond horizontal sweep ranges, 49 of the 300 micropulses at 3 MHz are displayed for a given trigger delay in each of six images. Example 2D image arrays with profiling examples will be presented. Hamamatsu C5680 product web page.
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TUPOA26	Initial Observations of Micropulse Elongation of Electron Beams in a SCRF Accelerator*	ion, laser, gun, MMI	337
	A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA
	Funding: * Work at Fermilab supported by Fermi Research Alliance, LLC under Contract No. DE-AC02- 07CH11359 with the United States Department of Energy Commissioning at the SCRF accelerator at the Fermilab Accelerator Science and Technology (FAST) Facility has included the implementation of a versatile bunch-length monitor located after the 4-dipole chicane bunch compressor for electron beam energies of 20-50 MeV and integrated charges in excess of 10 nC. The team has initially used a Hamamatsu C5680 synchroscan streak camera. An Al-coated Si screen was used to generate optical transition radiation (OTR) resulting from the beam's interaction with the screen. The chicane bypass beamline allowed the measurements of the bunch length without the compression stage at the downstream beamline location using OTR and the streak camera. The UV component of the drive laser had previously been characterized with a Gaussian fit σ of 3.5-3.7 ps. However, the uncompressed electron beam is expected to elongate due to space charge forces in an initial 1.5-m drift from the gun to the first SCRF accelerator cavity. We have observed electron beam bunch lengths from 5 to 14 ps (σ) for micropulse charges of 60 pC to 800 pC, respectively. Commissioning of the system and initial results with uncompressed and compressed beam will be presented. A.H. Lumpkin et al., Proceedings of FEL14, MOP021, Basel, Switzerland, www. JACoW.org
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TUPOA27	From Relativistic Electrons to X-ray Phase Contrast Imaging	ion, linac, GUI, software	341
	A.H. Lumpkin Fermilab, Batavia, Illinois, USA M.A. Anastasio, A.B. Garson Washington University in St. Louis, St. Louis, Missouri, USA
	Funding: Work at Fermilab partly supported by Fermi Research Alliance, LLC under Contract No.DE-AC02-07CH11359 with the U.S.DoE. Work at Washington Univ. in St. Louis was supported in part by NSF CBET1263988. X-ray phase contrast (XPC) imaging is an emerging technology that holds great promise for biomedical applications due to its ability to provide information about soft tissue structure . The need for high spatial resolution at the boundaries of the tissues is noted for this process. Based on results from imaging of relativistic electron beams with single crystals , we proposed transferring single-crystal imaging technology to this bio-imaging issue. Using a microfocus x-ray tube (17 kVp) and the exchangeable phosphor feature of the camera system, we compared the point spread function (PSF) of the system with the reference P43 phosphor to that with several rare earth garnet single crystals of varying thickness. Based on single Gaussian peak fits to the collimated x-ray images, we observed a four times smaller system PSF (21 microns (FWHM)) with the 25-mm diameter single crystals than with the reference polycrystalline phosphor's 80-micron value. Initial images of 33-micron diameter carbon fibers have also been obtained with small crystals installed. Tests with a full-scale 88-mm diameter single crystal (patent-pending configuration) are being planned. A. Appel, M.A. Anastasio, and E.M. Brey, Tissue Eng. Part B Rev 17 (5), 321 (2011). **A.H. Lumpkin, et al., Phys. Rev. ST-AB 14 (6), 060704 (2011).
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TUPOA28	Feasibility of OTR Imaging for Laser-Driven Plasma Accelerator Electron-Beam Diagnostics	ion, polarization, laser, plasma	345
	A.H. Lumpkin Fermilab, Batavia, Illinois, USA M. Downer The University of Texas at Austin, Austin, Texas, USA D.W. Rule Private Address, Silver Spring, USA
	Funding: * Work at Fermilab partly supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. DoE. ** Work at the Univ. of Texas supported by DoE grant DE-SC0011617. Recent measurements of betatron x-ray emission from quasi-monoenergetic electrons accelerating to 500 MeV within a laser plasma accelerator (LPA) enabled estimates of normalized transverse emittance well below 1 mm-mrad and divergences of order 1/gamma [1]. Such unprecedented LPA beam parameters can, in principle, be addressed by utilizing the properties of linearly polarized optical transition radiation (OTR) that provide additional beam parameter sensitivity. We propose a set of complementary measurements of beam size and divergence with near-field and far-field OTR imaging, respectively, on LPA electron beams ranging in energy from 100 MeV [2] to 2 GeV [3]. The feasibility is supported by analytical modeling for beam size sensitivity and divergence sensitivity. In the latter case, the calculations indicate that the parallel polarization component of the far-field OTR pattern is sensitive to divergences from 0.1 to 0.4 mrad (σ) at 2 GeV, and it is similarly sensitive to divergences from 1 to 5 mrad (σ) at 100 MeV. We anticipate the signal levels from charges of 100 pC will require a 16-bit cooled CCD camera. Other practical challenges in the LPA will also be discussed. 1.G. R. Plateau et al., Phys. Rev. Lett. 109, 064802 (2012). 2.Hai-EnTsai, Chih-Hao Pai, and M.C. Downer, AIP Proc. 1507, 330 (2012) 3.Xiaoming Wang et al., Nature Communications 4,1988(2013).
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TUPOA29	Beam Position Monitoring System for the PIP-II Injector Test Accelerator	ion, pick-up, electronics, linac	349
	N. Patel, C.I. Briegel, J.S. Diamond, N. Eddy, B.J. Fellenz, J. Fitzgerald, V.E. Scarpine Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359. The Proton Improvement Plan II (PIP-II) injector test accelerator is an integrated systems test for the front-end of a proposed continuous-wave (CW) compatible, pulsed H⁻ superconducting RF linac. This linac is part of Fermilab's PIP-II upgrade. This injector test accelerator will help minimize the technical risk elements for PIP-II and validate the concept of the front-end. Major goals of the injector accelerator are to test a CW RFQ and H⁻ source, a bunch-by-bunch Medium-Energy Beam Transport (MEBT) beam chopper and stable beam acceleration through low-energy superconducting cavities. Operation and characterization of this injector places stringent demands on the types and performance of the accelerator beam diagnostics. A beam position monitor (BPM) system has been developed for this application and early commissioning measurements have been taken of beam transport through the beamline.
	Poster TUPOA29 [0.469 MB]
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TUPOA30	Fermilab Switchyard Resonant Beam Position Monitor Electronics Upgrade Results	ion, electronics, controls, power-supply	352
	T.B. Petersen, J.S. Diamond, N. Liu, P.S. Prieto, D. Slimmer, A.C. Watts Fermilab, Batavia, Illinois, USA
	The readout electronics for the resonant beam position monitors (BPMs) in the Fermilab Switchyard (SY) have been upgraded, utilizing a low noise amplifier transition board and Fermilab designed digitizer boards. The stripline BPMs are estimated to have an average signal output of between -110 dBm and -80 dBm, with an esti-mated peak output of -70 dBm. The external resonant circuit is tuned to the SY machine frequency of 53.10348 MHz. Both the digitizer and transition boards have vari-able gain in order to accommodate the large dynamic range and irregularity of the resonant extraction spill. These BPMs will aid in auto-tuning of the SY beamline as well as enabling operators to monitor beam position through the spill.
	Poster TUPOA30 [0.833 MB]
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TUPOA38	Real-Time Magnetic Electron Energy Spectrometer for Use With Medical Linear Acceletors	ion, linac, detector, real-time	361
	P.E. Maggi, H.R. Hogstrom, K.L. Matthews II LSU, Baton Rouge, USA R.L. Carver Mary Bird Perkins Cancer Center, Our Lady of the Lake, Baton Rouge, USA
	Accelerator characterization and quality assurance is an integral part of electron linear accelerator (linac) use in a medical setting. The current clinical method for radia-tion metrology of electron beams (dose on central axis versus depth in water) only provides a surrogate for the underlying performance of the accelerator and does not provide direct information about the electron energy spectrum. We have developed an easy to use real-time magnetic electron energy spectrometer for characterizing the electron beams of medical linacs. Our spectrometer uses a 0.57 T permanent magnet block as the dispersive element and scintillating fibers coupled to a CCD camera as the position sensitive detector. The goal is to have a device capable of 0.12 MeV energy resolution (which corresponds to a range shift of 0.5 mm) with a minimum readout rate of 1 Hz, over an energy range of 5 to 25 MeV. This work describes the real-time spectrometer system, the detector response model, and the spectrum unfolding method. Measured energy spectra from multi-ple electron beams from an Elekta Infinity Linac are presented.
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TUPOA47	Development of Short Undulators for Electron-Beam-Radiation Interaction Studies	ion, undulator, radiation, laser	380
	P. Piot Fermilab, Batavia, Illinois, USA M.B. Andorf, G. Fagerberg, M. Figora Northern Illinois University, DeKalb, Illinois, USA
	Funding: Work supported by the US DOE contract DE-SC0013761 with Northern Illinois University Interaction of an electron beam with external field or its own radiation has widespread applications ranging from coherent radiation generation, phase space cooling or formation of time-structured beam. An efficient coupling mechanism between an electron beam and radiation field relies on the use of a magnetic undulator. In this contribution we detail the construction and magnetic measurements of short (11 period) undulators with 7-cm period built using parts of the ALADDIN U3 undulator. Possible use of these undulators at two accelerator test facilities to support experiment relevant to cooling techniques and radiation souces are discussed. F. C. Younger, W. Jorge Pearce, B. Ng, Nucl. Instrum. Meth Phys. Res. A 347, pp. 96-101 (1994).
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TUPOA57	Using High Precision Beam Position Monitors at the Cornell Electron Storage Ring (CESR) to Measure the One Way Speed of Light Anisotropy	ion, positron, dipole, simulation	399
	W.F. Bergan, M.J. Forster, N.T. Rider, D. L. Rubin, D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA B.A. Schmookler MIT, Cambridge, Massachusetts, USA B. Wojtsekhowski CMU, Pittsburgh, Pennsylvania, USA
	Funding: NSF PHY-1416318 NSF DGE-1144153 The Cornell Electron Storage Ring (CESR) has been equipped with a number of high-precision beam position monitors which are capable of measuring the orbit of a circulating beam with a precision of a few microns. This technology will enable a precision measurement of deviations in the one-way speed of light. An anisotropic speed of light will alter the beam momentum as it travels around the ring, resulting in a change of orbit over the course of a sidereal day. Using counter-circulating electron and positron beams, we will be able to suppress many of the systematics such as those relating to variations in RF voltage or magnet strength. We show here initial feasibility studies to measure the stability of our beam position monitors and the various systematic effects which may hide our signal and discuss ways in which we can minimize their impact.
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TUPOA59	Successful Laboratory-Industrial Partnerships: the Cornell-Friatec Segmented Insulator for High Voltage DC Photocathode Guns	ion, gun, vacuum, high-voltage	405
	K.W. Smolenski, B.M. Dunham Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D.L. Barth, M. Muehlbauer, S. Wacker FRIATEC AG, Mannheim, Germany J.M. Maxson UCLA, Los Angeles, California, USA
	High voltage DC photocathode guns currently offer the most reliable path to electron beams with high current and brightness. The performance of a gun is directly dependent on its vacuum and high voltage capabilities, determined in large part by the ceramic insulators. The insulator must meet XHV standards, bear the load of pressurized SF6 on its exterior, support the massive electrode structures as well as holding off DC voltages up to 750kV. Construction of UHV and high voltage capable insulators require high purity ceramics and metal components proven to minimize thermal stress between the brazed ceramic rings and metal guard rings. The use of replaceable guard rings is a critical way of controlling manufacturing costs while extending the life cycle of the insulator. Successful fabrication requires proven manufacturing methods in flatness, parallelism, and maintaining alignment of many parts during the brazing process. Taking a scalable, modular approach, the insulator design can be applied to a variety of gun voltages and can be used by other projects. The Cornell-Friatec insulator was designed collaboratively and has now been produced in quantity for Cornell and elsewhere.
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TUPOA68	Design, Simulations and Experimental Demonstration of an Intra-Pulse Ramped-Energy Travelling Wave Linac for Cargo Inspection	ion, linac, simulation, beam-loading	421
	S.V. Kutsaev, R.B. Agustsson, A. Arodzero, R.D.B. Berry, S. Boucher, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A. Laurich, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A. Verma RadiaBeam, Santa Monica, California, USA
	Funding: This work has been supported by the US Department of Homeland Security, Domestic Nuclear Detection Office, under competitively awarded contract HSHQDC-13-C-B0019. Novel radiographic imaging techniques [1] based on adaptive, intra-pulse ramped-energy short X-ray packets of pulses, a new type of fast X-ray detectors, and advanced image processing are currently some of the most promising methods for real-time cargo inspection systems. RadiaBeam Technologies is currently building the high-speed Adaptive Railroad Cargo Inspection System (ARCIS), which will enable better than 5 mm line pair resolution, penetration greater than 450 mm of steel equivalent, material discrimination over the range of 6 mm to 250 mm, 100% image sampling rate at speed 45 km/h, and minimal average dose. One of the core elements of ARCIS is a new S-band travelling wave linac with a wide range of energy control that allows energy ramping from 2 to 9 MeV within a single 16 μs RF pulse using the beam loading effect. In this paper, we will discuss the linac design approach and its principal components, as well as engineering and manufacturing aspects. The results of the experimental demonstration of intra-pulse energy ramping will be presented. [1] A. Arodzero, S. Boucher, A. Murokh, S. Vinogradov, S.V. Kutsaev. System and Method for Adaptive X-ray Cargo Inspection. US Patent Application 2015/1472051.
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TUPOA73	Commissioning and First Results From a Channeling-Radiation Experiment at FAST	ion, detector, gun, radiation	428
	J. Hyun Sokendai, Ibaraki, Japan D.R. Broemmelsiek, D.R. Edstrom, A.L. Romanov, J. Ruan, T. Sen, V.D. Shiltsev Fermilab, Batavia, Illinois, USA A. Halavanau, D. Mihalcea Northern Illinois University, DeKalb, Illinois, USA P. Kobak BYU-I, Rexburg, USA W.D. Rush KU, Lawrence, Kansas, USA
	X-rays have widespread applications in science. Developing compact and high-quality X-ray sources, easy to disseminate, has been an on going challenge. Our group has explored the possible use of channeling radiation driven by a 50 MeV low-emittance electron beam to produce narrowband hard X-rays (photon energy from 40 keV to 140 keV). In this contribution we present the simulated X-ray spectrum including the background bremsstrahlung contribution, and optimization of the relevant electron-beam parameters required to maximize the X-ray brilliance. The results of experiments carried out at Fermilab's FAST facility – which include a 50 MeV superconducting linac and a high-brightness photoinjector – are also discussed. The average brilliance in our experiment is expected to be about one order of magnitude higher than that in previous experiments.
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TUA3CO03	Compact Ring-Based X-Ray Source With on-Orbit and on-Energy Laser-Plasma Injection	ion, laser, plasma, radiation	435
	M. Turner CERN, Geneva, Switzerland J.R. Cheatam, A.L. Edelen CSU, Fort Collins, Colorado, USA J. Gerity Texas A&M University, College Station, USA A. Lajoie, C.Y. Wong NSCL, East Lansing, Michigan, USA G. Lawler UCLA, Los Angeles, California, USA O. Lishilin DESY Zeuthen, Zeuthen, Germany K. Moon UNIST, Ulsan, Republic of Korea A. A. Sahai, A. Seryi JAI, London, United Kingdom K. Shih SBU, Stony Brook, New York, USA B. Zerbe MSU, East Lansing, Michigan, USA
	Funding: We acknowledge the stimulating atmosphere and support of US Particle Accelerator School, class of June 2016, where this design study was performed. We report here the results of a one week long investigation into the conceptual design of an X-ray source based on a compact ring with on-orbit and on-energy laser-plasma accelerator (mini-project 10.4 from [1]). We performed these studies during the June 2016 USPAS class "Physics of Accelerators, Lasers, and Plasma…" applying the art of inventiveness TRIZ. We describe three versions of the light source with the constraints of the electron beam with energy 1 GeV or 3 GeV and a magnetic lattice design being normal conducting (only for the 1 GeV beam) or superconducting (for either beam). The electron beam recirculates in the ring, to increase the effective photon flux. We describe the design choices, present relevant parameters, and describe insights into such machines. [1] Unifying physics of accelerators, lasers and plasma, A. Seryi, CRC Press, 2015.
	Slides TUA3CO03 [8.411 MB]
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TUB3IO02	Overview of Electron Source Development for High Repetition Rate FEL Facilities	ion, gun, cathode, emittance	445
	F. Sannibale LBNL, Berkeley, California, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 'fsannibale@lbl.gov An increasing science demand for high-repetition rate (MHz-class) FEL facilities, from IR to X-rays, has been pushing institutions and groups around the world to develop proposals addressing such a need, and some of them have been already funded and are under construction. Such facilities require the development of high-brightness high-repetition rate electron guns, and a number of groups worldwide started to develop R&D programs to develop electron guns capable of operating at this challenging regime. Here we describe the approaches and technologies used by the different programs and discuss advantages and challenges for each of them. A review of the present achievements is included, as well as a brief analysis to understand if the present technology performance is sufficient to operate present and future high repetition rate FEL facilities.
	Slides TUB3IO02 [7.951 MB]
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TUB3CO03	Demonstration of fresh slice self seeding in a hard X-ray free electron laser	ion, experiment, simulation, FEL	450
	C. Emma, C. Pellegrini UCLA, Los Angeles, USA M.W. Guetg, A.A. Lutman, A. Marinelli, J. Wu SLAC, Menlo Park, California, USA
	We discuss the first demonstration of fresh slice self seeding (FSSS) in a hard X-ray Free Electron Laser (XFEL). The FSSS method utilizes a single electron beam to generate a strong seed pulse and amplify it with a small energy spread electron slice. This extends the capability of self seeded XFELs by producing short pulses, not limited by the duration set by the self-seeding monochromator system, with high peak intensity. The scheme relies on using a parallel plate dechirper to impart a spatial chirp on the beam, and appropriate orbit control to lase with different electron beam slices before and after the self-seeding monochromator. The performance of the FSSS method is analyzed with start-to-end simulations for the Linac Coherent Light Source (LCLS). The simulations include the effect of the parallel plate dechirper and propagation of the radiation field through the monochromator. We also present results of the first successful demonstration of FSSS at LCLS. The radiation properties of FSSS X-ray pulses are compared with the Self-Amplified Spontaneous Emission (SASE) mode of FEL operation for the same electron beam parameters.
	Slides TUB3CO03 [10.423 MB]
	Poster TUB3CO03 [3.275 MB]
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TUB3CO04	A New Thermionic RF Electron Gun for Synchrotron Light Sources	ion, gun, cathode, coupling	453
	S.V. Kutsaev, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A.V. Smirnov RadiaBeam Systems, Santa Monica, California, USA R.B. Agustsson, J.J. Hartzell, A. Verma RadiaBeam, Santa Monica, California, USA A. Nassiri, Y. Sun, G.J. Waldschmidt, A. Zholents ANL, Argonne, Illinois, USA E.A. Savin MEPhI, Moscow, Russia
	Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Science, under contract DE-SC0015191 and contract No. DE-AC02-06CH11357. A thermionic RF gun is a compact and efficient source of electrons used in many practical applications. RadiaBeam Systems and the Advanced Photon Source of Argonne National Laboratory collaborate in developing of a reliable and robust thermionic RF gun for synchrotron light sources which would offer substantial improvements over existing thermionic RF guns and allow stable operation with up to 1A of beam peak current at a 100 Hz pulse repetition rate and a 1.5 μs RF pulse length. In this paper, we discuss the electromagnetic and engineering design of the cavity, and report the progress towards high power tests of the cathode assembly of the new gun.
	Slides TUB3CO04 [2.661 MB]
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TUB4IO01	Status of the Los Alamos Multi-Probe Facility for Matter-Radiation Interactions in Extremes	ion, FEL, experiment, linac	464
	J.L. Erickson, R.W. Garnett LANL, Los Alamos, New Mexico, USA
	The Matter-Radiation Interactions in Extremes (MaRIE) project will provide capability that will address the control of performance and production of materials at the mesoscale. MaRIE will characterize the behavior of interfaces, defects, and microstructure between the spatial scales of atomic structures and those of the engineering continuum where there is a current capability gap. The mission need is well-met with an x-ray source, coherent to optimize disordered imaging capability, brilliant and high-rep-rate to provide time-dependent information, and high enough energy to see into and through the mesoscale of materials of interest. It will be designed for time-dependence from electronic motion (picosecond) through sound waves (nanosecond) through thermal diffusion (millisecond) to manufacturing (seconds and above). The mission need, the requirements, a plausible alternative reference design of a 12-GeV linac-based 42-keV x-ray free-electron laser, and the status of the project will be described.
	Slides TUB4IO01 [16.013 MB]
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TUB4IO02	Accelerator Technical Progress and First Commissioning Results from the European XFEL	ion, linac, FEL, MMI	469
	R. Wichmann DESY, Hamburg, Germany
	The construction of the European XFEL is coming to an end. The linac tunnel will be closed and commissioning of the main linac will start. The status of the construction project is reviewed. Commissioning of the injector of the European XFEL was already performed in 2016 while construction of the main linac was continuing. The commissioning goals and achievements for the XFEL injector will be reviewed. Proposed Speaker: W. Decking, DESY
	Slides TUB4IO02 [13.428 MB]
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TUB4CO03	Optimization of Compton Source Performance Through Electron Beam Shaping	ion, radiation, brightness, photon	474
	A. Malyzhenkov, N.A. Yampolsky LANL, Los Alamos, New Mexico, USA
	We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of these sources is limited by the electron beam quality since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6d electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized then if the electron phase space is transformed in a way so that all electrons scatter off the x-ray photons of same frequency in the same direction. We describe the x-ray photon beam quality through the Wigner function (6d photon phase space distribution) and derive it for the ICS source when the electron and laser rms matrices are arbitrary. We find the optimal uncorrelated electron beam phase space distribution resulting in the highest brightness of the ICS source for the simple on axis case as an example.
	Slides TUB4CO03 [1.673 MB]
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TUPOB13	Simulations of Space Charge Neutralization in a Magnetized Electron Cooler	ion, simulation, collider, experiment	511
	J. Gerity, P.M. McIntyre Texas A&M University, College Station, USA D.L. Bruhwiler, C.C. Hall RadiaSoft LLC, Boulder, Colorado, USA V. Moens EPFL, Lausanne, Switzerland C.S. Park, G. Stancari Fermilab, Batavia, Illinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Award Number DE-SC0015212. Magnetized electron cooling at relativistic energies and Ampere scale current is essential to achieve the proposed ion luminosities in a future electron-ion collider (EIC). Neutralization of the space charge in such a cooler can significantly increase the magnetized dynamic friction and, hence, the cooling rate. The Warp framework is being used to simulate magnetized electron beam dynamics during and after the build up of neutralizing ions, via ionization of residual gas in the cooler. The design follows previous experiments at Fermilab as a verification case. We also discuss the relevance to EIC designs.
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TUPOB16	A Simple Method for Measuring the Electron-Beam Magnetization	ion, solenoid, cathode, emittance	521
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA G. Ha POSTECH, Pohang, Kyungbuk, Republic of Korea P. Piot Fermilab, Batavia, Illinois, USA J.G. Power, E.E. Wisniewski ANL, Argonne, Illinois, USA G. Qiang TUB, Beijing, People's Republic of China
	There are a number of projects that require magnetized beams, such as electron cooling or aiding in flat beam transforms. Here we explore a simple technique to characterize the magnetization, observed through the angular momentum of magnetized beams. These beams are produced through photoemission. The generating drive laser first passes through microlens arrays (fly-eye light condensers) to form a transversely modulated pulse incident on the photocathode surface. The resulting charge distribution is then accelerated from the photocathode. We explore the evolution of the pattern via the relative shearing of the beamlets, providing information about the angular momentum. This method is illustrated through numerical simulations and preliminary measurements carried out at the Argonne Wakefield Accelerator (AWA) facility are presented.
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TUPOB18	Beam Test of Masked-Chicane Micro-Buncher	ion, simulation, bunching, controls	528
	Y.-M. Shin Northern Illinois University, DeKalb, Illinois, USA D.R. Broemmelsiek, D.J. Crawford, D.R. Edstrom, A.H. Lumpkin, J. Ruan, J.K. Santucci, J.C.T. Thangaraj, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA A.T. Green Northern Illinois Univerity, DeKalb, Illinois, USA
	Funding: This work was supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. We also thank the FAST Department team for the helpful discussion and technical supports. Masking a dispersive beamline such as a dogleg or a chicane [1, 2] is a simple way to shape a beam in the longitudinal and transverse space. This technique is often employed to generate arbitrary bunch profiles for beam/laser-driven accelerators and FEL undulators or even to reduce a background noise from dark currents in electron linacs. We have been investigating a beam-modulation of a slit-masked chicane, which was deployed for crystal-channeling experiments at the injector beamline of the Fermilab Accelerator Science and Technology (FAST) facility. With a nominal beam of 3 ps bunch length, Elegant simulations showed that a slit-mask with slit period 900 um and aperture width 300 um induces a modulation with bunch-to-bunch space of about 187 um (0.25 nC), 270 um (1 nC) and 325 um (3.2 nC) with 3 ~ 6% correlated energy spread: An initial energy modulation pattern has been observed in the electron spectrometer downstream of the masked chicane using a micropulse charge of 260 pC and 40 micropulses. Investigations of the beam longitudinal modulation are planned with a Martin-Puplett interferometer and a synchro-scan streak camera at a station between the chicane and spectrometer. [1] D.C.Nguyen, B.E.Carlsten, NIMA 375, 597 (1996) [2] P.Muggli, V.Yakimeno, M.Babzien, et al., PRL 101, 054801 (2008)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB18
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TUPOB19	FEL Wiggler Bussbar Field Compensation	ion, wiggler, storage-ring, FEL	532
	B. Li, H. Hao, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA J.Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China
	Abstract The Duke storage ring is a dedicated driver for the storage ring based free-electron laser (FEL) and the High Intensity Gamma-ray Source (HIGS). The high intensity gamma-ray beam is produced using Compton scattering between the electron and FEL photon beams. The beam displacement and angle at the collision point need to be maintained constant during the gamma-ray beam production. The magnetic field of the copper bussbars carrying the current to the FEL wigglers can impact the beam orbit. The compensation scheme in-general is complicated. In this work, we report preliminary results of a bussbar compensation scheme for one of the wiggler and power supply configurations. Significant reductions of the orbit distortions have been realized using this compensation.
	Poster TUPOB19 [3.693 MB]
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TUPOB22	Dependence of the Coupling of Dipole Motion From Bunch to Bunch Caused by Electron Clouds at CesrTA Due to Variations in Bunch Length and Chromaticity	ion, damping, positron, dipole	538
	M.G. Billing, L.Y. Bartnik, M.J. Forster, N.T. Rider, J.P. Shanks, M.B. Spiegel, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA R. Holtzapple CalPoly, San Luis Obispo, California, USA E.C. Runburg University of Notre Dame, Indiana, USA
	The Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) has been utilized to probe the interaction of the electron cloud with a 2.1 GeV stored positron beam. Recent experiments have characterized any dependence of beam'electron cloud (EC) interactions on the bunch length (or synchrotron tune) and the vertical chromaticity. The measurements were performed on a 30-bunch positron train with 14 nsec spacing between bunches, at a fixed current of 0.75 mA/bunch. The dynamics of the stored beam, in the presence of the EC, was quantified using 20 turn-by-turn beam position monitors in CESR to measure the correlated bunch-by-bunch dipole motion. In this paper we report on the observations from these experiments and analyze the coupling of di-pole motion from bunches within the train to subsequent bunches, caused by the EC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB22
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TUPOB23	Electron Cloud Simulations for the Low-Emittance Upgrade at the Cornell Electron Storage Ring	ion, operation, positron, synchrotron	542
	J.A. Crittenden, Y. Li, S. Poprocki, J.E. San Soucie Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the National Science Foundation DMR 13-32208 The Cornell Electron Storage Ring operations group is planning a major upgrade of the storage ring performance as an X-ray user facility. The principal modification foresees replacing the former e⁻e⁺ interaction region with six double-bend achromats, reducing the emittance by a factor of four. The beam energy will increase from 5.3 to 6.0 GeV and single-beam operation will replace the present two-beam e⁻e⁺ operation. The initial phase of the project will operate a single positron beam, so electron cloud buildup may contribute to performance limitations. This work describes a synchrotron radiation analysis of the new ring, and employs its results to provide ring-wide estimates of cloud buildup and consequences for the lattice optics.
	Poster TUPOB23 [4.832 MB]
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TUPOB24	Optimization of Linear Induction Radiography Accelerator with Electron Beam with Energy Variation	ion, target, solenoid, induction	546
	Y.H. Wu, Y.J. Chen LLNL, Livermore, California, USA
	Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The current interest for the next generation linear induction radiography accelerator (LIA) is to generate multiple electron beam pulses with high peak currents. The beam energy and current may vary from pulse to pulse. Conse-quently, the transport and control of multi-pulsing intense electron beams through a focus-ing lattice over a long distance on such machine becomes challenging. Simulation studies of multi-pulse LIAs using AMBER [1] and BREAKUP Code [2] are described. These include optimized focusing magnetic tune for beams with energy and current variations, and steering correction for corkscrew motion. The impact of energy variation and accelerating voltage error on radiograph performance are discussed.
	Poster TUPOB24 [1.419 MB]
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TUPOB25	Unfolding Electron Beam Parameters Using Spot Size Measurement From Magnet Scan	ion, target, emittance, beam-transport	549
	Y.H. Wu, Y.J. Chen, J. Ellsworth LLNL, Livermore, California, USA
	Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The Flash X-ray Radiography (FXR) [1] line-ar induction accelerator at Lawrence Livermore National Laboratory produces x-ray bursts for radiographs. The machine is able to produce x-ray spot sizes less than 2mm. Using the spot sizes measured from the magnet scanning, the beam parameters are unfolded by modelling the FXR LINAC with the simulation code AMBER [2] and the envelope code XENV [3]. In this study, the most recent spot size measurement results and techniques used to extract the beam parameters are described. Using the unfolded beam parameters as the initial condition, the backstreaming ions' neutralization factor f = 0.3 is found by comparing the calculated spot sizes with measured spot sizes at the target.
