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Igarashi, Yu; Yamaguchi, Ichiro*; Oda, Keiji*; Fukushi, Masahiro*; Sakama, Minoru*; Iimoto, Takeshi*
Nihon Hoshasen Anzen Kanri Gakkai-Shi, 21(2), p.74 - 76, 2022/11
no abstracts in English
Kanasaki, Masato; Jinno, Satoshi*; Sakaki, Hironao; Kondo, Kiminori; Oda, Keiji*; Yamauchi, Tomoya*; Fukuda, Yuji
Plasma Physics and Controlled Fusion, 58(3), p.034013_1 - 034013_6, 2016/03
Times Cited Count：23 Percentile：77.87(Physics, Fluids & Plasmas)In order to understand the synergetic interplay between the Coulomb explosion of clusters and the background gas dynamics, we have conducted ion acceleration experiments using CO
clusters (250 nm in dia.) embedded in background H gas with the J-KAREN laser (1 J, 40 fs, 10
contrast) at JAEA-KPSI. By a careful analysis of etch pit positions on CR-39 and their structures including the etch pit growth behavior analysis with the multi-step etching technique, energy spectra for protons from the background gas and carbon/oxygen ions from the clusters are obtained separately. The maximum energies of protons and carbon/oxygen ions are determined as 1.6 MeV and 1.1 MeV/u, respectively. Based on the experimental results, the acceleration mechanism of the background gas ions induced by Coulomb explosion of clusters is discussed with the help from numerical simulations which employ a particle-in-cell (PIC) method including relaxation and ionization processes of plasma particles.
Kanasaki, Masato; Fukuda, Yuji; Kondo, Kiminori; Oda, Keiji*; Yamauchi, Tomoya*
Reza Kenkyu, 42(2), p.168 - 173, 2014/02
In laser-driven ion acceleration experiments using the cluster-gas targets, a significant amount of fast electrons, which drives the ion acceleration, are produced along with high energy ions with several-tens of MeV. In our recent experiment using CO clusters embedded in H gas conducted with the J-KAREN laser facility (1 J, 40 fs) at JAEA-KPSI, the maximum energy of electrons reaches up to 200 MeV. Such fast electrons can produce photo-neutrons via bremsstrahlung processes followed by photo-nuclear reactions. When the CR-39 is exposed to photo-neutrons, it records etchable tracks of generated ions depending on their species and energy as background noises. In order to diagnose the laser-accelerated protons precisely using CR-39, we have developed the discrimination method for laser-accelerated protons and photo-neutrons on CR-39 based on the incident angle and incident energy.
Fukuda, Yuji; Sakaki, Hironao; Kanasaki, Masato; Yogo, Akifumi; Jinno, Satoshi; Tampo, Motonobu*; Faenov, A. Ya.*; Pikuz, T. A.*; Hayashi, Yukio; Kando, Masaki; et al.
Proceedings of SPIE, Vol.8779 (Internet), p.87790F_1 - 87790F_7, 2013/05
Times Cited Count：0 Percentile：0.05(Engineering, Biomedical)We demonstrate a new ion diagnosis method for high energy ions by utilizing a combination of a single CR-39 detector and plastic plates, which enables to detect high energy ions beyond the detection threshold limit of the CR-39. This detection method coupled with a magnetic spectrometer is applied to identify high energy ions of 50 MeV per nucleon in laser-driven ion acceleration experiments using cluster-gas targets.
Fukuda, Yuji; Sakaki, Hironao; Kanasaki, Masato; Yogo, Akifumi; Jinno, Satoshi; Tampo, Motonobu; Faenov, A. Ya.*; Pikuz, T.; Hayashi, Yukio; Kando, Masaki; et al.
Radiation Measurements, 50, p.92 - 96, 2013/03
Times Cited Count：12 Percentile：67.14(Nuclear Science & Technology)A new diagnosis method for high energy ions utilizing a single CR-39 detector mounted on plastic plates is demonstrated to identify the presence of the high energy component beyond the CR-39's detection threshold limit. On irradiation with a 25 MeV per nucleon He ion beam from conventional rf-accelerators, a large number of etch pits having elliptical opening shapes are observed on the rear surface. Detailed investigations reveal that these etch pits are created by heavy ions inelastically backscattered from the plastic plates. This ion detection method is applied to laser-driven ion acceleration experiments using cluster-gas targets, and acceleration of ions with energies up to 50 MeV per nucleon are identified.
Kanasaki, Masato; Hattori, Atsuto; Sakaki, Hironao; Fukuda, Yuji; Yogo, Akifumi; Jinno, Satoshi; Nishiuchi, Mamiko; Ogura, Koichi; Kondo, Kiminori; Oda, Keiji*; et al.
