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Ogura, Koichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Yogo, Akifumi; Nishiuchi, Mamiko; Orimo, Satoshi; Sagisaka, Akito; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; et al.
Japanese Journal of Applied Physics, 51(4), p.048003_1 - 048003_2, 2012/04
Times Cited Count：2 Percentile：8.93(Physics, Applied)A proton beam driven by a repetitive high-intensity-laser is utilized to induce a 
Li(p,n)Be nuclear reaction. The total activity of Be are evaluated by two different methods. The activity obtained measuring the decay 
-rays after 1912 shots at 1 Hz is 1.7
0.2 Bq. This is in good agreement with 1.60.3 Bq evaluated from the proton energy distribution measured using a time-of-flight detector and the nuclear reaction cross-sections. We conclude that the production of activity can be monitored in real time using the time-of-flight-detector placed inside a diverging proton beam coupled with a high-speed signal processing system.
Ogura, Koichi; Fukumi, Atsushi*; Li, Z.*; Orimo, Satoshi; Sagisaka, Akito; Nishiuchi, Mamiko; Kado, Masataka; Mori, Michiaki; Yogo, Akifumi; Hayashi, Yukio; et al.
Journal of the Vacuum Society of Japan, 52(10), p.570 - 574, 2009/10
For accurate control of relativistic laser-plasma interaction under the repetitive operation, we have to measure and control the laser irradiation conditions such as laser parameters, the target shooting accuracy and so on as well as measuring proton parameter on each laser shot. The displacement of the laser shooting position on a tape target, that are used in the high energy proton generation using an ultra-short Ti:sapphire laser system, is measured by observing an X-ray image from laser plasma with an X-ray pinhole camera for each laser shot. The displacement of the shooting position on the target is about 20micron and the accuracy of the target positioning is within 20micron which is small enough for present laser focusing optics with an F number of 3.6 (f=179mm). The technique contributes to accurate control of a repetitive laser driven proton accelerators.
Yogo, Akifumi; Daido, Hiroyuki; Mori, Michiaki; Kiriyama, Hiromitsu; Bulanov, S. V.; Bolton, P. R.; Esirkepov, T. Z.; Ogura, Koichi; Sagisaka, Akito; Orimo, Satoshi; et al.
Reza Kenkyu, 37(6), p.449 - 454, 2009/06
The acceleration of protons driven by a high-intensity laser is comprehensively investigated via control of the target density by using ASE just before the time of the main-laser interaction. Two cases were investigated for which the ASE intensity differed by three orders of magnitude: In the low contrast case the beam centre for higher energy protons is shifted closer to the laser-propagation direction of 45
, while the center of lower-energy beam remains near the target normal direction. Particle-in-cell simulations reveal that the characteristic proton acceleration is due to the quasistatic magnetic field on the target rear side with the magnetic pressure sustaining a charge separation electrostatic field.
Ogura, Koichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Yogo, Akifumi; Nishiuchi, Mamiko; Orimo, Satoshi; Sagisaka, Akito; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; et al.
Applied Physics Express, 2(6), p.066001_1 - 066001_3, 2009/05
Times Cited Count：14 Percentile：49.78(Physics, Applied)Protons with energies up to 3.5 MeV have been generated by a 10 Hz compact laser with an intensity of about 10
W/cm
, focused on a 7.5 mm thick polyimide target. These protons were used to induce a nuclear reaction of 
B(p,n)C. A total activity of 11.1 Bq was created after 60-shot laser irradiation. The possibility of thin layer activation (TLA) using a high-intensity ultra-short pulsed laser is discussed.
Sagisaka, Akito; Daido, Hiroyuki; Pirozhkov, A. S.; Ma, J.-L.; Yogo, Akifumi; Ogura, Koichi; Orimo, Satoshi; Mori, Michiaki; Nishiuchi, Mamiko; Kawachi, Tetsuya; et al.