	Poster TUPOB25 [0.576 MB]
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TUPOB29	Simulations of Nonlinear Beam Dynamics in the JLEIC Electron Collider Ring	ion, sextupole, emittance, dynamic-aperture	555
	F. Lin, Y.S. Derbenev, V.S. Morozov, F.C. Pilat, G.H. Wei, Y. Zhang JLab, Newport News, Virginia, USA Y. Cai, Y.M. Nosochkov, M.K. Sullivan SLAC, Menlo Park, California, USA M.-H. Wang Self Employment, Private address, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515. The short lengths of colliding bunches in the proposed Jefferson Lab Electron-Ion Collider (JLEIC) allow for small beta-star values at the interaction point (IP) yielding a high luminosity. The strong focusing associated with the small beta-stars results in high natural chromaticities and potentially a beam smear at the IP. Rapid growth of the electron equilibrium emittances and momentum spread with energy further complicates the situation. We investigated nonlinear dynamics correction schemes that overcome these problems and allow for stable beam dynamics and sufficient beam lifetime at the highest electron energy. In this paper, we present and compare tracking simulation results for various schemes considering their emittance contributions.
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TUPOB31	Compensation of Chromaticity in the JLEIC Electron Collider Ring	ion, sextupole, emittance, dipole	561
	Y.M. Nosochkov, Y. Cai, M.K. Sullivan SLAC, Menlo Park, California, USA Y.S. Derbenev, F. Lin, V.S. Morozov, F.C. Pilat, G.H. Wei, Y. Zhang JLab, Newport News, Virginia, USA M.-H. Wang Self Employment, Private address, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515. The Jefferson Lab Electron-Ion Collider (JLEIC) is being designed to achieve a high luminosity of up to 10³⁴ 1/(cm²*sec). The latter requires a small beam size at the interaction point demanding a strong final focus (FF) quadrupole system. The strong beam focusing in the FF unavoidably creates a large chromaticity which has to be compensated in order to avoid a severe degradation of momentum acceptance. This has to be done while preserving sufficient dynamic aperture. An additional design requirement for the chromaticity compensation optics in the electron ring is preservation of the low beam emittance. This paper reviews the development and selection of a chromaticity correction scheme for the electron collider ring.
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TUPOB36	Simulation Study on JLEIC High Energy Bunched Electron Cooling	ion, emittance, simulation, collider	568
	H. Zhang, S.V. Benson, J. Chen, Y.S. Derbenev, R. Li, Y. Roblin, Y. Zhang JLab, Newport News, Virginia, USA H. Huang, L. Luo ODU, Norfolk, Virginia, USA
	Funding: * Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during the collision at the collider ring. Different with other electron coolers using DC electron beam, the proposed electron cooler at the JLEIC ion collider ring uses high energy bunched electron beam, provided by an ERL. In this paper, we report some recent simulation study on how the electron cooling rate will be affected by the bunched electron beam properties, such as the correlation between the longitudinal position and momentum, the bunch size, and the Larmor emittance.
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TUPOB43	Magnetic Cloaking of Charged Particle Beams	ion, detector, superconducting-magnet, dipole	588
	K.G. Capobianco-Hogan, A.A. Adhyatman, G. Arrowsmith-Kron, G. Bello Portmann, D.B. Bhatti, R. Cervantes, B.D. Coe, A. Deshpande, N. Feege, S.P. Jeffas, T.C. Krahulik, J.J. LaBounty, T.M. LaByer, A. Oliveira, H.A. Powers, R.S. Sekelsky, V.D. Shethna, N. Ward, H.J. van Nieuwenhuizen Stony Brook University, Stony Brook, USA R. Cervantes University of Washington, CENPA, Seattle, USA B.D. Coe BNL, Upton, Long Island, New York, USA
	In order to measure the momentum of particles produced by asymmetric collisions in the proposed Electron Ion Collider, a magnetic field should be introduced perpendicular to the path of the beam to increase momentum resolution without bending or depolarizing it. A magnetic cloak consisting of a superconducting magnetic shield surrounded by a ferromagnetic layer is capable of shielding the interior from a magnetic field – thereby protecting the beam – without distorting the field outside of the cloak – permitting detector coverage at high pseudorapidity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB43
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TUPOB56	The eRHIC Ring-Ring Design	ion, proton, luminosity, dipole	616
	C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A.V. Fedotov, W. Fischer, Y. Hao, A. Hershcovitch, Y. Luo, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, S. Seletskiy, T.V. Shaftan, V.V. Smaluk, S. Tepikian, F.J. Willeke, H. Witte, Q. Wu BNL, Upton, Long Island, New York, USA
	The ring-ring version of the eRHIC electron-ion collider design aims at providing electron-proton collisions with a center-of-mass energy ranging from 32 to 141 GeV at a luminosity reaching 10³³ cm^-2 sec^-1. This design of the double-ring collider also supports electron-ion collisions with similar electron-nucleon luminosities, and is upgradeable to 10³⁴ cm^-2 sec^-1 using bunched beam electron cooling of the hadron beam. The baseline luminosities are achievable using existing technologies and beam parameters that have been routinely achieved at RHIC in hadron-hadron collisions or elsewhere in e⁺e⁻ collisions. This minimizes the risk associated with the challenging luminosity goal and is keeping the technical risk of the e-RHIC electron-ion collider low. The latest design status will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB56
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TUPOB60	Permanent Magnets for High Energy Nuclear Physics Accelerators	ion, quadrupole, permanent-magnet, dipole	622
	N. Tsoupas, S.J. Brooks, A.K. Jain, F. Méot, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the US Department of Energy The proposed eRHIC accelerator1 will collide 20 GeV polarized electrons with 250 GeV polarized protons or 100 GeV/n polarized 3He ions or other unpolarized heavy ions. The electron accelerator of the eRHIC will be based on a 1.665 GeV Energy Recovery Linac (ERL) placed in the RHIC tunnel and two Fixed Field Alternating Gradient (FFAG) recirculating rings placed alongside the RHIC accelerator. The electron bunches reach the 20 GeV energy after passing 12 times through the ERL by recirculation in the FFAG rings. The FFAG rings consist of FODO cells comprised of one focusing and one defocusing quadrupoles made of permanent magnet material. Similarly other sections of the electron accelerator will utilize permanent magnets. In this presentation we will discuss details on the design of these magnets and their advantages over the current-excited magnets. 1. <http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf>
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TUPOB62	Benchmark of Strong-Strong Beam-Beam Simulation of the Kink Instability in an Electron Ion Collider Design	ion, proton, simulation, emittance	628
	J. Qiang, R.D. Ryne LBNL, Berkeley, California, USA Y. Hao BNL, Upton, Long Island, New York, USA
	The kink instability limits the performance of a potential linac-ring based electron-ion collider design. In this paper, we report on the simulation study of the kink instability using a self-consistent strong-strong beam-beam model.
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TUPOB63	POSINST Simulation on Fermilab Main Injector and Recycler Ring	ion, dipole, simulation, proton	632
	Y. Ji IIT, Chicago, Illinois, USA L.K. Spentzouris Illinois Institute of Technology, Chicago, Illinois, USA R.M. Zwaska Fermilab, Batavia, Illinois, USA
	The Fermilab accelerator complex is currently undergoing an upgrade from 400kW to 700kW. This intensity could push operations into the region where electron cloud (e-cloud) generation could be observed and even cause instabilities. The POSINST simulation code was used to study how in- creasing beam intensities will affect electron cloud genera- tion. Threshold simulations show how the e-cloud density depend on the beam intensity and secondary electron yield (SEY) in the Main Injector (MI) and Recycler Ring (RR).
	Poster TUPOB63 [1.542 MB]
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WEA1CO04	Hollow Electron Beam Collimation for HL-LHC - Effect on the Beam Core	ion, simulation, experiment, emittance	651
	M. Fitterer, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA R. Bruce, S. Papadopoulou, G. Papotti, D. Pellegrini, S. Redaelli, D. Valuch, J.F. Wagner CERN, Geneva, Switzerland
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy. Collimation with hollow electron beams or lenses (HEL) is currently one of the most promising concepts for active halo control in HL-LHC. In previous studies it has been shown that the halo can be efficiently removed with a hollow electron lens. Equally important as an efficient removal of the halo, is also to demonstrate that the core stays unperturbed. In this paper, we present a summary of the experiment at the LHC and simulations in view of the effect of the HEL on the beam core in case of a pulsed operation.
	Slides WEA1CO04 [1.830 MB]
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WEA1CO05	Microwave Instability Studies in NSLS-II	ion, lattice, simulation, wiggler	655
	A. Blednykh, B. Bacha, G. Bassi, Y. Chen-Wiegart, W.X. Cheng, O.V. Chubar, V.V. Smaluk BNL, Upton, Long Island, New York, USA
	Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886. The microwave instability in the NSLS-II has been studied for the current configuration of insertion devices, 9 In-Vacuum Undulators (IVU's), 3EPU's, 3 Damping Wigglers. The energy spread as a function of single bunch current has been measured based on the frequency spectrum of IVU for X-Ray Spectroscopy (SRX) beam line. The results for two lattices, bare lattice with nominal energy spread 0.0005 and a lattice with one DW magnet gap closed (nominal energy spread 0.0007) are compared. In addition we used a Spectrum Analyzer to measure the beam spectrum. The instability thresholds for two different lattices cross-checked numerically using the particle tracking code SPACE and longitudinal impedance.
	Slides WEA1CO05 [2.380 MB]
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WEA2CO03	Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA	ion, simulation, dipole, positron	672
	S. Poprocki, J.A. Crittenden, S.N. Hearth, J.D. Perrin, D. L. Rubin, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, and PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538. We report on measurements of electron cloud (EC) induced tune shifts and emittance growth at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) with comparison to tracking simulation predictions. Experiments were performed with 2.1 GeV positrons in a 30 bunch train with 14 ns bunch spacing and 9 mm bunch length, plus a witness bunch at varying distance from the train to probe the cloud as it decays. Complementary data with an electron beam were obtained to distinguish EC effects from other sources of tune shifts and emittance growth. High resolution electric field maps are computed with EC buildup simulation codes (ECLOUD) in the small region around the beam as the bunch passes through the cloud. These time-sliced field maps are input to a tracking simulation based on a weak-strong model of the interaction of the positron beam (weak) with the electron cloud (strong). Tracking through the full lattice over multiple radiation damping times with electron cloud elements in the dipole and field-free regions predict vertical emittance growth, and tune shifts in agreement with the measurements.
	Slides WEA2CO03 [1.227 MB]
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WEA2CO04	Vlasov Analysis of Microbunching Gain for Magnetized Beams	ion, bunching, simulation, radiation	675
	C.-Y. Tsai Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA Y.S. Derbenev, D. Douglas, R. Li, C. Tennant JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE- AC05-06OR23177. For a high-brightness electron beam with low energy and high bunch charge traversing a recirculation beamline, coherent synchrotron radiation and space charge effect may result in the microbunching instability (MBI). Both tracking simulation and Vlasov analysis for an early design of Circulator Cooler Ring* for the Jefferson Lab Electron Ion Collider reveal significant MBI. It is envisioned these could be substantially suppressed by using a magnetized beam. In this work, we extend the existing Vlasov analysis, originally developed for a non-magnetized beam, to the description of transport of a magnetized beam including relevant collective effects. The new formulation will be further employed to confirm prediction of microbunching suppression for a magnetized beam transport in a recirculating machine design. *Ya. Derbenev and Y. Zhang, COOL'09 (FRM2MCCO01)
	Slides WEA2CO04 [4.662 MB]
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WEPOA01	Effect of Proton Bunch Parameter Variation on AWAKE	ion, wakefield, injection, plasma	684
	N. Savard University of Victoria, Victoria BC, Canada P. Muggli MPI, Muenchen, Germany J. Vieira IPFN, Lisbon, Portugal
	In AWAKE, long proton bunches propagate through a plasma, generating wakefields through the self-modulation instability (SMI). The phase velocity of these wakefields changes during the first 4 m of propagation and growth of the SMI, after which it stabilizes at the proton bunch velocity. This means that the ideal injection point for electrons to be accelerated is after 4 m into the plasma. Using the PIC code OSIRIS, we study how small changes in the initial proton bunch parameters (such as charge, radial and longitudinal bunch length, etc) to be expected in the experiment affect the phase velocity of the wakefields, primarily by looking at the difference in the phase of the wakefields at the point of injection (along the bunch and along the plasma) when changing these parameters by a small amount (±5%). We also look for the region of optimal acceleration/focusing for electron injection. Ultimately, it is found that small changes in the initial proton bunch parameters are not expected to significantly impact electron injection experiments in the future.
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WEPOA05	EBIS Charge Breeder for RAON Facility	ion, vacuum, gun, ISOL	696
	S.A. Kondrashev, J.-W. Kim, Y.K. Kwon, Y.H. Park, H.J. Son IBS, Daejeon, Republic of Korea
	New large scale accelerator facility called RAON is under design in Institute for Basic Science (IBS, Daejeon, Korea). Both technics of rare isotope production Isotope Separation On-Line (ISOL) and In-Flight Fragmentation (IF) will be combined within one facility for the first time to provide wide variety of rare isotope ion beams for nuclear physics experiments and applied research. Electron Beam Ion Source (EBIS) charge breeder will be used to prepare rare isotope ion beams produced by ISOL method for efficient acceleration. Beams of different rare isotopes will be charge-bred by an EBIS charge breeder to a charge-to-mass ratio (q/A) ≥ 1/4 and accelerated by linac post-accelerator to energies of 18.5 MeV/u. RAON EBIS charge breeder will provide the next step in the development of breeder technology by implementation of electron beam with current up to 3 A and utilization of wide (8') warm bore of 6 T superconducting solenoid. The design of RAON EBIS charge breeder and results of dumping of high power DC and pulsed electron beam into collector will be presented and discussed.
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WEPOA06	New Coolers for Ion Ion Colliders	ion, collider, gun, proton	700
	V.V. Parkhomchuk BINP SB RAS, Novosibirsk, Russia
	For crucial contributions in the proof of principle of electron cooling, for leading contribution to the experimental and theoretical development of electron cooling, and for achievement of the planned parameters of coolers for facilities in laboratories around the world the 2016 "Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators" was awarded to Vasili Parkhomchuk. In this paper new future coolers for ion*ion collider will be discussed.
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WEPOA12	Interleaving Lattice Design for APS Linac	ion, lattice, linac, gun	713
	S. Shin, Y. Sun, A. Zholents ANL, Argonne, Illinois, USA
	In order to realize and test advanced accelerator concepts and hardware, the existing beamline with both old and new components are being reconfigured in Linac Extension Area (LEA) of APS linac. Photo injector, which had been installed in the beginning of APS linac, will provide low emittance electron beam into the LEA. The thermionic RF gun beam for storage ring and photo-cathode RF gun beam for LEA will be operated though the LINAC in an interleaved fashion. In this presentation, technical issues as well as beam dynamics on the design for interleaving operation will be described.
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WEPOA17	On the Possibility of Using Nonlinear Elements for Landau Damping in High-Intensity Beams	ion, octupole, insertion, optics	729
	E. Gianfelice-Wendt, Y.I. Alexahin, V.A. Lebedev, A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE Direct space-charge force shifts the incoherent tunes down from the coherent ones switching off Landau damping of coherent oscillations at high beam intensity. To restore it the nonlinear elements can be employed which move back tunes of large amplitude particles. In the present report we consider the possibility of creating a "nonlinear integrable optics" insertion in the Fermilab Recycler to host either octupoles or hollow electron lens for this purpose. For comparison we also consider the classic scheme with distributed octupole families. It is shown that for the Proton Improvement Plan II parameters the required nonlinear tuneshift can be created without destroying the dynamic aperture.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA17
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WEPOA24	Installation and Commissioning of an Ultrafast Electron Diffraction Facility as Part of the ATF-II Upgrade	ion, operation, experiment, MMI	742
	M.A. Palmer, M. Babzien, M.G. Fedurin, C. Folz, M. Fulkerson, K. Kusche, J.J. Li, R. Malone, T.V. Shaftan, J. Skaritka, L. Snydstrup, C. Swinson, F.J. Willeke BNL, Upton, Long Island, New York, USA
	Funding: This work was funded by the US Department of Energy under contract DE-SC0012704. The Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL) is presently carrying out an upgrade, ATF-II, which will provide significantly expanded experimental space and capabilities for its users. One of the new capabilities being integrated into the ATF-II program is an Ultrafast Electron Diffraction (UED) beam line, which was originally deployed in the BNL Source Development Laboratory. Inclusion of the UED in the ATF-II research portfolio will enable ongoing development and extension of the UED capabilities for use in materials research. We discuss the design, installation and commissioning of the UED beam line at ATF-II as well as plans for future upgrades.
	Poster WEPOA24 [18.332 MB]
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WEPOA33	Novel Metallic Structures for Wakefield Acceleration	ion, wakefield, cavity, acceleration	762
	X.Y. Lu, M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA
	Funding: US DOE, Office of High Energy Physics Three novel ideas for wakefield acceleration (WFA) of electrons with metallic periodic subwavelength structures will be presented. The first idea is a deep corrugation structure for collinear WFA. A design for the Argonne Wakefield Accelerator is shown. An analytical model is developed and it agrees with the CST wakefield solver. A scaling study has been performed, and ways to increase the gradient will be discussed. The deep corrugation structure can generate a higher gradient than a dielectric tube with the same beam aperture when excited by the same bunch. The second idea is an elliptical structure for two-beam acceleration (TBA). The unit cell is an elliptical cavity, and the drive beam hole and the witness beam hole are located around the two focal points. The TBA process has been calculated and will be presented. The third idea is a metamaterial ‘wagon wheel' structure for a power extractor design. The fundamental mode is a TM mode with a negative group velocity. A power extractor at 11.7 GHz based on the structure can reach a GW power level when a train of 40 nC bunches with 1.3 GHz rep rate are sent in.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA33
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WEPOA40	Construction Status of a RF-Injector with a CNT-Tip Cathode for High Brightness Field-Emission Tests	ion, cathode, gun, emittance	785
	Y.-M. Shin, G. Fagerberg, M. Figora Northern Illinois University, DeKalb, Illinois, USA A.T. Green Northern Illinois Univerity, DeKalb, Illinois, USA
	We have been constructing a S-band RF-injector system for field-emission tests of a CNT-tip cathode. A pulsed Sband klystron is installed and fully commissioned with 5.5 MW peak power in a 2.5 microsecond pulse length and 1 Hz repetition rate. A single-cell RFgun is designed to produce with 0.5 - 1 pC electron bunches in a photo-emission mode within a 50 fs - 3 ps at 0.5- 1 MeV. The measured RF system jitters are within 1 % in magnitude and 0.2° in phase, which would induce 3.4 keV and 0.25 keV of energy jitters, corresponding to 80 fs and 5 fs of temporal jitters, respectively. Our PIC simulations indicate that the designed bunch compressor reduces the TOAjitter by about an order of magnitude. Emission current and beam brightness of the field-emitted beam are improved by implanting CNT tips on the cathode surface, since they reduce the emission area, while providing high current emission. Once the system is completely commissioned in field-emission mode, the CNT-tip cathode will be tested in terms of klystron-power levels to map out its I-V characteristics under pulse emission condition.
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WEPOA42	RF Design of a 1.3-GHz High Average Beam Power SRF Electron Source	ion, cathode, gun, simulation	789
	N. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA I.V. Gonin, R.D. Kephart, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	There is a significant interest in developing high-average power electron sources, particularly those integrated with Superconducting Radio Frequency (SRF) accelerator systems. Even though there are examples of high-average-power electron sources, they are not compact, highly efficient, or available at a reasonable cost. Adapting the recent advances in SRF cavities, RF power sources, and innovative solutions for an SRF gun and cathode system, we have developed a design concept for a compact SRF high-average power electron linac. This design will produce electron beams with energies up to 10 MeV. In this paper, we present the design results of our cathode structure integrated with modified 9-cell accelerating structure.
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WEPOA44	Accleration System of Beam Brightness Booster	ion, space-charge, brightness, proton	796
	V.G. Dudnikov Muons, Inc, Illinois, USA A.V. Dudnikov BINP SB RAS, Novosibirsk, Russia
	The brightness and intensity of a circulating proton beam now can be increased up to space charge limit by means of charge exchange injection or by an electron cooling but cannot be increased above this limit. Significantly higher brightness can be produced by means of the charge exchange injection with the space charge compensation [1]. The brightness of the space charge compensated beam is limited at low level by development of the electron-proton (e-p) instability [2]. Fortunately, e-p instability can be self-stabilized at a high beam density. A beam brightness booster (BBB) for significant increase of accumulated beam brightness is discussed. Accelerating system with a space charge compensation is proposed and described. The superintense beam production can be simplified by developing of nonlinear nearly integrable focusing system with broad spread of betatron tune and the broadband feedback system for e-p instability suppression . [1] V. Dudnikov, in Proceedings of the Particle Accelerator Conference, Chicago, 2001.. [2] G. Budker, et al., Sov. Atomic Energy 22, 384 (1967);
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WEPOA45	Positive and Negative Ions Radio Frequency Sources with Solenoidal Magnetic Field	ion, plasma, solenoid, ion-source	799
	V.G. Dudnikov, R.P. Johnson Muons, Inc, Illinois, USA G. Dudnikova ICT SB RAS, Novosibirsk, Russia B. Han, S. Murrey, C. Stinson ORNL RAD, Oak Ridge, Tennessee, USA T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA
	Funding: The work was supported in part by US DOE Contract DE-AC05-00OR22725 and by STTR grant, DE-SC0011323. Operation of Radio Frequency surfaces plasma sources (RF SPS) with a solenoidal magnetic field are described. RF SPS with solenoidal and saddle antennas are discussed. Dependences of beam current and extraction current on RF power, gas flow, solenoidal magnetic field and filter magnetic field are presented.
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WEPOA55	Modulator Simulations for Coherent Electron Cooling	ion, simulation, quadrupole, plasma	816
	J. Ma, X. Wang SBU, Stony Brook, New York, USA V. Litvinenko, V. Samulyak, G. Wang, K. Yu BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA V. Samulyak SUNY SB, Stony Brook, New York, USA
	Highly resolved numerical simulations of the modulator, the first section of the proposed coherent electron cooling (CEC) device, have been performed using the code SPACE. The beam parameters for simulations are relevant to the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Numerical convergence has been studied using various numbers of macro-particles and mesh refinements of computational domain. A good agreement of theory and simulations has been obtained for the case of stationary and moving ions in uniform electron clouds with realistic distribution of thermal velocities. The main result of the paper is the prediction of modulation processes for ions with reference and off-reference coordinates in realistic Gaussian electron bunches with quadrupole field.
	Poster WEPOA55 [1.510 MB]
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WEPOA57	Stabilized Operation Mode of Laser Ion Source Using Pulsed Magnetic Field	ion, laser, ion-source, solenoid	823
	S. Ikeda, M.R. Costanzo, T. Kanesue, R.F. Lambiase, C.J. Liaw, M. Okamura BNL, Upton, Long Island, New York, USA
	A laser ion source (LIS) provides several types of singly charged ions into an electron beam ion source (EBIS) followed by linear accelerator injectors for the Relativistic Heavy Ion Collider (RHIC) and the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory. In the present set-up of the LIS, beam current shape varies with time drastically. It is expected that the present current shape is not optimal for the ion trap of the EBIS. However, there are no knobs to modify the shape flexibly. Therefore, as an upgrade of the LIS, we install a coil and a pulsed circuit* that generates a fast-rising pulsed magnetic field to tailor the beam current shape. In this presentation, the effect of the magnetic field on the beam profile from the LIS and the performance of the injectors, such as the transmission and the charge injected into an accelerator downstream, are described.
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WEPOA62	The Center for Bright Beams	ion, brightness, cavity, cathode	830
	J.R. Patterson, G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA Y.K. Kim University of Chicago, Chicago, Illinois, USA
	Funding: National Science Foundation award PHY-1549132. The Center for Bright Beams (CBB) is a new National Science Foundation-supported Science and Technology Center. CBB's research goal is to increase the brightness of electron beams while reducing the cost and size of key technologies. To achieve this, it will augment the capabilities of accelerator physicists with those of physical chemists, materials scientists, condensed matter physicists, plasma physicists, and mathematicians. This approach has the potential to increase the brightness of electron sources through better photocathodes, the efficiency and gradient of SRF cavities through deeper understanding of superconducting compounds and their surfaces, and better understanding of beam storage and transport and the associated optics by using new mathematical techniques.
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WEA3IO01	Emittance Growth from Modulated Focusing in Bunched Beam Cooling	ion, emittance, simulation, betatron	833
	M. Blaskiewicz BNL, Upton, Long Island, New York, USA
	The low energy RHIC electron cooling (LEReC) project at Brookhaven employs a linac to supply electrons with kinetic energies from 1.6 to 2.6 MeV. Along with cooling the stored ion beam the electron bunches create a coherent space charge field which can cause emittance growth. This is the primary source of heating when the cooling is well tuned. An analytic theory of this process is presented and compared with simulations.
	Slides WEA3IO01 [4.160 MB]
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WEA3IO02	Start-to-End Beam Dynamics Optimization of X-Ray FEL Light Source Accelerators	ion, linac, controls, FEL	838
	J. Qiang LBNL, Berkeley, California, USA
	State-of-the-art tools have been developed that allow start-to-end modeling of the beam formation at the cathode, to its transport, acceleration, and delivery to the undulator. Algorithms are based on first principles, enabling the capture of detailed physics such as shot-noise driven micro-bunching instabilities. The most recent generation of the IMPACT code, using multi-level parallelization on massively parallel supercomputers, now enables multi-objective parametric optimization. This is facilitated by recent advances such as the unified differential evolution algorithm. The most recent developments will be described, together with applications to the modeling of LCLS-II. J. Qiang, et al, http://www.optimization-online.org/DB_FILE/2015/03/4796.pdf, submitted **J. Qiang, et al, in preparation
	Slides WEA3IO02 [10.928 MB]
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WEA4CO05	Accelerator Physics Design Requirements and Challenges of RF Based Electron Cooler LEReC	ion, cavity, cathode, emittance	867
	A.V. Fedotov, M. Blaskiewicz, W. Fischer, D. Kayran, J. Kewisch, S. Seletskiy, J.E. Tuozzolo BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A Low Energy RHIC electron Cooler (LEReC) is presently under construction at BNL to improve the luminosity of the Relativistic Heavy Ion Collider (RHIC). The required electron beam will be provided by a photoemission electron gun and accelerated by a RF linear accelerator. As a result, LEReC will be first bunched beam electron cooler. In addition, this will be the first electron cooler to cool beams under collisions. The achievement of very tight electron beam parameters required for cooling is very challenging and is being addressed by a proper beam transport and engineering design. In this paper, we describe accelerator physics requirements, design considerations and parameters, as well as associated challenges of such electron cooling approach.
	Slides WEA4CO05 [4.866 MB]
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WEPOB18	Bend Magnet Head Loads and Out of Orbit Scenarios	ion, photon, software, lattice	931
	T.T. Valicenti, J.A. Carter, P.K. Den Hartog, K.J. Suthar ANL, Argonne, Illinois, USA
	This paper presents an analytical calculation of the spatial power spectrum emitted from relativistic electrons passing through a series of bend magnets. Using lattice files from the software Elegant, both the ideal and missteered trajectories taken by the beam are considered in determination of the power profile. Calculations were performed for the Advanced Photon Source Upgrade multi-bend-achromat storage-ring. Results were validated with Synrad, a monte-carlo based program designed at CERN. The power distribution and integrated total power values are in agreement with Synrad's results within one percent error. The analytic solution used in this software gives a both quick and accurate tool for calculating the heat load on a photon absorber. The location and orientation can be optimized in order to reduce the peak intensity and thus the maximum thermal stress. This can be used with any optimization or FEA software and gives rise to a versatile set of uses for the developed program.
	Poster WEPOB18 [2.491 MB]
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WEPOB23	Performance of the Full-Length Vertical Polarizing Undulator Prototype for LCLS-II	ion, undulator, FEL, operation	946
	N.O. Strelnikov, E. Gluskin, I. Vasserman, J.Z. Xu ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357 As part of the LCLS-II R&D program, a novel 3.4-meter long undulator prototype with horizontal main magnetic field and dynamic force compensation - called the horizontal gap vertical polarization undulator (HGVPU) - has recently been developed at the Advanced Photon Source (APS). Initial steps of the project included designing, building, and a testing 0.8-meter long prototype. Extensive mechanical testing of the HGVPU has been carried out. The magnetic tuning was accomplished by applying a set of magnetic shims. As a result, the performance of the HGVPU meets all the stringent requirements for the LCLS-II insertion device, which includes limits on the field integrals and phase errors for all operational gaps, as well as the reproducibility and accuracy of the gap settings. The HGVPU has been included in the baseline of the LCLS-II project for the hard x-ray undulator line.
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WEPOB25	Analytical Modeling of Electron Back-Bombardment Induced Current Increase in Un-Gated Thermionic Cathode Rf Guns	ion, gun, cathode, simulation	953
	J.P. Edelen Fermilab, Batavia, Illinois, USA J.R. Harris Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA Y. Sun ANL, Argonne, Illinois, USA
	In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, field-enhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.
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WEPOB26	Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun	ion, cathode, gun, experiment	956
	J.P. Edelen Fermilab, Batavia, Illinois, USA J.R. Harris Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA Y. Sun ANL, Argonne, Illinois, USA
	Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an un-gated thermionic cathode RF gun to high average current.

