LINAC2016 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
MO2A04	Low Emittance and High Current Electron Linac Development at Tsinghua University	gun, emittance, electron, experiment	17
	C.-X. Tang, H.B. Chen, Z.J. Chi, Y.-C. Du, W.-H. Huang, J. Shi, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, Z. Zhang, Z. Zhang, L.M. Zheng, Z. Zhou TUB, Beijing, People's Republic of China
	A 50MeV electron linac have been developed in Tsinghua University, which consists of a 1.6Cell photocathode rf gun, a 3-meter s-band SLAC type traveling wave (TW) accelerating structure an a s-band TW buncher. The photocathode rf gun is working at 120MV/m, 2856MHz, with very small dark current. The emittance of the electron beam is less than 1mm.mrad at 500pC, and 0.5mm.mrad at 200pC. The linac is designed for Tsinghua Thomson scattering X-ray source (TTX), and 2x10⁷ photon/bunch at 50keV has been got and some application experiments with the x-ray have been carried out. The new photocathode rf gun and x-band high gradient accelerating structure development will also be introducted in this talk.
	Slides MO2A04 [11.413 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO2A04
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MO3A01	Status of SwissFEL	linac, electron, undulator, gun	22
	F. Löhl PSI, Villigen PSI, Switzerland
	SwissFEL is a hard x-ray free-electron laser facility that is currently constructed at PSI. This paper gives an overview of the facility, describes the main sub-systems of the accelerator, and summarizes the installation and commissioning status.
	Slides MO3A01 [315.102 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO3A01
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MO3A02	Achievement of Small Beam Size at ATF2 Beamline	optics, sextupole, wakefield, simulation	27
	T. Okugi KEK, Ibaraki, Japan
	The beam commissioning of the ATF2 facility at KEK - a 1.3 GeV prototype of the compact local chromaticity correction final focus system for the linear collider - achieved 44nm beam size, very close to ideal expected size of 37nm, by developing various knobs and improving the performances of the interferometric Shintake monitor at the same time. These results have opened the way to reliable and predictable operation of the linear collider.
	Slides MO3A02 [3.495 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO3A02
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MOOP09	Dielectric and THz Acceleration (Data) Programme at the Cockcroft Institute	acceleration, electron, wakefield, accelerating-gradient	62
	S.P. Jamison, Y.M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.B. Appleby, H.L. Owen, T.H. Pacey, T.H. Pacey, G.X. Xia UMAN, Manchester, United Kingdom G. Burt, R. Letizia, C. Paoloni Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A.W. Cross USTRAT/SUPA, Glasgow, United Kingdom D.M. Graham The University of Manchester, The Photon Science Institute, Manchester, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work has been funded by STFC Normal conducting RF systems are currently able to pro-vide gradients of around 100 MV/m, limited by break-down on the metallic structures. The breakdown rate is known to scale with pulse length and, in conventional RF systems, this is limited by the filling time of the RF struc-ture. Progressing to higher frequencies, from RF to THz and optical, can utilise higher gradient structures due to the fast filling times. Further increases in gradient may be possible by replacing metallic structures with dielectric structures. The DATA programme at the Cockcroft Insti-tute is investigating concepts for particle acceleration with laser driven THz sources and dielectric structures, beam driven dielectric and metallic structures, and optical and infrared laser acceleration using grating and photonic structures. A cornerstone of the programme is the VELA and CLARA electron accelerator test facility at Daresbury Laboratory which will be used for proof-of-principle experiments demonstrating particle acceleration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP09
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MOPLR013	Investigations on Electron Beam Imperfections at PITZ	electron, simulation, solenoid, gun	165
	M. Krasilnikov, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, G. Pathak, Y. Renier, T. Rublack, F. Stephan, G. Vashchenko, Q.T. Zhao DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria C. Hernandez-Garcia JLab, Newport News, Virginia, USA
	Since more than a decade, the photo injector test facility at DESY, Zeuthen site (PITZ), has developed and optimized high brightness electron sources for modern Free Electros Lasers like FLASH and the European XFEL. Despite a very high performance of the photo injector was experimentally demonstrated, several discrepancies between measurements and beam dynamics simulations have been revealed. Although the optimized measured values of the projected transverse emittance are close to those obtained from the beam dynamics simulations, the corresponding experimental machine parameters show certain systematic deviations from the simulated optimized setup. As a source for these deviations, electron beam imperfections were experimentally investigated. This includes studies on bunch charge production, electron beam imaging using the RF gun with its solenoid, and investigations on the transverse asymmetry of the electron beam generated in a rotationally symmetric gun cavity. Experimental studies were supplied with corresponding beam dynamics simulations. The paper reports on results of these studies.
	Poster MOPLR013 [2.140 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR013
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MOPLR035	Fabrication of Superconducting Spoke Cavity for Compact Photon Source	cavity, photon, linac, scattering	212
	M. Sawamura, R. Hajima QST, Tokai, Japan H. Hokonohara, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan T. Kubo, T. Saeki KEK, Ibaraki, Japan
	Funding: This study is supported by Photon and Quantum Basic Research Coordinated Development Program of MEXT, Japan. The spoke cavity is expected to have advantages for compact ERL accelerator for X-ray source based on laser Compton scattering. We have been developing the spoke cavity under a research program of MEXT, Japan to establish the fabrication process. Since our designed shape of the spoke is complicated due to increase the RF properties, one-step press forming with one set of molds will cause so large strain to break the sheet. We designed the mold components including the process of press work. The press forming tests of the spoke cavity have been done with the various materials of sheets to check molding performance. In this paper we present status of the spoke cavity fabrication.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR035
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MOPLR071	A 3-MeV Linac for Development of Accelerator Components at J-PARC	linac, rfq, operation, ion	298
	Y. Kondo, H. Asano, E. Chishiro, K. Hirano, T. Itou, Y. Kawane, N. Kikuzawa, S.I. Meigo, A. Miura, S. Mizobata, T. Morishita, H. Oguri, K. Ohkoshi, A. Ohzone, Y. Sato, S. Shinozaki, K. Shinto, H. Takei, K. Tsutsumi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Z. Fang, Y. Fukui, K. Futatsukawa, K. Ikegami, T. Miyao, K. Nanmo, T. Shibata, T. Sugimura, A. Takagi KEK, Ibaraki, Japan T. Hori Nippon Advanced Technology Co., Ltd., Tokai, Japan T. Ishiyama, T. Maruta KEK/JAEA, Ibaraki-Ken, Japan M. Mayama, Y. Sawabe Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