IEEE Transactions on Plasma Science, 36(4), p.1812 - 1816, 2008/08
Times Cited Count：4 Percentile：17.27(Physics, Fluids & Plasmas)We observe UV harmonics and protons with a thin-foil target irradiated with a high-intensity Ti:sapphire laser. The laser intensity dependency of UV harmonics and proton signal is measured by varying the distance between the target surface and the best focus of the laser beam. In the case of appropriate condition for proton generation with a maximum energy of 
2.7 MeV, the weak broad spectrum in the UV region is generated. The UV harmonics up to fourth-order are generated as the target is moved away from the best focus position. In this condition the maximum energy of protons is reduced to 1 MeV.
Mori, Michiaki; Yogo, Akifumi; Kiriyama, Hiromitsu; Nishiuchi, Mamiko; Ogura, Koichi; Orimo, Satoshi; Ma, J.*; Sagisaka, Akito; Kanazawa, Shuhei; Kondo, Shuji; et al.
IEEE Transactions on Plasma Science, 36(4), p.1872 - 1877, 2008/08
Times Cited Count：7 Percentile：28.47(Physics, Fluids & Plasmas)A dependence of cut-off proton kinetic energy on laser prepulse duration has been observed. ASE pedestal duration is controlled by a fast electro-optic pulse slicer where the risetime is estimated to be 130 ps. We demonstrate a new correlated spectral technique for determining this risetime using a stretched, frequency chirped pulse.
Yogo, Akifumi; Daido, Hiroyuki; Bulanov, S. V.; Nemoto, Koshichi*; Oishi, Yuji*; Nayuki, Takuya*; Fujii, Takashi*; Ogura, Koichi; Orimo, Satoshi; Sagisaka, Akito; et al.
Physical Review E, 77(1), p.016401_1 - 016401_6, 2008/01
Times Cited Count：113 Percentile：97.37(Physics, Fluids & Plasmas)The duration-controlled amplified spontaneous emission with intensity of 
W/cm
is used to convert a 7.5 
m thick polyimide foil into a near-critical plasma, in which the 
-polarized, 45 fs, 
W/cm laser pulse generates 3.8 MeV protons, emitted at some angle between the target normal and the laser propagation direction of 45. Particle-in-cell simulations reveal that the efficient proton acceleration is due to generation of the quasistatic magnetic field on the target rear side with the magnetic pressure inducing and sustaining a charge separation electrostatic field.
Yogo, Akifumi; Daido, Hiroyuki; Bulanov, S. V.; Esirkepov, T. Z.; Nemoto, Koshichi*; Oishi, Yuji*; Nayuki, Takuya*; Fujii, Takashi*; Ogura, Koichi; Orimo, Satoshi; et al.
Journal of Physics; Conference Series, 112, p.042034_1 - 042034_4, 2008/00
Times Cited Count：1 Percentile：55.21(Physics, Fluids & Plasmas)In this work, we present a new method to enhance the proton generation by a 10
-contrast laser. High-energy protons up to 3.8 MeV are observed with 7.5-m-thick insulator (Polyimide) target irradiated by a laser pulse having energy of 0.8 J and an intensity of 10
-W/cm. Using two time-of-flight (TOF) spectrometers simultaneously in different directions, we measure the direction dependency of proton-energy spectra. As a result, we find that high-energy component of proton beam is shifted away from the target normal toward the laser-propagation direction, when the laser is focused with 45 incident angle. The TOF measurements over 130 laser shots confirm that the generation of the high-energy protons, which are steered away from the target normal, depends strongly on the laser-focusing condition.
m thick copper tape target irradiated by s-, circularly-, and p-polarized 55-fs laser pulsesLi, Z.*; Daido, Hiroyuki; Fukumi, Atsushi*; Bulanov, S. V.; Sagisaka, Akito; Ogura, Koichi; Yogo, Akifumi; Nishiuchi, Mamiko; Orimo, Satoshi; Mori, Michiaki; et al.
