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Journal Articles

Unified description of the fission probability for highly excited nuclei

Iwamoto, Hiroki; Meigo, Shinichiro

Journal of Nuclear Science and Technology, 56(2), p.160 - 171, 2019/02

 Times Cited Count:2 Percentile:33.75(Nuclear Science & Technology)

We present a new model to describe the fission probability of the high-energy fission model, as deduced from the intranuclear cascade calculation with the Intra-Nuclear Cascade model of Li$`{e}$ge (INCL) version 4.6 and Prokofiev's phenomenological systematics of the proton-induced fission cross sections. This model is implemented in the de-excitation model of the Generalized Evaporation Model (GEM), and applied to Monte Carlo spallation reaction simulation using the Particle and Heavy Ion Transport code System (PHITS). Comparing with experimental data for subactinide nuclei shows that this model can provide a unified prediction of the proton-, neutron-, and deuteron-induced fission cross sections with markedly improved accuracy. The calculated fission fragments tend to shift to higher mass numbers. To account for the isotopic distributions of fission fragments within the framework of a coupled INCL/GEM, modification of INCL is required, especially for description of the highly-excited states of residual nuclei.

JAEA Reports

Measurement of high-energy neutron fluxes and spectra around the J-PARC mercury spallation neutron target using multi-foil activation method

Kasugai, Yoshimi; Harada, Masahide; Kai, Tetsuya; Oi, Motoki; Meigo, Shinichiro; Maekawa, Fujio

JAEA-Data/Code 2015-033, 28 Pages, 2016/03

JAEA-Data-Code-2015-033.pdf:1.78MB

The high-energy neutron fluxes and spectra around the mercury spallation neutron source at MLF of J-PARC were measured by the multi-foil activation method. The threshold energies of neutron reactions utilized in this experiment covered from 0.1 to 50 MeV. The foil irradiation was carried out on the first beam-run of MLF from May 30th to 31th, 2008. After the irradiation, the induced radioactivity of each foil was measured using an HPGe detector, and the neutron-induced reaction-rate distribution around the mercury target was determined. Using these data, the high-energy neutron fluxes and spectra were deduced with unfolding method in which the neutron spectra calculated with PHITS code were used as the initial-guess spectra. By comparison between the initial and the unfolded spectra, it was shown that most of the calculation results, which had been the basis of the neutronics design of the MLF target assembly, were consistent with the experimental data within $$pm$$30%.

Journal Articles

Characterization of radionuclides formed by high-energy neutron irradiation

Yokoyama, Sumi; Sato, Kaoru; Noguchi, Hiroshi; Tanaka, Susumu; Iida, Takao*; Furuichi, Shinya*; Kanda, Yukio*; Oki, Yuichi*; Kaneto, Taihei*

Radiation Protection Dosimetry, 116(1-4), p.401 - 405, 2005/12

 Times Cited Count:1 Percentile:10.9(Environmental Sciences)

The physicochemical property of radionuclides suspended in the air is an important parameter to evaluate internal doses due to the inhalation of the airborne radionuclides and to develop the air monitoring system in high-energy proton accelerator facilities. This study focuses on the property of radioactive airborne chlorine ($$^{38}$$Cl and $$^{39}$$Cl) and sulfur ($$^{38}$$S) formed from Ar gas by irradiation with high-energy neutrons. As a result of the irradiation to a mixture of Ar gas and dry air, $$^{38}$$Cl and $$^{39}$$Cl existed as non-acidic gas and $$^{38}$$S was present as acidic gas. Further, it was found that in the high-energy neutron irradiation to aerosol containing-Ar gas, the higher the amount of radioactive aerosols becomes, the lower that of radioactive acidic gas becomes.

Journal Articles

Radiation safety design for the J-PARC project

Nakashima, Hiroshi; Nakane, Yoshihiro; Masukawa, Fumihiro; Matsuda, Norihiro; Oguri, Tomomi*; Nakano, Hideo*; Sasamoto, Nobuo*; Shibata, Tokushi*; Suzuki, Takenori*; Miura, Taichi*; et al.

