IPAC2016 - Classification: 02 Photon Sources and Electron Accelerators / A23 Other Linac-based Photon Sources

Paper	Title	Page
TUPOW041	Optimization Studies for the Beam Dynamic in the RF Linac of the ELI-NP Gamma Beam System	1850
	C. Vaccarezza, D. Alesini, M. Bellaveglia, M.E. Biagini, G. Di Pirro, A. Gallo, A. Ghigo, S. Guiducci, A. Vannozzi, A. Variola INFN/LNF, Frascati (Roma), Italy A. Bacci, I. Drebot, D.T. Palmer, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy G. Campogiani Rome University La Sapienza, Roma, Italy A. Giribono, A. Mostacci, L. Palumbo University of Rome La Sapienza, Rome, Italy V. Petrillo Universita' degli Studi di Milano & INFN, Milano, Italy L. Sabbatini Consorzio Laboratorio Nicola Cabibbo, Frascati, Italy
	The ELI-NP GBS is an high spectral density and monochromatic gamma ray source based upon the inverse Compton scattering effect now under construction in Magurele. Its relevant specifications are brilliance higher than 10²¹, 0.5% monochromaticity and a 0.2-19.5 MeV energy tunability. Strong requirements are set for the electron beam dynamic: the control of both the transverse normalized emittance and the energy spread to optimize the spectral density and guarantee the mono chromaticity of the emitted radiation. On this basis the RF Linac optimization has been performed for the designed energy range; a sensitivity analysis of the machine to possible jitters, errors and so on has been also performed, the simulations results hare here presented.
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TUPOW042	Expected Gamma Spectra at ELI-NP-GBS	1854
	I. Drebot, C. Curatolo Universita' degli Studi di Milano e INFN, Milano, Italy A. Bacci, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Giribono University of Rome "La Sapienza", Rome, Italy V. Petrillo Universita' degli Studi di Milano & INFN, Milano, Italy C. Vaccarezza, A. Variola INFN/LNF, Frascati (Roma), Italy
	The ELI-NP-GBS is an advanced source of up to 20 MeV Gamma Rays based on Compton back-scattering. We present the investigation of the production of the ELI-NP gamma photon beam generated by Compton back-scattering between the electron bunch accelerated in the linac and the laser pulse. At the interaction point (IP), the Compton backscattering properties, as spectral flux, brilliance and polarization are evaluated by the Klein-Nishina cross section. The gamma beam produced has energy ranging from 0.2 to 19.5 MeV and bandwidth of 0.5%. In order to define the optimal layout and evaluate the performances of the collimation and detection systems, a detailed Monte Carlo simulation activity has been carried out taking into account possible jitters and errors.
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TUPOW043	Electron Beam Dynamics Studies for ELI-NP GBS Linac	1857
SUPSS017	use link to see paper's listing under its alternate paper code
	A. Giribono, F. Cardelli, L. Palumbo, L. Piersanti University of Rome La Sapienza, Rome, Italy D. Alesini, A. Gallo, C. Vaccarezza, A. Vannozzi INFN/LNF, Frascati (Roma), Italy A. Bacci, C. Curatolo, I. Drebot, V. Petrillo, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy G. Campogiani Rome University La Sapienza, Roma, Italy F. Cardelli, L. Piersanti INFN-Roma1, Rome, Italy L. Palumbo INFN-Roma, Roma, Italy
	The ELI-NP Gamma Beam System is an advanced gamma ray source based on the Compton back-scattering effect with unprecedented specifications of brilliance ( >10²¹), monochromaticity (0.5%) and energy tunability (0.2 - 19.5 MeV), presently under construction in Magurele-Bucharest (RO). Here the head-on collision is foreseen between an intense high power laser beam and a high brightness high quality electron beam with a maximum kinetic energy of 740 MeV. The electron beam dynamics analysis and control for the ELI-NP GBS Linac in the single and multi bunch mode have been investigated and are here illustrated.
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TUPOW044	Experimental Investigation of THz Smith-Purcell Radiation From Composite Corrugated Capillary	1861
	K. Lekomtsev, A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan A. Ponomarenko, A.A. Tishchenko MEPhI, Moscow, Russia
	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. Terahertz part of electromagnetic spectrum has a variety of potential applications ranging from fundamental to security applications. Further advances in development of a linac based, tunable, and narrow band coherent source of THz radiation are very important. Mechanisms of Cherenkov radiation and Smith-Purcell radiation (SPR) [] may be used for generation of THz radiation via coherent emission [, ]. In this report we will present experimental investigations of the SPR generated from the corrugated capillary with a reflector, using the femtosecond multi-bunch electron beam of LUCX accelerator at KEK, Japan [*]. LUCX is capable to generate a train of 4 bunches each with 200 femtosecond (60 micrometer) duration and 200 micrometer transverse size. We will discuss the composite design of the capillary, measurements of the SPR angular distributions and the comparison of these measurements with PIC simulations. In addition, we will discuss SPR spectral characteristics; bunch energy modulation, introduced by the corrugated capillary; and the way in which the bunch spacing changes the spectrum and angular distributions of SPR. K.Lekomtsev et al., NIMB 355 (2015) 164 A. M. Cook et al., PRL 103, (2009) 095003. S. E. Korbly et al., PRL 94, (2005) 054803. ***A. Aryshev, arXiv:1507.03302 [physics.acc-ph]
