IPAC2015 - List of Authors (Terunuma, N.)

Paper	Title	Page
MOBC1	Towards Ultra-Low β^* in ATF2	38
	M. Patecki, A.V. Aloev, D.R. Bett, M. Modena, R. Tomás CERN, Geneva, Switzerland K. Kubo, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan E. Marín, G.R. White SLAC, Menlo Park, California, USA
	The Accelerator Test Facility 2 (ATF2) has already demonstrated the feasibility of Final Focus Systems based on the local chromaticity correction scheme and its focusing capabilities by reaching a vertical beam size at the virtual Interaction Point (IP) of less than 50 nm. The value of the chromaticity in ATF2 is comparable with the expected chromaticity in ILC, but 4 times lower than in a design of CLIC. ATF2 gives the unique possibility to test operation at CLIC chromaticity values by reducing the vertical beta function at the IP by a factor of 4 (the inverse proportionality of chromaticity with beta function value at IP is assumed). The experience collected in this way would be beneficial for both ILC and CLIC projects. Simulations show that the multipolar errors and Final Doublet fringe fields spoil the IP beam sizes at ATF2. Either increasing a value of the horizontal beta function or installing a pair of octupole magnets mitigate the impact of these aberrations. This paper summarizes the studies towards the realization of the ultra-low β^* optics in ATF2 and reports on the progress of the construction of the octupoles.
	Slides MOBC1 [1.566 MB]
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MOPJE065	Contribution of Optical Aberrations to Spot-size Increase with Bunch Intensity at ATF2	455
	M. Patecki, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland K. Kubo, S. Kuroda, T. Naito, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan M. Patecki Warsaw University of Technology, Warsaw, Poland G.R. White SLAC, Menlo Park, California, USA
	A primary goal of ATF2 (Accelerator Test Facility) is to demonstrate a low vertical beam size at the interaction point (IP) of about 37 nm. Measurements over the past years indicate that the ATF2 vertical beam size strongly rises with bunch intensity. Several different origins of this increase are considered, e.g. wakefields occurring between the ATF damping ring and the IP, and/or intrabeam scattering (IBS) causing the increase of transverse emittances and energy spread in the damping ring with the increase of the bunch intensity. In this paper we address the second possibility. Past measurements and simulations of the IBS effects in the ATF are used to model the intensity-dependent initial emittances and energy spread at the entrance of the final focus. Particle tracking simulations predict the IP vertical beam size growth expected from the known optical aberrations for initial beam parameters corresponding to varying bunch intensities. Comparing simulation results with emittance measurements at different locations allows us to draw some conclusions about the impact of IBS in the damping ring on the IP spot size, and about possible single-bunch wakefields in the ATF2.
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MOPHA003	Status of ATF2 IP-BPM Project	777
	O.R. Blanco-García, P. Bambade, F. Bogard, P. Cornebise, S. Wallon LAL, Orsay, France D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich JAI, Oxford, United Kingdom P. Burrows, G.B. Christian, C. Perry Oxford University, Physics Department, Oxford, Oxon, United Kingdom Y. Honda, K. Kubo, S. Kuroda, T. Naito, T. Okugi, T.T. Tauchi, N. Terunuma KEK, Ibaraki, Japan S.W. Jang, E.-S. Kim KNU, Deagu, Republic of Korea
	The efforts during the second half of 2014 towards nano-metric beam position measurement and stabilization at the Interaction Point (IP) section of the Accelerator Test Facility (ATF) at KEK are presented. Recent improvements to the beam position monitor (BPM) data analysis and processing electronics, as well as the installation of a new set of C-Band BPMs, are reviewed.