	We are constructing a linac for development of accelerator components at J-PARC. This linac consists of a H⁻ ion source, a low energy beam transport (LEBT), an radio frequency quadrupole (RFQ) linac, and a diagnostics bean line. The beam energy is 3 MeV, the beam current is 30 mA, and the duty factor is 0.6%, which corresponds to 0.5 kW. The accelerator itself has a capacity of at least 1 kW. However, the beam power is limited by radiation dose, because there are no radiation shields between the accessible area during the operation. The source and LEBT are same as the J-PARC linac's. The RFQ is a used one in the J-PARC linac, called RFQ I. At first, we are planning to conduct experiments of the laser charge exchange development for the transmutation facility. Then, this linac will be used for the development accelerator components such as beam scrapers, bunch shape monitors, laser profile monitors, and so on. We will be able to install new devices into the actual J-PARC linac after the full testing. The development of H⁻ ion source can be carried out at this system, and also RFQ in the future. In this paper, present status of this 3-MeV linac at J-PARC is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR071
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TU3A01	Beam Commissioning Results From the R&D ERL at BNL	gun, cathode, SRF, cavity	374
	D. Kayran, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, L.R. Hammons, J.P. Jamilkowski, P. K. Kankiya, R.F. Lambiase, V. Litvinenko, R.J. Michnoff, T.A. Miller, J. Morris, V. Ptitsyn, T. Seda, B. Sheehy, K.S. Smith, E. Wang, W. Xu BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, L.R. Hammons, V. Litvinenko, V. Ptitsyn Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy BNL R&D ERL beam commissioning started in June 2014 []. The key components of R&D ERL are the highly damped 5-cell 704 MHz superconducting RF cavity and the high-current superconducting RF gun. The gun is equipped with a multi-alkaline photocathode insertion system. The first photocurrent from ERL SRF gun has been observed in November 2014. In June 2015 a high charge 0.5nC and 20 uA average current were demonstrated. In July 2015 gun to dump beam test started. The beam was successfully transported from the SRF gun through the injection system, then through the linac to the beam dump. All ERL components have been installed. In October 2015, SRF gun cavity has been found contaminated during severe cathode stalk RF conditioning. This cavity has been sent for repair and modification for later use in low-energy RHIC electron cooler (LEReC)[]. LEReC scheduled to start commissioning in early of 2018. We present our results of BNL ERL beam commissioning, the measured beam properties, the operational status, and future prospects. ) D.Kayran et al., Status and commissioning results of the R&D ERL at BNL. Proc. ERL2015, p. 11-14 **)J. Kewisch et al., ERL for Low Energy Electron Cooling at RHIC (LEReC). Proc. ERL2015, p. 67-71
	Slides TU3A01 [12.502 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU3A01
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TUOP01	Applying Transverse Gradient Undulators to Suppression of Microbunching Instability	electron, linac, FEL, simulation	380
	D. Huang, H.X. Deng, C. Feng, D. Gu, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	Funding: Major State Basic Research Development Program of China (2011CB808300). National Natural Science Foundation of China (NSFC), grant No. 11275253. The microbunching instability developed during the beam compression process in the linear accelerator (LIN-AC) of a free-electron laser (FEL) facility has always been a problem that degrades the lasing performance, and even no FEL is able to be produced if the beam quality is destroyed too much by the instability. A common way to suppress the microbunching instability is to introduce extra uncorrelated energy spread by the laser heater that heats the beam through the interaction between the electron and laser beam, as what has been successfully implemented in the Linac Coherent Light Source and Fermi@Elettra. In this paper, a simple and effective scheme is proposed to suppress the microbunching instability by adding two transverse gradient undulators (TGU) before and after the magnetic bunch compressor. The additional uncorrelated energy spread and the density mixing from the transverse spread brought up by the first TGU results in significant suppression of the instability. Meanwhile, the extra slice energy spread and the transverse emittance can also be effectively recovered by the second TGU. The magnitude of the suppression can be easily controlled by varying the strength of the magnetic fields of the TGUs. Theoretical analysis and numerical simulations demonstrate the capability of the proposed technique in the LINAC of an x-ray free-electron laser facility.
	Slides TUOP01 [1.148 MB]
	Poster TUOP01 [0.447 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP01
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TUPRC022	UPS Study for CsK2Sb Photocathode	cathode, electron, experiment, ion	465
	M. Kuriki, T. Konomi, Y. Seimiya KEK, Ibaraki, Japan L. Guo, M. Urano, A. Yokota HU/AdSM, Higashi-Hiroshima, Japan K. Negishi Iwate University, Morioka, Iwate, Japan
	CsK2Sb photo-cathode is one of the ideal cathode for accelerators requiring the high brightness electron beam. It can be driven with a green laser which can be generated as SHG from solid state laser. The QE (Quantum Efficiency) of photo-electron emission is as high as more than 10% with 532nm light. The material is robust and the typical operational lifetime is more than several months. It is also vital against the high intensity beam extraction. The photo-cathode is generated as a thin film in-situ and the material property and optimized condition for the cathode formation is not understood well. In this article, we present UPS analysis of CsK2Sb cathode for deeper understanding.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC022
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TUPLR013	Lifetime Study of CKk2Sb Robust Photo-Cathode for a High Brightness Electron Source	cathode, vacuum, electron, brightness	500
	M. Kuriki, Y. Seimiya KEK, Ibaraki, Japan L. Guo, K. Moriya, M. Urano, A. Yokota HU/AdSM, Higashi-Hiroshima, Japan K. Negishi Iwate University, Morioka, Iwate, Japan
	CsK2Sb photo-cathode is one of the ideal cathode for accelerators requiring the high brightness electron beam. It can be driven with a green laser which can be generated as SHG from solid state laser. The QE (Quantum Efficiency) of photo-electron emission is as high as more than 10% with 532nm light. In this article, the robustness of the cathode is studied. Two indexes of lifetime regarding to time and extracted charge density were evaluated experimentally. The result shows that the cathode is robust enough for a high brightness accelerator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR013
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TUPLR015	Design of a Gamma-Ray Source Based on Inverse Compton Scattering at the Fast Superconducting Linac	electron, photon, cavity, brightness	503
	D. Mihalcea Northern Illinois University, DeKalb, Illinois, USA B.T. Jacobson, A.Y. Murokh RadiaBeam, Santa Monica, California, USA P. Piot, J. Ruan Fermilab, Batavia, Illinois, USA