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TUPOW045	Pre-bunched Electron Beam Emittance Simulation and Measurement	1864
	Yu.D. Kliuchevskaia, S.M. Polozov MEPhI, Moscow, Russia A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	LUCX facility at KEK is used as the high brightness pre-bunched electron beam source for radiation experiments. Emittance measurement and optimization is one of the important research activities for newly developed operation mode of the facility. Characterization of the pre-bunched beam (THz sequence of a hundred femtosecond bunches) properties opens a possibility to establish detailed simulation of the THz FEL radiation yield and continuously improve pre-bunched beam dynamics insight. Emittance has been measured by the Q-scan method. The measurement results and possible ways of emittance optimization are discussed. The measurement results are compared with beam dynamics simulation done by self-consistent BEAMDULAC-BL code.
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TUPOW046	Development and Upgrade Plan of an X-ray Source Based on Laser Compton Scattering in Laser Undulator Compact X-ray Source(LUCX)	1867
	M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan M. Kageyama, M. Kuribayashi Rigaku Corporation, XG & Core Technology, Tokyo, Japan A. Momose, M.P. Olbinado, Y. Wu Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Sendai, 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 Laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. Our aim is to obtain a clear X-ray image in a shorter period of times and the target number of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth. In the accelerator, an electron beam with the energy of 18-24 MeV is generated by an S-band normal conducting accelerator. The beam is collided with a laser pulse stacked in a 4-mirror planar optical cavity and then 6-10 keV X-rays are generated by LCS. Presently, the generation of X-rays with the number of 3x10⁶ photons/pulse at the collision point has been achieved. X-ray imaging test such as refraction contrast images and phase contrast imaging with Talbot interferometer has also started. To increase the intensity of X-rays, we are continuing the tuning of the electron beam and the optical cavity because the exposure time of X-ray imaging is too long now. We are also planning to increase the beam energy by appending the accelerating tube. In this conference, the recent results and upgrade plan in LUCX will be reported.
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TUPOW047	Generation of a Coherent Cherenkov Radiation by using Electron Bunch Tilting	1870
	K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan R. Kuroda, Y. Taira AIST, Tsukuba, Ibaraki, Japan M. Nishida, M. Washio Waseda University, Tokyo, Japan J. Urakawa KEK, Ibaraki, Japan
	We have been developing a compact accelerator based a laser photocathode rf electron gun at Waseda University. Low emittance and short bunched electron beam can be generated from the gun. Also, the rf transverse deflecting cavity was developed for the bunch length measurement. We performed an experiment for generating a coherent Cherenkov radiation using bunch tilting. The rf transverse deflector can give a tilt for the electron bunch, and the tilt angle was set to the Cherenkov radiating angle which determined by the target refractive index. We successfully demonstrated a coherent Cherenkov radiation and the characterization of the radiation. The principle of coherent Cherenkov radiation generation, the experimental results and future prospective will be presented at the conference.
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TUPOW049	Expected Results From Channeling Radiation Experiments at Fast	1873
	T. Sen, D.R. Broemmelsiek, D.R. Edstrom Fermilab, Batavia, Illinois, USA J. Hyun Sokendai, Ibaraki, Japan D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA W.D. Rush KU, Lawrence, Kansas, USA
	Funding: Fermilab is operated by Fermi Research Alliance LLC under DOE contract No. DE-AC02CH11359 The photoinjector at the new Fermilab FAST facility will accelerate electron beams to about 50 GeV. After initial beam commissioning, channeling radiation experiments to generate hard X-rays will be performed. In the initial stage, low bunch charge beams will be used to keep the photon count rate low and avoid pile up in the detector. We report here on the optics solutions, the expected channaling spectrum including background from bremmstrahlung and the use of a Compton scatterer for higher bunch charge operation.
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TUPOW050	Parametric X-rays at FAST	1877
	T. Sen Fermilab, Batavia, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance LLC under DOE contract No. DE-AC02CH11359 We discuss the generation of parametric X-rays (PXR) in the photoinjector at the new FAST facility at Fermilab. Detailed calculations of the intensity spectrum, energy and angular widths and spectral brilliance with a diamond crystal are presented. We also report on expected results with PXR generated while the beam is channeling. The low emittance electron beam makes this facility a promising source for creating brilliant X-rays.
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TUPOW051	Optimization of Electron Beam and Laser Pulse Alignment and Focusing at Interaction Point for a Compact FEL Based Inverse-Compton Scattering X-Ray Source	1881