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High Energy Coulomb Scattered Electrons Detected in Air Used as the Main Beam Overlap Diagnostics for Tuning the RHIC Electron Lenses

ion, proton, alignment, detector

20

P. Thieberger, Z. Altinbas, C. Carlson, C. Chasman, M.R. Costanzo, C. Degen, K.A. Drees, W. Fischer, D.M. Gassner, X. Gu, K. Hamdi, J. Hock, Y. Luo, A. Marusic, T.A. Miller, M.G. Minty, C. Montag, A.I. Pikin
BNL, Upton, Long Island, New York, USA
S.M. White
ESRF, Grenoble, France

Funding: Work supported by Brookhaven Science Associates under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
A new type of electron-ion beam overlap monitor has been developed for the RHIC electron lenses. Low energy electrons acquire high energies in small impact parameter Coulomb scattering collisions with relativistic ions. Such electrons can traverse thin vacuum windows and be conveniently detected in air. Counting rates are maximized to optimize beam overlap. Operational experience with the electron backscattering detectors during the 2015 p-p RHIC run will be presented. Other possible real-time non-invasive beam-diagnostic applications of high energy Coulomb-scattered electrons will be briefly discussed.
Most of this material appears in an article by the same authors entitled "High energy Coulomb-scattered electrons for relativistic particle beam diagnostics", Phys. Rev. Accel. Beams 19, 041002 (2016)

Slides MOA3IO01 [2.164 MB]

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MOA3CO03

Bunch Shape Monitor Measurements at the LANSCE Linac

ion, linac, target, detector

25

I.N.D. Draganic, D. Baros, C.M. Fortgang, R.W. Garnett, R.C. McCrady, J.F. O'Hara, L. Rybarcyk, C.E. Taylor, H.A. Watkins
LANL, Los Alamos, New Mexico, USA
A. Feschenko, V. Gaidash, Yu.V. Kiselev
RAS/INR, Moscow, Russia

Two Bunch Shape Monitors (BSM) [1] have been developed, fabricated and assembled for the first direct longitudinal beam measurements at the Los Alamos Neutron Science Center (LANSCE) linear accelerator (linac). The BSM detectors use different radio frequencies for the deflecting field: first harmonic (201.25 MHz) and second harmonic (402.5 MHz) of fundamental accelerator radio frequency. The first BSM is designed to record the proton beam longitudinal phase distribution after the new RFQ accelerator at a beam energy of 750 keV with phase resolution of 1.0 degree and covering phase range of 180 degree at 201.25 MHz. The second BSM is installed between DTL tanks 3 and 4 of the LANSCE linac in order to scan both H⁺ and H⁻ beams at a beam energy of 73 MeV with a phase resolution up to 0.5 degree in the phase range of 90 degree at 201.25 MHz. Preliminary results of bunch shape measurements for both beams under different beam gates (pulse length of 150 us, 1 Hz repetition rate, etc.) will be presented and compared high performance simulation results (HPSIM) [2].
[1] A. Feschenko, Proc. of RUPAC2012, FRXOR01, Saint Petersburg, Russia, pp. 181 - 185.
[2] X. Pang, L. Rybarcyk, and S. Baily, Proc. of HB2014, MOPAB30, East Lansing, MI, USA, pp. 99-102.

Slides MOA3CO03 [4.942 MB]

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MOB3IO01

Commissioning of the Phase-I SuperKEKB B-Factory and Update on the Overall Status

ion, vacuum, emittance, coupling

32

Y. Ohnishi, T. Abe, T. Adachi, K. Akai, Y. Arimoto, K. Egawa, Y. Enomoto, J.W. Flanagan, H. Fukuma, Y. Funakoshi, K. Furukawa, N. Iida, H. Iinuma, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, H. Kaji, T. Kamitani, T. Kawamoto, S. Kazama, M. Kikuchi, T. Kobayashi, K. Kodama, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, S. Nakamura, T.T. Nakamura, H. Nakayama, T. Natsui, M. Nishiwaki, K. Ohmi, T. Oki, S. Sasaki, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, H. Sugimoto, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, S. Uehara, S. Uno, X. Wang, K. Watanabe, Y. Yano, S.I. Yoshimoto, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong
KEK, Ibaraki, Japan
M.E. Biagini, M. Boscolo, S. Guiducci
INFN/LNF, Frascati (Roma), Italy
D. El Khechen
LAL, Orsay, France

The SuperKEKB B-Factory at KEK (Japan), after few years of shutdown for the construction and renovation, has finally come to the Phase-1 commissioning of the LER and HER rings, without the final focus system and the Belle II detector. Vacuum scrubbing, optics tuning and beam related background measurements were performed in this phase. Low emittance tuning techniques have also been applied in order to set up the rings for Phase-2 with colliding beams next year. An update of the final focus system construction, as well as the status of the injection system with the new positron damping ring and high current/low emittance electron gun is also presented.

Slides MOB3IO01 [10.375 MB]

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MOB3CO03

RHIC Au-Au Operation at 100 GeV in Run16

ion, operation, cavity, luminosity

42

X. Gu, J.G. Alessi, E.N. Beebe, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, W. Fischer, C.J. Gardner, D.M. Gassner, Y. Hao, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, P.F. Ingrassia, J.P. Jamilkowski, J.S. Laster, V. Litvinenko, C. Liu, Y. Luo, M. Mapes, G.J. Marr, A. Marusic, G.T. McIntyre, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, I. Pinayev, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, R. Than, P. Thieberger, J.E. Tuozzolo, G. Wang, Q. Wu, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang
BNL, Upton, Long Island, New York, USA

In order to achieve higher instantaneous and integrated luminosities, the average Au bunch intensity in RHIC has been increased by 30% compared to the preceding Au run. This increase was accomplished by merging bunches in the RHIC injector AGS. Luminosity leveling for one of the two interaction points (IP) with collisions was realized by continuous control of the vertical beam separation. Parallel to RHIC physics operation, the electron beam commissioning of a novel cooling technique with potential application in eRHIC, Coherent electron Cooling as a proof of principle (CeCPoP), was carried out. In addition, a 56 MHz superconducting RF cavity was commissioned and made operational. In this paper we will focus on the RHIC performance during the 2016 Au-Au run.

Slides MOB3CO03 [2.173 MB]

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MOB4IO02

ERL-Ring and Ring-Ring Designs for the eRHIC Electron-Ion Collider

ion, luminosity, proton, linac

64

V. Ptitsyn
BNL, Upton, Long Island, New York, USA

An overview of the eRHIC project.

Slides MOB4IO02 [6.001 MB]

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MOPOB39

A 600 Volt Multi-Stage, High Repetition Rate GaN FET Switch

ion, linac, ECR, operation

152

G.W. Saewert, D. Frolov, H. Pfeffer
Fermilab, Batavia, Illinois, USA

Using recently available GaN FETs, a 600 Volt three-stage, multi-FET switch has been developed having 2 nanosecond rise time driving a 200 Ω load with the potential of approaching 30 MHz average switching rates. Possible applications include driving particle beam choppers kicking bunch-by-bunch and beam deflectors where the rise time needs to be custom tailored. This paper reports on the engineering issues addressed, the design approach taken and some performance results of this switch.