Radiation Protection Dosimetry, 115(1-4), p.564 - 568, 2005/12

 Times Cited Count:8 Percentile:50.83(Environmental Sciences)

The High Intensity Proton Accelerator Project, named as J-PARC, is in progress, aiming at studies on the latest basic science and the advancing nuclear technology. In the project, the high-energy proton accelerator complex of the world highest intensity is under construction. In order to establish a reasonable shielding design, both simplified and detailed design methods were used in the shielding design of J-PARC. This paper reviews the present status of the radiation safety design study for J-PARC.

Journal Articles

Experimental study on spatial uniformity of H$$^{-}$$ ion beam in a large negative ion source

Hanada, Masaya; Seki, Takayoshi*; Takado, Naoyuki*; Inoue, Takashi; Morishita, Takatoshi; Mizuno, Takatoshi*; Hatayama, Akiyoshi*; Imai, Tsuyoshi*; Kashiwagi, Mieko; Sakamoto, Keishi; et al.

Fusion Engineering and Design, 74(1-4), p.311 - 317, 2005/11

 Times Cited Count:7 Percentile:46.37(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Sub-millimeter synchrotron X-ray focusing by crystal bender

Yoneda, Yasuhiro; Matsumoto, Norimasa; Furukawa, Yukito*; Ishikawa, Tetsuya*

Physica Scripta, T115, p.995 - 997, 2005/00

Sagittal focusing is known as one of the most efficient focusing methods for synchrotron X-rays which increases the photon density at the sample position. Results are reported on the performance of a fixed height exit bender with an unribbed silicon (311) crystal. The fixed height exit was achieved by using a 4-point bending mechanism. This bending mechanism is designed for the SPring-8 standard double crystal monochromator (DCM) of bending-magnet beamlines and the bender is installed as a second crystal of the DCM. By using unribbed crystal, the focusing beam size was kept 0.5 mm in the energy ranges from 35 - 60 keV. Since mirrors for high-energy X-rays are still under development at the moment, focusing techniques by crystal bender are demanded for many practical applications.

Journal Articles

Measurement of depth distributions of $$^{3}$$H and $$^{14}$$C induced in concrete shielding of an electron accelerator facility

Endo, Akira; Harada, Yasunori; Kawasaki, Katsuya; Kikuchi, Masamitsu

Applied Radiation and Isotopes, 60(6), p.955 - 958, 2004/06

 Times Cited Count:6 Percentile:42.06(Chemistry, Inorganic & Nuclear)

no abstracts in English

Journal Articles

Experimental comparison between plasma and gas neutralization of high-energy negative ion beams

Hanada, Masaya; Kashiwagi, Mieko; Inoue, Takashi; Watanabe, Kazuhiro; Imai, Tsuyoshi

Review of Scientific Instruments, 75(5), p.1813 - 1815, 2004/05

 Times Cited Count:21 Percentile:70.83(Instruments & Instrumentation)

A proof-of-principle test on plasma neutralizer, that is capable of enhancing a system efficiency of neutral beam injector for future fusion reactors, has been carried out. A 2 m long and 0.6 m diamater neutralizer with multicusp magnet line was used, improving the confinement of primary electrons flowed from both ends of the neutralizer by a pair of magnets. This improvement produced relatively high density Ar plasma of 10$$^{11}$$ - 10$$^{12}$$cm$$^{-3}$$ at low operating pressure of 0.002 Pa - 0.03 Pa. In the neutralization experiment, 200 keV H$$^{-}$$ ion beams were neturalized with the plasms and gas. Compared with the gas neutralization, the maximaum neutralization efficiency by the plasma was 6% higher than that by the gas. Further, an optimum Ar gas line density for maximizing the neutralization efficiency was 30% lower than that by the gas. These results are in good agreements with results analyzed from the cross-section data for neturalization. Thus, it was experimentally verified that the neutralization effiency can be enhanced at relatively low line density by using the plasma.

