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T Omori,
M Fukuda, T Hirose,
Y Kurihara,
R Kuroda,
M Nomura,
A Ohashi,
T Okugi,
K Sakaue,
T Saito,
J Urakawa,
M Washio,
I Yamazaki
[show abstract]
[hide abstract]
ABSTRACT: We have demonstrated for the first time the production of highly polarized short-pulse positrons with a finite energy spread in accordance with a new scheme that consists of two-quantum processes, such as inverse Compton scattering and electron-positron pair creation. Using a circularly polarized laser beam of 532 nm scattered off a high-quality, 1.28 GeV electron beam, we have obtained polarized positrons with an intensity of 2 x 10(4) e+ /bunch. The magnitude of positron polarization has been determined to be 73 +/- 15(stat) +/- 19(syst)% by means of a newly designed positron polarimeter.
Physical Review Letters 04/2006; 96(11):114801. · 7.37 Impact Factor
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S Araki,
Y Higashi,
Y Honda,
Y Kurihara,
M. Kuriki,
T. Okugi,
T Omori,
T Taniguchi,
N Terunuma,
J. Urakawa, [......],
N. Sasao,
H Yokoyama,
M Fukuda,
K Hirano,
M Takano,
T Takahashi,
H Sato,
A. Tsunemi,
J Gao,
V. Soskov
[show abstract]
[hide abstract]
ABSTRACT: We describe a scheme for producing polarised positrons at the ILC from polarised X-rays created by Compton scattering of a few-GeV electron beam off a CO2 or YAG laser. This scheme is very energy effective using high finesse laser cavities in conjunction with an electron storage ring.
10/2005;
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Y Honda,
K Kubo,
S Anderson,
S Araki,
K Bane,
A Brachmann,
J Frisch,
M Fukuda,
K Hasegawa,
H Hayano, [......],
N Toge,
J Urakawa,
V Vogel,
M Woodley,
A Wolski,
I Yamazaki,
Yoshio Yamazaki,
G Yocky,
A Young,
F Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: For high luminosity in electron-positron linear colliders, it is essential to generate low vertical emittance beams. We report on the smallest vertical emittance achieved in single-bunch-mode operation of the Accelerator Test Facility, which satisfies the requirement of the x-band linear collider. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured at low intensity is 4 pm at a beam energy of 1.3 GeV, which corresponds to the normalized emittance of 1.0x1.0(-8) m. It increases by a factor of 1.5 for a bunch intensity of 10(10) electrons. The measured data agreed to the calculation of intrabeam scattering within much better than a factor of 2.
Physical Review Letters 03/2004; 92(5):054802. · 7.37 Impact Factor
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M Fukuda,
T Aoki,
K Dobashi, T Hirose,
T Iimura,
Y Kurihara,
T Okugi,
T Omori,
I Sakai,
J Urakawa,
M Washio
[show abstract]
[hide abstract]
ABSTRACT: We have developed a polarimetry of ultrashort pulse gamma rays based on the fact that gamma rays penetrating in the forward direction through a magnetized iron carry information on the helicity of the original gamma rays. Polarized, short-pulse gamma rays of (1.1+/-0.2)x10(6)/bunch with a time duration of 31 ps and a maximum energy of 55.9 MeV were produced via Compton scattering of a circularly polarized laser beam of 532 nm off an electron beam of 1.28 GeV. The first demonstration of asymmetry measurements of short-pulse gamma rays was conducted using longitudinally magnetized iron of 15 cm length. It is found that the gamma-ray intensity is in good agreement with the simulated value of 1.0x10(6). Varying the degree of laser polarization, the asymmetry for 100% laser polarization was derived to be (1.29+/-0.12)%, which is also consistent with the expected value of 1.3%.
Physical Review Letters 11/2003; 91(16):164801. · 7.37 Impact Factor
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V Yakimenko,
I V Pogorelsky,
I V Pavlishin,
I Ben-Zvi,
K Kusche,
Yu Eidelman, T Hirose,
T Kumita,
Y Kamiya,
J Urakawa,
B Greenberg,
A Zigler
[show abstract]
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ABSTRACT: We describe our studies of the generation of plasma wake fields by a relativistic electron bunch and of phasing between the longitudinal and transverse fields in the wake. The leading edge of the electron bunch excites a high-amplitude plasma wake inside the overdense plasma column, and the acceleration and focusing wake fields are probed by the bunch tail. By monitoring the dependence of the acceleration upon the plasma's density, we approached the beam-matching condition and achieved an energy gain of 0.6 MeV over the 17 mm plasma length, corresponding to an average acceleration gradient of 35 MeV/m. Wake-induced modulation in energy and angular divergence of the electron bunch are mapped within a wide range of plasma density. We confirm a theoretical prediction about the phase offset between the accelerating and focusing components of plasma wake.