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MOPHA008	Investigation of Beam Halo Using In Vacuum Diamond Sensor at ATF2	791
	S. Liu, P. Bambade, F. Bogard, P. Cornebise, V. Kubytskyi, C. Sylvia LAL, Orsay, France A. Faus-Golfe, N. Fuster-Martínez IFIC, Valencia, Spain T. Tauchi, N. Terunuma KEK, Ibaraki, Japan T. Tauchi, N. Terunuma Sokendai, Ibaraki, Japan
	Funding: Chinese Scholarship Council, CNRS and P2IO LABEX Beam halo transverse distribution measurements are of great importance for the understanding of background sources of the nano-meter beam size monitor at the interaction point (IPBSM) of ATF2. One of the most critical issues for the beam halo measurement is to reach high dynamic range. Two in vacuum diamond sensor beam halo scanners (DSv) with four strips each have been developed for the investigation of beam halo transverse distributions at ATF2. The first DSv was installed for horizontal beam halo scanning after the interaction point (IP) of ATF2, in Nov. 2014. It aims to measure the beam halo distribution with large dynamic range (~10⁶), and investigate the possibility of probing the Compton recoil electrons produced in the interaction with the IPBSM laser beams. Studies to characterize the DS performance and measurements of horizontal beam halo performed in Nov.-Dec. 2014 are presented.
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TUBC1	Recent Progress and Operational Status of the Compact ERL at KEK	1359
	S. Sakanaka, M. Adachi, S. Adachi, T. Akagi, M. Akemoto, D.A. Arakawa, S. Araki, S. Asaoka, M. Egi, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X.J. Jin, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, A. Kosuge, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sasaki, K. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, N. Terunuma, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, J. Urakawa, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan R. Hajima, S. Matsuba, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma JAEA, Ibaraki-ken, Japan J.G. Hwang KNU, Deagu, Republic of Korea M. Kuriki Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan
	Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program from the MEXT, and by the MEXT grant for promoting technology for nuclear security. The Compact Energy Recovery Linac (cERL) is a superconducting test accelerator aimed at establishing technologies for the ERL-based future light source. After its construction during 2009 to 2013, the first CW beams of 20 MeV were successfully transported through the recirculation loop in February 2014. Then, initial tuning of beams and evaluations of beam properties were carried out. From September to December in 2014, we are constructing a Laser Compton Scattering (LCS) source* which aims at demonstrating technology for the future high-flux quasi-monochromatic gamma-ray source. In the next run of the cERL, which begins at the end of January 2015, we plan such works as an increase in the beam current (from 10 uA to 100 uA), commissioning of the LCS source, and sustained tuning of beams for lower emittance. We will report up-to-date results of these developments. * N. Nakamura et al., IPAC2014, MOPRO110; S. Sakanaka et al., LINAC14, TUPOL01. ** R. Nagai et al., IPAC2014, WEPRO003.
	Slides TUBC1 [2.679 MB]
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TUPWA065	Generation of Multi-bunch Beam with Beam Loading Compensation by Using RF Amplitude Modulation in Laser Undulator Compact X-ray (LUCX)	1576
	M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan K. Sakaue, M. Washio RISE, Tokyo, Japan