	Funding: This work is sponsored by the DNDO via contract with NIU. A Watt-level average-power gamma-ray source is currently under development at the FermiLab Accelerator Science & Technology (FAST) facility. The source is based on the inverse Compton scattering of a high-brightness 300-MeV beam against a high-power laser beam circulating in an optical cavity. The back scattered gamma rays are expected to have photon energies up to 1.5 MeV. This paper discusses the optimization of the source, its performance and the main challenges ahead.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR015
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TH2A01	The Linac Laser Notcher for the Fermilab Booster	linac, booster, cavity, injection	710
	D.E. Johnson, K.L. Duel, M.H. Gardner, T.R. Johnson, D. Slimmer Fermilab, Batavia, Illinois, USA S. Patil PriTel, Inc., Naperville, USA J. Tafoya Optical Engines, Inc., Colorado Springs, USA
	In synchrotron machines, the beam extraction is accomplished by a combination of septa and kicker magnets which deflect the beam from an accelerator into another. Ideally the kicker field must rise/fall in between the beam bunches. However, in reality, an intentional beam-free time region (aka "notch") is created on the beam pulse to assure that the beam can be extracted with minimal losses. In the case of the Fermilab Booster, the notch is created in the ring near injection energy by the use of fast kickers which deposit the beam in a shielded collimation region within the accelerator tunnel. With increasing beam power it is desirable to create this notch at the lowest possible energy to minimize activation. The Fermilab Proton Improvement Plan (PIP) initiated an R&D project to build a laser system to create the notch within a linac beam pulse at 750 keV. This talk will describe the concept for the laser notcher and discuss our current status, commissioning results, and future plans.
	Slides TH2A01 [15.170 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH2A01
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TH2A02	Results From the Laserwire Emittance Scanner and Profile Monitor at CERN's Linac4	detector, electron, linac, emittance	715
	T. Hofmann, U. Raich, F. Roncarolo CERN, Geneva, Switzerland G.E. Boorman, A. Bosco, S.M. Gibson Royal Holloway, University of London, Surrey, United Kingdom G.E. Boorman, A. Bosco, S.M. Gibson JAI, Egham, Surrey, United Kingdom
	A novel, non-invasive, H⁻ laser-wire scanner has been tested during the beam commissioning of CERN's new Linac4. Emittance measurements were performed at beam energies of 3 and 12 MeV with this new device and were found to closely match the results of conventional slit-grid methods. In 2015, the configuration of this laser-wire scanner was substantially modified. In the new setup the electrons liberated by the photo-detachment process are deflected away from the main beam and focused onto a single crystal diamond detector that can be moved in order to follow the laser beam scan. The beam profiles measured with the new laser-wire setup at 50 MeV, 80 MeV and 10⁷ MeV are in good agreement with the measurements of nearby SEM grids and wire-scanners. The design of the final laser-wire scanner for the full 160 MeV beam energy will also be presented. In Linac4 two independent laser-wire devices will be installed in the transfer line to the BOOSTER ring. Each device will be composed of two parts: one hosting the laser-wire and the electron detector and the second hosting the segmented diamond detector used to acquire the transverse profiles of the H⁰ beamlets.
	Slides TH2A02 [3.164 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH2A02
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TH3A01	Making Molecular Movie with MeV Electrons	electron, experiment, alignment, detector	725
	X. Shen, X.J. Wang SLAC, Menlo Park, California, USA
	SLAC launched the Ultrafast Electron Diffraction and Imaging (UED&UEM) initiative with the objective of developing the world leading ultrafast electron scattering instrumentation, complementary to the X-ray Free Electron Laser - Linac Coherent Light Source (LCLS). SLAC has developed a UED setup at the Accelerator Structure Test Area (ASTA), with the goal of providing MeV, 100-femtosecond-scale electron pulses to support an ultrafast science program [1]. The first UED ultrafast science experiment published in Nano Letters, where large amplitude wrinkles of monolayer MoS2 generated by the light pulse' more than 15 percent of the layer's thickness, was observed. This is the first time anyone has visualized these ultrafast atomic motions. Ultrafast MeV electrons also made it possible the direct measurement of phonon occupations as energy is transferred from electrons into the lattice in laser-heated gold (APL). The rotational wavepacket dynamics of laser-aligned nitrogen molecules were captured in gas-phase electron diffraction experiment using MeV electrons. We achieved an unprecedented combination of 100-fs (rms) temporal resolution and sub-Angstrom (0.76 Å) spatial resolution that makes it possible to resolve the position of the nuclei within the molecule(Nature Communications). [1] S. Weathersby, et al., Rev. Sci. Instrum. 86, 073702 (2015).
	Slides TH3A01 [6.518 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH3A01
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TH3A02	The Los Alamos Multi-Probe Facility for Matter-Radiation Interactions in Extremes	electron, linac, photon, proton	729
	R.W. Garnett LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396. A next-generation signature facility based on multi-probe capabilities is being planned at Los Alamos. This new facility will enable the first in a new generation of game-changing scientific facilities for the materials community. The new Matter-Radiation Interactions in Extremes (MaRIE) facility will be used to discover and design the advanced materials needed to meet 21st-century national security and energy-security challenges to develop next-generation materials that will perform predictably in extreme environments. The MaRIE facility will include a new 12-GeV electron linac using a state-of-the-art electron photoinjector and superconducting accelerator technology to drive a 42-keV XFEL to generate x rays of unprecedented flux and quality, coupled with the existing proton-beam capabilities of the LANSCE proton linac, new experimental halls, and new materials fabrication/characterization facilities. A description of this new facility, its requirements, and planned uses and capabilities will be presented. Status of the project will also be presented.
	Slides TH3A02 [5.060 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH3A02
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TH3A03	The VELA and CLARA Test Facilities at Daresbury Laboratory	FEL, electron, gun, cavity	734
	P.A. McIntosh, D. Angal-Kalinin, J.A. Clarke, L.S. Cowie, B.D. Fell, S.P. Jamison, B.L. Militsyn, Y.M. Saveliev, D.J. Scott, N. Thompson, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A. Gleeson, T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The Versatile Electron Linear Accelerator (VELA) provides enabling infrastructures targeted at the development and testing of novel and compact accelerator technologies, specifically through partnership with academia and industry, aimed at addressing applications in medicine, health, security, energy and industrial processing. The facility is now fully commissioned and is taking advantage of the variable electron beam parameters to demonstrate new techniques/processes or otherwise develop new technologies for future commercial realization. Examples of which include; electron diffraction and new cargo scanning processes. The Compact Linear Accelerator for Research and Applications (CLARA) will be a novel FEL test facility, focused on the generation of ultra-short photon pulses with extreme levels of stability and synchronization. The principal aim is to experimentally demonstrate that sub-cooperation length pulse generation with FELs is viable, and to compare the various schemes being championed. The results will translate directly to existing and future X-ray FELs, enabling attosecond pulse generation. Both the VELA and CLARA facilities are co-located at Daresbury Laboratory and provide the UK with a unique platform for scientific and commercial R&D using ultra-short pulse, high precision electron and photon beams.