Radiation Measurements, 50, p.46 - 49, 2013/03
Times Cited Count：15 Percentile：74.42(Nuclear Science & Technology)A precise measurement has been made utilizing a stacked CR-39 detectors unit for laser accelerated high intensity protons. The proton beams are derived from a thin polyimide target exposed to an high intense Ti:sapphire laser 8 J energy and 40 fs duration. The sample sets, stacked radiochromic film and CR-39 detectors covered with 13 
m aluminum filter, are irradiated under vacuum condition. By analyzing the etch pits on the last layer of CR-39 which recorded etchable tracks, the proton energy in high energy region is evaluate more precisely than in the past. The residual ranges for each particle in the last layer has been obtained from etch pit growth curves with multi-stepetching technique. The maximum energy of proton is 14.39
0.05 MeV. This method allows us to measure the maximum energy of proton precisely, which is obtained up to the hundredth place in unit of MeV in the laser-driven particle acceleration experiment.
Kanasaki, Masato; Yamauchi, Tomoya*; Fukuda, Yuji; Sakaki, Hironao; Hori, Toshihiko*; Tampo, Motonobu; Kurashima, Satoshi; Kamiya, Tomihiro; Oda, Keiji*; Kondo, Kiminori
AIP Conference Proceedings 1465, p.142 - 147, 2012/07
Times Cited Count：1 Percentile：46.45(Physics, Applied)A new diagnosis method has been developed utilizing back scattered particles for high energy intense ion beams. The CR-39 detector mounted on the uniform back-scatterer was irradiated with 
He
ions with an energy 25 MeV/n, which is never recorded as etchable track in CR-39. We found that it is possible to diagnose the high energy intense ion beams by analyzing the etch pits created on the rear surface of CR-39 that directly contacted on the back-scatterers. It turns out that most of etch pits in the rear surface are made by the backscattered particles through the investigation of the growth pattern of each etch pit with multi-step etching technique. This method allows simple diagnosis of the ion beam profile and the presence of high energy component of ions beyond the detection threshold limit of the CR-39 in mixed radiation fields such as laser-driven ion acceleration experiments.
Kanasaki, Masato; Fukuda, Yuji; Sakaki, Hironao; Hori, Toshihiko; Tampo, Motonobu; Kondo, Kiminori; Kurashima, Satoshi; Kamiya, Tomihiro; Oda, Keiji*; Yamauchi, Tomoya*
Japanese Journal of Applied Physics, 51(5), p.056401_1 - 056401_4, 2012/05
Times Cited Count：6 Percentile：26.76(Physics, Applied)A single CR-39 detector mounted on plastic plates is irradiated with a 100 MeV He ion beam. Although the beam energy is much greater than the detection threshold limit of the CR-39 detector, a large number of etch pits having elliptical openings are observed on the rear surface. Detailed investigations reveal that these etch pits are created by heavy ions inelastically backscattered from the plastic plates. This method allows a simple diagnosis of the ion beam profile and the presence of the high-energy component beyond the detection threshold limit of the CR-39 detector, especially in mixed-radiation fields such as laser-driven ion acceleration experiments.
Kanasaki, Masato; Fukuda, Yuji; Sakaki, Hironao; Nishiuchi, Mamiko; Kondo, Kiminori; Kurashima, Satoshi; Kamiya, Tomihiro; Hattori, Atsuto*; Oda, Keiji*; Yamauchi, Tomoya*
Purazuma, Kaku Yugo Gakkai-Shi, 88(5), p.261 - 275, 2012/05
CR-39 solid state nuclear track detector, which was developed for optical lens, has been applied for various field such as radon surveys, measurement of galactic cosmic ray, cell irradiation experiment and so on. The CR-39 detectors have the great advantages of being insensitive to high energy photons and electrons and capable of detecting only ions in the mixed fields such as laser driven relativistic plasmas. Though there are some analytical methods of CR-39 to diagnose ion beam, unfortunately, only few researchers in the field of plasma know the methods. This article looks at how to use CR-39 detectors and introduce the accomplishment of the joint study JAEA and Kobe Univ. for application of CR-39 detectors to ion beam diagnosis.