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MOPOB53

Simulation of Ping-Pong Multipactor with Continuous Electron Seeding

ion, simulation, multipactoring, resonance

181

M. Siddiqi, R.A. Kishek
UMD, College Park, Maryland, USA

Funding: National Science Foundation grant No. PHY1535519
Multipactor is a discharge induced by the impact of electrons on a surface due to radio-frequency (RF) electromagnetic fields and secondary electron emission (SEE). Depending on the impact energy and RF phase of the incident electron, a growth in the electron density is possible. Multipactor can lead to device breakdown in many applications, such as particle accelerator structures and rf systems, satellite communication equipment, and microwave components. Multipactor can also be a precursor for electron cloud effects. Due to the critical need to mitigate multipactor, a more comprehensive theory has been introduced that views multipactor as a global effect that can be analyzed through the concepts of iterative maps and nonlinear dynamics *. In order to test this novel approach, multipactor is simulated in a parallel-plate waveguide using the WARP particle-in-cell code. Different parameters are varied in the simulation to determine the conditions that add to multipactor growth, such as geometry dimensions, electron seeding scenarios, and an applied DC electric field. These computational results and their implications on the further development of this theory will be presented.
*R.A. Kishek, Physics of Plasmas 20, 056702 (2013).

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MOPOB56

Frequency Domain Simulations of Rf Cavity Structures and Coupler Designs for Co-Linear X-Band Energy Booster (CXEB) with ACE3P

ion, cavity, GUI, simulation

191

T. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

Due to their higher intrinsic shunt impedance X-band accelerating structures offer significant gradients with relatively modest input powers, and this can lead to more compact light sources. At the Colorado State University Accelerator Laboratory (CSUAL) we would like to adapt this technology to our 1.3-GHz, L-band accelerator system using a passively driven 11.7 GHz traveling wave X-band configuration that capitalizes on the high shunt impedances achievable in X-band accelerating structures in order to increase our overall beam energy in a manner that does not require investment in an expensive, custom, high-power X-band klystron system. Here we provide the frequency domain simulation results using the ACE3P Electromagnetic Suite's OMEGA3P and S3P for our proposed Co-linear X-band Energy Booster (CXEB) system that will allow us to achieve our goal of reaching the maximum practical net potential across the X-band accelerating structures while driven solely by the beam from the L-band system.

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MOPOB68

A New Method for Grain Texture Manipulation in Post-Deposition Niobium Films

ion, laser, niobium, controls

221

J. Musson, K. Macha, H.L. Phillips
JLab, Newport News, Virginia, USA
W. Cao, H. Elsayed-Ali
ODU, Norfolk, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Old Dominion University
Niobium films are frequently grown using forms of energetic condensation, with modest substrate temperatures to control grain structure. As an alternative, energetic deposition onto a cold substrate results in a dense amorphous film, with a much larger energy density than the re-crystallized state. Re-crystallization is then performed using a pulsed UV (HIPPO) laser, with minimal damage to the substrate. In addition, a graded interface between the substrate and Nb film is created during the early stages of energetic deposition. Experimental approach and apparatus are described.

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MOPOB76

Field Emission Dark Current Simulation for eRHIC ERL Cavities

ion, cavity, SRF, simulation

235

C. Xu, I. Ben-Zvi, Y. Hao, V. Ptitsyn, K.S. Smith, B. P. Xiao, W. Xu
BNL, Upton, Long Island, New York, USA

The eRHIC project will be a electron and proton collider proposed in BNL. These high repetition rates will require Super-Conducting Radio-Frequency cavities with fundamental frequency of 650MHZ for high current applications. Each with a string of two of those cavities. The strong electromagnetic fields in the SRF cavities will extract electrons from the cavity walls and will accelerate those. Most dark current will be deposited locally, although some electrons may reach several neighbour cyromodules, thereby gaining substantial energy before they hit a collimator or other aperture. Simulation of these effects is therefore crucial for the design of the machine. Track3P code was used to simulate field-emission electrons from different SRF cavities setup to optimize the field emission dark current characterizes.

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TUB1CO02

Operating Synchrotron Light Sources with a High Gain Free Electron Laser

ion, FEL, undulator, emittance

259

S. Di Mitri, M. Cornacchia
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The peak current required by a high gain free electron laser (FEL) is not deemed to be compatible with the multi-bunch filling pattern of synchrotrons. We show that this problem can be overcome by virtue of magnetic bunch length compression in a ring section and that, after lasing, the beam returns to equilibrium conditions without beam quality disruption*. As a consequence of bunch length compression, the peak current stimulates a high gain FEL emission, while the large energy spread makes the beam less sensitive to the FEL heating and to the microwave instability. The beam large energy spread is matched to the FEL energy bandwidth through a transverse gradient undulator. Feasibility of lasing at 25 nm is shown for the Elettra synchrotron light source (SLS) at 1 GeV. Viable scenarios for the upgrade of existing or planned SLSs to the new hybrid insertion devices-plus-FEL operational mode are discussed, while ensuring little impact on the standard beamlines functionality.
* S. Di Mitri and M. Cornacchia, NJP 17 (2015) 113006

Slides TUB1CO02 [2.353 MB]

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TUA2IO01

AWAKE - A Proton Driven Plasma Wakefield Acceleration Experiment at CERN

ion, plasma, proton, wakefield

266

A. Caldwell
MPI-P, München, Germany

It is the aim of the AWAKE project at CERN to demonstrate the acceleration of electrons in the wake created by a proton beam passing through plasma. The proton beam will be modulated as a result of the transverse two-stream instability into a series ofμbunches that will then drive strong wakefields. The wakefields will then be used to accelerate electrons with GV/m strength fields. The AWAKE experiment is currently being commissioned and first data taking is expected this year. The status of the experimental program is described as well as first thoughts on future steps.

Slides TUA2IO01 [24.428 MB]

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TUB2IO02

Advanced Concepts for Seeded FELs

ion, FEL, controls, laser

284

E. Ferrari, E. Allaria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The use of an external laser to seed an electron beam at the beginning of the Free Electron Laser process has been proposed as a way to improve temporal coherence of modern short wavelength FELs. More recent studies and experiments have shown that electron beam manipulation through interaction with a seed laser can be exploited for tailoring FEL properties to specific users requests. Recently, experiment for phase control, multi-color emission and coherent control have been reported.

Slides TUB2IO02 [15.975 MB]

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TUB2CO04

Corrugated Structure Insertion to Extend SASE Bandwidth Up to 3% at the European XFEL

ion, radiation, undulator, FEL

293

I. Zagorodnov, G. Feng, T. Limberg
DESY, Hamburg, Germany

The usage of x-ray free electron laser (XFEL) in femtosecond nanocrystallography involves sequential illumination of many small crystals of arbitrary orientation. Hence a wide radiation bandwidth could be useful in order to obtain and to index a larger number of Bragg peaks used for determination of crystal orientation. Considering the baseline configuration of the European XFEL in Hamburg, and based on beam dynamics simulations, we demonstrate here that usage of corrugated structures allows for a considerable increase in radiation bandwidth. It allows for data collection with a 3% bandwidth, a few micrjoule radiation pulse energy, a few fs pulse duration, and a photon energy 4.1 keV.

Slides TUB2CO04 [5.848 MB]

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TUPOA04

Study on THz Imaging by Using the Coherent Cherenkov Radiation

ion, radiation, experiment, detector

296

M. Nishida, M. Brameld, M. Washio
Waseda University, Tokyo, Japan
R. Kuroda, Y. Taira
AIST, Tsukuba, Ibaraki, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan

THz frequency is a special electromagnetic wave which is categorized between a radio wave and a light wave. It can pass through the various materials like a radio wave and can be transported with optical components like a light wave. Thus, it's suitable for imaging application of materials. At Waseda University, it's possible to generate a high-quality electron beam using Cs-Te photocathode RF-Gun and the electron beam is applied to several application researches. As an application of this electron beam, we generate a coherent Cherenkov radiation, and succeed in observing a high power THz light. The successful results of high power THz radiation encourage us to perform the THz imaging with transmission and reflection imaging using some materials, cross-section imaging using a simple material. On studying the THz imaging, it is necessary to clarify the spatial resolution. So, we tried to evaluate the spatial resolution in our device. Furthermore, our target is to get the three-dimensional THz images. We will introduce the CT technique in order to obtain the clear cross-section image. In this conference, we report the recent results of the THz imaging and future prospective.

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TUPOA05

Development of a Fiber Laser for Improving the Pulse Radiolysis System

ion, laser, radiation, gun

299

Y. Saito, S.Y. Soeta, M. Washio
Waseda University, Tokyo, Japan
Y. Hosaka, K. Sakaue
RISE, Tokyo, Japan

When material is irradiated by the ionizing radiation, short-lived and highly reactive substance intermediate active species are made and then react with substances. The chemical reaction is determined by intermediate active species in early process. Proving the behavior of intermediate active species is important for understanding and controlling radiation chemical reaction. In Waseda university we been developing a Pulse Radiolysis System, a method to measure the behavior of intermediate species, for radiation chemical analysis with RF electron gun. Currently we are developing a Supercontinuum ray(SC ray)as a probe ray to improve Pulse Radiolysis System. We have introduced a SC ray using Yb fiver laser and PCF(Photonic Crystal Fiber). But this type of prove light isn't stable enough in the visible light region. Therefore we started to study Er fiber laser oscillator as new prove ray source. We have succeeded to oscillate a Er fs laser pulse, second harmonic generation and measurement of hydrated electron in ns time resolution. In this presentation we will report current research about generation of SC ray, Er fiber laser system and dose rate effect against the hydrated electron.

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TUPOA13

First Test Run for High Density Material Imaging Experiment Using Relativistic Electron Beam at the Argonne Wakefield Accelerator

ion, target, experiment, diagnostics

311

Y.R. Wang
AAI/ANL, Argonne, Illinois, USA
S. Cao, X.K. Shen, Z.M. Zhang, Q.T. Zhao
IMP/CAS, Lanzhou, People's Republic of China
M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA

A test facility, AWA, has been commissioned and in operation since last year. It can provide beam of several bunches in a train of nano-seconds and 10s of nC with energy up to 70 MeV. In addition, the AWA can accommodate various beamlines for experiments. One of the proposed experiments is to use the AWA beam as a diagnostics for time resolved high density material, typically a target with high Z and time dependent, imaging experiments. When electron beam scatters after passing through the target, and the angular and energy distribution of beam will depend on the density and thickness of the target. A small aperture is used to collimate the scattered electron beam for off axis particles, and the target image will be detected by imaging plate. By measuring the scatted angle and energy at the imaging plate would yield information of the target. In this paper, we report on the AWA electron imaging (EI) system setup, which consist of a target, imaging optics and drift transport. The AWA EI beam line was installed on June, 2016 and the first test run was performed on August, 2016. This work will have implication on the high energy density physics and even future nuclear fusion studies.

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TUPOA19

50-MeV Run of the IOTA/FAST Electron Accelerator

ion, gun, emittance, cavity

326

D.R. Edstrom, C.M. Baffes, C.I. Briegel, D.R. Broemmelsiek, K. Carlson, B.E. Chase, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, B.J. Fellenz, E.R. Harms, M.J. Kucera, J.R. Leibfritz, A.H. Lumpkin, D.J. Nicklaus, E. Prebys, P.S. Prieto, J. Reid, A.L. Romanov, J. Ruan, J.K. Santucci, T. Sen, V.D. Shiltsev, Y.-M. Shin, G. Stancari, J.C.T. Thangaraj, R.M. Thurman-Keup, A. Valishev, A. Warner, S.J. Wesseln
Fermilab, Batavia, Illinois, USA
A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA
A. Halavanau, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Hyun
Sokendai, Ibaraki, Japan
P. Kobak
BYU-I, Rexburg, USA
W.D. Rush
KU, Lawrence, Kansas, USA

Funding: Supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC.
The low-energy section of the photoinjector-based electron linear accelerator at the Fermilab Accelerator Science & Technology (FAST) facility was recently commissioned to an energy of 50 MeV. This linear accelerator relies primarily upon pulsed SRF acceleration and an optional bunch compressor to produce a stable beam within a large operational regime in terms of bunch charge, total average charge, bunch length, and beam energy. Various instrumentation was used to characterize fundamental properties of the electron beam including the intensity, stability, emittance, and bunch length. While much of this instrumentation was commissioned in a 20 MeV running period prior, some (including a new Martin-Puplett interferometer) was in development or pending installation at that time. All instrumentation has since been recommissioned over the wide operational range of beam energies up to 50 MeV, intensities up to 4 nC/pulse, and bunch structures from ~1 ps to more than 50 ps in length.

Poster TUPOA19 [4.636 MB]

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TUPOA25

Initial Demonstration of 9-MHz Framing Camera Rates on the FAST Drive Laser Pulse Trains*

ion, laser, optics, radiation

333

A.H. Lumpkin, D.R. Edstrom, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: * Work at Fermilab supported by Fermi Research Alliance, LLC under Contract No. DE-AC02- 07CH11359 with the United States Department of Energy.
Although beam centroid information at the MHz-micropulse-repetition rate has routinely been achieved at various facilities with rf BPMS, the challenge of recording beam size information at that rate is more daunting. The Integrable Optics Test Accelerator (IOTA) ring being planned at Fermilab has ~8 MHz revolution rates. To simulate the IOTA synchrotron radiation source temporal structure, we have used the UV component of the drive laser of the Fermilab Accelerator Science and Technology (FAST) Facility. This laser is normally set at 3 MHz, but has also been run at 9 MHz. We have configured our Hamamatsu C5680 streak camera in a framing camera mode using a slow vertical sweep plugin unit with the dual axis horizontal sweep unit**. A two-dimensional array of images sampled at the MHz rate can then be displayed on the streak tube phosphor and recorded by the CCD readout camera at up to 10 Hz. As an example, by using the 10 microsecond vertical sweep with the 100 microsecond horizontal sweep ranges, 49 of the 300 micropulses at 3 MHz are displayed for a given trigger delay in each of six images. Example 2D image arrays with profiling examples will be presented.
**Hamamatsu C5680 product web page.

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TUPOA26

Initial Observations of Micropulse Elongation of Electron Beams in a SCRF Accelerator*

ion, laser, gun, MMI

337

A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

Funding: * Work at Fermilab supported by Fermi Research Alliance, LLC under Contract No. DE-AC02- 07CH11359 with the United States Department of Energy
Commissioning at the SCRF accelerator at the Fermilab Accelerator Science and Technology (FAST) Facility has included the implementation of a versatile bunch-length monitor located after the 4-dipole chicane bunch compressor for electron beam energies of 20-50 MeV and integrated charges in excess of 10 nC. The team has initially used a Hamamatsu C5680 synchroscan streak camera. An Al-coated Si screen was used to generate optical transition radiation (OTR) resulting from the beam's interaction with the screen. The chicane bypass beamline allowed the measurements of the bunch length without the compression stage at the downstream beamline location using OTR and the streak camera. The UV component of the drive laser had previously been characterized with a Gaussian fit σ of 3.5-3.7 ps**. However, the uncompressed electron beam is expected to elongate due to space charge forces in an initial 1.5-m drift from the gun to the first SCRF accelerator cavity. We have observed electron beam bunch lengths from 5 to 14 ps (σ) for micropulse charges of 60 pC to 800 pC, respectively. Commissioning of the system and initial results with uncompressed and compressed beam will be presented.
**A.H. Lumpkin et al., Proceedings of FEL14, MOP021, Basel, Switzerland, www. JACoW.org

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TUPOA27

From Relativistic Electrons to X-ray Phase Contrast Imaging

ion, linac, GUI, software

341

A.H. Lumpkin
Fermilab, Batavia, Illinois, USA
M.A. Anastasio, A.B. Garson
Washington University in St. Louis, St. Louis, Missouri, USA

Funding: Work at Fermilab partly supported by Fermi Research Alliance, LLC under Contract No.DE-AC02-07CH11359 with the U.S.DoE. Work at Washington Univ. in St. Louis was supported in part by NSF CBET1263988.
X-ray phase contrast (XPC) imaging is an emerging technology that holds great promise for biomedical applications due to its ability to provide information about soft tissue structure *. The need for high spatial resolution at the boundaries of the tissues is noted for this process. Based on results from imaging of relativistic electron beams with single crystals **, we proposed transferring single-crystal imaging technology to this bio-imaging issue. Using a microfocus x-ray tube (17 kVp) and the exchangeable phosphor feature of the camera system, we compared the point spread function (PSF) of the system with the reference P43 phosphor to that with several rare earth garnet single crystals of varying thickness. Based on single Gaussian peak fits to the collimated x-ray images, we observed a four times smaller system PSF (21 microns (FWHM)) with the 25-mm diameter single crystals than with the reference polycrystalline phosphor's 80-micron value. Initial images of 33-micron diameter carbon fibers have also been obtained with small crystals installed. Tests with a full-scale 88-mm diameter single crystal (patent-pending configuration) are being planned.
*A. Appel, M.A. Anastasio, and E.M. Brey, Tissue Eng. Part B Rev 17 (5), 321 (2011).
**A.H. Lumpkin, et al., Phys. Rev. ST-AB 14 (6), 060704 (2011).

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TUPOA28

Feasibility of OTR Imaging for Laser-Driven Plasma Accelerator Electron-Beam Diagnostics

ion, polarization, laser, plasma

345

A.H. Lumpkin
Fermilab, Batavia, Illinois, USA
M. Downer
The University of Texas at Austin, Austin, Texas, USA
D.W. Rule
Private Address, Silver Spring, USA

Funding: * Work at Fermilab partly supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. DoE. ** Work at the Univ. of Texas supported by DoE grant DE-SC0011617.
Recent measurements of betatron x-ray emission from quasi-monoenergetic electrons accelerating to 500 MeV within a laser plasma accelerator (LPA) enabled estimates of normalized transverse emittance well below 1 mm-mrad and divergences of order 1/gamma [1]. Such unprecedented LPA beam parameters can, in principle, be addressed by utilizing the properties of linearly polarized optical transition radiation (OTR) that provide additional beam parameter sensitivity. We propose a set of complementary measurements of beam size and divergence with near-field and far-field OTR imaging, respectively, on LPA electron beams ranging in energy from 100 MeV [2] to 2 GeV [3]. The feasibility is supported by analytical modeling for beam size sensitivity and divergence sensitivity. In the latter case, the calculations indicate that the parallel polarization component of the far-field OTR pattern is sensitive to divergences from 0.1 to 0.4 mrad (σ) at 2 GeV, and it is similarly sensitive to divergences from 1 to 5 mrad (σ) at 100 MeV. We anticipate the signal levels from charges of 100 pC will require a 16-bit cooled CCD camera. Other practical challenges in the LPA will also be discussed.
1.G. R. Plateau et al., Phys. Rev. Lett. 109, 064802 (2012).
2.Hai-EnTsai, Chih-Hao Pai, and M.C. Downer, AIP Proc. 1507, 330 (2012)
3.Xiaoming Wang et al., Nature Communications 4,1988(2013).

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TUPOA29

Beam Position Monitoring System for the PIP-II Injector Test Accelerator

ion, pick-up, electronics, linac

349

N. Patel, C.I. Briegel, J.S. Diamond, N. Eddy, B.J. Fellenz, J. Fitzgerald, V.E. Scarpine
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359.
The Proton Improvement Plan II (PIP-II) injector test accelerator is an integrated systems test for the front-end of a proposed continuous-wave (CW) compatible, pulsed H⁻ superconducting RF linac. This linac is part of Fermilab's PIP-II upgrade. This injector test accelerator will help minimize the technical risk elements for PIP-II and validate the concept of the front-end. Major goals of the injector accelerator are to test a CW RFQ and H⁻ source, a bunch-by-bunch Medium-Energy Beam Transport (MEBT) beam chopper and stable beam acceleration through low-energy superconducting cavities. Operation and characterization of this injector places stringent demands on the types and performance of the accelerator beam diagnostics. A beam position monitor (BPM) system has been developed for this application and early commissioning measurements have been taken of beam transport through the beamline.

Poster TUPOA29 [0.469 MB]

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TUPOA30

Fermilab Switchyard Resonant Beam Position Monitor Electronics Upgrade Results

ion, electronics, controls, power-supply

352

T.B. Petersen, J.S. Diamond, N. Liu, P.S. Prieto, D. Slimmer, A.C. Watts
Fermilab, Batavia, Illinois, USA

The readout electronics for the resonant beam position monitors (BPMs) in the Fermilab Switchyard (SY) have been upgraded, utilizing a low noise amplifier transition board and Fermilab designed digitizer boards. The stripline BPMs are estimated to have an average signal output of between -110 dBm and -80 dBm, with an esti-mated peak output of -70 dBm. The external resonant circuit is tuned to the SY machine frequency of 53.10348 MHz. Both the digitizer and transition boards have vari-able gain in order to accommodate the large dynamic range and irregularity of the resonant extraction spill. These BPMs will aid in auto-tuning of the SY beamline as well as enabling operators to monitor beam position through the spill.

Poster TUPOA30 [0.833 MB]

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TUPOA38

Real-Time Magnetic Electron Energy Spectrometer for Use With Medical Linear Acceletors

ion, linac, detector, real-time

361

P.E. Maggi, H.R. Hogstrom, K.L. Matthews II
LSU, Baton Rouge, USA
R.L. Carver
Mary Bird Perkins Cancer Center, Our Lady of the Lake, Baton Rouge, USA

Accelerator characterization and quality assurance is an integral part of electron linear accelerator (linac) use in a medical setting. The current clinical method for radia-tion metrology of electron beams (dose on central axis versus depth in water) only provides a surrogate for the underlying performance of the accelerator and does not provide direct information about the electron energy spectrum. We have developed an easy to use real-time magnetic electron energy spectrometer for characterizing the electron beams of medical linacs. Our spectrometer uses a 0.57 T permanent magnet block as the dispersive element and scintillating fibers coupled to a CCD camera as the position sensitive detector. The goal is to have a device capable of 0.12 MeV energy resolution (which corresponds to a range shift of 0.5 mm) with a minimum readout rate of 1 Hz, over an energy range of 5 to 25 MeV. This work describes the real-time spectrometer system, the detector response model, and the spectrum unfolding method. Measured energy spectra from multi-ple electron beams from an Elekta Infinity Linac are presented.