SUPSS019	use link to see paper's listing under its alternate paper code
	P. Niknejadi, J. Madey University of Hawaii, Honolulu,, USA
	Funding: This work was funded under the Department of Homeland Security Grant No. 2010-DN-077-ARI045. In July 2015, the first beam of 10 keV X-rays from our FEL based inverse-Compton scattering X-ray source was detected.* In this setup, 3 micron laser pulses at 2.856 GHz repetition rate from a free electron laser are collided head-on with 40 MeV electron bunches driving the laser. To attain our objective the ebeam was required to have 1) a tight focus at the X-ray interaction point, 2) vertical and horizontal envelopes matched to the downstream undulator, 3) minimized transverse dimensions for low ionizing radiation. Optimization of these quantities required information on the evolution of the beam profiles between the beam spot images on the available insertable screens, leading to the need for a simulator to accurately trace the beam profiles through the system. A simulator was developed and used to optimize the system Twiss parameters by comparing the effectiveness of the beam profiles computed by fitting the profiles to the observed beam spot images along the beamline for different cathode positions. This method proved to be considerably more flexible and effective than the more traditional quadrupole scan technique. Summery of the designed system and results are provided. * John M. J. Madey, ARI final report, December 2015.
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TUPOW052	LLNL Laser-Compton X-ray Characterization	1885
SUPSS018	use link to see paper's listing under its alternate paper code
	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 Laser-Compton X-rays have been produced at LLNL, and results agree very well with modeling predictions. An X-ray CCD camera and image plates were calibrated and used to characterize the 30 keV X-ray beam. A resolution test pattern was imaged to measure the source size. K-edge absorption images using thin foils confirm the narrow bandwidth of the source and offer electron beam diagnostics.
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TUPOW053	Measurement of Terahertz Generation in a Metallic, Corrugated Beam Pipe	1889
	K.L.F. Bane SLAC, Menlo Park, California, USA S.P. Antipov ANL, Argonne, Illinois, USA M.G. Fedurin, K. Kusche, C. Swinson BNL, Upton, Long Island, New York, USA D. Xiang Shanghai Jiao Tong University, Shanghai, People's Republic of China
	Funding: Work supported by the Department of Energy, Office of Science, Office of Basic Energy Science, under Contract No. DE-AC02-76SF00515 A method for producing narrow-band THz radiation proposes passing an ultra-relativistic beam through a metallic pipe with small periodic corrugations. We present results of a measurement of such an arrangement at BNL's Advanced Test Facility (ATF). Our pipe was copper and was 5 cm long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a corrugation depth (peak-to-peak) of 60 um. In the experiment we measured both the effect on the beam of the structure wakefield and the spectral properties of the radiation excited by the beam. We began by injecting a relatively long beam–-compared to the wavelength of the radiation–-to excite the structure, and then used a downstream spectrometer to infer the radiation wavelength. This was followed by injecting a shorter bunch, and then using an interferometer (also downstream of the corrugated pipe) to measure the spectrum of the induced THz radiation. Our experimental set-up was simple and not optimized for the efficient collection of the radiation by e.g. the use of tapered horns. As such it can be considered a proof-of-principle experiment. K. Bane and G. Stupakov, NIM A677 (2012) 67-73.
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TUPOW054	Characterization of a Sub-THz Radiation Source Based on a 3 MeV Electron Beam and Future Plans	1892
	A.V. Smirnov, R.B. Agustsson, T.J. Campese, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A.Y. Murokh, M. Ruelas RadiaBeam, Santa Monica, California, USA W. Berg, J.C. Dooling, L. Erwin, R.R. Lindberg, S.J. Pasky, N. Sereno, Y.-E. Sun, A. Zholents ANL, Argonne, Ilinois, USA Y. Kim KAERI, Jeongeup-si, Republic of Korea
	Funding: This work was supported by the U.S. Department of Energy (award No. DE-SC-FOA-0007702) Design features and some past experimental results are presented for a sub-THz wave source employing the Advanced Photon Source's RF thermionic electron gun. The setup includes a compact alpha-magnet, four quadrupoles, a novel radiator, a THz transport line, and THz diagnostics. The radiator is composed of a dielectric-free, planar, over-sized structure with gratings. The gratings are integrated into a combined horn antenna and ~90° permanent bending magnet. The magnetic lattice enables operation in different modes, including conversion to a flat beam for efficient interaction with the radiating structure. The experiment described demonstrated the generation of narrow bandwidth THz radiation from a compact, laser and undulator-free, table-top system. This concept could be scaled to create a THz-sub-THz source capable of operating in long-pulse, multi-bunch, and CW modes. Additionally, the system can be used to remove unwanted time-dependent energy variations in longitudinally compressed electron bunches or for various time-dependent beam diagnostics. Plans for future experiments and upgrades are also discussed.
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Paper