	We have developed a compact X-ray source based on inverse Compton scattering between an electron beam and a laser pulse stacked in an optical cavity at Laser Undulator Compact X-ray (LUCX) accelerator in KEK. The accelerator consists of a 3.6 cell photo-cathode rf-gun, a 12cell standing wave accelerating structure and a 4-mirror planar optical cavity. Our aim is to obtain a clear X-ray image in a shorter period of times and the target flux of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth at present. To achieve this target, it is necessary to increase the intensity of an electron beam to 500nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24MeV beam with total charge of 600nC in 1000bunches with beam-loading compensation by using the delta T method and the amplitude modulation of RF pulse. The bunch-by-bunch energy difference is within 1.3% peak to peak. We will report the results of the multi-bunch beam generation and acceleration in this accelerator. This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
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TUPWA066	Development of a High Average Power Laser for High Brightness X-ray Source and Imaging at cERL	1579
	A. Kosuge, T. Akagi, S. Araki, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan R. Hajima, M. Mori, T. Shizuma JAEA, Ibaraki-ken, Japan R. Nagai JAEA/ERL, Ibaraki, Japan
	Funding: This study is supported by Photon and Quantum Basic Research Coordinated Development Program of MEXT, Japan. High brightness X-rays via laser-Compton scattering (LCS) of laser photons stored in an optical cavity by a relativistic electron beam is useful for many scientific and industrial applications such as X-ray imaging. The construction of compact Energy Recovery Linac (cERL) is now in progress at KEK to generate low-emittance and high-current electron beams. In order to demonstrate the generation of high brightness LCS X-rays, it is necessary to develop a high average power injection laser and an optical four-mirror ring cavity with two concave mirrors which is used to produce a small spot laser beam inside the cavity. In this presentation, we will show the result of the development of the high average laser system, the LCS X-rays generation, and the X-ray imaging.
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TUPWA070	CST Simulations of THz Cherenkov Smith-purcell Radiation from Corrugated Capillary	1594
	K. Lekomtsev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan P. Karataev JAI, Egham, Surrey, United Kingdom A. Ponomarenko, A.A. Tishchenko MEPhI, Moscow, Russia
	Recent advances in generation of femtosecond pre-bunched beams have a potential to generate coherent THz radiation occurring via combination of Smith-Purcell radiation (SPR) and Cherenkov radiation (ChR) generated in a corrugated capillary. This mechanism was studied theoretically . LUCX accelerator at High Energy Accelerator Research Organisation (KEK) has been upgraded by introducing fs Ti:Sa laser system and it is currently generating short tens of fs electron bunches . In this report we present EM simulations of Ch.SPR generated in a corrugated channel in infinite dielectric and in a dielectric corrugated capillary. CST PIC solver is used as a simulation tool. It was earlier used for simulation of Transition radiation *. Intensity dependencies of ChR and SPR peaks as functions of the capillary radius and the corrugation depth are compared with the theoretical investigation . Output of THz radiation from the dielectric capillary with a radiation reflector is simulated. * A.A. Ponomarenko et. al, NIMB 309 (2013) 223-226. M. Fukuda et. al, NIMA 637 (2011) S67. * K.V. Lekomtsev et. al, J. Phys.: Conf. Ser. 517, (2014) 012016.
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TUPJE002	Demonstration of High-flux Photon Generation from an ERL-based Laser Compton Photon Source	1607