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TUPOA47

Development of Short Undulators for Electron-Beam-Radiation Interaction Studies

ion, undulator, radiation, laser

380

P. Piot
Fermilab, Batavia, Illinois, USA
M.B. Andorf, G. Fagerberg, M. Figora
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by the US DOE contract DE-SC0013761 with Northern Illinois University
Interaction of an electron beam with external field or its own radiation has widespread applications ranging from coherent radiation generation, phase space cooling or formation of time-structured beam. An efficient coupling mechanism between an electron beam and radiation field relies on the use of a magnetic undulator. In this contribution we detail the construction and magnetic measurements of short (11 period) undulators with 7-cm period built using parts of the ALADDIN U3 undulator*. Possible use of these undulators at two accelerator test facilities to support experiment relevant to cooling techniques and radiation souces are discussed.
* F. C. Younger, W. Jorge Pearce, B. Ng, Nucl. Instrum. Meth Phys. Res. A 347, pp. 96-101 (1994).

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TUPOA57

Using High Precision Beam Position Monitors at the Cornell Electron Storage Ring (CESR) to Measure the One Way Speed of Light Anisotropy

ion, positron, dipole, simulation

399

W.F. Bergan, M.J. Forster, N.T. Rider, D. L. Rubin, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.A. Schmookler
MIT, Cambridge, Massachusetts, USA
B. Wojtsekhowski
CMU, Pittsburgh, Pennsylvania, USA

Funding: NSF PHY-1416318 NSF DGE-1144153
The Cornell Electron Storage Ring (CESR) has been equipped with a number of high-precision beam position monitors which are capable of measuring the orbit of a circulating beam with a precision of a few microns. This technology will enable a precision measurement of deviations in the one-way speed of light. An anisotropic speed of light will alter the beam momentum as it travels around the ring, resulting in a change of orbit over the course of a sidereal day. Using counter-circulating electron and positron beams, we will be able to suppress many of the systematics such as those relating to variations in RF voltage or magnet strength. We show here initial feasibility studies to measure the stability of our beam position monitors and the various systematic effects which may hide our signal and discuss ways in which we can minimize their impact.

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TUPOA59

Successful Laboratory-Industrial Partnerships: the Cornell-Friatec Segmented Insulator for High Voltage DC Photocathode Guns

ion, gun, vacuum, high-voltage

405

K.W. Smolenski, B.M. Dunham
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
D.L. Barth, M. Muehlbauer, S. Wacker
FRIATEC AG, Mannheim, Germany
J.M. Maxson
UCLA, Los Angeles, California, USA

High voltage DC photocathode guns currently offer the most reliable path to electron beams with high current and brightness. The performance of a gun is directly dependent on its vacuum and high voltage capabilities, determined in large part by the ceramic insulators. The insulator must meet XHV standards, bear the load of pressurized SF6 on its exterior, support the massive electrode structures as well as holding off DC voltages up to 750kV. Construction of UHV and high voltage capable insulators require high purity ceramics and metal components proven to minimize thermal stress between the brazed ceramic rings and metal guard rings. The use of replaceable guard rings is a critical way of controlling manufacturing costs while extending the life cycle of the insulator. Successful fabrication requires proven manufacturing methods in flatness, parallelism, and maintaining alignment of many parts during the brazing process. Taking a scalable, modular approach, the insulator design can be applied to a variety of gun voltages and can be used by other projects. The Cornell-Friatec insulator was designed collaboratively and has now been produced in quantity for Cornell and elsewhere.

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TUPOA68

Design, Simulations and Experimental Demonstration of an Intra-Pulse Ramped-Energy Travelling Wave Linac for Cargo Inspection

ion, linac, simulation, beam-loading

421

S.V. Kutsaev, R.B. Agustsson, A. Arodzero, R.D.B. Berry, S. Boucher, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A. Laurich, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A. Verma
RadiaBeam, Santa Monica, California, USA

Funding: This work has been supported by the US Department of Homeland Security, Domestic Nuclear Detection Office, under competitively awarded contract HSHQDC-13-C-B0019.
Novel radiographic imaging techniques [1] based on adaptive, intra-pulse ramped-energy short X-ray packets of pulses, a new type of fast X-ray detectors, and advanced image processing are currently some of the most promising methods for real-time cargo inspection systems. RadiaBeam Technologies is currently building the high-speed Adaptive Railroad Cargo Inspection System (ARCIS), which will enable better than 5 mm line pair resolution, penetration greater than 450 mm of steel equivalent, material discrimination over the range of 6 mm to 250 mm, 100% image sampling rate at speed 45 km/h, and minimal average dose. One of the core elements of ARCIS is a new S-band travelling wave linac with a wide range of energy control that allows energy ramping from 2 to 9 MeV within a single 16 μs RF pulse using the beam loading effect. In this paper, we will discuss the linac design approach and its principal components, as well as engineering and manufacturing aspects. The results of the experimental demonstration of intra-pulse energy ramping will be presented.
[1] A. Arodzero, S. Boucher, A. Murokh, S. Vinogradov, S.V. Kutsaev. System and Method for Adaptive X-ray Cargo Inspection. US Patent Application 2015/1472051.

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TUPOA73

Commissioning and First Results From a Channeling-Radiation Experiment at FAST

ion, detector, gun, radiation

428

J. Hyun
Sokendai, Ibaraki, Japan
D.R. Broemmelsiek, D.R. Edstrom, A.L. Romanov, J. Ruan, T. Sen, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA
A. Halavanau, D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA
P. Kobak
BYU-I, Rexburg, USA
W.D. Rush
KU, Lawrence, Kansas, USA

X-rays have widespread applications in science. Developing compact and high-quality X-ray sources, easy to disseminate, has been an on going challenge. Our group has explored the possible use of channeling radiation driven by a 50 MeV low-emittance electron beam to produce narrowband hard X-rays (photon energy from 40 keV to 140 keV). In this contribution we present the simulated X-ray spectrum including the background bremsstrahlung contribution, and optimization of the relevant electron-beam parameters required to maximize the X-ray brilliance. The results of experiments carried out at Fermilab's FAST facility – which include a 50 MeV superconducting linac and a high-brightness photoinjector – are also discussed. The average brilliance in our experiment is expected to be about one order of magnitude higher than that in previous experiments.

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TUA3CO03

Compact Ring-Based X-Ray Source With on-Orbit and on-Energy Laser-Plasma Injection

ion, laser, plasma, radiation

435

M. Turner
CERN, Geneva, Switzerland
J.R. Cheatam, A.L. Edelen
CSU, Fort Collins, Colorado, USA
J. Gerity
Texas A&M University, College Station, USA
A. Lajoie, C.Y. Wong
NSCL, East Lansing, Michigan, USA
G. Lawler
UCLA, Los Angeles, California, USA
O. Lishilin
DESY Zeuthen, Zeuthen, Germany
K. Moon
UNIST, Ulsan, Republic of Korea
A. A. Sahai, A. Seryi
JAI, London, United Kingdom
K. Shih
SBU, Stony Brook, New York, USA
B. Zerbe
MSU, East Lansing, Michigan, USA

Funding: We acknowledge the stimulating atmosphere and support of US Particle Accelerator School, class of June 2016, where this design study was performed.
We report here the results of a one week long investigation into the conceptual design of an X-ray source based on a compact ring with on-orbit and on-energy laser-plasma accelerator (mini-project 10.4 from [1]). We performed these studies during the June 2016 USPAS class "Physics of Accelerators, Lasers, and Plasma…" applying the art of inventiveness TRIZ. We describe three versions of the light source with the constraints of the electron beam with energy 1 GeV or 3 GeV and a magnetic lattice design being normal conducting (only for the 1 GeV beam) or superconducting (for either beam). The electron beam recirculates in the ring, to increase the effective photon flux. We describe the design choices, present relevant parameters, and describe insights into such machines.
[1] Unifying physics of accelerators, lasers and plasma, A. Seryi, CRC Press, 2015.

Slides TUA3CO03 [8.411 MB]

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TUB3IO02

Overview of Electron Source Development for High Repetition Rate FEL Facilities

ion, gun, cathode, emittance

445

F. Sannibale
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 'fsannibale@lbl.gov
An increasing science demand for high-repetition rate (MHz-class) FEL facilities, from IR to X-rays, has been pushing institutions and groups around the world to develop proposals addressing such a need, and some of them have been already funded and are under construction. Such facilities require the development of high-brightness high-repetition rate electron guns, and a number of groups worldwide started to develop R&D programs to develop electron guns capable of operating at this challenging regime. Here we describe the approaches and technologies used by the different programs and discuss advantages and challenges for each of them. A review of the present achievements is included, as well as a brief analysis to understand if the present technology performance is sufficient to operate present and future high repetition rate FEL facilities.

Slides TUB3IO02 [7.951 MB]

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TUB3CO03

Demonstration of fresh slice self seeding in a hard X-ray free electron laser

ion, experiment, simulation, FEL

450

C. Emma, C. Pellegrini
UCLA, Los Angeles, USA
M.W. Guetg, A.A. Lutman, A. Marinelli, J. Wu
SLAC, Menlo Park, California, USA

We discuss the first demonstration of fresh slice self seeding (FSSS) in a hard X-ray Free Electron Laser (XFEL). The FSSS method utilizes a single electron beam to generate a strong seed pulse and amplify it with a small energy spread electron slice. This extends the capability of self seeded XFELs by producing short pulses, not limited by the duration set by the self-seeding monochromator system, with high peak intensity. The scheme relies on using a parallel plate dechirper to impart a spatial chirp on the beam, and appropriate orbit control to lase with different electron beam slices before and after the self-seeding monochromator. The performance of the FSSS method is analyzed with start-to-end simulations for the Linac Coherent Light Source (LCLS). The simulations include the effect of the parallel plate dechirper and propagation of the radiation field through the monochromator. We also present results of the first successful demonstration of FSSS at LCLS. The radiation properties of FSSS X-ray pulses are compared with the Self-Amplified Spontaneous Emission (SASE) mode of FEL operation for the same electron beam parameters.

Slides TUB3CO03 [10.423 MB]

Poster TUB3CO03 [3.275 MB]

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TUB3CO04

A New Thermionic RF Electron Gun for Synchrotron Light Sources

ion, gun, cathode, coupling

453

S.V. Kutsaev, A.Y. Murokh, E.A. Savin, A.Yu. Smirnov, A.V. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
R.B. Agustsson, J.J. Hartzell, A. Verma
RadiaBeam, Santa Monica, California, USA
A. Nassiri, Y. Sun, G.J. Waldschmidt, A. Zholents
ANL, Argonne, Illinois, USA
E.A. Savin
MEPhI, Moscow, Russia

Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Science, under contract DE-SC0015191 and contract No. DE-AC02-06CH11357.
A thermionic RF gun is a compact and efficient source of electrons used in many practical applications. RadiaBeam Systems and the Advanced Photon Source of Argonne National Laboratory collaborate in developing of a reliable and robust thermionic RF gun for synchrotron light sources which would offer substantial improvements over existing thermionic RF guns and allow stable operation with up to 1A of beam peak current at a 100 Hz pulse repetition rate and a 1.5 μs RF pulse length. In this paper, we discuss the electromagnetic and engineering design of the cavity, and report the progress towards high power tests of the cathode assembly of the new gun.

Slides TUB3CO04 [2.661 MB]

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TUB4IO01

Status of the Los Alamos Multi-Probe Facility for Matter-Radiation Interactions in Extremes

ion, FEL, experiment, linac

464

J.L. Erickson, R.W. Garnett
LANL, Los Alamos, New Mexico, USA

The Matter-Radiation Interactions in Extremes (MaRIE) project will provide capability that will address the control of performance and production of materials at the mesoscale. MaRIE will characterize the behavior of interfaces, defects, and microstructure between the spatial scales of atomic structures and those of the engineering continuum where there is a current capability gap. The mission need is well-met with an x-ray source, coherent to optimize disordered imaging capability, brilliant and high-rep-rate to provide time-dependent information, and high enough energy to see into and through the mesoscale of materials of interest. It will be designed for time-dependence from electronic motion (picosecond) through sound waves (nanosecond) through thermal diffusion (millisecond) to manufacturing (seconds and above). The mission need, the requirements, a plausible alternative reference design of a 12-GeV linac-based 42-keV x-ray free-electron laser, and the status of the project will be described.

Slides TUB4IO01 [16.013 MB]

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TUB4IO02

Accelerator Technical Progress and First Commissioning Results from the European XFEL

ion, linac, FEL, MMI

469

R. Wichmann
DESY, Hamburg, Germany

The construction of the European XFEL is coming to an end. The linac tunnel will be closed and commissioning of the main linac will start. The status of the construction project is reviewed. Commissioning of the injector of the European XFEL was already performed in 2016 while construction of the main linac was continuing. The commissioning goals and achievements for the XFEL injector will be reviewed.
Proposed Speaker: W. Decking, DESY

Slides TUB4IO02 [13.428 MB]

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TUB4CO03

Optimization of Compton Source Performance Through Electron Beam Shaping

ion, radiation, brightness, photon

474

A. Malyzhenkov, N.A. Yampolsky
LANL, Los Alamos, New Mexico, USA

We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of these sources is limited by the electron beam quality since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6d electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized then if the electron phase space is transformed in a way so that all electrons scatter off the x-ray photons of same frequency in the same direction. We describe the x-ray photon beam quality through the Wigner function (6d photon phase space distribution) and derive it for the ICS source when the electron and laser rms matrices are arbitrary. We find the optimal uncorrelated electron beam phase space distribution resulting in the highest brightness of the ICS source for the simple on axis case as an example.

Slides TUB4CO03 [1.673 MB]

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TUPOB13

Simulations of Space Charge Neutralization in a Magnetized Electron Cooler

ion, simulation, collider, experiment

511

J. Gerity, P.M. McIntyre
Texas A&M University, College Station, USA
D.L. Bruhwiler, C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA
V. Moens
EPFL, Lausanne, Switzerland
C.S. Park, G. Stancari
Fermilab, Batavia, Illinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Award Number DE-SC0015212.
Magnetized electron cooling at relativistic energies and Ampere scale current is essential to achieve the proposed ion luminosities in a future electron-ion collider (EIC). Neutralization of the space charge in such a cooler can significantly increase the magnetized dynamic friction and, hence, the cooling rate. The Warp framework is being used to simulate magnetized electron beam dynamics during and after the build up of neutralizing ions, via ionization of residual gas in the cooler. The design follows previous experiments at Fermilab as a verification case. We also discuss the relevance to EIC designs.

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TUPOB16

A Simple Method for Measuring the Electron-Beam Magnetization

ion, solenoid, cathode, emittance

521

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
G. Ha
POSTECH, Pohang, Kyungbuk, Republic of Korea
P. Piot
Fermilab, Batavia, Illinois, USA
J.G. Power, E.E. Wisniewski
ANL, Argonne, Illinois, USA
G. Qiang
TUB, Beijing, People's Republic of China

There are a number of projects that require magnetized beams, such as electron cooling or aiding in flat beam transforms. Here we explore a simple technique to characterize the magnetization, observed through the angular momentum of magnetized beams. These beams are produced through photoemission. The generating drive laser first passes through microlens arrays (fly-eye light condensers) to form a transversely modulated pulse incident on the photocathode surface. The resulting charge distribution is then accelerated from the photocathode. We explore the evolution of the pattern via the relative shearing of the beamlets, providing information about the angular momentum. This method is illustrated through numerical simulations and preliminary measurements carried out at the Argonne Wakefield Accelerator (AWA) facility are presented.

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TUPOB18

Beam Test of Masked-Chicane Micro-Buncher

ion, simulation, bunching, controls

528

Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA
D.R. Broemmelsiek, D.J. Crawford, D.R. Edstrom, A.H. Lumpkin, J. Ruan, J.K. Santucci, J.C.T. Thangaraj, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA

Funding: This work was supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. We also thank the FAST Department team for the helpful discussion and technical supports.
Masking a dispersive beamline such as a dogleg or a chicane [1, 2] is a simple way to shape a beam in the longitudinal and transverse space. This technique is often employed to generate arbitrary bunch profiles for beam/laser-driven accelerators and FEL undulators or even to reduce a background noise from dark currents in electron linacs. We have been investigating a beam-modulation of a slit-masked chicane, which was deployed for crystal-channeling experiments at the injector beamline of the Fermilab Accelerator Science and Technology (FAST) facility. With a nominal beam of 3 ps bunch length, Elegant simulations showed that a slit-mask with slit period 900 um and aperture width 300 um induces a modulation with bunch-to-bunch space of about 187 um (0.25 nC), 270 um (1 nC) and 325 um (3.2 nC) with 3 ~ 6% correlated energy spread: An initial energy modulation pattern has been observed in the electron spectrometer downstream of the masked chicane using a micropulse charge of 260 pC and 40 micropulses. Investigations of the beam longitudinal modulation are planned with a Martin-Puplett interferometer and a synchro-scan streak camera at a station between the chicane and spectrometer.
[1] D.C.Nguyen, B.E.Carlsten, NIMA 375, 597 (1996)
[2] P.Muggli, V.Yakimeno, M.Babzien, et al., PRL 101, 054801 (2008)

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TUPOB19

FEL Wiggler Bussbar Field Compensation

ion, wiggler, storage-ring, FEL

532

B. Li, H. Hao, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
J.Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Abstract The Duke storage ring is a dedicated driver for the storage ring based free-electron laser (FEL) and the High Intensity Gamma-ray Source (HIGS). The high intensity gamma-ray beam is produced using Compton scattering between the electron and FEL photon beams. The beam displacement and angle at the collision point need to be maintained constant during the gamma-ray beam production. The magnetic field of the copper bussbars carrying the current to the FEL wigglers can impact the beam orbit. The compensation scheme in-general is complicated. In this work, we report preliminary results of a bussbar compensation scheme for one of the wiggler and power supply configurations. Significant reductions of the orbit distortions have been realized using this compensation.

Poster TUPOB19 [3.693 MB]

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TUPOB22

Dependence of the Coupling of Dipole Motion From Bunch to Bunch Caused by Electron Clouds at CesrTA Due to Variations in Bunch Length and Chromaticity

ion, damping, positron, dipole

538

M.G. Billing, L.Y. Bartnik, M.J. Forster, N.T. Rider, J.P. Shanks, M.B. Spiegel, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
R. Holtzapple
CalPoly, San Luis Obispo, California, USA
E.C. Runburg
University of Notre Dame, Indiana, USA

The Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) has been utilized to probe the interaction of the electron cloud with a 2.1 GeV stored positron beam. Recent experiments have characterized any dependence of beam'electron cloud (EC) interactions on the bunch length (or synchrotron tune) and the vertical chromaticity. The measurements were performed on a 30-bunch positron train with 14 nsec spacing between bunches, at a fixed current of 0.75 mA/bunch. The dynamics of the stored beam, in the presence of the EC, was quantified using 20 turn-by-turn beam position monitors in CESR to measure the correlated bunch-by-bunch dipole motion. In this paper we report on the observations from these experiments and analyze the coupling of di-pole motion from bunches within the train to subsequent bunches, caused by the EC.

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TUPOB23

Electron Cloud Simulations for the Low-Emittance Upgrade at the Cornell Electron Storage Ring

ion, operation, positron, synchrotron

542

J.A. Crittenden, Y. Li, S. Poprocki, J.E. San Soucie
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the National Science Foundation DMR 13-32208
The Cornell Electron Storage Ring operations group is planning a major upgrade of the storage ring performance as an X-ray user facility. The principal modification foresees replacing the former e⁻e⁺ interaction region with six double-bend achromats, reducing the emittance by a factor of four. The beam energy will increase from 5.3 to 6.0 GeV and single-beam operation will replace the present two-beam e⁻e⁺ operation. The initial phase of the project will operate a single positron beam, so electron cloud buildup may contribute to performance limitations. This work describes a synchrotron radiation analysis of the new ring, and employs its results to provide ring-wide estimates of cloud buildup and consequences for the lattice optics.

Poster TUPOB23 [4.832 MB]

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TUPOB24

Optimization of Linear Induction Radiography Accelerator with Electron Beam with Energy Variation

ion, target, solenoid, induction

546

Y.H. Wu, Y.J. Chen
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The current interest for the next generation linear induction radiography accelerator (LIA) is to generate multiple electron beam pulses with high peak currents. The beam energy and current may vary from pulse to pulse. Conse-quently, the transport and control of multi-pulsing intense electron beams through a focus-ing lattice over a long distance on such machine becomes challenging. Simulation studies of multi-pulse LIAs using AMBER [1] and BREAKUP Code [2] are described. These include optimized focusing magnetic tune for beams with energy and current variations, and steering correction for corkscrew motion. The impact of energy variation and accelerating voltage error on radiograph performance are discussed.

Poster TUPOB24 [1.419 MB]

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TUPOB25

Unfolding Electron Beam Parameters Using Spot Size Measurement From Magnet Scan

ion, target, emittance, beam-transport

549

Y.H. Wu, Y.J. Chen, J. Ellsworth
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The Flash X-ray Radiography (FXR) [1] line-ar induction accelerator at Lawrence Livermore National Laboratory produces x-ray bursts for radiographs. The machine is able to produce x-ray spot sizes less than 2mm. Using the spot sizes measured from the magnet scanning, the beam parameters are unfolded by modelling the FXR LINAC with the simulation code AMBER [2] and the envelope code XENV [3]. In this study, the most recent spot size measurement results and techniques used to extract the beam parameters are described. Using the unfolded beam parameters as the initial condition, the backstreaming ions' neutralization factor f = 0.3 is found by comparing the calculated spot sizes with measured spot sizes at the target.

