The Role of collision ionization of K-shell ions in nonequilibrium plasmas produced by the action of super strong, ultrashort PW-class laser pulses on micron-scale argon clusters with intensity up to 5 10 W/cm

Skobelev, I. Yu.*; Ryazantsev, S. N.*; Kulikov, R. K.*; Sedov, M. V.*; Filippov, E. D.*; Pikuz, S. A.*; Asai, Takafumi*; Kanasaki, Masato*; Yamauchi, Tomoya*; Jinno, Satoshi; et al.

Photonics (Internet), 10(11), p.1250_1 - 1250_11, 2023/11

https://doi.org/10.3390/photonics10111250

It is challenging to clearly distinguish the impacts of the optical field and collisional ionization in the evolution of the charge state of a plasma produced when matter interacts with high-intensity laser pulses. In this work, time-dependent calculations of plasma kinetics are used to show that it is possible only when low-density gaseous targets with sufficiently small clusters are used. In the case of Ar plasma, the upper limit of the cluster radius was estimated to be m.

Universal scaling for the spin-electricity conversion on surface states of topological insulators

Yamamoto, Keita*; Shiomi, Yuki*; Segawa, Koji*; Ando, Yoichi*; Saito, Eiji

Physical Review B, 94(2), p.024404_1 - 024401_6, 2016/05

https://doi.org/10.1103/PhysRevB.94.024404

We have investigated spin-electricity conversion on surface states of bulk-insulating topological insulator (TI) materials using a spin-pumping technique. The sample structure is Ni-Fe/Cu/TI trilayers, in which magnetic proximity effects on the TI surfaces are negligibly small owing to the inserted Cu layer. Voltage signals produced by the spin-electricity conversion are clearly observed and are enhanced with decreasing temperature, in line with the dominant surface transport at lower temperatures. The efficiency of the spin-electricity conversion is greater for TI samples with a higher resistivity of bulk states and longer mean free path of surface states, consistent with the surface spin-electricity conversion.

Status of laser Compton scattered -ray source at JAEA 150-MeV microtron

Hajima, Ryoichi; Ferdows, M.; Hayakawa, Takehito; Shizuma, Toshiyuki; Kando, Masaki; Daito, Izuru*; Negm, H.*; Ogaki, Hideaki*

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1943 - 1945, 2014/07

http://accelconf.web.cern.ch/AccelConf/IPAC2014/papers/wepro004.pdf

The International Atomic Energy Agency Nuclear Energy Management School 2012

Ohgama, Kazuya; Ando, Yoko; Yamaguchi, Mika; Ikuta, Yuko; Shinohara, Nobuo; Murakami, Hiroyuki; Yamashita, Kiyonobu; Uesaka, Mitsuru*; Demachi, Kazuyuki*; Komiyama, Ryoichi*; et al.

JAEA-Review 2013-004, 76 Pages, 2013/05

JAEA-Review-2013-004.pdf:13.53MB

JAEA together with the Japan Nuclear Human Resource Development Network (JN-HRD Net), the University of Tokyo (UT) and the Japan Atomic Industrial Forum (JAIF) cohosted the IAEA-Nuclear Energy Management School in Tokai Village, aiming that Japan will be the center of nuclear HRD in the Asian region. In the school, not only lectures by IAEA experts, but also lectures by Japanese experts and technical visits were included for foreign participants. The school contributed to the internationalization of Japanese young professionals, development of nuclear human resource of other countries, and enhancement of cooperation between IAEA and Japan. Additionally, collaborative relationship within JN-HRD Net was strengthened by the school. In this report, findings obtained during the preparatory work and the school period are reported for future international nuclear HRD activities in Japan.

High flux laser-Compton scattered -ray source by SBS pulse compressed laser

Daito, Izuru; Kando, Masaki; Shizuma, Toshiyuki; Hayakawa, Takehito; Angell, C.; Hajima, Ryoichi; Ogaki, Hideaki*

Purazuma, Kaku Yugo Gakkai-Shi, 88(10), p.553 - 554, 2012/10

http://ci.nii.ac.jp/naid/110009544560

no abstracts in English

Polarization-analyzed resonant inelastic X-ray scattering of the orbital excitations in KCuF

Ishii, Kenji; Ishihara, Sumio*; Murakami, Yoichi*; Ikeuchi, Kazuhiko*; Kuzushita, Kaori*; Inami, Toshiya; Owada, Kenji; Yoshida, Masahiro; Jarrige, I.; Tatami, Naka*; et al.