	R. Nagai, R. Hajima, M. Mori, T. Shizuma JAEA, Ibaraki-ken, Japan T. Akagi, S. Araki, Y. Honda, A. Kosuge, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	A high-flux photon source from the laser Compton scattering (LCS) by an electron beam in an energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear materials. In order to demonstrate accelerator and laser technologies required for a LCS photon generation, a LCS photon source is under construction at the Compact ERL (cERL). The LCS photon source consists of a mode-locked fiber laser and a laser enhancement cavity. Flux monitors and a data aqcuisition system are also under construction. The commissioning of the LCS photon source will be started in February 2015 and LCS photon generation is scheduled in March 2015. The demonstration result of the LCS photon source will be presented in detail.
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TUPJE011	Laser-Compton Scattering X-ray Source Based on Normal Conducting Linac and Optical Enhancement Cavity	1635
	K. Sakaue, M. Washio Waseda University, Tokyo, Japan S. Araki, M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Funding: Work 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 KEK-LUCX (Laser Undulator Compact X-ray source) facility. The LUCX system is based on S-band normal conducting linac with an energy of 30 MeV and optical enhancement cavity for photon target. As a photon target, we invented a burst mode laser pulse storage technique for a normal conducting linac, which enables to store the high power laser pulses at the timing of electron bunchs. The peak storage power exceeds to more than 250 kW with 357 MHz repetition. Electron linac is under operation with multi-bunch mode, 1000 bunches/train with 600 pC charge in each bunches. We have succeeded to produce 1000 pulse/train LCS X-ray train. Combining high repetition rate electron linac and burst mode optical enhancement cavity, more than 10⁹ ph./sec/10%b.w. flux would be possible. In this conference, the introduction of our test facility LUCX, recent expermental results, and future prospective including normal conducting LCS X-ray source will be presented.
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TUPTY019	Realistic Beam Halo Model study in the Extraction Line of ATF2	2038
	N. Fuster-Martínez, A. Faus-Golfe IFIC, Valencia, Spain P. Bambade, S. Liu, S. Wallon LAL, Orsay, France K. Kubo, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan E. Marín, G.R. White SLAC, Menlo Park, California, USA
	Funding: Work supported by IDC-20101074, FPA2013-47883-C2-1-P and ANR-11-IDEX-0003-02 The understanding and control of the transverse beam halo distributions is an important issue to reduce sources of background noise in Future Linear Colliders (FLC) and specifically at ATF2. A realistic model of the beam halo in the old extraction line of the ATF damping ring was obtained in 2005, based on wire scanner measurements. Recently, new measurements were done in the new extraction line of ATF2, using both wire scanners, in 2013, and Optical Transition Radiation monitors (OTR), in 2014. The beam halo propagation through the ATF2 beamline by means of tracking simulations has been investigated using as input a purely Gaussian and uniform beam halo model.
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WEPMN059	Design Study and Construction of a Transverse Beam Halo Collimation System for ATF2	3062
	N. Fuster-Martínez, A. Faus-Golfe IFIC, Valencia, Spain P. Bambade, S. Liu, S. Wallon LAL, Orsay, France K. Kubo, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan I. Podadera, F. Toral CIEMAT, Madrid, Spain
	Funding: Work supported by IDC-20121074, FPA2013-47883-C2-1-P and ANR-11-IDEX-0003-02 The feasibility and efficiency of a transverse beam halo collimation system for reducing the background in the ATF2 beamline has been studied in simulations. In this paper the design and construction of a retractable transverse beam halo collimator device is presented. The wakefield induced-impact of a realistic mechanical prototype has been studied with CST PS, as well as the wakefield beam dynamics impact by using the tracking code PLACET.
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Paper