Physics Letters A, 369(5-6), p.483 - 487, 2007/10
Times Cited Count：9 Percentile：51.08(Physics, Multidisciplinary)The energy spectra of energetic protons emitted in the normal direction from a 5-m thick copper tape irradiated by p-, circularly-, and s-polarized 55-fs laser pulses with intensity of 8-9
10
W/cm are measured together with the angular distribution and energy spectra of hot electrons by the target normal direction. The protons with energy up to 1.34 MeV in the rear target normal direction and hot electrons in the laser propagation direction are found. The characters of protons and electrons driven by the circularly-polarized irradiation are close to that driven by the p-polarized one, which is much different from the case at laser intensity of 2-310W/cm.
Sagisaka, Akito; Daido, Hiroyuki; Ogura, Koichi; Orimo, Satoshi; Hayashi, Yukio; Mori, Michiaki; Nishiuchi, Mamiko; Yogo, Akifumi; Kado, Masataka; Fukumi, Atsushi*; et al.
Journal of the Korean Physical Society, 51(1), p.442 - 446, 2007/07
Times Cited Count：1 Percentile：10.86(Physics, Multidisciplinary)The recent progress of the laser driven accelerators which include high power laser driven electrons and ions are reviewed. The studies at JAEA Kansai are mainly described. Based on the recent progres, the various aspects of the applications are also reviewed.
Yogo, Akifumi; Daido, Hiroyuki; Fukumi, Atsushi*; Li, Z.*; Ogura, Koichi; Sagisaka, Akito; Pirozhkov, A. S.; Nakamura, Shu*; Iwashita, Yoshihisa*; Shirai, Toshiyuki*; et al.
Physics of Plasmas, 14(4), p.043104_1 - 043104_6, 2007/04
Times Cited Count：63 Percentile：88.17(Physics, Fluids & Plasmas)Fast protons are observed by a newly-developed 
time-of-flight spectrometer, which provides 
proton-energy distributions immediately after the irradiation of a laser pulse having an intensity of 
W/cm onto a 5-m-thick copper foil. The maximum proton energy is found to increase when the intensity of a fs-prepulse arriving 9 ns before the main pulse increases from 10
to 10
W/cm. Interferometric measurement indicates that the preformed-plasma expansion at the front surface is smaller than 15 m, which corresponds to the spatial resolution of the diagnostics. This sharp gradient of the plasma makes a beneficial effect on increasing the absorption efficiency of the main-pulse energy, resulting in the increase in the proton energy. This is supported by the result that the X-ray intensity from the laser plasma clearly increases with the prepulse intensity.
Kotaki, Hideyuki; Oishi, Yuji*; Nayuki, Takuya*; Fujii, Takashi*; Nemoto, Koshichi*; Nakajima, Kazuhisa
Review of Scientific Instruments, 78(3), p.036102_1 - 036102_3, 2007/03
Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)no abstracts in English
Daido, Hiroyuki; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Mori, Michiaki; Ma, J.-L.; Pirozhkov, A. S.; Kiriyama, Hiromitsu; Kanazawa, Shuhei; et al.
Proceedings of 7th Pacific Rim Conference on Lasers and Electro-Optics (CLEO-PR 2007) (CD-ROM), p.77 - 79, 2007/00
We are developing a proton accelerator using an intense lasers with a focused intensity of 
10
W/cm. To monitor proton energy spectra as well as plasma parameters at each laser shot, we are using real time detectors. The proton energy of MeV is stably obtained for applications.
Daido, Hiroyuki; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Yogo, Akifumi; Mori, Michiaki; Li, Z.*; Kiriyama, Hiromitsu; Kanazawa, Shuhei; et al.
X-Ray Lasers 2006; Springer Proceedings in Physics, Vol.115, p.595 - 605, 2007/00
At present, using ultra-short high intensity lasers at APRC, JAEA Kansai photon research institute, we are developing laser driven multiple quantum beams such as protons, X-rays, electrons and THz waves. These beams are perfectly synchronized with each other. The pulse duration of each beam is lass than a pico-second. They have sharp directionality with high brightness. If we properly combined these, we have new pump-probe techniques for various applications.