Takahashi, Fumiaki; Oda, Keiji*
JAEA-Conf 2007-002, p.171 - 176, 2007/02
no abstracts in English
Oda, Keiji*; Takahashi, Fumiaki; Expert Committee on Concepts of Dosimetric Quantities Used in Radiological protection, Japan Health
Proceedings of 2nd Asian and Oceanic Congress Radiological Protection (AOCRP-2) (CD-ROM), p.52 - 55, 2006/10
no abstracts in English
Takahashi, Fumiaki; Endo, Akira; Yamaguchi, Yasuhiro; Oda, Keiji*
Hoken Butsuri, 41(3), p.180 - 187, 2006/09
no abstracts in English
Oda, Keiji*; Imasaka, Yuichi*; Yamauchi, Tomoya*; Nakane, Yoshihiro; Endo, Akira; Tawara, Hiroko*; Yamaguchi, Yasuhiro
Radiation Measurements, 40(2-6), p.570 - 574, 2005/11
Times Cited Count：7 Percentile：44.9(Nuclear Science & Technology)no abstracts in English
Oda, Keiji*; Ichijo, H.*; Miyawaki, Nobumasa*; Yamauchi, Tomoya*; Nakane, Yoshihiro
Radiation Measurements, 34(1-6), p.171 - 175, 2001/06
Times Cited Count：7 Percentile：48.68(Nuclear Science & Technology)no abstracts in English
Hara, Keiji; Oda, Hideki*; Fujiwara, Hiroshi*; Tsukamoto, Masaki*; Mano, Tadashi
Genshiryoku Bakkuendo Kenkyu, 6(2), p.233 - 253, 2000/05
None
Endo, Akira; Sato, Tatsuhiko; Satoh, Daiki; Shikaze, Yoshiaki; Tanimura, Yoshihiko; Saegusa, Jun; Tsutsumi, Masahiro; Yamaguchi, Yasuhiro; Kaneko, Hirohisa; Oda, Keiji*; et al.
no journal, ,
no abstracts in English
Fukuda, Yuji; Kanasaki, Masato; Sakaki, Hironao; Hori, Toshihiko*; Tampo, Motonobu; Kondo, Kiminori; Kurashima, Satoshi; Kamiya, Tomihiro; Oda, Keiji*; Yamauchi, Tomoya*
no journal, ,
Recently, CR-39 detectors have been widely used in the studies of laser-driven ion acceleration experiments. In such experiments, however, the energies of accelerated ions often exceed the detection threshold limit of the CR-39. Therefore, a simple method to detect high energy ions using the CR-39 is required. We have developed a new simple diagnosis method, namely a backscattering technique, for high energy ions by utilizing the combination of CR-39 detectors and plastic backscatters. Proof-of-principle experiments for the new method were carried out at the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) facility in JAEA, which delivered He ion beam with an energy of 100 MeV. The result shows that this method enables us to characterize high energy ion beams which energies are beyond the detection threshold limit of CR-39. High energy ions accelerated by using J-KAREN laser are successfully detected with this method.
Kanasaki, Masato; Yamauchi, Tomoya*; Nishiuchi, Mamiko; Pirozhkov, A. S.; Sakaki, Hironao; Ogura, Koichi; Tanimoto, Tsuyoshi; Yogo, Akifumi; Hori, Toshihiko*; Sagisaka, Akito; et al.
no journal, ,
A precise energy measurement for the laser-driven proton beam has been performed by utilizing stacked CR-39 covered with 13-m thick aluminum filter. The proton beam was generated by exposing a thin foil target to an intense femtosecond laser pulse from the J-KAREN laser system. By analyzing the etch pit growth curves with multi-step etching technique. It, it is found that the maximum energy of the proton beam was evaluated ten times more precise than that by using the conventional time-of-flight (TOF) method.
Kanasaki, Masato; Fukuda, Yuji; Sakaki, Hironao; Yogo, Akifumi; Jinno, Satoshi; Nishiuchi, Mamiko; Ogura, Koichi; Kondo, Kiminori; Oda, Keiji*; Yamauchi, Tomoya*
no journal, ,
Recently, solid state nuclear track detectors such as CR-39 detectors have been extensively used in laser-driven ion acceleration experiments, because CR-39 can record the tracks of ion clearly even in the intense fields of photons and high energy electrons. By analyzing the etch pit growth behavior, we can obtain not only the radial intensity distribution of ion beam, but the energy and nuclear species for each ion precisely. This method allows us to measure the maximum energy of proton precisely, which is obtained up to the hundredth place in unit of MeV in the laser-driven particle acceleration experiment.
Hattori, Atsuto*; Kanasaki, Masato; Fukuda, Yuji; Sakaki, Hironao; Yogo, Akifumi; Jinno, Satoshi; Nishiuchi, Mamiko; Ogura, Koichi; Kondo, Kiminori; Oda, Keiji*; et al.
no journal, ,
A precise measurement has been made utilizing a stacked CR-39 detectors for laser accelerated protons. The protons are accelerated from a thin polyimide target irradiated by intense Ti:sapphire laser (8 J energy and 40 fs duration). By analyzing the etch pits on the last layer of CR-39, the maximum proton energy is evaluated more precisely than in the past. The residual ranges for each particle in the last layer has been obtained from etch pit growth curves with the multi-step etching technique. The maximum energy of proton obtained is 14.390.05 MeV. This method allows us to measure the maximum energy of proton precisely, which is ten times higher than that of the conventional methods.