Poster TUPOB25 [0.576 MB]

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TUPOB29

Simulations of Nonlinear Beam Dynamics in the JLEIC Electron Collider Ring

ion, sextupole, emittance, dynamic-aperture

555

F. Lin, Y.S. Derbenev, V.S. Morozov, F.C. Pilat, G.H. Wei, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Cai, Y.M. Nosochkov, M.K. Sullivan
SLAC, Menlo Park, California, USA
M.-H. Wang
Self Employment, Private address, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
The short lengths of colliding bunches in the proposed Jefferson Lab Electron-Ion Collider (JLEIC) allow for small beta-star values at the interaction point (IP) yielding a high luminosity. The strong focusing associated with the small beta-stars results in high natural chromaticities and potentially a beam smear at the IP. Rapid growth of the electron equilibrium emittances and momentum spread with energy further complicates the situation. We investigated nonlinear dynamics correction schemes that overcome these problems and allow for stable beam dynamics and sufficient beam lifetime at the highest electron energy. In this paper, we present and compare tracking simulation results for various schemes considering their emittance contributions.

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TUPOB31

Compensation of Chromaticity in the JLEIC Electron Collider Ring

ion, sextupole, emittance, dipole

561

Y.M. Nosochkov, Y. Cai, M.K. Sullivan
SLAC, Menlo Park, California, USA
Y.S. Derbenev, F. Lin, V.S. Morozov, F.C. Pilat, G.H. Wei, Y. Zhang
JLab, Newport News, Virginia, USA
M.-H. Wang
Self Employment, Private address, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
The Jefferson Lab Electron-Ion Collider (JLEIC) is being designed to achieve a high luminosity of up to 10³⁴ 1/(cm²*sec). The latter requires a small beam size at the interaction point demanding a strong final focus (FF) quadrupole system. The strong beam focusing in the FF unavoidably creates a large chromaticity which has to be compensated in order to avoid a severe degradation of momentum acceptance. This has to be done while preserving sufficient dynamic aperture. An additional design requirement for the chromaticity compensation optics in the electron ring is preservation of the low beam emittance. This paper reviews the development and selection of a chromaticity correction scheme for the electron collider ring.

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TUPOB36

Simulation Study on JLEIC High Energy Bunched Electron Cooling

ion, emittance, simulation, collider

568

H. Zhang, S.V. Benson, J. Chen, Y.S. Derbenev, R. Li, Y. Roblin, Y. Zhang
JLab, Newport News, Virginia, USA
H. Huang, L. Luo
ODU, Norfolk, Virginia, USA

Funding: * Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
In the JLab Electron Ion Collider (JLEIC) project the traditional electron cooling technique is used to reduce the ion beam emittance at the booster ring, and to compensate the intrabeam scattering effect and maintain the ion beam emittance during the collision at the collider ring. Different with other electron coolers using DC electron beam, the proposed electron cooler at the JLEIC ion collider ring uses high energy bunched electron beam, provided by an ERL. In this paper, we report some recent simulation study on how the electron cooling rate will be affected by the bunched electron beam properties, such as the correlation between the longitudinal position and momentum, the bunch size, and the Larmor emittance.

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TUPOB43

Magnetic Cloaking of Charged Particle Beams

ion, detector, superconducting-magnet, dipole

588

K.G. Capobianco-Hogan, A.A. Adhyatman, G. Arrowsmith-Kron, G. Bello Portmann, D.B. Bhatti, R. Cervantes, B.D. Coe, A. Deshpande, N. Feege, S.P. Jeffas, T.C. Krahulik, J.J. LaBounty, T.M. LaByer, A. Oliveira, H.A. Powers, R.S. Sekelsky, V.D. Shethna, N. Ward, H.J. van Nieuwenhuizen
Stony Brook University, Stony Brook, USA
R. Cervantes
University of Washington, CENPA, Seattle, USA
B.D. Coe
BNL, Upton, Long Island, New York, USA

In order to measure the momentum of particles produced by asymmetric collisions in the proposed Electron Ion Collider, a magnetic field should be introduced perpendicular to the path of the beam to increase momentum resolution without bending or depolarizing it. A magnetic cloak consisting of a superconducting magnetic shield surrounded by a ferromagnetic layer is capable of shielding the interior from a magnetic field – thereby protecting the beam – without distorting the field outside of the cloak – permitting detector coverage at high pseudorapidity.

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TUPOB56

The eRHIC Ring-Ring Design

ion, proton, luminosity, dipole

616

C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A.V. Fedotov, W. Fischer, Y. Hao, A. Hershcovitch, Y. Luo, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, S. Seletskiy, T.V. Shaftan, V.V. Smaluk, S. Tepikian, F.J. Willeke, H. Witte, Q. Wu
BNL, Upton, Long Island, New York, USA

The ring-ring version of the eRHIC electron-ion collider design aims at providing electron-proton collisions with a center-of-mass energy ranging from 32 to 141 GeV at a luminosity reaching 10³³ cm^-2 sec^-1. This design of the double-ring collider also supports electron-ion collisions with similar electron-nucleon luminosities, and is upgradeable to 10³⁴ cm^-2 sec^-1 using bunched beam electron cooling of the hadron beam. The baseline luminosities are achievable using existing technologies and beam parameters that have been routinely achieved at RHIC in hadron-hadron collisions or elsewhere in e⁺e⁻ collisions. This minimizes the risk associated with the challenging luminosity goal and is keeping the technical risk of the e-RHIC electron-ion collider low. The latest design status will be presented.

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TUPOB60

Permanent Magnets for High Energy Nuclear Physics Accelerators

ion, quadrupole, permanent-magnet, dipole

622

N. Tsoupas, S.J. Brooks, A.K. Jain, F. Méot, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US Department of Energy
The proposed eRHIC accelerator1 will collide 20 GeV polarized electrons with 250 GeV polarized protons or 100 GeV/n polarized 3He ions or other unpolarized heavy ions. The electron accelerator of the eRHIC will be based on a 1.665 GeV Energy Recovery Linac (ERL) placed in the RHIC tunnel and two Fixed Field Alternating Gradient (FFAG) recirculating rings placed alongside the RHIC accelerator. The electron bunches reach the 20 GeV energy after passing 12 times through the ERL by recirculation in the FFAG rings. The FFAG rings consist of FODO cells comprised of one focusing and one defocusing quadrupoles made of permanent magnet material. Similarly other sections of the electron accelerator will utilize permanent magnets. In this presentation we will discuss details on the design of these magnets and their advantages over the current-excited magnets.
1. <http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf>

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TUPOB62

Benchmark of Strong-Strong Beam-Beam Simulation of the Kink Instability in an Electron Ion Collider Design

ion, proton, simulation, emittance

628

J. Qiang, R.D. Ryne
LBNL, Berkeley, California, USA
Y. Hao
BNL, Upton, Long Island, New York, USA

The kink instability limits the performance of a potential linac-ring based electron-ion collider design. In this paper, we report on the simulation study of the kink instability using a self-consistent strong-strong beam-beam model.

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TUPOB63

POSINST Simulation on Fermilab Main Injector and Recycler Ring

ion, dipole, simulation, proton

632

Y. Ji
IIT, Chicago, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA
R.M. Zwaska
Fermilab, Batavia, Illinois, USA

The Fermilab accelerator complex is currently undergoing an upgrade from 400kW to 700kW. This intensity could push operations into the region where electron cloud (e-cloud) generation could be observed and even cause instabilities. The POSINST simulation code was used to study how in- creasing beam intensities will affect electron cloud genera- tion. Threshold simulations show how the e-cloud density depend on the beam intensity and secondary electron yield (SEY) in the Main Injector (MI) and Recycler Ring (RR).

Poster TUPOB63 [1.542 MB]

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WEA1CO04

Hollow Electron Beam Collimation for HL-LHC - Effect on the Beam Core

ion, simulation, experiment, emittance

651

M. Fitterer, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA
R. Bruce, S. Papadopoulou, G. Papotti, D. Pellegrini, S. Redaelli, D. Valuch, J.F. Wagner
CERN, Geneva, Switzerland

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy.
Collimation with hollow electron beams or lenses (HEL) is currently one of the most promising concepts for active halo control in HL-LHC. In previous studies it has been shown that the halo can be efficiently removed with a hollow electron lens. Equally important as an efficient removal of the halo, is also to demonstrate that the core stays unperturbed. In this paper, we present a summary of the experiment at the LHC and simulations in view of the effect of the HEL on the beam core in case of a pulsed operation.

Slides WEA1CO04 [1.830 MB]

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WEA1CO05

Microwave Instability Studies in NSLS-II

ion, lattice, simulation, wiggler

655

A. Blednykh, B. Bacha, G. Bassi, Y. Chen-Wiegart, W.X. Cheng, O.V. Chubar, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886.
The microwave instability in the NSLS-II has been studied for the current configuration of insertion devices, 9 In-Vacuum Undulators (IVU's), 3EPU's, 3 Damping Wigglers. The energy spread as a function of single bunch current has been measured based on the frequency spectrum of IVU for X-Ray Spectroscopy (SRX) beam line. The results for two lattices, bare lattice with nominal energy spread 0.0005 and a lattice with one DW magnet gap closed (nominal energy spread 0.0007) are compared. In addition we used a Spectrum Analyzer to measure the beam spectrum. The instability thresholds for two different lattices cross-checked numerically using the particle tracking code SPACE and longitudinal impedance.

Slides WEA1CO05 [2.380 MB]

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WEA2CO03

Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA

ion, simulation, dipole, positron

672

S. Poprocki, J.A. Crittenden, S.N. Hearth, J.D. Perrin, D. L. Rubin, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, and PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538.
We report on measurements of electron cloud (EC) induced tune shifts and emittance growth at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) with comparison to tracking simulation predictions. Experiments were performed with 2.1 GeV positrons in a 30 bunch train with 14 ns bunch spacing and 9 mm bunch length, plus a witness bunch at varying distance from the train to probe the cloud as it decays. Complementary data with an electron beam were obtained to distinguish EC effects from other sources of tune shifts and emittance growth. High resolution electric field maps are computed with EC buildup simulation codes (ECLOUD) in the small region around the beam as the bunch passes through the cloud. These time-sliced field maps are input to a tracking simulation based on a weak-strong model of the interaction of the positron beam (weak) with the electron cloud (strong). Tracking through the full lattice over multiple radiation damping times with electron cloud elements in the dipole and field-free regions predict vertical emittance growth, and tune shifts in agreement with the measurements.

Slides WEA2CO03 [1.227 MB]

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WEA2CO04

Vlasov Analysis of Microbunching Gain for Magnetized Beams

ion, bunching, simulation, radiation

675

C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
Y.S. Derbenev, D. Douglas, R. Li, C. Tennant
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE- AC05-06OR23177.
For a high-brightness electron beam with low energy and high bunch charge traversing a recirculation beamline, coherent synchrotron radiation and space charge effect may result in the microbunching instability (MBI). Both tracking simulation and Vlasov analysis for an early design of Circulator Cooler Ring* for the Jefferson Lab Electron Ion Collider reveal significant MBI. It is envisioned these could be substantially suppressed by using a magnetized beam. In this work, we extend the existing Vlasov analysis, originally developed for a non-magnetized beam, to the description of transport of a magnetized beam including relevant collective effects. The new formulation will be further employed to confirm prediction of microbunching suppression for a magnetized beam transport in a recirculating machine design.
*Ya. Derbenev and Y. Zhang, COOL'09 (FRM2MCCO01)

Slides WEA2CO04 [4.662 MB]

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WEPOA01

Effect of Proton Bunch Parameter Variation on AWAKE

ion, wakefield, injection, plasma

684

N. Savard
University of Victoria, Victoria BC, Canada
P. Muggli
MPI, Muenchen, Germany
J. Vieira
IPFN, Lisbon, Portugal

In AWAKE, long proton bunches propagate through a plasma, generating wakefields through the self-modulation instability (SMI). The phase velocity of these wakefields changes during the first 4 m of propagation and growth of the SMI, after which it stabilizes at the proton bunch velocity. This means that the ideal injection point for electrons to be accelerated is after 4 m into the plasma. Using the PIC code OSIRIS, we study how small changes in the initial proton bunch parameters (such as charge, radial and longitudinal bunch length, etc) to be expected in the experiment affect the phase velocity of the wakefields, primarily by looking at the difference in the phase of the wakefields at the point of injection (along the bunch and along the plasma) when changing these parameters by a small amount (±5%). We also look for the region of optimal acceleration/focusing for electron injection. Ultimately, it is found that small changes in the initial proton bunch parameters are not expected to significantly impact electron injection experiments in the future.

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WEPOA05

EBIS Charge Breeder for RAON Facility

ion, vacuum, gun, ISOL

696

S.A. Kondrashev, J.-W. Kim, Y.K. Kwon, Y.H. Park, H.J. Son
IBS, Daejeon, Republic of Korea

New large scale accelerator facility called RAON is under design in Institute for Basic Science (IBS, Daejeon, Korea). Both technics of rare isotope production Isotope Separation On-Line (ISOL) and In-Flight Fragmentation (IF) will be combined within one facility for the first time to provide wide variety of rare isotope ion beams for nuclear physics experiments and applied research. Electron Beam Ion Source (EBIS) charge breeder will be used to prepare rare isotope ion beams produced by ISOL method for efficient acceleration. Beams of different rare isotopes will be charge-bred by an EBIS charge breeder to a charge-to-mass ratio (q/A) ≥ 1/4 and accelerated by linac post-accelerator to energies of 18.5 MeV/u. RAON EBIS charge breeder will provide the next step in the development of breeder technology by implementation of electron beam with current up to 3 A and utilization of wide (8') warm bore of 6 T superconducting solenoid. The design of RAON EBIS charge breeder and results of dumping of high power DC and pulsed electron beam into collector will be presented and discussed.

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WEPOA06

New Coolers for Ion Ion Colliders

ion, collider, gun, proton

700

V.V. Parkhomchuk
BINP SB RAS, Novosibirsk, Russia

For crucial contributions in the proof of principle of electron cooling, for leading contribution to the experimental and theoretical development of electron cooling, and for achievement of the planned parameters of coolers for facilities in laboratories around the world the 2016 "Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators" was awarded to Vasili Parkhomchuk. In this paper new future coolers for ion*ion collider will be discussed.

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WEPOA12

Interleaving Lattice Design for APS Linac

ion, lattice, linac, gun

713

S. Shin, Y. Sun, A. Zholents
ANL, Argonne, Illinois, USA

In order to realize and test advanced accelerator concepts and hardware, the existing beamline with both old and new components are being reconfigured in Linac Extension Area (LEA) of APS linac. Photo injector, which had been installed in the beginning of APS linac, will provide low emittance electron beam into the LEA. The thermionic RF gun beam for storage ring and photo-cathode RF gun beam for LEA will be operated though the LINAC in an interleaved fashion. In this presentation, technical issues as well as beam dynamics on the design for interleaving operation will be described.

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WEPOA17

On the Possibility of Using Nonlinear Elements for Landau Damping in High-Intensity Beams

ion, octupole, insertion, optics

729

E. Gianfelice-Wendt, Y.I. Alexahin, V.A. Lebedev, A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE
Direct space-charge force shifts the incoherent tunes down from the coherent ones switching off Landau damping of coherent oscillations at high beam intensity. To restore it the nonlinear elements can be employed which move back tunes of large amplitude particles. In the present report we consider the possibility of creating a "nonlinear integrable optics" insertion in the Fermilab Recycler to host either octupoles or hollow electron lens for this purpose. For comparison we also consider the classic scheme with distributed octupole families. It is shown that for the Proton Improvement Plan II parameters the required nonlinear tuneshift can be created without destroying the dynamic aperture.

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WEPOA24

Installation and Commissioning of an Ultrafast Electron Diffraction Facility as Part of the ATF-II Upgrade

ion, operation, experiment, MMI

742

M.A. Palmer, M. Babzien, M.G. Fedurin, C. Folz, M. Fulkerson, K. Kusche, J.J. Li, R. Malone, T.V. Shaftan, J. Skaritka, L. Snydstrup, C. Swinson, F.J. Willeke
BNL, Upton, Long Island, New York, USA

Funding: This work was funded by the US Department of Energy under contract DE-SC0012704.
The Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL) is presently carrying out an upgrade, ATF-II, which will provide significantly expanded experimental space and capabilities for its users. One of the new capabilities being integrated into the ATF-II program is an Ultrafast Electron Diffraction (UED) beam line, which was originally deployed in the BNL Source Development Laboratory. Inclusion of the UED in the ATF-II research portfolio will enable ongoing development and extension of the UED capabilities for use in materials research. We discuss the design, installation and commissioning of the UED beam line at ATF-II as well as plans for future upgrades.

Poster WEPOA24 [18.332 MB]

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WEPOA33

Novel Metallic Structures for Wakefield Acceleration

ion, wakefield, cavity, acceleration

762

X.Y. Lu, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

Funding: US DOE, Office of High Energy Physics
Three novel ideas for wakefield acceleration (WFA) of electrons with metallic periodic subwavelength structures will be presented. The first idea is a deep corrugation structure for collinear WFA. A design for the Argonne Wakefield Accelerator is shown. An analytical model is developed and it agrees with the CST wakefield solver. A scaling study has been performed, and ways to increase the gradient will be discussed. The deep corrugation structure can generate a higher gradient than a dielectric tube with the same beam aperture when excited by the same bunch. The second idea is an elliptical structure for two-beam acceleration (TBA). The unit cell is an elliptical cavity, and the drive beam hole and the witness beam hole are located around the two focal points. The TBA process has been calculated and will be presented. The third idea is a metamaterial ‘wagon wheel' structure for a power extractor design. The fundamental mode is a TM mode with a negative group velocity. A power extractor at 11.7 GHz based on the structure can reach a GW power level when a train of 40 nC bunches with 1.3 GHz rep rate are sent in.

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WEPOA40

Construction Status of a RF-Injector with a CNT-Tip Cathode for High Brightness Field-Emission Tests

ion, cathode, gun, emittance

785

Y.-M. Shin, G. Fagerberg, M. Figora
Northern Illinois University, DeKalb, Illinois, USA
A.T. Green
Northern Illinois Univerity, DeKalb, Illinois, USA

We have been constructing a S-band RF-injector system for field-emission tests of a CNT-tip cathode. A pulsed Sband klystron is installed and fully commissioned with 5.5 MW peak power in a 2.5 microsecond pulse length and 1 Hz repetition rate. A single-cell RFgun is designed to produce with 0.5 - 1 pC electron bunches in a photo-emission mode within a 50 fs - 3 ps at 0.5- 1 MeV. The measured RF system jitters are within 1 % in magnitude and 0.2° in phase, which would induce 3.4 keV and 0.25 keV of energy jitters, corresponding to 80 fs and 5 fs of temporal jitters, respectively. Our PIC simulations indicate that the designed bunch compressor reduces the TOAjitter by about an order of magnitude. Emission current and beam brightness of the field-emitted beam are improved by implanting CNT tips on the cathode surface, since they reduce the emission area, while providing high current emission. Once the system is completely commissioned in field-emission mode, the CNT-tip cathode will be tested in terms of klystron-power levels to map out its I-V characteristics under pulse emission condition.

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WEPOA42

RF Design of a 1.3-GHz High Average Beam Power SRF Electron Source

ion, cathode, gun, simulation

789

N. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
I.V. Gonin, R.D. Kephart, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

There is a significant interest in developing high-average power electron sources, particularly those integrated with Superconducting Radio Frequency (SRF) accelerator systems. Even though there are examples of high-average-power electron sources, they are not compact, highly efficient, or available at a reasonable cost. Adapting the recent advances in SRF cavities, RF power sources, and innovative solutions for an SRF gun and cathode system, we have developed a design concept for a compact SRF high-average power electron linac. This design will produce electron beams with energies up to 10 MeV. In this paper, we present the design results of our cathode structure integrated with modified 9-cell accelerating structure.

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WEPOA44

Accleration System of Beam Brightness Booster

ion, space-charge, brightness, proton

796

V.G. Dudnikov
Muons, Inc, Illinois, USA
A.V. Dudnikov
BINP SB RAS, Novosibirsk, Russia

The brightness and intensity of a circulating proton beam now can be increased up to space charge limit by means of charge exchange injection or by an electron cooling but cannot be increased above this limit. Significantly higher brightness can be produced by means of the charge exchange injection with the space charge compensation [1]. The brightness of the space charge compensated beam is limited at low level by development of the electron-proton (e-p) instability [2]. Fortunately, e-p instability can be self-stabilized at a high beam density. A beam brightness booster (BBB) for significant increase of accumulated beam brightness is discussed. Accelerating system with a space charge compensation is proposed and described. The superintense beam production can be simplified by developing of nonlinear nearly integrable focusing system with broad spread of betatron tune and the broadband feedback system for e-p instability suppression .
[1] V. Dudnikov, in Proceedings of the Particle Accelerator Conference, Chicago, 2001..
[2] G. Budker, et al., Sov. Atomic Energy 22, 384 (1967);

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WEPOA45

Positive and Negative Ions Radio Frequency Sources with Solenoidal Magnetic Field

ion, plasma, solenoid, ion-source

799

V.G. Dudnikov, R.P. Johnson
Muons, Inc, Illinois, USA
G. Dudnikova
ICT SB RAS, Novosibirsk, Russia
B. Han, S. Murrey, C. Stinson
ORNL RAD, Oak Ridge, Tennessee, USA
T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA

Funding: The work was supported in part by US DOE Contract DE-AC05-00OR22725 and by STTR grant, DE-SC0011323.
Operation of Radio Frequency surfaces plasma sources (RF SPS) with a solenoidal magnetic field are described. RF SPS with solenoidal and saddle antennas are discussed. Dependences of beam current and extraction current on RF power, gas flow, solenoidal magnetic field and filter magnetic field are presented.

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WEPOA55

Modulator Simulations for Coherent Electron Cooling

ion, simulation, quadrupole, plasma

816

J. Ma, X. Wang
SBU, Stony Brook, New York, USA
V. Litvinenko, V. Samulyak, G. Wang, K. Yu
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
V. Samulyak
SUNY SB, Stony Brook, New York, USA

Highly resolved numerical simulations of the modulator, the first section of the proposed coherent electron cooling (CEC) device, have been performed using the code SPACE. The beam parameters for simulations are relevant to the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Numerical convergence has been studied using various numbers of macro-particles and mesh refinements of computational domain. A good agreement of theory and simulations has been obtained for the case of stationary and moving ions in uniform electron clouds with realistic distribution of thermal velocities. The main result of the paper is the prediction of modulation processes for ions with reference and off-reference coordinates in realistic Gaussian electron bunches with quadrupole field.