	Slides TH3A03 [11.795 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH3A03
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THOP12	Electron Linac Upgrade for Thomx Project	gun, linac, emittance, electron	773
	L. Garolfi, C. Bruni, M. El Khaldi LAL, Orsay, France N. Faure, A. Perez Delaume PMB-ALCEN, PEYNIER, France
	The injector Linac for Thomx * consists of an electron gun and S-band accelerating section. The RF gun is a 2.5 cells photo-injector able to provide electron bunches with 5 MeV energy. During the commissioning phase, a standard S-band accelerating section is able to achieve around 50 MeV corresponding to around 45 keV X-rays energy. Since the maximum targeted X-ray energy is 90 keV, the Linac design will provide a beam energy of 70 MeV. The Linac upgrade of the machine covers many different aspects. The purpose is to increase the compactness of the accelerator complex whereas the beam properties for ring injection are kept. A LAL Orsay-PMB ALCEN collaboration has been established. The program foresees the RF design, prototyping and power tests of a high-gradient compact S-band accelerating structure. To fulfill the technical specifications at the interaction point, the Linac must be carefully designed. Beam dynamics simulations have been performed for optimizing the emittance and the energy spread for the ring entrance. The best set of parameters together with the effect of the accelerating section to the beam dynamics at the end of the LINAC will be presented. * A. Variola, et al, "The Thomx Project Status", Proceedings of IPAC2014, Dresden, Germany.
	Slides THOP12 [1.726 MB]
	Poster THOP12 [0.823 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP12
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THPLR012	Beam-Loading Compensation of a Multi-Bunch Electron Beam by Using RF Amplitude Modulation in Laser Undulator Compact X-Ray Source (LUCX)	gun, electron, beam-loading, cavity	867
	M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Washio Waseda University, 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 via laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. In here, a multi-bunch electron beam is generated by a 3.6cell photo-cathode RF-gun and accelerated to 18-24MeV by a 12cell booster. And then 6-10 keV X-rays are generated by LCS between the beam and a laser pulse stored in a 4-mirror planar optical cavity. Our aim is to take a phase contrast image with Talbot interferometer within a few minutes at present. The target flux of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth. For an electron beam, the target of the intensity is 500nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24MeV beam with total charge of 600nC in 1000bunches. The energy difference is within 1.3% peak to peak. The beam-loading is compensated by delta T method and amplitude modulation(AM) of the RF pulse. However there is the energy difference at the RF-gun. It is assumed that this causes the reduction of the X-ray flux due to change of the focused beam size. To reduce the energy difference, AM is also applied to the RF pulse for the gun. We will show the results of the beam-loading compensation and the generation of X-rays. Y. Yokoyama et al. , Proceedings IPAC2011, TUPC059 (2011).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR012
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THPLR014	Laser-Driven Dielectric Nano-Beam Accelerator for Radiation Biology Researches	electron, acceleration, simulation, ion	873
	K. Koyama, M. Yoshida KEK, Ibaraki, Japan Z. Chen, H. Okamoto The University of Tokyo, Tokyo, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was partly supported by JSPS KAKENHI (B)(Grant-in-Aid for Scientific Research) Grant Number 15H03595. Since a laser-driven dielectric accelerator (LDA) is most likely to deliver a nano-beam with a small scale device, a combination of the LDA and a biological cell observation device such as a fluorescence microscope seems to be a powerful tool for radiation biology researches. The LDA consists of single or a pair of binary-blazed transmission grating. In case of normal incidence, a grating constant must be the same with a laser wavelength to synchronize with the electron and an acceleration field. Although demonstration experiments have been published from SLAC and MPQ, there are many problems to be solved, especially in the non-relativistic energy region. A crucial problem is to make it clear whether electrons are accelerated with negligibly small wiggling or lateral shift. We are simulating at various conditions with the aid of CST-code. We also analyze an oblique incidence (OI) scheme for the efficient acceleration of slow electron. The OI-scheme enables to use the grating of larger grating constant. Adoption of the large grating constant makes it easy to fabricate the grating. Besides analytical works, we are making gratings and developing an Yb-doped fiber laser for the acceleration experiment. Gratings of two different materials, a glass silica and crystal silica, were fabricated by the e-beam lithography technique.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR014
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THPLR019	A Laser Pulse Controller for the Injector Laser at FLASH and European XFEL	operation, timing, undulator, hardware	882
	C. Grün, S. Schreiber, T. Schulz DESY, Hamburg, Germany
	FLASH is a multi-beamline free-electron laser user facility which provides femtosecond long high brilliant photon pulses in the extreme-UV and soft-X ray wavelength range. One pulsed superconducting linac accelerates electron bunches for two undulator beamlines, while a third beamline is under construction. Within each RF-pulse, trains of hundreds of electron bunches are produced in a photo-cathode RF gun, accelerated in the linac and distributed by fast kickers into the undulator beamlines. In order to fulfill the parameter ranges of the multiple user experiments each bunch train can be tuned individually in bunch number from 0 - 800, spacing from 1 μs - 25 μs and intensity from 0.1 nC - 1 nC. To make this possible, three injector laser systems are used and this allows FLASH to vary independently the laser settings for the designated undulator beamlines. A laser controller has been developed to make a multi-users operation mode possible. The controller uses a Field Programmable Gate Array (FPGA) to control the time structure of the laser pulses and it provides the interface for the timing and the machine protection system. The controller has been implemented using the MicroTCA.4 technology. The controller was ported to the injector laser system at the European XFEL facility and is in operation since end 2015.
	Poster THPLR019 [1.967 MB]
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Paper