Title

Page

Towards Ultra-Low β^* in ATF2

38

M. Patecki, A.V. Aloev, D.R. Bett, M. Modena, R. Tomás
CERN, Geneva, Switzerland
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
E. Marín, G.R. White
SLAC, Menlo Park, California, USA

The Accelerator Test Facility 2 (ATF2) has already demonstrated the feasibility of Final Focus Systems based on the local chromaticity correction scheme and its focusing capabilities by reaching a vertical beam size at the virtual Interaction Point (IP) of less than 50 nm. The value of the chromaticity in ATF2 is comparable with the expected chromaticity in ILC, but 4 times lower than in a design of CLIC. ATF2 gives the unique possibility to test operation at CLIC chromaticity values by reducing the vertical beta function at the IP by a factor of 4 (the inverse proportionality of chromaticity with beta function value at IP is assumed). The experience collected in this way would be beneficial for both ILC and CLIC projects. Simulations show that the multipolar errors and Final Doublet fringe fields spoil the IP beam sizes at ATF2. Either increasing a value of the horizontal beta function or installing a pair of octupole magnets mitigate the impact of these aberrations. This paper summarizes the studies towards the realization of the ultra-low β^* optics in ATF2 and reports on the progress of the construction of the octupoles.

Slides MOBC1 [1.566 MB]

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MOPJE065

Contribution of Optical Aberrations to Spot-size Increase with Bunch Intensity at ATF2

455

M. Patecki, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
K. Kubo, S. Kuroda, T. Naito, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
M. Patecki
Warsaw University of Technology, Warsaw, Poland
G.R. White
SLAC, Menlo Park, California, USA

A primary goal of ATF2 (Accelerator Test Facility) is to demonstrate a low vertical beam size at the interaction point (IP) of about 37 nm. Measurements over the past years indicate that the ATF2 vertical beam size strongly rises with bunch intensity. Several different origins of this increase are considered, e.g. wakefields occurring between the ATF damping ring and the IP, and/or intrabeam scattering (IBS) causing the increase of transverse emittances and energy spread in the damping ring with the increase of the bunch intensity. In this paper we address the second possibility. Past measurements and simulations of the IBS effects in the ATF are used to model the intensity-dependent initial emittances and energy spread at the entrance of the final focus. Particle tracking simulations predict the IP vertical beam size growth expected from the known optical aberrations for initial beam parameters corresponding to varying bunch intensities. Comparing simulation results with emittance measurements at different locations allows us to draw some conclusions about the impact of IBS in the damping ring on the IP spot size, and about possible single-bunch wakefields in the ATF2.

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MOPHA003

Status of ATF2 IP-BPM Project

777

O.R. Blanco-García, P. Bambade, F. Bogard, P. Cornebise, S. Wallon
LAL, Orsay, France
D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich
JAI, Oxford, United Kingdom
P. Burrows, G.B. Christian, C. Perry
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
Y. Honda, K. Kubo, S. Kuroda, T. Naito, T. Okugi, T.T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
S.W. Jang, E.-S. Kim
KNU, Deagu, Republic of Korea

The efforts during the second half of 2014 towards nano-metric beam position measurement and stabilization at the Interaction Point (IP) section of the Accelerator Test Facility (ATF) at KEK are presented. Recent improvements to the beam position monitor (BPM) data analysis and processing electronics, as well as the installation of a new set of C-Band BPMs, are reviewed.

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MOPHA008

Investigation of Beam Halo Using In Vacuum Diamond Sensor at ATF2

791

S. Liu, P. Bambade, F. Bogard, P. Cornebise, V. Kubytskyi, C. Sylvia
LAL, Orsay, France
A. Faus-Golfe, N. Fuster-Martínez
IFIC, Valencia, Spain
T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
T. Tauchi, N. Terunuma
Sokendai, Ibaraki, Japan

Funding: Chinese Scholarship Council, CNRS and P2IO LABEX
Beam halo transverse distribution measurements are of great importance for the understanding of background sources of the nano-meter beam size monitor at the interaction point (IPBSM) of ATF2. One of the most critical issues for the beam halo measurement is to reach high dynamic range. Two in vacuum diamond sensor beam halo scanners (DSv) with four strips each have been developed for the investigation of beam halo transverse distributions at ATF2. The first DSv was installed for horizontal beam halo scanning after the interaction point (IP) of ATF2, in Nov. 2014. It aims to measure the beam halo distribution with large dynamic range (~10⁶), and investigate the possibility of probing the Compton recoil electrons produced in the interaction with the IPBSM laser beams. Studies to characterize the DS performance and measurements of horizontal beam halo performed in Nov.-Dec. 2014 are presented.

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TUBC1

Recent Progress and Operational Status of the Compact ERL at KEK

1359

S. Sakanaka, M. Adachi, S. Adachi, T. Akagi, M. Akemoto, D.A. Arakawa, S. Araki, S. Asaoka, M. Egi, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X.J. Jin, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, A. Kosuge, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sasaki, K. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, N. Terunuma, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, J. Urakawa, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
R. Hajima, S. Matsuba, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
JAEA, Ibaraki-ken, Japan
J.G. Hwang
KNU, Deagu, Republic of Korea
M. Kuriki
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
Y. Seimiya
HU/AdSM, Higashi-Hiroshima, Japan

Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program from the MEXT, and by the MEXT grant for promoting technology for nuclear security.
The Compact Energy Recovery Linac (cERL) is a superconducting test accelerator aimed at establishing technologies for the ERL-based future light source. After its construction during 2009 to 2013, the first CW beams of 20 MeV were successfully transported through the recirculation loop in February 2014*. Then, initial tuning of beams and evaluations of beam properties were carried out. From September to December in 2014, we are constructing a Laser Compton Scattering (LCS) source** which aims at demonstrating technology for the future high-flux quasi-monochromatic gamma-ray source. In the next run of the cERL, which begins at the end of January 2015, we plan such works as an increase in the beam current (from 10 uA to 100 uA), commissioning of the LCS source, and sustained tuning of beams for lower emittance. We will report up-to-date results of these developments.
* N. Nakamura et al., IPAC2014, MOPRO110; S. Sakanaka et al., LINAC14, TUPOL01.
** R. Nagai et al., IPAC2014, WEPRO003.

Slides TUBC1 [2.679 MB]

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TUPWA065

Generation of Multi-bunch Beam with Beam Loading Compensation by Using RF Amplitude Modulation in Laser Undulator Compact X-ray (LUCX)

1576

M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
K. Sakaue, M. Washio
RISE, Tokyo, Japan

We have developed a compact X-ray source based on inverse Compton scattering between an electron beam and a laser pulse stacked in an optical cavity at Laser Undulator Compact X-ray (LUCX) accelerator in KEK. The accelerator consists of a 3.6 cell photo-cathode rf-gun, a 12cell standing wave accelerating structure and a 4-mirror planar optical cavity. Our aim is to obtain a clear X-ray image in a shorter period of times and the target flux of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth at present. To achieve this target, it is necessary to increase the intensity of an electron beam to 500nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24MeV beam with total charge of 600nC in 1000bunches with beam-loading compensation by using the delta T method and the amplitude modulation of RF pulse. The bunch-by-bunch energy difference is within 1.3% peak to peak. We will report the results of the multi-bunch beam generation and acceleration in this accelerator.
This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

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TUPWA066

Development of a High Average Power Laser for High Brightness X-ray Source and Imaging at cERL

1579

A. Kosuge, T. Akagi, S. Araki, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
R. Hajima, M. Mori, T. Shizuma
JAEA, Ibaraki-ken, Japan
R. Nagai
JAEA/ERL, Ibaraki, Japan

Funding: This study is supported by Photon and Quantum Basic Research Coordinated Development Program of MEXT, Japan.
High brightness X-rays via laser-Compton scattering (LCS) of laser photons stored in an optical cavity by a relativistic electron beam is useful for many scientific and industrial applications such as X-ray imaging. The construction of compact Energy Recovery Linac (cERL) is now in progress at KEK to generate low-emittance and high-current electron beams. In order to demonstrate the generation of high brightness LCS X-rays, it is necessary to develop a high average power injection laser and an optical four-mirror ring cavity with two concave mirrors which is used to produce a small spot laser beam inside the cavity. In this presentation, we will show the result of the development of the high average laser system, the LCS X-rays generation, and the X-ray imaging.

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TUPWA070

CST Simulations of THz Cherenkov Smith-purcell Radiation from Corrugated Capillary

1594

K. Lekomtsev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
P. Karataev
JAI, Egham, Surrey, United Kingdom
A. Ponomarenko, A.A. Tishchenko
MEPhI, Moscow, Russia

Recent advances in generation of femtosecond pre-bunched beams have a potential to generate coherent THz radiation occurring via combination of Smith-Purcell radiation (SPR) and Cherenkov radiation (ChR) generated in a corrugated capillary. This mechanism was studied theoretically *. LUCX accelerator at High Energy Accelerator Research Organisation (KEK) has been upgraded by introducing fs Ti:Sa laser system and it is currently generating short tens of fs electron bunches **. In this report we present EM simulations of Ch.SPR generated in a corrugated channel in infinite dielectric and in a dielectric corrugated capillary. CST PIC solver is used as a simulation tool. It was earlier used for simulation of Transition radiation ***. Intensity dependencies of ChR and SPR peaks as functions of the capillary radius and the corrugation depth are compared with the theoretical investigation *. Output of THz radiation from the dielectric capillary with a radiation reflector is simulated.
* A.A. Ponomarenko et. al, NIMB 309 (2013) 223-226.
** M. Fukuda et. al, NIMA 637 (2011) S67.
*** K.V. Lekomtsev et. al, J. Phys.: Conf. Ser. 517, (2014) 012016.