Poster WEPOA55 [1.510 MB]

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WEPOA57

Stabilized Operation Mode of Laser Ion Source Using Pulsed Magnetic Field

ion, laser, ion-source, solenoid

823

S. Ikeda, M.R. Costanzo, T. Kanesue, R.F. Lambiase, C.J. Liaw, M. Okamura
BNL, Upton, Long Island, New York, USA

A laser ion source (LIS) provides several types of singly charged ions into an electron beam ion source (EBIS) followed by linear accelerator injectors for the Relativistic Heavy Ion Collider (RHIC) and the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory. In the present set-up of the LIS, beam current shape varies with time drastically. It is expected that the present current shape is not optimal for the ion trap of the EBIS. However, there are no knobs to modify the shape flexibly. Therefore, as an upgrade of the LIS, we install a coil and a pulsed circuit* that generates a fast-rising pulsed magnetic field to tailor the beam current shape. In this presentation, the effect of the magnetic field on the beam profile from the LIS and the performance of the injectors, such as the transmission and the charge injected into an accelerator downstream, are described.

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WEPOA62

The Center for Bright Beams

ion, brightness, cavity, cathode

830

J.R. Patterson, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Y.K. Kim
University of Chicago, Chicago, Illinois, USA

Funding: National Science Foundation award PHY-1549132.
The Center for Bright Beams (CBB) is a new National Science Foundation-supported Science and Technology Center. CBB's research goal is to increase the brightness of electron beams while reducing the cost and size of key technologies. To achieve this, it will augment the capabilities of accelerator physicists with those of physical chemists, materials scientists, condensed matter physicists, plasma physicists, and mathematicians. This approach has the potential to increase the brightness of electron sources through better photocathodes, the efficiency and gradient of SRF cavities through deeper understanding of superconducting compounds and their surfaces, and better understanding of beam storage and transport and the associated optics by using new mathematical techniques.

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WEA3IO01

Emittance Growth from Modulated Focusing in Bunched Beam Cooling

ion, emittance, simulation, betatron

833

M. Blaskiewicz
BNL, Upton, Long Island, New York, USA

The low energy RHIC electron cooling (LEReC) project at Brookhaven employs a linac to supply electrons with kinetic energies from 1.6 to 2.6 MeV. Along with cooling the stored ion beam the electron bunches create a coherent space charge field which can cause emittance growth. This is the primary source of heating when the cooling is well tuned. An analytic theory of this process is presented and compared with simulations.

Slides WEA3IO01 [4.160 MB]

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WEA3IO02

Start-to-End Beam Dynamics Optimization of X-Ray FEL Light Source Accelerators

ion, linac, controls, FEL

838

J. Qiang
LBNL, Berkeley, California, USA

State-of-the-art tools have been developed that allow start-to-end modeling of the beam formation at the cathode, to its transport, acceleration, and delivery to the undulator. Algorithms are based on first principles, enabling the capture of detailed physics such as shot-noise driven micro-bunching instabilities. The most recent generation of the IMPACT code, using multi-level parallelization on massively parallel supercomputers, now enables multi-objective parametric optimization. This is facilitated by recent advances such as the unified differential evolution algorithm*. The most recent developments will be described, together with applications to the modeling of LCLS-II**.
*J. Qiang, et al, http://www.optimization-online.org/DB_FILE/2015/03/4796.pdf, submitted
**J. Qiang, et al, in preparation

Slides WEA3IO02 [10.928 MB]

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WEA4CO05

Accelerator Physics Design Requirements and Challenges of RF Based Electron Cooler LEReC

ion, cavity, cathode, emittance

867

A.V. Fedotov, M. Blaskiewicz, W. Fischer, D. Kayran, J. Kewisch, S. Seletskiy, J.E. Tuozzolo
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A Low Energy RHIC electron Cooler (LEReC) is presently under construction at BNL to improve the luminosity of the Relativistic Heavy Ion Collider (RHIC). The required electron beam will be provided by a photoemission electron gun and accelerated by a RF linear accelerator. As a result, LEReC will be first bunched beam electron cooler. In addition, this will be the first electron cooler to cool beams under collisions. The achievement of very tight electron beam parameters required for cooling is very challenging and is being addressed by a proper beam transport and engineering design. In this paper, we describe accelerator physics requirements, design considerations and parameters, as well as associated challenges of such electron cooling approach.

Slides WEA4CO05 [4.866 MB]

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WEPOB18

Bend Magnet Head Loads and Out of Orbit Scenarios

ion, photon, software, lattice

931

T.T. Valicenti, J.A. Carter, P.K. Den Hartog, K.J. Suthar
ANL, Argonne, Illinois, USA

This paper presents an analytical calculation of the spatial power spectrum emitted from relativistic electrons passing through a series of bend magnets. Using lattice files from the software Elegant, both the ideal and missteered trajectories taken by the beam are considered in determination of the power profile. Calculations were performed for the Advanced Photon Source Upgrade multi-bend-achromat storage-ring. Results were validated with Synrad, a monte-carlo based program designed at CERN. The power distribution and integrated total power values are in agreement with Synrad's results within one percent error. The analytic solution used in this software gives a both quick and accurate tool for calculating the heat load on a photon absorber. The location and orientation can be optimized in order to reduce the peak intensity and thus the maximum thermal stress. This can be used with any optimization or FEA software and gives rise to a versatile set of uses for the developed program.

Poster WEPOB18 [2.491 MB]

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WEPOB23

Performance of the Full-Length Vertical Polarizing Undulator Prototype for LCLS-II

ion, undulator, FEL, operation

946

N.O. Strelnikov, E. Gluskin, I. Vasserman, J.Z. Xu
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
As part of the LCLS-II R&D program, a novel 3.4-meter long undulator prototype with horizontal main magnetic field and dynamic force compensation - called the horizontal gap vertical polarization undulator (HGVPU) - has recently been developed at the Advanced Photon Source (APS). Initial steps of the project included designing, building, and a testing 0.8-meter long prototype. Extensive mechanical testing of the HGVPU has been carried out. The magnetic tuning was accomplished by applying a set of magnetic shims. As a result, the performance of the HGVPU meets all the stringent requirements for the LCLS-II insertion device, which includes limits on the field integrals and phase errors for all operational gaps, as well as the reproducibility and accuracy of the gap settings. The HGVPU has been included in the baseline of the LCLS-II project for the hard x-ray undulator line.

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WEPOB25

Analytical Modeling of Electron Back-Bombardment Induced Current Increase in Un-Gated Thermionic Cathode Rf Guns

ion, gun, cathode, simulation

953

J.P. Edelen
Fermilab, Batavia, Illinois, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
Y. Sun
ANL, Argonne, Illinois, USA

In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, field-enhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.

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WEPOB26

Observation of Repetition-Rate Dependent Emission From an Un-Gated Thermionic Cathode Rf Gun

ion, cathode, gun, experiment

956

J.P. Edelen
Fermilab, Batavia, Illinois, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA
Y. Sun
ANL, Argonne, Illinois, USA

Recent work at Fermilab in collaboration with the Advanced Photon Source and members of other national labs, designed an experiment to study the relationship between the RF repetition rate and the average current per RF pulse. While existing models anticipate a direct relationship between these two parameters we observed an inverse relationship. We believe this is a result of damage to the barium coating on the cathode surface caused by a change in back-bombardment power that is unaccounted for in the existing theories. These observations shed new light on the challenges and fundamental limitations associated with scaling an un-gated thermionic cathode RF gun to high average current.

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WEPOB29

Modeling of Dark Current Generation and Transport Using the IMPACT-T Code

ion, cavity, cathode, space-charge

964

J. Qiang, K. Hwang
LBNL, Berkeley, California, USA

Dark current from unwanted electrons in photoinjector can present significant danger to the accelerator operation by causing damage to photocathode and power deposition onto conducting wall. In this paper, we present numerical models of dark current generation from the field emission and from the electron impact ionization of the residual gas that were recently developed in the IMPACT-T code. We also report on the application of above numerical model to an LCLS-II like photoinjector.

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WEPOB30

Simulation of the Shot-Noise Driven Microbunching Instability Experiment at the LCLS

ion, simulation, laser, bunching

967

J. Qiang
LBNL, Berkeley, California, USA
Y. Ding, P. Emma, Z. Huang, D.F. Ratner, T.O. Raubenheimer, F. Zhou
SLAC, Menlo Park, California, USA

The shot-noise driven microbunching instability can significantly degrade electron beam quality in next generation light sources. Experiments were carried out at the Linac Coherent Light Source (LCLS) to study this instability. In this paper, we will present start-to-end simulation of the shot-noise driven microbunching instability experiment at the LCLS.

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WEPOB31

Dark Current Study of a Standing Wave Disk-Loaded Waveguide Structure at 17 GHz

ion, simulation, experiment, multipactoring

971

H. Xu, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

Funding: US DoE, Office of High Energy Physics
We present calculations of the dark current in a high gradient accelerator with the intent of understanding its role in breakdown. The initial source of the dark current is the field emission of electrons. For a 17 GHz single-cell standing wave disk-loaded waveguide structure, the 3D particle-in-cell simulation shows that only a small portion of the charge emitted reaches the current monitors at the ends of the structure, while most of the current collides on the structure surfaces, causing secondary electron emission. In the simulation, a two-point multipactor process is observed on the side wall of the cell due to the low electric field on the surface. The multipactor approaches a steady state within nanoseconds when the electric field is suppressed by the electron cloud formed so that the average secondary electron yield is reduced. This multipactor current can cause the ionization of the metal material and surface outgassing, leading to breakdown. We report first results from an experiment designed to extract dark current directly from an accelerator cell from the side through two slits. First results show that the dark current behavior deviates from the field emission theory.

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WEPOB35

LLNL Laser-Compton X-Ray Characterization

ion, laser, simulation, scattering

977

Y. Hwang, T. Tajima
UCI, Irvine, California, USA
G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344
30 keV Compton-scattered X-rays have been produced at LLNL. The flux, bandwidth, and X-ray source focal spot size have been characterized using an X-ray ICCD camera and results agree very well with modeling predictions. The RMS source size inferred from direct electron beam spot size measurement is 17 um , while imaging of the penumbra yields an upper bound of 42 um. The accuracy of the latter method is limited by the spatial resolution of the imaging system, which has been characterized as well, and is expected to improve after the upgrade of the X-ray camera later this year.

Poster WEPOB35 [37.648 MB]

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WEPOB47

Development of a Short Period Cryogenic Undulator at RadiaBeam

ion, undulator, cryogenics, simulation

995

F.H. O'Shea, R.B. Agustsson, Y.C. Chen, A.J. Palmowski, E. Spranza
RadiaBeam, Santa Monica, California, USA

Funding: Work supported by DOE under contracts DE-SC0006288 and NNSA SSAA DE-NA0001979.
RadiaBeam Technologies has developed a 7-mm period length cryogenic undulator prototype to test fabrications techniques in cryogenic undulator production. We present here our first prototype, the production techniques used to fabricate it, its magnetic performance at room temperature and the temperature uniformity after cool down.

Poster WEPOB47 [2.725 MB]

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WEPOB48

THz and Sub-THz Capabilities of a Table-Top Radiation Source Driven by an RF Thermionic Electron Gun

ion, radiation, undulator, experiment

998

A.V. Smirnov, R.B. Agustsson, S. Boucher, T.J. Campese, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A.Y. Murokh, F.H. O'Shea, E. Spranza
RadiaBeam, Santa Monica, California, USA
W. Berg, M. Borland, J.C. Dooling, L. Erwin, R.R. Lindberg, S.J. Pasky, N. Sereno, Y. Sun, A. Zholents
ANL, Argonne, Illinois, USA
W. Bruns
WBFB, Berlin, Germany
M.J. de Loos, S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

Funding: This work was supported by the U.S. Department of Energy (award No. DE-SC-FOA-0007702).
Design features and experimental results are presented for a sub-mm wave source [1] based on APS RF thermionic electron gun. The setup includes compact alpha-magnet, quadrupoles, sub-mm-wave radiators, and THz optics. The sub-THz radiator is a planar, oversized structure with gratings. Source upgrade for generation frequencies above 1 THz is discussed. The THz radiator will use a short-period undulator having 1 T field amplitude, ~20 cm length, and integrated with a low-loss oversized waveguide. Both radiators are integrated with a miniature horn antenna and a small ~90°-degree in-vacuum bending magnet. The electron beamline is designed to operate different modes including conversion to a flat beam interacting efficiently with the radiator. The source can be used for cancer diagnostics, surface defectoscopy, and non-destructive testing. Sub-THz experiment demonstrated a good potential of a robust, table-top system for generation of a narrow bandwidth THz radiation. This setup can be considered as a prototype of a compact, laser-free, flexible source capable of generation of long trains of Sub-THz and THz pulses with repetition rates not available with laser-driven sources.
[1] A. V. Smirnov, R. Agustsson, W. J. Berg et al., Phys. Rev. ST Accel. Beams 18, 090703(2015)

Poster WEPOB48 [1.335 MB]

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WEPOB49

LCLS Injector Laser Profile Shaping Using Digital Micromirror Device

laser, ion, cathode, target

1001

S. Li
Stanford University, Stanford, California, USA
S.C. Alverson, D.K. Bohler, A.R. Fry, S. Gilevich, Z. Huang, A. Miahnahri, D.F. Ratner, J. Robinson, F. Zhou
SLAC, Menlo Park, California, USA

In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The emittance of the beam is highly related to the transverse profile of the injector laser. Currently the LCLS injector laser has undesired features, such as hot spots, which carry over to the electron beam. These undesired features increase electron emittance, degrade the FEL performance, and complicate operations. The injector laser shaping project at LCLS aims to produce arbitrary electron beam profiles, such as cut-Gaussian, uniform, and parabolic, and to study the effect of spatial profiles on beam emittance and FEL performance. Effectively it also allows easy transition between the two spare lasers, where the operators can use the spatial shaper to achieve identical profiles for the two lasers. In this paper, we describe the experimental methods to achieve laser profile shaping and electron beam profile shaping respectively, and demonstrate promising results.

Poster WEPOB49 [1.850 MB]

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WEPOB54

DC Photogun Gun Test for RHIC Low Energy Electron Cooler (LEReC).

ion, gun, laser, cavity

1008

D. Kayran, Z. Altinbas, D.R. Beavis, S. Bellavia, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, J. Halinski, K. Hamdi, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, G.J. Mahler, T.A. Miller, S.K. Nayak, T. Rao, S. Seletskiy, B. Sheehy, J.E. Tuozzolo, Z. Zhao
BNL, Upton, Long Island, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
Non-magnetized bunched electron cooling of low-energy RHIC requires electron beam energy in range of 1.6-2.6 MeV, with average current up to 45 mA, very small energy spread, and low emittance [1]. A 400 kV DC gun equipped with photocathode and laser delivery system will serve as a source of high-quality electron beam. Acceleration will be achieved by an SRF 704 MHz booster cavity and other RF components that are scheduled to be operational in early 2018. The DC gun testing in its installed location in RHIC will start in early 2017. During this stage we plan to test the critical equipment in close to operation conditions: laser beam delivery system, cathode QE lifetime, DC gun, beam instrumentation, high power beam dump system, and controls. In this paper, we describe the gun test set up, major components, and parameters to be achieved and measured during the gun beam test.
[1] A. Fedotov. Bunched beam electron cooling for Low Energy RHIC operation. ICFA Beam Dynamics letter, No. 65, p. 22 (December 2014)

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WEPOB55

Simulation of Stray Electrons in the RHIC Low Energy Cooler

ion, cathode, cavity, SRF

1012

J. Kewisch
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Low Energy RHIC electron Cooler, under construction at BNL, accelerates electrons with a 400 kV DC gun and a 2.2 MeV SRF booster cavity. Electrons which leave the cathode at the wrong time will not be accelerated to the correct energies and will not reach the beam dump at the end of the accelerator. Thy may impact the beam pipe after incorrect deflection in dipoles or after being slowed down longitudinally in the booster while the transverse momentum is not affected. In some cases their direction is reversed in the booster and they will impact the cathode. We simulated the trajectories of these electrons using the GPT tracking code. The results are qualitative, not quantitative, since the sources and numbers of the stray electrons are unknown.

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WEPOB56

Beam Optics for the RHIC Low Energy Electron Cooler (LEReC)

ion, booster, emittance, space-charge

1015

J. Kewisch, A.V. Fedotov, D. Kayran, S. Seletskiy
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A Low-energy RHIC Electron Cooler (LEReC) system is presently under construction at Brookhaven National Laboratory. This device shall enable gold ion collisions at energies below the design injection energy with sufficient luminosity. Electron beam with energies between 1.6, 2.0 and 2.6 MeV are necessary. This machine will be the first to attempt electron cooling using bunched electron beam, using a 703 MHz SRF cavity for acceleration. Special consideration must be given to the effect of space charge forces on the transverse and longitudinal beam quality. We will present the current layout of the cooler and beam parameter simulations using the computer codes PARMELA.

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WEPOB60

Commissioning of CeC PoP Accelerator

ion, cavity, hadron, gun

1027

I. Pinayev, Z. Altinbas, J.C.B. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, W. Fu, D.M. Gassner, Y. Hao, M. Harvey, T. Hayes, R.L. Hulsart, J.P. Jamilkowski, Y.C. Jing, P. K. Kankiya, D. Kayran, R. Kellermann, V. Litvinenko, G.J. Mahler, M. Mapes, K. Mernick, R.J. Michnoff, K. Mihara, T.A. Miller, G. Narayan, P. Orfin, M.C. Paniccia, D. Phillips, T. Rao, F. Severino, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, V. Soria, Z. Sorrell, R. Than, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, W. Xu, A. Zaltsman, Z. Zhao
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling is new cooling technique to be tested at BNL. Presently we are in the commissioning stage of the accelerator system. In this paper we present status of various systems and achieved beam parameters as well as operational experience. Near term future plans are also discussed.

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WEPOB61

Magnetic Shielding of LEReC Cooling Section

ion, shielding, solenoid, simulation

1030

S. Seletskiy, A.V. Fedotov, D.M. Gassner, D. Kayran, G.J. Mahler, W. Meng
BNL, Upton, Long Island, New York, USA

The transverse angle of the electron beam trajectory in the low energy RHIC Electron Cooling (LEReC) accelerator cooling section (CS) must be much smaller than 100 urad. This requirement sets 2.3 mG limit on the ambient transverse magnetic field. The maximum ambient field in the RHIC tunnel along the cooling section was measured to be 0.52 G. In this paper we discuss the design of the proposed LEReC CS magnetic shielding, which is capable of providing required attenuation.

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WEPOB62

Absolute Energy Measurement of the LEReC Electron Beam

ion, dipole, simulation, HOM

1033

S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, T.A. Miller, P. Thieberger
BNL, Upton, Long Island, New York, USA

The goal of future operation of the low energy RHIC Electron Cooling (LEReC) accelerator is to cool the RHIC ion beams. To provide successful cooling, the velocities of the RHIC ion beam and the LEReC electron beam must be matched with 10^-4 accuracy. While the energy of ions will be known with the required accuracy, the e-beam energy can have an initial offset as large as 5%. The final setting of the e-beam energy will be performed by observing either the Schottky spectrum of debunched ions co-traveling with the e-beam or the recombination signal. Yet, to start observing such signals one has to set the absolute energy of the electron beam with an accuracy better than 10^-2, preferably better than 5·10^-3. In this paper we discuss how such accuracy can be reached by utilizing the LEReC 180 degree bend as a spectrometer.

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WEPOB68

DESIGN AND SIMULATION OF EMITTANCE MEASUREMENT WITH MULTI-SLIT FOR LEREC

ion, emittance, simulation, space-charge

1045

C. Liu, A.V. Fedotov, J. Kewisch, M.G. Minty
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
To improve the luminosity of beam energy scan of low energy Au-Au collision, a electron machine is under con- struction to cool ion beams in both RHIC rings with pulsed electron beam. Over the course of the project, a multi- slit device is needed to characterize the transverse beam emittance of three energies, 0.4, 1.6 and 2.6 MeV. This re- port shows the optimization and compromise of the design, which include the slit width, slit spacing, and drift space from the multi-slit to the downstream profile monitor.

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THA2CO03

New 1.4 Cell RF Photoinjector Design for High Brightness Beam Generation

ion, cathode, brightness, laser

1083

E. Pirez, P. Musumeci
UCLA, Los Angeles, California, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
J.M. Maxson
Cornell University, Ithaca, New York, USA

Funding: This work was partially funded by NSF grant 145583
The new electromagnetic and mechanical designs of the S-band 1.4 cell photoinjector are discussed. A novel fabrication method is adopted to replace the brazing process with a clamping technique achieving lower breakdown probability. The photoinjector is designed to operate at a 120 MV/m gradient and an optimal injection phase of 70 degrees to improve the extraction field by a factor of 1.9 compared to standard 1.6 cell designs with the same peak field. New geometries and features are implemented to improve beam quality for the demand of high brightness beam applications.

Slides THA2CO03 [2.444 MB]

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THA2CO04

Bench Measurements of a Multi-Frequency Prototype Cavity for the Fast Kicker in the JLEIC Circulator Cooler Ring

ion, cavity, simulation, kicker

1087

Y.L. Huang
IMP/CAS, Lanzhou, People's Republic of China
J. Guo, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S.DOE Contract No. DE-AC05-06OR23177
A multi-frequency copper prototype cavity with 5 odd harmonic modes (from 95.26 MHz to 857.34 MHz) is fabricated and bench measured at JLab. This quarter wavelength resonator (QWR) based deflecting cavity is an half scale prototype of the five-mode cavity (from 47.63 MHz to 428.67 MHz) in the QWRs group developed for the ultrafast harmonic RF kicker in the proposed Jefferson Lab Electron Ion Collider (JLEIC, formerly MEIC). With this prototype cavity, several RF measurements are performed and the results show good agreement with the simulation results.