Sagisaka, Akito; Utsumi, Takayuki*; Daido, Hiroyuki; Ogura, Koichi; Orimo, Satoshi; Takai, Mamiko; Hayashi, Yukio; Mori, Michiaki; Yogo, Akifumi; Kado, Masataka; et al.
Journal of Plasma Physics, 72(6), p.1281 - 1284, 2006/12
Times Cited Count：0 Percentile：0.01(Physics, Fluids & Plasmas)no abstracts in English
Sagisaka, Akito; Pirozhkov, A. S.; Daido, Hiroyuki; Fukumi, Atsushi*; Li, Z.*; Ogura, Koichi; Yogo, Akifumi; Oishi, Yuji*; Nayuki, Takuya*; Fujii, Takashi*; et al.
Applied Physics B, 84(3), p.415 - 419, 2006/09
Times Cited Count：20 Percentile：64.78(Optics)no abstracts in English
Yogo, Akifumi; Nishiuchi, Mamiko; Fukumi, Atsushi*; Li, Z.*; Ogura, Koichi; Sagisaka, Akito; Orimo, Satoshi; Kado, Masataka; Hayashi, Yukio; Mori, Michiaki; et al.
Applied Physics B, 83(4), p.487 - 489, 2006/06
Times Cited Count：9 Percentile：41.95(Optics)We present experimental results on protons accelerated up to 950 keV from a 3-m thick tantalum foil with a 133-nm thick polystyrene layer on its rear surface, irradiated with a laser pulse having the duration of 70 fs and the intensity of 
W/cm. The energy distribution of fast protons was measured simultaneously with that of the hot-electrons from the rear surface. The proton yield from the polystyrene-coated target is about 10 times as high as that from the uncoated metal target. This enhancement of the proton yield is roughly proportional to the increase of hydrogen atoms given by the 133-nm thick polystyrene layer, assuming a contaminant layer of 10-nm thickness is on the metal surface without coating. This result shows that the polystyrene layer contributes to the yield enhancement.
Sagisaka, Akito; Daido, Hiroyuki; Fukumi, Atsushi*; Takai, Mamiko; Yogo, Akifumi; Li, Z.*; Ogura, Koichi; Orimo, Satoshi; Hayashi, Yukio; Mori, Michiaki; et al.
Proceedings of RCNP-JAEA Workshop on Nuclear Photon Science "Hadron-nuclear physics probed by photon", p.195 - 200, 2006/00
High energy ions, electrons, and X-ray are generated from ultrashort pulse high-intensity laser-matter interactions. High-energy protons are observed with a thin-foil target irradiated with a high intensity Ti:sapphire laser at the peak intensity of 2.710 W/cm. The maximum proton energy is 900 keV.
Fukumi, Atsushi*; Takai, Mamiko; Daido, Hiroyuki; Li, Z.*; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Kado, Masataka; Hayashi, Yukio; Mori, Michiaki; et al.
Physics of Plasmas, 12(10), p.100701_1 - 100701_4, 2005/10
Times Cited Count：45 Percentile：79.3(Physics, Fluids & Plasmas)A study of proton emission from a 3-m thick Ta foil target irradiated by-, 
- and circularly polarized laser pulses with respect to the targetplane has been carried out. Protons with energies up to 880 keV were observed in the target normaldirection under the irradiation by the -polarized laser pulse, which yieldedthe highest efficiency for proton emission. In contrast, - and circularlypolarized laser pulses gave the maximum energies of 610 keV and 680 keV,respectively. The difference in the maximum energy between the - and-polarized cases was associated with the difference between thesheath fields estimated from electron spectra.
Yamazaki, Atsushi; Kotaki, Hideyuki; Daito, Izuru; Kando, Masaki; Bulanov, S. V.; Esirkepov, T. Z.; Kondo, Shuji; Kanazawa, Shuhei; Homma, Takayuki*; Nakajima, Kazuhisa; et al.
Physics of Plasmas, 12(9), p.093101_1 - 093101_5, 2005/09
Times Cited Count：70 Percentile：88.77(Physics, Fluids & Plasmas)no abstracts in English