Title

Page

Optimization Studies for the Beam Dynamic in the RF Linac of the ELI-NP Gamma Beam System

1850

C. Vaccarezza, D. Alesini, M. Bellaveglia, M.E. Biagini, G. Di Pirro, A. Gallo, A. Ghigo, S. Guiducci, A. Vannozzi, A. Variola
INFN/LNF, Frascati (Roma), Italy
A. Bacci, I. Drebot, D.T. Palmer, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
G. Campogiani
Rome University La Sapienza, Roma, Italy
A. Giribono, A. Mostacci, L. Palumbo
University of Rome La Sapienza, Rome, Italy
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy
L. Sabbatini
Consorzio Laboratorio Nicola Cabibbo, Frascati, Italy

The ELI-NP GBS is an high spectral density and monochromatic gamma ray source based upon the inverse Compton scattering effect now under construction in Magurele. Its relevant specifications are brilliance higher than 10²¹, 0.5% monochromaticity and a 0.2-19.5 MeV energy tunability. Strong requirements are set for the electron beam dynamic: the control of both the transverse normalized emittance and the energy spread to optimize the spectral density and guarantee the mono chromaticity of the emitted radiation. On this basis the RF Linac optimization has been performed for the designed energy range; a sensitivity analysis of the machine to possible jitters, errors and so on has been also performed, the simulations results hare here presented.