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MO2A04

Low Emittance and High Current Electron Linac Development at Tsinghua University

gun, emittance, electron, experiment

17

C.-X. Tang, H.B. Chen, Z.J. Chi, Y.-C. Du, W.-H. Huang, J. Shi, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, Z. Zhang, Z. Zhang, L.M. Zheng, Z. Zhou
TUB, Beijing, People's Republic of China

A 50MeV electron linac have been developed in Tsinghua University, which consists of a 1.6Cell photocathode rf gun, a 3-meter s-band SLAC type traveling wave (TW) accelerating structure an a s-band TW buncher. The photocathode rf gun is working at 120MV/m, 2856MHz, with very small dark current. The emittance of the electron beam is less than 1mm.mrad at 500pC, and 0.5mm.mrad at 200pC. The linac is designed for Tsinghua Thomson scattering X-ray source (TTX), and 2x10⁷ photon/bunch at 50keV has been got and some application experiments with the x-ray have been carried out. The new photocathode rf gun and x-band high gradient accelerating structure development will also be introducted in this talk.

Slides MO2A04 [11.413 MB]

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MO3A01

Status of SwissFEL

linac, electron, undulator, gun

22

F. Löhl
PSI, Villigen PSI, Switzerland

SwissFEL is a hard x-ray free-electron laser facility that is currently constructed at PSI. This paper gives an overview of the facility, describes the main sub-systems of the accelerator, and summarizes the installation and commissioning status.

Slides MO3A01 [315.102 MB]

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MO3A02

Achievement of Small Beam Size at ATF2 Beamline

optics, sextupole, wakefield, simulation

27

T. Okugi
KEK, Ibaraki, Japan

The beam commissioning of the ATF2 facility at KEK - a 1.3 GeV prototype of the compact local chromaticity correction final focus system for the linear collider - achieved 44nm beam size, very close to ideal expected size of 37nm, by developing various knobs and improving the performances of the interferometric Shintake monitor at the same time. These results have opened the way to reliable and predictable operation of the linear collider.

Slides MO3A02 [3.495 MB]

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MOOP09

Dielectric and THz Acceleration (Data) Programme at the Cockcroft Institute

acceleration, electron, wakefield, accelerating-gradient

62

S.P. Jamison, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.B. Appleby, H.L. Owen, T.H. Pacey, T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom
G. Burt, R. Letizia, C. Paoloni
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A.W. Cross
USTRAT/SUPA, Glasgow, United Kingdom
D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work has been funded by STFC
Normal conducting RF systems are currently able to pro-vide gradients of around 100 MV/m, limited by break-down on the metallic structures. The breakdown rate is known to scale with pulse length and, in conventional RF systems, this is limited by the filling time of the RF struc-ture. Progressing to higher frequencies, from RF to THz and optical, can utilise higher gradient structures due to the fast filling times. Further increases in gradient may be possible by replacing metallic structures with dielectric structures. The DATA programme at the Cockcroft Insti-tute is investigating concepts for particle acceleration with laser driven THz sources and dielectric structures, beam driven dielectric and metallic structures, and optical and infrared laser acceleration using grating and photonic structures. A cornerstone of the programme is the VELA and CLARA electron accelerator test facility at Daresbury Laboratory which will be used for proof-of-principle experiments demonstrating particle acceleration.

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MOPLR013

Investigations on Electron Beam Imperfections at PITZ

electron, simulation, solenoid, gun

165

M. Krasilnikov, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, G. Pathak, Y. Renier, T. Rublack, F. Stephan, G. Vashchenko, Q.T. Zhao
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
C. Hernandez-Garcia
JLab, Newport News, Virginia, USA

Since more than a decade, the photo injector test facility at DESY, Zeuthen site (PITZ), has developed and optimized high brightness electron sources for modern Free Electros Lasers like FLASH and the European XFEL. Despite a very high performance of the photo injector was experimentally demonstrated, several discrepancies between measurements and beam dynamics simulations have been revealed. Although the optimized measured values of the projected transverse emittance are close to those obtained from the beam dynamics simulations, the corresponding experimental machine parameters show certain systematic deviations from the simulated optimized setup. As a source for these deviations, electron beam imperfections were experimentally investigated. This includes studies on bunch charge production, electron beam imaging using the RF gun with its solenoid, and investigations on the transverse asymmetry of the electron beam generated in a rotationally symmetric gun cavity. Experimental studies were supplied with corresponding beam dynamics simulations. The paper reports on results of these studies.

Poster MOPLR013 [2.140 MB]

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MOPLR035

Fabrication of Superconducting Spoke Cavity for Compact Photon Source

cavity, photon, linac, scattering

212

M. Sawamura, R. Hajima
QST, Tokai, Japan
H. Hokonohara, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
T. Kubo, T. Saeki
KEK, Ibaraki, Japan

Funding: This study is supported by Photon and Quantum Basic Research Coordinated Development Program of MEXT, Japan.
The spoke cavity is expected to have advantages for compact ERL accelerator for X-ray source based on laser Compton scattering. We have been developing the spoke cavity under a research program of MEXT, Japan to establish the fabrication process. Since our designed shape of the spoke is complicated due to increase the RF properties, one-step press forming with one set of molds will cause so large strain to break the sheet. We designed the mold components including the process of press work. The press forming tests of the spoke cavity have been done with the various materials of sheets to check molding performance. In this paper we present status of the spoke cavity fabrication.