Journal Articles

Development of neutron-monitor detectors applicable to energies from thermal to 100MeV

Endo, Akira; Kim, E.; Yamaguchi, Yasuhiro; Sato, Tatsuhiko; Yoshizawa, Michio; Tanaka, Susumu; Nakamura, Takashi; Rasolonjatovo, A. H. D.*

Journal of Nuclear Science and Technology, 41(Suppl.4), p.510 - 513, 2004/03

no abstracts in English

Journal Articles

Glass formation at the limit of insufficient network formers

Kohara, Shinji*; Suzuya, Kentaro; Takeuchi, Ken*; Loong, C.-K.*; Grimsditch, M.*; Weber, J. K. R.*; Tangeman, J. A.*; Key, T. S.*

Science, 303(5664), p.1649 - 1652, 2004/03

 Times Cited Count:130 Percentile:95.18(Multidisciplinary Sciences)

Inorganic glasses normally exhibit a network of interconncted covalent-bonded structural elements that has no long-range order. In silicate glasses the network formers are based on SiO$$_4$$-tetrahedra interconnected via oxygen atoms at the corners. Conventional wisdom then implies that alkaline and alkaline-earth orthosilicate materials cannot be vitrified because they do not contain sufficient network forming SiO$$_2$$ to establish the needed interconnectivity. We have studied a bulk magnesium orthosilicate glass obtained by containerless melting-and-cooling. We find that the role of network former is largely taken on by corner- and edge-sharing of highly distorted ionic Mg-O species that adopt 4-, 5- and 6-coordination with oxygen. The results suggest that similar novel glassy phases may be found in the containerless environment of interstellar space.

Journal Articles

Radiation control system for J-PARC

Miyamoto, Yukihiro

Hokeikyo Nyusu, (32), p.2 - 3, 2003/10

no abstracts in English

Journal Articles

Defect production and radiation annealing in platinum irradiated with high-energy heavy ions

Chimi, Yasuhiro; Iwase, Akihiro; Iwata, Tadao*

Nuclear Instruments and Methods in Physics Research B, 209, p.159 - 164, 2003/08

 Times Cited Count:2 Percentile:21.68(Instruments & Instrumentation)

Accumulation of defects during energetic ion irradiation below $$sim$$10K in platinum thin films is studied by electrical resistivity measurements. Experimental results are analyzed by using a model which describes the production and selective radiation annealing of defects. For high-energy ($$sim$$100MeV) heavy ion irradiations, radiation annealing process due to electronic excitation is found mainly at the initial stage of irradiation. From the defect accumulation curve and defect recovery spectra, the effective temperature corresponding to the lattice agitation induced by electronic excitation is estimated.

Journal Articles

Study of particle size distribution and formation mechanism of radioactive aerosols generated in high-energy neutron fields

Endo, Akira; Sato, Kaoru; Noguchi, Hiroshi; Tanaka, Susumu; Iida, Takao*; Furuichi, Shinya*; Kanda, Yukio*; Oki, Yuichi*

Journal of Radioanalytical and Nuclear Chemistry, 256(2), p.231 - 237, 2003/05

 Times Cited Count:6 Percentile:42.8(Chemistry, Analytical)

Size distributions of $$^{38}$$Cl, $$^{39}$$Cl, $$^{82}$$Br and $$^{84}$$Br aerosols generated by irradiations of argon and krypton gases containing di-octyl phthalate (DOP) aerosols with 45MeV and 65MeV quasi-monoenergetic neutrons were measured to study the formation mechanism of radioactive particles in high energy radiation fields. Effects of the size distribution of the radioactive aerosols on the size of added DOP aerosols, the energy of irradiation neutrons and the kinds of nuclides were studied. The observed size distributions of the radioactive particles were explained by attachment of the radioactive atoms generated by the neutron-induced reactions to the DOP aerosols.

JAEA Reports

Proceedings of the 3rd Workshop on Dosimetry for External Radiations; November 28-29, 2002, Japan Atomic Energy Research Institute, Tokai, Ibaraki, Japan

Yoshizawa, Michio; Endo, Akira

JAERI-Conf 2003-002, 166 Pages, 2003/03

JAERI-Conf-2003-002.pdf:9.79MB

The present report is Proceedings of the Third Workshop on Dosimetry for External Radiations, held at the Tokai Research Establishment, Japan Atomic Energy Research Institute (JAERI), in November 28-29, 2002. The proceedings comprises 16 papers and a summary of general discussion. The Third Workshop, subtitled "On an opportunity of the completion of the facility of calibration standards for neutron at JAERI", focused on neutron dosimetry and included presentations on the status of international neutron standards, the development of calibration techniques of neutron dosimeters using accelerator neutron sources, and dosimetry for high-energy neutrons. The workshop identified the directions for the future research and development in this field.