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TUPJE002

Demonstration of High-flux Photon Generation from an ERL-based Laser Compton Photon Source

1607

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

A high-flux photon source from the laser Compton scattering (LCS) by an electron beam in an energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear materials. In order to demonstrate accelerator and laser technologies required for a LCS photon generation, a LCS photon source is under construction at the Compact ERL (cERL). The LCS photon source consists of a mode-locked fiber laser and a laser enhancement cavity. Flux monitors and a data aqcuisition system are also under construction. The commissioning of the LCS photon source will be started in February 2015 and LCS photon generation is scheduled in March 2015. The demonstration result of the LCS photon source will be presented in detail.

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TUPJE011

Laser-Compton Scattering X-ray Source Based on Normal Conducting Linac and Optical Enhancement Cavity

1635

K. Sakaue, M. Washio
Waseda University, Tokyo, Japan
S. Araki, M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work 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 KEK-LUCX (Laser Undulator Compact X-ray source) facility. The LUCX system is based on S-band normal conducting linac with an energy of 30 MeV and optical enhancement cavity for photon target. As a photon target, we invented a burst mode laser pulse storage technique for a normal conducting linac, which enables to store the high power laser pulses at the timing of electron bunchs. The peak storage power exceeds to more than 250 kW with 357 MHz repetition. Electron linac is under operation with multi-bunch mode, 1000 bunches/train with 600 pC charge in each bunches. We have succeeded to produce 1000 pulse/train LCS X-ray train. Combining high repetition rate electron linac and burst mode optical enhancement cavity, more than 10⁹ ph./sec/10%b.w. flux would be possible. In this conference, the introduction of our test facility LUCX, recent expermental results, and future prospective including normal conducting LCS X-ray source will be presented.

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TUPTY019

Realistic Beam Halo Model study in the Extraction Line of ATF2

2038

N. Fuster-Martínez, A. Faus-Golfe
IFIC, Valencia, Spain
P. Bambade, S. Liu, S. Wallon
LAL, Orsay, France
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
E. Marín, G.R. White
SLAC, Menlo Park, California, USA

Funding: Work supported by IDC-20101074, FPA2013-47883-C2-1-P and ANR-11-IDEX-0003-02
The understanding and control of the transverse beam halo distributions is an important issue to reduce sources of background noise in Future Linear Colliders (FLC) and specifically at ATF2. A realistic model of the beam halo in the old extraction line of the ATF damping ring was obtained in 2005, based on wire scanner measurements. Recently, new measurements were done in the new extraction line of ATF2, using both wire scanners, in 2013, and Optical Transition Radiation monitors (OTR), in 2014. The beam halo propagation through the ATF2 beamline by means of tracking simulations has been investigated using as input a purely Gaussian and uniform beam halo model.

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WEPMN059

Design Study and Construction of a Transverse Beam Halo Collimation System for ATF2

3062

N. Fuster-Martínez, A. Faus-Golfe
IFIC, Valencia, Spain
P. Bambade, S. Liu, S. Wallon
LAL, Orsay, France
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
I. Podadera, F. Toral
CIEMAT, Madrid, Spain

Funding: Work supported by IDC-20121074, FPA2013-47883-C2-1-P and ANR-11-IDEX-0003-02
The feasibility and efficiency of a transverse beam halo collimation system for reducing the background in the ATF2 beamline has been studied in simulations. In this paper the design and construction of a retractable transverse beam halo collimator device is presented. The wakefield induced-impact of a realistic mechanical prototype has been studied with CST PS, as well as the wakefield beam dynamics impact by using the tracking code PLACET.

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