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MOPLR071

A 3-MeV Linac for Development of Accelerator Components at J-PARC

linac, rfq, operation, ion

298

Y. Kondo, H. Asano, E. Chishiro, K. Hirano, T. Itou, Y. Kawane, N. Kikuzawa, S.I. Meigo, A. Miura, S. Mizobata, T. Morishita, H. Oguri, K. Ohkoshi, A. Ohzone, Y. Sato, S. Shinozaki, K. Shinto, H. Takei, K. Tsutsumi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Z. Fang, Y. Fukui, K. Futatsukawa, K. Ikegami, T. Miyao, K. Nanmo, T. Shibata, T. Sugimura, A. Takagi
KEK, Ibaraki, Japan
T. Hori
Nippon Advanced Technology Co., Ltd., Tokai, Japan
T. Ishiyama, T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Mayama, Y. Sawabe
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

We are constructing a linac for development of accelerator components at J-PARC. This linac consists of a H⁻ ion source, a low energy beam transport (LEBT), an radio frequency quadrupole (RFQ) linac, and a diagnostics bean line. The beam energy is 3 MeV, the beam current is 30 mA, and the duty factor is 0.6%, which corresponds to 0.5 kW. The accelerator itself has a capacity of at least 1 kW. However, the beam power is limited by radiation dose, because there are no radiation shields between the accessible area during the operation. The source and LEBT are same as the J-PARC linac's. The RFQ is a used one in the J-PARC linac, called RFQ I. At first, we are planning to conduct experiments of the laser charge exchange development for the transmutation facility. Then, this linac will be used for the development accelerator components such as beam scrapers, bunch shape monitors, laser profile monitors, and so on. We will be able to install new devices into the actual J-PARC linac after the full testing. The development of H⁻ ion source can be carried out at this system, and also RFQ in the future. In this paper, present status of this 3-MeV linac at J-PARC is presented.

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TU3A01

Beam Commissioning Results From the R&D ERL at BNL

gun, cathode, SRF, cavity

374

D. Kayran, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, L.R. Hammons, J.P. Jamilkowski, P. K. Kankiya, R.F. Lambiase, V. Litvinenko, R.J. Michnoff, T.A. Miller, J. Morris, V. Ptitsyn, T. Seda, B. Sheehy, K.S. Smith, E. Wang, W. Xu
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, L.R. Hammons, V. Litvinenko, V. Ptitsyn
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
BNL R&D ERL beam commissioning started in June 2014 [*]. The key components of R&D ERL are the highly damped 5-cell 704 MHz superconducting RF cavity and the high-current superconducting RF gun. The gun is equipped with a multi-alkaline photocathode insertion system. The first photocurrent from ERL SRF gun has been observed in November 2014. In June 2015 a high charge 0.5nC and 20 uA average current were demonstrated. In July 2015 gun to dump beam test started. The beam was successfully transported from the SRF gun through the injection system, then through the linac to the beam dump. All ERL components have been installed. In October 2015, SRF gun cavity has been found contaminated during severe cathode stalk RF conditioning. This cavity has been sent for repair and modification for later use in low-energy RHIC electron cooler (LEReC)[**]. LEReC scheduled to start commissioning in early of 2018. We present our results of BNL ERL beam commissioning, the measured beam properties, the operational status, and future prospects.
*) D.Kayran et al., Status and commissioning results of the R&D ERL at BNL. Proc. ERL2015, p. 11-14
**)J. Kewisch et al., ERL for Low Energy Electron Cooling at RHIC (LEReC). Proc. ERL2015, p. 67-71

Slides TU3A01 [12.502 MB]

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TUOP01

Applying Transverse Gradient Undulators to Suppression of Microbunching Instability

electron, linac, FEL, simulation

380

D. Huang, H.X. Deng, C. Feng, D. Gu, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Funding: Major State Basic Research Development Program of China (2011CB808300). National Natural Science Foundation of China (NSFC), grant No. 11275253.
The microbunching instability developed during the beam compression process in the linear accelerator (LIN-AC) of a free-electron laser (FEL) facility has always been a problem that degrades the lasing performance, and even no FEL is able to be produced if the beam quality is destroyed too much by the instability. A common way to suppress the microbunching instability is to introduce extra uncorrelated energy spread by the laser heater that heats the beam through the interaction between the electron and laser beam, as what has been successfully implemented in the Linac Coherent Light Source and Fermi@Elettra. In this paper, a simple and effective scheme is proposed to suppress the microbunching instability by adding two transverse gradient undulators (TGU) before and after the magnetic bunch compressor. The additional uncorrelated energy spread and the density mixing from the transverse spread brought up by the first TGU results in significant suppression of the instability. Meanwhile, the extra slice energy spread and the transverse emittance can also be effectively recovered by the second TGU. The magnitude of the suppression can be easily controlled by varying the strength of the magnetic fields of the TGUs. Theoretical analysis and numerical simulations demonstrate the capability of the proposed technique in the LINAC of an x-ray free-electron laser facility.

Slides TUOP01 [1.148 MB]

Poster TUOP01 [0.447 MB]

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TUPRC022

UPS Study for CsK2Sb Photocathode

cathode, electron, experiment, ion

465

M. Kuriki, T. Konomi, Y. Seimiya
KEK, Ibaraki, Japan
L. Guo, M. Urano, A. Yokota
HU/AdSM, Higashi-Hiroshima, Japan
K. Negishi
Iwate University, Morioka, Iwate, Japan

CsK2Sb photo-cathode is one of the ideal cathode for accelerators requiring the high brightness electron beam. It can be driven with a green laser which can be generated as SHG from solid state laser. The QE (Quantum Efficiency) of photo-electron emission is as high as more than 10% with 532nm light. The material is robust and the typical operational lifetime is more than several months. It is also vital against the high intensity beam extraction. The photo-cathode is generated as a thin film in-situ and the material property and optimized condition for the cathode formation is not understood well. In this article, we present UPS analysis of CsK2Sb cathode for deeper understanding.

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TUPLR013

Lifetime Study of CKk2Sb Robust Photo-Cathode for a High Brightness Electron Source

cathode, vacuum, electron, brightness

500

M. Kuriki, Y. Seimiya
KEK, Ibaraki, Japan
L. Guo, K. Moriya, M. Urano, A. Yokota
HU/AdSM, Higashi-Hiroshima, Japan
K. Negishi
Iwate University, Morioka, Iwate, Japan

CsK2Sb photo-cathode is one of the ideal cathode for accelerators requiring the high brightness electron beam. It can be driven with a green laser which can be generated as SHG from solid state laser. The QE (Quantum Efficiency) of photo-electron emission is as high as more than 10% with 532nm light. In this article, the robustness of the cathode is studied. Two indexes of lifetime regarding to time and extracted charge density were evaluated experimentally. The result shows that the cathode is robust enough for a high brightness accelerator.