Physical Review Letters 08/2003; 91(1):014802. · 7.37 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: An experiment to investigate the diffraction radiation from a single edge target has been performed at the accelerator test facility of KEK with the aim of developing noninvasive beam diagnostics. The yield and the angular distribution of diffraction radiation as a function of the impact parameter was measured in the visible light region. The distributions were qualitatively consistent with the theoretical expectation. This work exhibits the first observation of the incoherent diffraction radiation in the visible light region.
Physical Review Letters 04/2003; 90(10):104801. · 7.37 Impact Factor
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I. V. Pogorelsky,
I. Ben-Zvi, T. Hirose,
S. Kashiwagi,
K. Kusche,
T. Kumita,
T. Omori,
V. Yakimenko,
K. Yokoya,
J. Urakawa,
M. Washio
[show abstract]
[hide abstract]
ABSTRACT: The counter-propagating picosecond CO2 laser pulse and picosecond or femtosecond electron bunch produced by the photocathode linac shape the optimum configuration for the ultra-bright relativistic Thomson scattering x-ray source. Using these components, a proof-of-principle experiment at the ATF reached the x-ray photon yield of 8×106 measured in the 1.8–2.3 Å window per 3.5 ps pulse. Upon completion of the ongoing upgrade of the ATF laser and linac, 300 fs x-ray pulses with intensity of 5×1022 photon/second will be obtained. This will provide also an opportunity for fundamental study of the nonlinear Thomson scattering at the laser strength parameter close to 1. Finally, we discuss the feasibility of a high repetition rate Thomson source and how plasma channels facilitate this design. © 2001 American Institute of Physics.
AIP Conference Proceedings. 05/2001; 569(1):571-582.
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T. Hirose,
T. Okugi,
Y. Takayama,
H. Hayano,
S. Kamada,
K. Kubo,
T. Naito,
J. Urakawa,
S. Kashiwagi,
M. Takano,
M. Minty,
J. Turner,
M. Woodley,
F. Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: We applied three methods in order to measure the vertical
emittance of KEK-ATF. The first is a SR interferometer, the second
method is the emittance measurement by using wire scanners at the beam
extraction line. The last method is emittance estimation by measuring an
intensity dependence of a momentum spread, which is caused by the
intra-beam scattering. The measured vertical emittance for KEK-ATF is
0.02-0.06 nm, which is a few times larger than the design target of
KEK-ATF
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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A. Tsunemi,
A. Endo,
I. Pogorelsky,
I. Ben-Zvi,
K. Kusche,
J. Skaritka,
V. Yakimenko, T. Hirose,
J. Urakawa,
T. Omori,
M. Washio,
Y. Liu,
P. He,
D. Cline
[show abstract]
[hide abstract]
ABSTRACT: Laser-Compton scattering with picosecond CO<sub>2</sub> laser
pulses is proposed for generation of high-brightness X-rays. The
interaction chamber has been developed and the experiment is scheduled
for the generation of the X-rays of 4.7 keV, 10<sup>7</sup> photons in
10-ps pulse width using 50-MeV, 0.5-nC relativistic electron bunches and
6 GW CO<sub>2</sub> laser
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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Lasers and Electro-Optics, 1997. CLEO/Pacific Rim '97., Pacific Rim Conference on; 02/1997
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S Kashiwagi,
M Washio,
T Kobuki,
R Kuroda,
I Ben-Zvi,
I Pogorelsky,
K Kusche,
J Skaritka,
V Yakimenko,
X.J Wang, [......],
K Dobashi,
T Muto,
J Urakawa,
T Omori,
T Okugi,
A Tsunemi,
Y Liu,
P He,
D Cline,
Z Segalov
[show abstract]
[hide abstract]
ABSTRACT: We report the first results of high-intensity X-ray generation using Inverse Laser Compton scattering. This experiment was carried out by a US–Japan collaboration at the Brookhaven National Laboratory (BNL) Accelerator Test Facility (ATF) in September 1999. The 3.5 ps X-ray pulse at 6.5 keV, containing 3×106 X-ray photons was generated by the interaction of 60 MeV, 0.5 nC electron bunches and CO2 laser pulses of 600 MW peak power.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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[show abstract]
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ABSTRACT: A comprehensive description of a polarized positron project is presented in terms of physics motivations for utilizing a polarized positron in electron}positron collider experiments, a proof-of-principle experiment and a conceptual design of a polarized positron source for the future linear collider JLC. In order to verify a proposed method of creating highly polarized positron beams via successive two fundamental processes, i.e. Compton scattering and pair creation, we have been performing basic experiments both at KEK and BNL. First observation of positrons was made at KEK using an electron beam of 1.26 GeV and a laser of 2.33 eV. High-intensity picosecond X-rays were also generated at BNL using a specially designed Compton chamber. In order to realize polarized positron beams of the JLC which have considerably high intensity, i.e. 0.7;10 e>/pulse and a complicated multi-bunch structure, we have achieved a possible scheme for the Compton scattering system and a positron capture section into an L-band linac. 2000 Elsevier Science B.V. All rights reserved.