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TUPOW042

Expected Gamma Spectra at ELI-NP-GBS

1854

I. Drebot, C. Curatolo
Universita' degli Studi di Milano e INFN, Milano, Italy
A. Bacci, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Giribono
University of Rome "La Sapienza", Rome, Italy
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy
C. Vaccarezza, A. Variola
INFN/LNF, Frascati (Roma), Italy

The ELI-NP-GBS is an advanced source of up to 20 MeV Gamma Rays based on Compton back-scattering. We present the investigation of the production of the ELI-NP gamma photon beam generated by Compton back-scattering between the electron bunch accelerated in the linac and the laser pulse. At the interaction point (IP), the Compton backscattering properties, as spectral flux, brilliance and polarization are evaluated by the Klein-Nishina cross section. The gamma beam produced has energy ranging from 0.2 to 19.5 MeV and bandwidth of 0.5%. In order to define the optimal layout and evaluate the performances of the collimation and detection systems, a detailed Monte Carlo simulation activity has been carried out taking into account possible jitters and errors.

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TUPOW043

Electron Beam Dynamics Studies for ELI-NP GBS Linac

1857

SUPSS017

use link to see paper's listing under its alternate paper code

A. Giribono, F. Cardelli, L. Palumbo, L. Piersanti
University of Rome La Sapienza, Rome, Italy
D. Alesini, A. Gallo, C. Vaccarezza, A. Vannozzi
INFN/LNF, Frascati (Roma), Italy
A. Bacci, C. Curatolo, I. Drebot, V. Petrillo, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
G. Campogiani
Rome University La Sapienza, Roma, Italy
F. Cardelli, L. Piersanti
INFN-Roma1, Rome, Italy
L. Palumbo
INFN-Roma, Roma, Italy

The ELI-NP Gamma Beam System is an advanced gamma ray source based on the Compton back-scattering effect with unprecedented specifications of brilliance ( >10²¹), monochromaticity (0.5%) and energy tunability (0.2 - 19.5 MeV), presently under construction in Magurele-Bucharest (RO). Here the head-on collision is foreseen between an intense high power laser beam and a high brightness high quality electron beam with a maximum kinetic energy of 740 MeV. The electron beam dynamics analysis and control for the ELI-NP GBS Linac in the single and multi bunch mode have been investigated and are here illustrated.

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TUPOW044

Experimental Investigation of THz Smith-Purcell Radiation From Composite Corrugated Capillary

1861

K. Lekomtsev, A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
A. Ponomarenko, A.A. Tishchenko
MEPhI, Moscow, Russia

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.
Terahertz part of electromagnetic spectrum has a variety of potential applications ranging from fundamental to security applications. Further advances in development of a linac based, tunable, and narrow band coherent source of THz radiation are very important. Mechanisms of Cherenkov radiation and Smith-Purcell radiation (SPR) [*] may be used for generation of THz radiation via coherent emission [**, ***]. In this report we will present experimental investigations of the SPR generated from the corrugated capillary with a reflector, using the femtosecond multi-bunch electron beam of LUCX accelerator at KEK, Japan [****]. LUCX is capable to generate a train of 4 bunches each with 200 femtosecond (60 micrometer) duration and 200 micrometer transverse size. We will discuss the composite design of the capillary, measurements of the SPR angular distributions and the comparison of these measurements with PIC simulations. In addition, we will discuss SPR spectral characteristics; bunch energy modulation, introduced by the corrugated capillary; and the way in which the bunch spacing changes the spectrum and angular distributions of SPR.
*K.Lekomtsev et al., NIMB 355 (2015) 164
**A. M. Cook et al., PRL 103, (2009) 095003.
***S. E. Korbly et al., PRL 94, (2005) 054803.
****A. Aryshev, arXiv:1507.03302 [physics.acc-ph]

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TUPOW045

Pre-bunched Electron Beam Emittance Simulation and Measurement

1864

Yu.D. Kliuchevskaia, S.M. Polozov
MEPhI, Moscow, Russia
A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

LUCX facility at KEK is used as the high brightness pre-bunched electron beam source for radiation experiments. Emittance measurement and optimization is one of the important research activities for newly developed operation mode of the facility. Characterization of the pre-bunched beam (THz sequence of a hundred femtosecond bunches) properties opens a possibility to establish detailed simulation of the THz FEL radiation yield and continuously improve pre-bunched beam dynamics insight. Emittance has been measured by the Q-scan method. The measurement results and possible ways of emittance optimization are discussed. The measurement results are compared with beam dynamics simulation done by self-consistent BEAMDULAC-BL code.