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TUPLR015

Design of a Gamma-Ray Source Based on Inverse Compton Scattering at the Fast Superconducting Linac

electron, photon, cavity, brightness

503

D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA
B.T. Jacobson, A.Y. Murokh
RadiaBeam, Santa Monica, California, USA
P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: This work is sponsored by the DNDO via contract with NIU.
A Watt-level average-power gamma-ray source is currently under development at the FermiLab Accelerator Science & Technology (FAST) facility. The source is based on the inverse Compton scattering of a high-brightness 300-MeV beam against a high-power laser beam circulating in an optical cavity. The back scattered gamma rays are expected to have photon energies up to 1.5 MeV. This paper discusses the optimization of the source, its performance and the main challenges ahead.

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TH2A01

The Linac Laser Notcher for the Fermilab Booster

linac, booster, cavity, injection

710

D.E. Johnson, K.L. Duel, M.H. Gardner, T.R. Johnson, D. Slimmer
Fermilab, Batavia, Illinois, USA
S. Patil
PriTel, Inc., Naperville, USA
J. Tafoya
Optical Engines, Inc., Colorado Springs, USA

In synchrotron machines, the beam extraction is accomplished by a combination of septa and kicker magnets which deflect the beam from an accelerator into another. Ideally the kicker field must rise/fall in between the beam bunches. However, in reality, an intentional beam-free time region (aka "notch") is created on the beam pulse to assure that the beam can be extracted with minimal losses. In the case of the Fermilab Booster, the notch is created in the ring near injection energy by the use of fast kickers which deposit the beam in a shielded collimation region within the accelerator tunnel. With increasing beam power it is desirable to create this notch at the lowest possible energy to minimize activation. The Fermilab Proton Improvement Plan (PIP) initiated an R&D project to build a laser system to create the notch within a linac beam pulse at 750 keV. This talk will describe the concept for the laser notcher and discuss our current status, commissioning results, and future plans.

Slides TH2A01 [15.170 MB]

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TH2A02

Results From the Laserwire Emittance Scanner and Profile Monitor at CERN's Linac4

detector, electron, linac, emittance

715

T. Hofmann, U. Raich, F. Roncarolo
CERN, Geneva, Switzerland
G.E. Boorman, A. Bosco, S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
G.E. Boorman, A. Bosco, S.M. Gibson
JAI, Egham, Surrey, United Kingdom

A novel, non-invasive, H⁻ laser-wire scanner has been tested during the beam commissioning of CERN's new Linac4. Emittance measurements were performed at beam energies of 3 and 12 MeV with this new device and were found to closely match the results of conventional slit-grid methods. In 2015, the configuration of this laser-wire scanner was substantially modified. In the new setup the electrons liberated by the photo-detachment process are deflected away from the main beam and focused onto a single crystal diamond detector that can be moved in order to follow the laser beam scan. The beam profiles measured with the new laser-wire setup at 50 MeV, 80 MeV and 10⁷ MeV are in good agreement with the measurements of nearby SEM grids and wire-scanners. The design of the final laser-wire scanner for the full 160 MeV beam energy will also be presented. In Linac4 two independent laser-wire devices will be installed in the transfer line to the BOOSTER ring. Each device will be composed of two parts: one hosting the laser-wire and the electron detector and the second hosting the segmented diamond detector used to acquire the transverse profiles of the H⁰ beamlets.

Slides TH2A02 [3.164 MB]

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TH3A01

Making Molecular Movie with MeV Electrons

electron, experiment, alignment, detector

725

X. Shen, X.J. Wang
SLAC, Menlo Park, California, USA

SLAC launched the Ultrafast Electron Diffraction and Imaging (UED&UEM) initiative with the objective of developing the world leading ultrafast electron scattering instrumentation, complementary to the X-ray Free Electron Laser - Linac Coherent Light Source (LCLS). SLAC has developed a UED setup at the Accelerator Structure Test Area (ASTA), with the goal of providing MeV, 100-femtosecond-scale electron pulses to support an ultrafast science program [1]. The first UED ultrafast science experiment published in Nano Letters, where large amplitude wrinkles of monolayer MoS2 generated by the light pulse' more than 15 percent of the layer's thickness, was observed. This is the first time anyone has visualized these ultrafast atomic motions. Ultrafast MeV electrons also made it possible the direct measurement of phonon occupations as energy is transferred from electrons into the lattice in laser-heated gold (APL). The rotational wavepacket dynamics of laser-aligned nitrogen molecules were captured in gas-phase electron diffraction experiment using MeV electrons. We achieved an unprecedented combination of 100-fs (rms) temporal resolution and sub-Angstrom (0.76 Å) spatial resolution that makes it possible to resolve the position of the nuclei within the molecule(Nature Communications).
[1] S. Weathersby, et al., Rev. Sci. Instrum. 86, 073702 (2015).

Slides TH3A01 [6.518 MB]

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TH3A02

The Los Alamos Multi-Probe Facility for Matter-Radiation Interactions in Extremes

electron, linac, photon, proton

729

R.W. Garnett
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
A next-generation signature facility based on multi-probe capabilities is being planned at Los Alamos. This new facility will enable the first in a new generation of game-changing scientific facilities for the materials community. The new Matter-Radiation Interactions in Extremes (MaRIE) facility will be used to discover and design the advanced materials needed to meet 21st-century national security and energy-security challenges to develop next-generation materials that will perform predictably in extreme environments. The MaRIE facility will include a new 12-GeV electron linac using a state-of-the-art electron photoinjector and superconducting accelerator technology to drive a 42-keV XFEL to generate x rays of unprecedented flux and quality, coupled with the existing proton-beam capabilities of the LANSCE proton linac, new experimental halls, and new materials fabrication/characterization facilities. A description of this new facility, its requirements, and planned uses and capabilities will be presented. Status of the project will also be presented.