27M. 291740(52):80-40.
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[show abstract]
[hide abstract]
ABSTRACT: An important role of positron (e+) polarization in future linear colliders is discussed in terms of effective polarization, which is closely related to the clear observation of interesting reaction processes in e−e+ collisions. In order to verify our proposed method, in which highly polarized e+ can be generated through Compton scattering of laser light off a relativistic electron (e−) beam, we performed an experiment to prove the principle and observed e+ productions for the first time. It was found that the production rates of e+ are not only consistent with those of e− and γ-ray but also in good agreement with numerical estimations.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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T Omori,
T Aoki,
K Dobashi, T Hirose,
Y Kurihara,
T Okugi,
I Sakai,
A Tsunemi,
J Urakawa,
M Washio,
K Yokoya
[show abstract]
[hide abstract]
ABSTRACT: We propose a design of a polarized positron source for linear colliders. The design is based on electron–positron pair creation from polarized γ-rays which are produced by Compton scattering of circularly polarized laser light off a high-energy electron beam. Polarized positrons are created from those γ-rays incident on a thin conversion target. A future linear collider of the TeV-energy region requires an extraordinary large number of positrons (∼1×1010 positrons/bunch) in a multi-bunch time structure. To meet these requirements, our design employs a high-current, low-emittance electron beam of lasers, and 200 laser–electron collision-points. At each collision point, a pair of specially designed parabolic mirrors is installed to achieve efficient head-on collisions. This system allows us to produce high-intensity polarized γ-rays, which effectively generate high-intensity polarized positrons with the magnitude of polarization greater than 50%.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
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T. Okugi, T Hirose,
H. Hayano,
S Kamada,
K Kubo,
T Naito,
K. Oide,
K Takata,
S Takeda,
N Terunuma,
N. Toge,
J. Urakawa,
S Kashiwagi,
M Takano,
D. McCormick,
Michiko G Minty,
M Ross,
M. Woodley,
Frank Zimmermann,
J. Corlett
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Frank Zimmermann,
S Araki,
X. Artru,
H Braun,
E. Bulyak,
R. Chehab,
M Chevallier,
M Fukuda,
J Gao,
P. Gladkikh, [......],
V M Strakhovenko,
M Takano,
T Takahashi,
T Taniguchi,
N Terunuma,
A. Tsunemi,
J. Urakawa,
A. Variola,
M Washio,
F Zomer
[show abstract]
[hide abstract]
ABSTRACT: We describe a possible layout and parameters of a polarized positron source for CLIC, where the positrons are produced from polarized gamma rays created by Compton scattering of a 1.3-GeV electron beam off a YAG laser. This scheme is very energy effective using high finesse laser cavities in conjunction with an electron storage ring. We point out the differences with respect to a similar system proposed for the ILC.
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Y Honda,
S Anderson,
S Araki,
Karl Leopold Freitag Bane,
A. Brachmann,
J Frisch,
M Fukuda,
K Hasegawa,
H. Hayano,
L. Hendrickson, [......],
J Turner,
J. Urakawa,
V. Vogel,
A Wolski,
M. Woodley,
I Yamazaki,
Y Yamazaki,
J Yocky,
A Young,
Frank Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: We report on the smallest vertical emittance achieved in single-bunch-mode operation of the ATF. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured is 4 pm in the limit of zero current. It increases by a factor of 1.5 for a bunch intensity of 10^10 electrons. There are no discrepancies between the measured data and the calculations of intra-beam scattering.