Slides THA2CO04 [7.286 MB]

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THB2IO02

Production of Medical Isotopes With Electron Linacs

ion, target, radiation, photon

1091

D.A. Rotsch, K. Alford, J.L. Bailey, D.L. Bowers, T. Brossard, M.A. Brown, S. Chemerisov, D. Ehst, J.P. Greene, R. Gromov, J.J. Grudzinski, L. Hafenrichter, A.S. Hebden, T.A. Heltemes, W.F. Henning, J. Jerden, C.D. Jonah, M. Kalensky, J.F. Krebs, V. Makarashvili, B.J. Micklich, J.A. Nolen, K.J. Quigley, J.F. Schneider, N.A. Smith, D.C. Stepinski, P. Tkac, G.F. Vandegrift, M. Virgo, K.A. Wesolowski, A.J. Youker
ANL, Argonne, Illinois, USA
Z. Sun
SCSU, Orangeburg, South Carolina, USA

Radioisotopes play important roles in numerous areas ranging from medical treatments to national security and basic research. Radionuclide production technology for medical applications has been pursued since the early 1900s both commercially and in nuclear science centers. Many medical isotopes are now in routine production and are used in day-to-day medical procedures. Despite these advancements, research is accelerating around the world to improve the existing production methodologies as well as to develop novel radionuclides for new medical applications. Electron linear accelerators (linacs) are unique sources of radioisotopes. Even though the basic technology has been around for decades, only recently have electron linacs capable of producing photons with sufficient energy and flux for radioisotope production become available. Housed in Argonne National Laboratory's building 211 is a newly upgraded 50 MeV/30-kW electron linear accelerator, capable of producing a wide range of radioisotopes. This talk will focus on the work being performed for the production of the medical isotopes 99Mo (99Mo/99mTc generator), 67Cu, and 47Sc.

Slides THB2IO02 [25.926 MB]

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THB2IO03

Fulfilling the Mission of Brookhaven ATF as DOE's Flagship User Facility in Accelerator Stewardship

ion, laser, acceleration, plasma

1096

I. Pogorelsky, I. Ben-Zvi, M.A. Palmer
BNL, Upton, Long Island, New York, USA

Funding: DOE
25 years ago, Brookhaven Accelerator Test Facility (ATF), sponsored by the U.S. Department of Energy's (DOE's) Office of High-Energy Physics (HEP), pioneered a concept of a proposal-driven user facility for advanced accelerator research using lasers and electron beams. Since then, the ATF became an internationally recognized destination for researchers to benefit from free access to unique equipment not affordable otherwise to individual institutions and businesses. We will show by examples how collaborative user research achieves high productivity when supported by the ATF's capabilities. Researchers from academia, industry and national laboratories coming to ATF successfully investigate wide range of topics. Recently endorsed as an Office of Science National User Facility and a flagship in Accelerator Stewardship, ATF continues broadening its user community. DOE is now planning a considerable expansion of the ATF's capabilities via simultaneously upgrading the parameters of the e-beam and laser.

Slides THB2IO03 [49.425 MB]

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THPOA04

Maximum Brightness of Linac-Driven Electron Beams in the Presence of Collective Effects

ion, brightness, linac, emittance

1101

S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Linear accelerators capable of delivering high brightness electron beams are essential components of a number of research tools, such as free electron lasers (FELs) and elementary particle colliders. In these facilities the charge density is high enough to drive undesirable collective effects (wakefields) that may increase the beam emittance relative to the injection level, eventually degrading the nominal brightness. We formulate a limit on the final electron beam brightness, imposed by the interplay of geometric transverse wakefield in accelerating structures and coherent synchrotron radiation in energy dispersive regions*. Numerous experimental data of VUV and X-ray FEL drivers validate our model. This is then used to show that a normalized brightness of 10¹⁶ A/m², promised so far by ultra-low charge beams (1-10 pC), can in fact be reached with a 100 pC charge beam in the Italian FERMI FEL linac, with the existing machine configuration.**
*Physical Review Special Topics - Accelerators And Beams 17, 110702 (2014)
**Physical Review Special Topics - Accelerators And Beams 16, 050701 (2013)

Poster THPOA04 [0.828 MB]

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THPOA05

Intrabeam Scattering in High Brightness Electron Linacs

ion, emittance, linac, quadrupole

1104

S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The role played by Intra-Beam Scattering (IBS) in high brightness electron linacs, like those driving free electron lasers, is studied analytically and with particle tracking. We found that IBS typically plays no significant role in the microbunching instability that develops in such accelerators*. A partial damping of the instability through IBS is envisaged, however, with dedicated magnetic insertions. The feasibility of linear and circular lattice designs to cumulate relevant IBS-induced energy spread, and the interplay with microbunching instability, are discussed theoretically, and with the help of tracking codes.
* S. Di Mitri, PRST-AB 17, 074401 (2014)

Poster THPOA05 [0.547 MB]

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THPOA07

Probablistic Estimation of Low Energy Electron Trapping in Quadrupoles

ion, quadrupole, storage-ring, simulation

1112

K.G. Sonnad
KEK, Ibaraki, Japan
J.A. Crittenden, K.G. Sonnad
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Electron cloud formation in quadrupoles is important for storage rings because they have the potential of being trapped for a time period that exceeds the revolution period of the beam. This can result in a turn by turn build up of cloud, that could potentially interfere with beam motion. The mechanism of electron trapping can be understood based on dynamics associated with the motion of an isolated charged particle in a magnetic field. In such a system, energy is conserved and so is the magnetic moment of the gyrating electron which is an adiabatic invariant. This leads to determination of a so called loss cone in velocity space. Using these principles we describe a method to estimate the probability distribution of trapping across the cross-section of a quadrupole for a given field gradient and electron energy. Such an estimate can serve as a precursor to more detailed numerical studies of electron cloud build and trapping in quadrupoles.

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THPOA21

Multipacting in HOM Coupler of LCLS-II 1.3 GHz SC Cavity

ion, HOM, multipactoring, cavity

1146

G.V. Romanov, T.N. Khabiboulline, A. Lunin
Fermilab, Batavia, Illinois, USA

During high power tests of the 1.3 GHz LCLS-2 cavity on the test stand at Fermilab an anomalous rise of temperature of the pickup antenna in the higher order mode (HOM) coupler was detected in accelerating gradient range of 5-10 MV/m. It was suggested that the multipacting in the HOM coupler may be a cause of this temperature rise. In this work the suggestion was studied, and the conditions and the location, where multipacting can develop, were found.

Poster THPOA21 [4.786 MB]

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THPOA35

Analysis of Microbunching Structures in Transverse and Longitudinal Phase Spaces

ion, bunching, simulation, lattice

1177

C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
R. Li
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Microbunching instability (MBI) has been a challenging issue in high-brightness electron beam transport for modern accelerators. The existing Vlasov analysis of MBI is based on single-pass configuration*. For multi-pass recirculation or a long beamline, the intuitive argument of quantifying MBI, by successive multiplication of MBI gains, was found to underestimate the effect**. More thorough analyses based on concatenation of gain matrices aimed to combine both density and energy modulations for a general beamline**. Yet, quantification still focuses on characterizing longitudinal phase space; microbunching residing in (x,z) or (x',z) was observed in particle tracking simulation. Inclusion of such cross-plane microbunching structures in Vlasov analysis shall be a crucial step to systematically characterize MBI for a beamline complex in terms of concatenating individual beamline segments. We derived a semi-analytical formulation to include the microbunching structures in longitudinal and transverse phase spaces. Having numerically implemented the generalized formulae, an example lattice*** is studied and reasonable agreement achieved when compared with particle tracking simulation.
* Heifets et al., PRSTAB 5, 064401 (2002), Huang and Kim, PRSTAB 5, 074401 (2002), and Vneturini, PRSTAB 10, 104401 (2007)
** Tsai et al., IPAC'16 (TUPOR020)
*** Di Mitri, PRSTAB 17, 074401 (2014)

Poster THPOA35 [4.710 MB]

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THPOA37

Study of 2D CSR Effects in a Compression Chicane

ion, simulation, dipole, FEL

1181

C.C. Hall
RadiaSoft LLC, Boulder, Colorado, USA
S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

The study of coherent synchrotron radiation (CSR) has been an area of great interest because of its negative impact on FEL performance. The modeling of CSR is frequently performed using a 1D approximation*, as 2D and 3D models can become extremely computational intensive. While experimental evidence is lacking in this area most studies show reasonable agreement between 1D and 2D CSR models for beam parameters in existing accelerators. In this work we focus on 2D modeling of CSR in a four-dipole chicane lattice based on the Jefferson Lab FEL. Comparison is shown between several models and measurement for energy loss due to CSR in the chicane. While good agreement is generally observed we also present investigation of several key differences observed in simulation. In particular, showing how the 1D and 2D CSR models deviate in regards to CSR and beam interaction within the drift spaces of the chicane and the downstream drift at the chicane end.
*E. Saldin, E. Schneidmiller, and M. Yurkov, Nucl. Instr. Meth. A398, 373 (1997).

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THPOA41

Simulations of Hole Injection in Diamond Detectors

ion, simulation, detector, injection

1184

G.I. Bell, D.A. Dimitrov, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, M. Gaowei, T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA
E.M. Muller
SBU, Stony Brook, New York, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences, under grant DE-SC0007577.
We present simulations of a semiconductor beam detector using the code VSIM. The 3D simulations involve the movement and scattering of electrons and holes in the semiconductor, voltages which may be applied to external contacts, and self-consistent electrostatic fields inside the device. Electrons may experience a Schottky barrier when attempting to move from the semiconductor into a metal contact. The strong field near the contact, due to trapped electrons, can result in hole injection into the semiconductor due to transmission of electrons from the valence band of the semiconductor into the metal contact. Injected holes are transported in the applied field leading to current through the detector. We compare our simulation results with experimental results from a prototype diamond X-ray detector.

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THPOA42

3D Modeling and Simulations of Electron Emission From Photocathodes With Controlled Rough Surfaces

ion, simulation, cathode, scattering

1187

D.A. Dimitrov, G.I. Bell, D.N. Smithe, C.D. Zhou
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, J. Smedley
BNL, Upton, Long Island, New York, USA
S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA

Funding: This work is supported by the US DOE Office of Science, department of Basic Energy Sciences under grant DE-SC0013190.
Developments in materials design and synthesis have resulted in photocathodes that can have a high quantum efficiency (QE), operate at visible wavelengths, and are robust enough to operate in high electric field gradient photoguns, for application to free electron lasers and in dynamic electron microscopy and diffraction. However, synthesis often results in roughness, ranging from the nano to the microscale. The effect of this roughness in a high gradient accelerator is to produce a small transverse accelerating gradient, which therefore results in emittance growth. Although analytical formulations of the effects of roughness have been developed, a full theoretical model and experimental verification are lacking, and our work aims to bridge this gap. We report results on electron emission modeling and 3D simulations from photocathodes with controlled surface roughness similar to grated surfaces that have been fabricated by nanolithography. The simulations include both charge carrier dynamics in the photocathode material and a general electron emission modeling that includes field enhancement effects at rough surfaces. The models are being implemented in the VSim code.

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THPOA45

Update of the SEY Measurement at Fermilab Main Injector

ion, vacuum, proton, operation

1190

Y. Ji
IIT, Chicago, Illinois, USA
L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA
R.M. Zwaska
Fermilab, Batavia, Illinois, USA

Studies of in-situ Secondary electron yield (SEY) mea- surements of material samples at the Main Injector (MI) beam pipe wall location started in 2013. [2, 3] These studies aimed at understanding how the beam conditioning of differ- ent materials evolve if they function as MI vacuum chamber walls. The engineering run of the SEY measurement test stand was finished in 2014. From 2014 to 2016 the Fermilab accelerator intensity has increased from 24 × 10¹² protons to 42 × 1012 protons. The beam conditioning effect on SS316L and TiN coated SS316L has been observed throughout this period. [1] Improvement of the data acquisition procedure and hardware has been performed. A deconditioning pro- cess was observed during the accelerator annual shut down in 2016.

Poster THPOA45 [3.113 MB]

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THPOA48

Model of Electron Cloud Instability in Fermilab Recycler

ion, proton, simulation, dipole

1197

S. A. Antipov
University of Chicago, Chicago, Illinois, USA
A.V. Burov, S. Nagaitsev
Fermilab, Batavia, Illinois, USA

An electron cloud instability might limit the intensity in the Fermilab Recycler after the PIP-II upgrade. A multibunch instability typically develops in the horizontal plane within a hundred turns and, in certain conditions, leads to beam loss. Recent studies have indicated that the instability is caused by an electron cloud, trapped in the Recycler index dipole magnets. We developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function dipoles. The resulting instability growth rate of about 30 revolutions is consistent with experimental observations and qualitatively agrees with the simulation in the PEI code. The model allows an estimation of the instability rate for the future in-tensity upgrades.

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THPOA49

Electron Cloud Trapping in Recycler Combined Function Dipole Magnets

ion, dipole, proton, vacuum

1200

S. A. Antipov
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev
Fermilab, Batavia, Illinois, USA

Electron cloud can lead to a fast instability in intense proton and positron beams in circular accelerators. In the Fermilab Recycler the electron cloud is confined within its combined function magnets. We show that combined function magnets trap the electron cloud with their magnetic field, present the results of analytical estimates of trapping, and compare them to numerical simulations of electron cloud formation. The electron cloud in a combined function magnet is located at the beam center and up to 1% of the particles can be trapped by its magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multi-turn accumulations allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The multi-turn build-up can be stopped by injection of a single clearing bunch of 1*10¹⁰ p at any position in the ring.

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THPOA50

Development of an Optical Cavity for LCS Sources at the Compact ERL

cavity, ion, laser, photon

1204

T. Akagi, S. Araki, Y. Honda, A. Kosuge, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
R. Hajima, M. Mori, R. Nagai, T. Shizuma
QST, Tokai, Japan

High-energy photons from the laser Compton scattering (LCS) sources are expected to be applied in various fields in a wide range photon energies from keV to GeV. High-flux and narrow-bandwidth LCS photon beam is realized in an energy recovery linac (ERL). An electron beam of high-average current and small-emittance collides with accumulating laser pulses in an enhancement cavity for generating high-flux LCS photon beam. We have developed the high-finesse bow-tie ring cavity for the LCS experiment at the Compact ERL (cERL) in KEK. In this presentation, we will report the detail of the optical cavity.

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THPOA51

Improvement of X-Ray Generation by Using Laser Compton Scattering in Laser Undulator Compact X-Ray Source(LUCX)

ion, laser, gun, photon

1207

M.K. Fukuda, S. Araki, Y. Honda, Y. Sumitomo, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have been developing a compact X-ray source based on the laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. We have started to take X-ray images such as refraction contrast images and phase contrast imaging with Talbot interferometer. In this accelerator, 6-10keV X-rays are generated by LCS. An electron beam is produced by a 3.6cell RF-gun and accelerated to 18-24MeV by a 12cell accelerating tube. A laser pulse is stored in a 4-mirror planar optical cavity to enhance the power. To increase the flux of LCS X-rays, we perform an optimization of the beam-loading compensation, improvement of the intensity of an electron beam and a laser light at the collision point. We report the result of the X-ray generation in this accelerator.

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THPOA53

Luminosity Increase in Laser-Compton Scattering by Crab Crossing Method

ion, laser, luminosity, photon

1213

Y. Koshiba, D. Igarashi, S. Ota, T. Takahashi, M. Washio
RISE, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

In collider experiments such as KEKB, crab crossing method is a promising way to increase the luminosity and KEK (High Energy Accelerator Research Organization) has achieved the luminosity record in 2009. We are planning to apply crab crossing to laser-Compton scattering, which is a collision of electron beam and laser, to gain a higher luminosity leading to a higher brightness X-ray source. It is well known that the collision angle between electron beam and laser affects the luminosity. It is the best when the collision angle is zero, head-on collision, to get a higher luminosity but difficult to construct such system especially when using an optical cavity for laser. Concerning this difficulty, we are planning crab crossing by tilting the electron beam using an rf-deflector. Although crab crossing in laser-Compton scattering has been already proposed*, nowhere has demonstrated yet. We are going to demonstrate and conduct experimental study at our compact accelerator system in Waseda University. In this conference, we will report about our compact accelerator system, laser system for laser-Compton scattering, and expected results of crab crossing laser-Compton scattering.
*V. Alessandro, et al. "Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators." Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.

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THPOA61

A Possible Emittance Reduction Scheme for PLSII

ion, lattice, emittance, quadrupole

1226

T.-Y. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

As the upgrade of PLS, PLSII is a 3 GeV light source in 12 super-periods (281.8 m circumference) with 5.8 nm design emittance and can store electron beam up to 400 mA with 3 superconducting RF cavities. PLSII lattice is a double bend achromatic (DBA) lattice with 2 straight sections for each cell (24 straight sections). After comple-tion of PLSII, multi-bend achromatic lattice has widely been adopted to accomplish low emittance. This paper discusses how a minimal change can modify the PLSII's DBA to a quadruple bend achromatic (QBA) lattice and reduce the emittance to about a half value.

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THPOA62

Clearing Magnet Design for APS-U

ion, storage-ring, permanent-magnet, vacuum

1228

M. Abliz, J.H. Grimmer, Y. Jaski, M. Ramanathan, F. Westferro
ANL, Argonne, Illinois, USA

Abstract Advanced Photon Source is in the process of developing an upgrade of the storage ring. The Upgrade will be converting the current double bend lattice to a multi-bend lattice (MBA). In addition, the storage ring will be operated at 6 GeV and 200 mA with regular swap-out injection to keep the stored beam current constant. The swap-out injection will take place with beamline shutters open. For radiation safety to ensure that no electrons can exit the storage ring, a passive method of protecting the beamline and containing the electrons inside the storage ring tunnel is proposed. A clearing magnet will be located in all beamline front ends inside the storage ring tunnel. This article will discuss the principle, design and mechanical design of the clearing magnet scheme for the APS-Upgrade.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA62

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THPOA68

The First Particle-Based Proof of Principle Numerical Simulation of Electron Cooling

ion, proton, simulation, emittance

1241

S. Abeyratne, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

Envisioned particle accelerators such as JLEIC demand unprecedented luminosities of 10³⁴ cm -2 s -1 and small emittances are key to achieve them. Electron cooling, where a 'cold' electron beam and the 'hot' proton or ion beam co-propagate in the cooling section of the accelerator, can be used to reduce the emittance growth. It is required to precisely calculate the cooling force among particles to estimate accurately the cooling time. There are different methods to simulate electron cooling. We have developed a novel code, Particles' High-order Adaptive Dynamics (PHAD), for electron cooling. This code differs from other established methods since it is the first particle-based simulation method employing full particle nonlinear dynamics. In this paper we present the first results obtained that establish electron cooling of heavy ions.

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THA3CO04

Space Charge Compensation Using Electron Columns and Electron Lenses at IOTA

ion, proton, space-charge, solenoid

1257

C.S. Park, D. Milana, V.D. Shiltsev, G. Stancari, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA
D. Milana
Politecnico/Milano, Milano, Italy

Funding: This work was supported by the United States Department of Energy under contract DE-AC02-07CH11359.
The ability to transport a high current proton beam in a ring is ultimately limited by space charge effects. Two novel ways to overcome this limit in a proton ring are by adding low energy, externally matched electron beams (electron lens, e-lens), and by taking advantage of residual gas ionization induced neutralization to create an electron column (e-column). Theory predicts that an appropriately confined electrons can completely compensate the space charge through neutralization, both transversely and longitudinally. In this report, we will discuss the current status of the Fermilab's e-lens experiment for the space charge compensation. In addition, we will show how the IOTA e-column compensates space charge with the WARP simulations. The dynamics of proton beams inside of the e-column isunderstood by changing the magnetic field of a solenoid, the voltage on the electrodes, and the vacuum pressure, and by looking for electron accumulation, as well as by considering various beam dynamics in the IOTA ring.

Slides THA3CO04 [42.834 MB]

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FRA1CO04

6D Phase Space Measurement of Low Energy, High Intensity Hadron Beam

ion, simulation, emittance, quadrupole

1271

B.L. Cathey
ORNL RAD, Oak Ridge, Tennessee, USA
A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. The work has been partially supported by NSF grant 1535312
The goal of this project is to demonstrate a method for measuring the full 6D phase space of an low energy, high intensity hadron beam. This is done by combining 4D emittance measurement techniques along with dispersion measurement and a beam shape monitor to provide the energy and phase space components. The measurement will be performed on new Beam Testing Facility (BTF) at the Spallation Neutron Source (SNS), a 2.5 MeV functional duplicate of the SNS accelerator front end.

Slides FRA1CO04 [8.295 MB]

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FRA1CO05

Progress of Gas-Filled Multi-RF-Cavity Beam Profile Monitor for Intense Neutrino Beams

ion, plasma, cavity, experiment

1275

K. Yonehara, M. Backfish, A. Moretti, A.V. Tollestrup, A.C. Watts, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer
Muons, Inc, Illinois, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
Q. Liu
Case Western Reserve University, Cleveland, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
A novel pressurized gas-filled multi-RF-cavity beam profile monitor has been studied that is simple and robust in high-radiation environments. Charged particles passing through each RF-cavity in the monitor produce intensity-dependent ionized plasma, which changes the gas permittivity. The sensitivity to beam intensity is adjustable using gas pressure and RF gradient. The performance of the gas-filled beam profile monitor has been numerically simulated to evaluate the sensitivity of permittivity measurements. The result indicates that the RF resonator will be useful to measure the beam profile with a charged beam intensity range from 10⁶ to 10¹³ protons/bunch. The range covers the expected beam intensities in NuMI and LBNF. The demonstration of the monitor with intense proton beams are taken place at Fermilab to validate the simulation result. The result will be given in this presentation.

Slides FRA1CO05 [3.750 MB]

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FRA1CO06

Measurement of Coherent Transition Radiation Using Interferometer and Photoconductive Antenna

ion, laser, linac, polarization

1279

K. Kan, M. Gohdo, T. Kondoh, I. Nozawa, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Ultrashort electron beams are essential for light sources and time-resolved measurements. Electron beams can emit terahertz (THz) pulses using coherent transition radiation (CTR). Michelson interferometer* is one of candidates for analyzing the pulse width of an electron beam based on frequency-domain analysis. Recently, electron beam measurement using a photoconductive antenna (PCA)** based on time-domain analysis has been investigated. In this presentation, measurement of femtosecond electron beam with 35 MeV energy and < 1 nC from a photocathode based linac will be reported. Frequency- and time- domain analysis of THz pulse of CTR by combining the interferometer and PCA will be carried out.
* I. Nozawa, K. Kan et al., Phys. Rev. ST Accel. Beams 17, 072803 (2014).
** K. Kan et al., Appl. Phys. Lett. 102, 221118 (2013).

Slides FRA1CO06 [2.334 MB]

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