Physical Review B, 83(24), p.241101_1 - 241101_4, 2011/06

https://doi.org/10.1103/PhysRevB.83.241101

Induction of DNA DSB and its rejoining in clamped and non-clamped tumours after exposure to carbon ion beams in comparison to X-rays

Hirayama, Ryoichi*; Uzawa, Akiko*; Matsumoto, Yoshitaka*; Noguchi, Miho; Kase, Yuki*; Takase, Nobuhiro*; Ito, Atsushi*; Koike, Sachiko*; Ando, Koichi*; Okayasu, Ryuichi*; et al.

Radiation Protection Dosimetry, 143(2-4), p.508 - 512, 2011/02

https://doi.org/10.1093/rpd/ncq478

We studied double-strand breaks (DSB) induction and rejoining in clamped and non-clamped transplanted tumours in mice leg after exposure to 80 keV/m carbon ions and X-rays. The yields of DSB in the tumours were analysed by a static-field gel electrophoresis. The OER of DSB after X-rays was 1.68, and this value was not changed after 1 h rejoining time (1.40). These damages in oxygenated conditions were rejoined 60-70% within 1 h in situ. No difference was found between the exposure to X-rays and carbon ions for the induction and rejoining of DSB. Thus, the values of OER and rejoined fraction after exposure to carbon ions were similar to those after X-rays, and the calculated relative biological effectivenesses of carbon ion were around 1 under both oxygen conditions. The yields of DSB in vivo depend on exposure doses, oxygen conditions and rejoining time, but not on the types of radiation quality.

Radioprotection by DMSO in nitrogen-saturated mammalian cells exposed to helium ion beams

Hirayama, Ryoichi*; Matsumoto, Yoshitaka*; Kase, Yuki*; Noguchi, Miho; Ando, Koichi*; Ito, Atsushi*; Okayasu, Ryuichi*; Furusawa, Yoshiya*

Radiation Physics and Chemistry, 78(12), p.1175 - 1178, 2009/12

https://doi.org/10.1016/j.radphyschem.2009.07.006

The contribution of OH radical-mediated indirect action by particle beams under hypoxic irradiation condition was investigated by using a radical scavenger. V79 cells were irradiated with 150 MeV/nucleon helium ions at an LET of 2.2 keV/mm in the presence or absence of DMSO, and their colony survivals were determined. The contribution of indirect action to cell killing under hypoxic condition was estimated to be 52 %. We conclude that OH radical mediated indirect action still has a half in total contribution on cell killing under hypoxic condition.

Opportunities for TeV laser acceleration

Kando, Masaki; Kiriyama, Hiromitsu; Koga, J. K.; Bulanov, S. V.; Chao, A. W.*; Esirkepov, T. Z.; Hajima, Ryoichi; Tajima, Toshiki

AIP Conference Proceedings 1024, p.197 - 207, 2008/06

https://doi.org/10.1063/1.2958193

no abstracts in English

Experimental plan for observation of laser intensity dependent Doppler red shift in Thomson scattering

Nishimori, Nobuyuki; Hajima, Ryoichi; Kando, Masaki; Bulanov, S. V.

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.580 - 582, 2007/00

Thomson scattering wavelength between a single photon at wavelength and an electron with velocity c is given by in head-on collision configuration. As the incident laser intensity increases, the scattering wavelength is Doppler red shifted and given by . Here a=eA/mc is the dimensionless laser vector potential. The Doppler red shift is very similar to that in an undulator radiation whose wavelength becomes longer as the undulator gap narrows. The intensity dependent Doppler red shift in Thomson scattering has not been experimentally demonstrated yet to our knowledge. This is in contrast to the undulator radiation whose wavelength can easily be tuned for user experiments. In this paper, an experimental plan for observation of laser intensity dependent Doppler red shift in Thomson scattering is presented.