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TUPOW046

Development and Upgrade Plan of an X-ray Source Based on Laser Compton Scattering in Laser Undulator Compact X-ray Source(LUCX)

1867

M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
M. Kageyama, M. Kuribayashi
Rigaku Corporation, XG & Core Technology, Tokyo, Japan
A. Momose, M.P. Olbinado, Y. Wu
Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Sendai, 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 Laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. Our aim is to obtain a clear X-ray image in a shorter period of times and the target number of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth. In the accelerator, an electron beam with the energy of 18-24 MeV is generated by an S-band normal conducting accelerator. The beam is collided with a laser pulse stacked in a 4-mirror planar optical cavity and then 6-10 keV X-rays are generated by LCS. Presently, the generation of X-rays with the number of 3x10⁶ photons/pulse at the collision point has been achieved. X-ray imaging test such as refraction contrast images and phase contrast imaging with Talbot interferometer has also started. To increase the intensity of X-rays, we are continuing the tuning of the electron beam and the optical cavity because the exposure time of X-ray imaging is too long now. We are also planning to increase the beam energy by appending the accelerating tube. In this conference, the recent results and upgrade plan in LUCX will be reported.

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TUPOW047

Generation of a Coherent Cherenkov Radiation by using Electron Bunch Tilting

1870

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

We have been developing a compact accelerator based a laser photocathode rf electron gun at Waseda University. Low emittance and short bunched electron beam can be generated from the gun. Also, the rf transverse deflecting cavity was developed for the bunch length measurement. We performed an experiment for generating a coherent Cherenkov radiation using bunch tilting. The rf transverse deflector can give a tilt for the electron bunch, and the tilt angle was set to the Cherenkov radiating angle which determined by the target refractive index. We successfully demonstrated a coherent Cherenkov radiation and the characterization of the radiation. The principle of coherent Cherenkov radiation generation, the experimental results and future prospective will be presented at the conference.

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TUPOW049

Expected Results From Channeling Radiation Experiments at Fast

1873

T. Sen, D.R. Broemmelsiek, D.R. Edstrom
Fermilab, Batavia, Illinois, USA
J. Hyun
Sokendai, Ibaraki, Japan
D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
W.D. Rush
KU, Lawrence, Kansas, USA

Funding: Fermilab is operated by Fermi Research Alliance LLC under DOE contract No. DE-AC02CH11359
The photoinjector at the new Fermilab FAST facility will accelerate electron beams to about 50 GeV. After initial beam commissioning, channeling radiation experiments to generate hard X-rays will be performed. In the initial stage, low bunch charge beams will be used to keep the photon count rate low and avoid pile up in the detector. We report here on the optics solutions, the expected channaling spectrum including background from bremmstrahlung and the use of a Compton scatterer for higher bunch charge operation.

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TUPOW050

Parametric X-rays at FAST

1877

T. Sen
Fermilab, Batavia, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance LLC under DOE contract No. DE-AC02CH11359
We discuss the generation of parametric X-rays (PXR) in the photoinjector at the new FAST facility at Fermilab. Detailed calculations of the intensity spectrum, energy and angular widths and spectral brilliance with a diamond crystal are presented. We also report on expected results with PXR generated while the beam is channeling. The low emittance electron beam makes this facility a promising source for creating brilliant X-rays.

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TUPOW051

Optimization of Electron Beam and Laser Pulse Alignment and Focusing at Interaction Point for a Compact FEL Based Inverse-Compton Scattering X-Ray Source

1881

SUPSS019

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P. Niknejadi, J. Madey
University of Hawaii, Honolulu,, USA

Funding: This work was funded under the Department of Homeland Security Grant No. 2010-DN-077-ARI045.
In July 2015, the first beam of 10 keV X-rays from our FEL based inverse-Compton scattering X-ray source was detected.* In this setup, 3 micron laser pulses at 2.856 GHz repetition rate from a free electron laser are collided head-on with 40 MeV electron bunches driving the laser. To attain our objective the ebeam was required to have 1) a tight focus at the X-ray interaction point, 2) vertical and horizontal envelopes matched to the downstream undulator, 3) minimized transverse dimensions for low ionizing radiation. Optimization of these quantities required information on the evolution of the beam profiles between the beam spot images on the available insertable screens, leading to the need for a simulator to accurately trace the beam profiles through the system. A simulator was developed and used to optimize the system Twiss parameters by comparing the effectiveness of the beam profiles computed by fitting the profiles to the observed beam spot images along the beamline for different cathode positions. This method proved to be considerably more flexible and effective than the more traditional quadrupole scan technique. Summery of the designed system and results are provided.
* John M. J. Madey, ARI final report, December 2015.