Journal Articles

Two-dimensional X-ray focusing by crystal bender and mirrors

Yoneda, Yasuhiro; Matsumoto, Norimasa; Furukawa, Yukito*; Ishikawa, Tetsuya*

AIP Conference Proceedings 705 (CD-ROM), 4 Pages, 2003/00

Results are reported on the performance of a fixed height exit bender with an unribbed silicon (311) crystal. The anticlasic crveture can be minimized for a recutangular Si (311) focusing crystal with "clamped" or "builtin" boundary conditions if the length to width ratio of the crystal is 1.42. The test crystal used in this study was manufactured from a 98mm$$times$$90mm$$times$$2mm dimension of float zone silicon. After final etching, the ratio of the crystal is 1.435. The sub-millimeter sagittal focusing was achieved by using a 4-point bending mechanism in energy ranges from 30keV to 60keV.

JAEA Reports

Design concept of radiation control system for the high intensity proton accelerator facility

Miyamoto, Yukihiro; Ikeno, Koichi; Akiyama, Shigenori*; Harada, Yasunori

JAERI-Tech 2002-086, 43 Pages, 2002/11

JAERI-Tech-2002-086.pdf:5.7MB

Description is given for the characteristic radiation environment for the High Intensity Proton Accelerator Facility and the design concept of the radiation control system of it. The facility is a large scale accelerator complex consisting of high energy proton accelerators carrying the highest beam intensity in the world and the related experimental facilities and therefore provides various issues relevant to the radiation environment. The present report describes the specifications for the radiation control system for the facility, determined in consideration of these characteristics.

Journal Articles

Particle size analysis of radioactive aerosols formed by irradiation of argon using 65MeV quasi-monoenergetic neutrons

Endo, Akira; Noguchi, Hiroshi; Tanaka, Susumu; Kanda, Yukio*; Oki, Yuichi*; Iida, Takao*; Sato, Kaoru; Tsuda, Shuichi

Applied Radiation and Isotopes, 56(4), p.615 - 620, 2002/04

 Times Cited Count:3 Percentile:24.08(Chemistry, Inorganic & Nuclear)

Formation mechanism and size distribution of radioactive aerosol particles generated in a high-energy neutron field were studied in order to evaluate a particle size parameter for internal dose evaluation in high-energy accelerator facilities. Argon gas containing DOP aerosols was irradiated by a 65MeV quasi-monoenergetic neutron beam of TIARA. The number size distribution of the DOP aerosols and the activity-weighted size distribution of $$^{38}$$Cl and $$^{39}$$Cl aerosols, formed from the (n, 2np) and (n, np) reactions of $$^{40}$$Ar, were measured using an electrical low-pressure impactor. The activity-weighted size distribution of the radioactive aerosols was well explained by the simple attachment model of the radioactive atoms to the DOP aerosols.

JAEA Reports

Proceedings of the 3rd Symposium on Science of Hadrons under Extreme Conditions; January 29-31, 2001, JAERI, Tokai, Japan

Chiba, Satoshi

JAERI-Conf 2001-012, 116 Pages, 2001/09

JAERI-Conf-2001-012.pdf:6.33MB

The third symposium on Science of Hadrons under Extreme Conditions, organized by the Research Group for Hadron Science, Advanced Science Research Center, was held at Tokai Research Establishment of JAERI on January 29 to 31, 2001. The symposium was devoted for discussions and presentations of research results in wide variety of hadron physics such as nuclear matter, high-energy nuclear reactions, quantum chromodynamics, neutron stars,supernovae, nucleosynthesis as well as finite nuclei to understand various aspects of hadrons under extreme conditions. Twenty two papers on these topics, including a special talk on the present status of JAERI-KEK joint project on high-intentisy proton accelerator, presented at the symposium aroused lively discussions among approximately 40 participants.

Journal Articles

Improvement of neutron detection efficiency with high sensitive CR-39 track detector

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:49.72(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Present status of nucleon-meson transport code NMTC/JAERI

Takada, Hiroshi; Meigo, Shinichiro; Niita, Koji*

Advanced Monte Carlo for Radiation Physics, Particle Transport Simulation and Applications, p.949 - 954, 2001/00

no abstracts in English

31 (Records 1-20 displayed on this page)