Slides TH3A02 [5.060 MB]

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TH3A03

The VELA and CLARA Test Facilities at Daresbury Laboratory

FEL, electron, gun, cavity

734

P.A. McIntosh, D. Angal-Kalinin, J.A. Clarke, L.S. Cowie, B.D. Fell, S.P. Jamison, B.L. Militsyn, Y.M. Saveliev, D.J. Scott, N. Thompson, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Gleeson, T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The Versatile Electron Linear Accelerator (VELA) provides enabling infrastructures targeted at the development and testing of novel and compact accelerator technologies, specifically through partnership with academia and industry, aimed at addressing applications in medicine, health, security, energy and industrial processing. The facility is now fully commissioned and is taking advantage of the variable electron beam parameters to demonstrate new techniques/processes or otherwise develop new technologies for future commercial realization. Examples of which include; electron diffraction and new cargo scanning processes. The Compact Linear Accelerator for Research and Applications (CLARA) will be a novel FEL test facility, focused on the generation of ultra-short photon pulses with extreme levels of stability and synchronization. The principal aim is to experimentally demonstrate that sub-cooperation length pulse generation with FELs is viable, and to compare the various schemes being championed. The results will translate directly to existing and future X-ray FELs, enabling attosecond pulse generation. Both the VELA and CLARA facilities are co-located at Daresbury Laboratory and provide the UK with a unique platform for scientific and commercial R&D using ultra-short pulse, high precision electron and photon beams.

Slides TH3A03 [11.795 MB]

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THOP12

Electron Linac Upgrade for Thomx Project

gun, linac, emittance, electron

773

L. Garolfi, C. Bruni, M. El Khaldi
LAL, Orsay, France
N. Faure, A. Perez Delaume
PMB-ALCEN, PEYNIER, France

The injector Linac for Thomx * consists of an electron gun and S-band accelerating section. The RF gun is a 2.5 cells photo-injector able to provide electron bunches with 5 MeV energy. During the commissioning phase, a standard S-band accelerating section is able to achieve around 50 MeV corresponding to around 45 keV X-rays energy. Since the maximum targeted X-ray energy is 90 keV, the Linac design will provide a beam energy of 70 MeV. The Linac upgrade of the machine covers many different aspects. The purpose is to increase the compactness of the accelerator complex whereas the beam properties for ring injection are kept. A LAL Orsay-PMB ALCEN collaboration has been established. The program foresees the RF design, prototyping and power tests of a high-gradient compact S-band accelerating structure. To fulfill the technical specifications at the interaction point, the Linac must be carefully designed. Beam dynamics simulations have been performed for optimizing the emittance and the energy spread for the ring entrance. The best set of parameters together with the effect of the accelerating section to the beam dynamics at the end of the LINAC will be presented.
* A. Variola, et al, "The Thomx Project Status", Proceedings of IPAC2014, Dresden, Germany.

Slides THOP12 [1.726 MB]

Poster THOP12 [0.823 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP12

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THPLR012

Beam-Loading Compensation of a Multi-Bunch Electron Beam by Using RF Amplitude Modulation in Laser Undulator Compact X-Ray Source (LUCX)

gun, electron, beam-loading, cavity

867

M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
Waseda University, 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 via laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. In here, a multi-bunch electron beam is generated by a 3.6cell photo-cathode RF-gun and accelerated to 18-24MeV by a 12cell booster. And then 6-10 keV X-rays are generated by LCS between the beam and a laser pulse stored in a 4-mirror planar optical cavity. Our aim is to take a phase contrast image with Talbot interferometer within a few minutes at present. The target flux of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth. For an electron beam, the target of the intensity is 500nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24MeV beam with total charge of 600nC in 1000bunches. The energy difference is within 1.3% peak to peak. The beam-loading is compensated by delta T method and amplitude modulation(AM) of the RF pulse*. However there is the energy difference at the RF-gun. It is assumed that this causes the reduction of the X-ray flux due to change of the focused beam size. To reduce the energy difference, AM is also applied to the RF pulse for the gun. We will show the results of the beam-loading compensation and the generation of X-rays.
* Y. Yokoyama et al. , Proceedings IPAC2011, TUPC059 (2011).

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THPLR014

Laser-Driven Dielectric Nano-Beam Accelerator for Radiation Biology Researches

electron, acceleration, simulation, ion

873

K. Koyama, M. Yoshida
KEK, Ibaraki, Japan
Z. Chen, H. Okamoto
The University of Tokyo, Tokyo, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was partly supported by JSPS KAKENHI (B)(Grant-in-Aid for Scientific Research) Grant Number 15H03595.
Since a laser-driven dielectric accelerator (LDA) is most likely to deliver a nano-beam with a small scale device, a combination of the LDA and a biological cell observation device such as a fluorescence microscope seems to be a powerful tool for radiation biology researches. The LDA consists of single or a pair of binary-blazed transmission grating. In case of normal incidence, a grating constant must be the same with a laser wavelength to synchronize with the electron and an acceleration field. Although demonstration experiments have been published from SLAC and MPQ, there are many problems to be solved, especially in the non-relativistic energy region. A crucial problem is to make it clear whether electrons are accelerated with negligibly small wiggling or lateral shift. We are simulating at various conditions with the aid of CST-code. We also analyze an oblique incidence (OI) scheme for the efficient acceleration of slow electron. The OI-scheme enables to use the grating of larger grating constant. Adoption of the large grating constant makes it easy to fabricate the grating. Besides analytical works, we are making gratings and developing an Yb-doped fiber laser for the acceleration experiment. Gratings of two different materials, a glass silica and crystal silica, were fabricated by the e-beam lithography technique.

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THPLR019

A Laser Pulse Controller for the Injector Laser at FLASH and European XFEL

operation, timing, undulator, hardware

882

C. Grün, S. Schreiber, T. Schulz
DESY, Hamburg, Germany

FLASH is a multi-beamline free-electron laser user facility which provides femtosecond long high brilliant photon pulses in the extreme-UV and soft-X ray wavelength range. One pulsed superconducting linac accelerates electron bunches for two undulator beamlines, while a third beamline is under construction. Within each RF-pulse, trains of hundreds of electron bunches are produced in a photo-cathode RF gun, accelerated in the linac and distributed by fast kickers into the undulator beamlines. In order to fulfill the parameter ranges of the multiple user experiments each bunch train can be tuned individually in bunch number from 0 - 800, spacing from 1 μs - 25 μs and intensity from 0.1 nC - 1 nC. To make this possible, three injector laser systems are used and this allows FLASH to vary independently the laser settings for the designated undulator beamlines. A laser controller has been developed to make a multi-users operation mode possible. The controller uses a Field Programmable Gate Array (FPGA) to control the time structure of the laser pulses and it provides the interface for the timing and the machine protection system. The controller has been implemented using the MicroTCA.4 technology. The controller was ported to the injector laser system at the European XFEL facility and is in operation since end 2015.

Poster THPLR019 [1.967 MB]

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