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TUPOW052

LLNL Laser-Compton X-ray Characterization

1885

SUPSS018

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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
Laser-Compton X-rays have been produced at LLNL, and results agree very well with modeling predictions. An X-ray CCD camera and image plates were calibrated and used to characterize the 30 keV X-ray beam. A resolution test pattern was imaged to measure the source size. K-edge absorption images using thin foils confirm the narrow bandwidth of the source and offer electron beam diagnostics.

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TUPOW053

Measurement of Terahertz Generation in a Metallic, Corrugated Beam Pipe

1889

K.L.F. Bane
SLAC, Menlo Park, California, USA
S.P. Antipov
ANL, Argonne, Illinois, USA
M.G. Fedurin, K. Kusche, C. Swinson
BNL, Upton, Long Island, New York, USA
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

Funding: Work supported by the Department of Energy, Office of Science, Office of Basic Energy Science, under Contract No. DE-AC02-76SF00515
A method for producing narrow-band THz radiation proposes passing an ultra-relativistic beam through a metallic pipe with small periodic corrugations*. We present results of a measurement of such an arrangement at BNL's Advanced Test Facility (ATF). Our pipe was copper and was 5 cm long; the aperture was cylindrically symmetric, with a 1 mm (radius) bore and a corrugation depth (peak-to-peak) of 60 um. In the experiment we measured both the effect on the beam of the structure wakefield and the spectral properties of the radiation excited by the beam. We began by injecting a relatively long beam–-compared to the wavelength of the radiation–-to excite the structure, and then used a downstream spectrometer to infer the radiation wavelength. This was followed by injecting a shorter bunch, and then using an interferometer (also downstream of the corrugated pipe) to measure the spectrum of the induced THz radiation. Our experimental set-up was simple and not optimized for the efficient collection of the radiation by e.g. the use of tapered horns. As such it can be considered a proof-of-principle experiment.
* K. Bane and G. Stupakov, NIM A677 (2012) 67-73.

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TUPOW054

Characterization of a Sub-THz Radiation Source Based on a 3 MeV Electron Beam and Future Plans

1892

A.V. Smirnov, R.B. Agustsson, T.J. Campese, Y.C. Chen, J.J. Hartzell, B.T. Jacobson, A.Y. Murokh, M. Ruelas
RadiaBeam, Santa Monica, California, USA
W. Berg, J.C. Dooling, L. Erwin, R.R. Lindberg, S.J. Pasky, N. Sereno, Y.-E. Sun, A. Zholents
ANL, Argonne, Ilinois, USA
Y. Kim
KAERI, Jeongeup-si, Republic of Korea

Funding: This work was supported by the U.S. Department of Energy (award No. DE-SC-FOA-0007702)
Design features and some past experimental results are presented for a sub-THz wave source employing the Advanced Photon Source's RF thermionic electron gun. The setup includes a compact alpha-magnet, four quadrupoles, a novel radiator, a THz transport line, and THz diagnostics. The radiator is composed of a dielectric-free, planar, over-sized structure with gratings. The gratings are integrated into a combined horn antenna and ~90° permanent bending magnet. The magnetic lattice enables operation in different modes, including conversion to a flat beam for efficient interaction with the radiating structure. The experiment described demonstrated the generation of narrow bandwidth THz radiation from a compact, laser and undulator-free, table-top system. This concept could be scaled to create a THz-sub-THz source capable of operating in long-pulse, multi-bunch, and CW modes. Additionally, the system can be used to remove unwanted time-dependent energy variations in longitudinally compressed electron bunches or for various time-dependent beam diagnostics. Plans for future experiments and upgrades are also discussed.

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