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Onuki, Yoshichika*; Karube, Kosuke*; Aoki, Dai*; Nakamura, Ai*; Homma, Yoshiya*; Matsuda, Tatsuma*; Haga, Yoshinori; Takeuchi, Tetsuya*
Journal of the Physical Society of Japan, 92(11), p.114703_1 - 114703_12, 2023/11
Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)Toyoshima, Atsushi; Kasamatsu, Yoshitaka*; Tsukada, Kazuaki; Asai, Masato; Ishii, Yasuo; Tome, Hayato*; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; Schdel, M.; et al.
Journal of Nuclear and Radiochemical Sciences, 11(1), p.7 - 11, 2010/06
The extraction behavior of rutherfordium (Rf) into trioctylphosphine oxide (TOPO) from 2.0 - 7.0 M HCl solution was studied together with that of the homologues Zr and Hf. The extracted yields of Rf, Zr, and Hf increased with an increase of HCl concentration, and the sequence of their extraction was Zr Hf Rf. It is suggested that the stability of the RfCl2(TOPO) complex is lower than that of the corresponding species of the homologues.
Chai, J.; Miyamoto, Yutaka; Kokubu, Yoko; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu; Oura, Yasuji*; Ebihara, Mitsuru*
Journal of Radioanalytical and Nuclear Chemistry, 272(2), p.397 - 401, 2007/05
Times Cited Count:2 Percentile:18.73(Chemistry, Analytical)Cm is an important nuclide because it has the next-shortest half-life (1.610 yr) from Pu among the transuranic nuclides. The disintegration of Cm to U by three decays and two decays and the chemical fractionation between Cm and U during the formation of solid materials in early solar system lead to changes in the ratios of U to U. This variation may provide strict constraints on the time interval between the last r-process nucleosynthetic event and the formation of the solar system. It is important to develop a practical analysis protocol to determine the isotope ratio of trace uranium in geochemical and environment samples. As uranium is the least abundant element in our solar system, analytical techniques with high sensitivity and precision are required. In this study, a double focusing inductively coupled plasma mass spectory was applied to measure isotopic ratio of uranium. By one set data obtained from the EDTA phase of the Jilin meteorite sample, the upper limit of Cm in the early solar system was calculated and Cm/U 0.003 was obtained.
Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Ichikawa, Shinichi; Ishii, Tetsuro; Nagame, Yuichiro; Nishinaka, Ichiro; Akiyama, Kazuhiko; Osa, Akihiko; Oura, Yasuji*; et al.
Physical Review Letters, 95(10), p.102502_1 - 102502_4, 2005/09
Times Cited Count:63 Percentile:87.64(Physics, Multidisciplinary)Excited states in Fm fed by the decay of No have been established through - and -electron coincidence spectroscopy using a gas-jet transport system and an on-line isotope separator. The spin-parity of the 124.1 keV level in Fm has been identified on the basis of the measured internal conversion coefficients. The configuration has been assigned to the ground state of No as well as to the 124.1 keV level. It was found that the ground state configuration of No is different from that of lighter isotones.
Raymond, S.*; Flouquet, J.*; Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Kaneko, Koji; Metoki, Naoto; Sugawara, Hitoshi*; Aoki, Yuji*; Sato, Hideyuki*
Physica B; Condensed Matter, 359-361, p.898 - 900, 2005/06
Times Cited Count:2 Percentile:11.66(Physics, Condensed Matter)The low lying magnetic excitations of the unconventional heavy fermion superconductor PrOsSb were studied by inelastic neutron scattering on single crystalline sample. The crystal field excitation first evidenced at 0.7 meV on powder samples is found to have a minimum of energy at the zone boundary corresponding to the wavevector of antiferro-quadrupolar instability. The evolution of the magnetic excitation spectrum under magnetic field confirms the singlet ground state.
Asai, Masato; Sakama, Minoru*; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.
European Physical Journal A, 23(3), p.395 - 400, 2005/02
Times Cited Count:16 Percentile:71.27(Physics, Nuclear)The EC decay of Am has been studied through -ray spectroscopy. Two EC-decaying states have been found in Am with half-lives of 3.6 min and 2.9 min. In Pu, we have found the octupole band and two-quasiparticle states one of which is a isomer with a 1.2 s half-life. The EC transitions from Am to the two-quasiparticle states in Pu show small values of 4.8--5.3, which allowed us to assign proton-neutron configurations of Am and the two-quasiparticle states.
Oshima, Masumi; Toh, Yosuke
Hamon, 15(1), p.86 - 89, 2005/01
A new beam line for multiple prompt -ray analysis(MPGA) has been constructed at JRR-3 neutron guide hall. The expected performance for MPGA is presented. This facility will be used for nuclear data and nuclear structure studies also.
Asai, Masato; Sakama, Minoru*; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.
European Physical Journal A, 22(3), p.411 - 416, 2004/12
Times Cited Count:9 Percentile:51.36(Physics, Nuclear)EC and decays of Am have been studied by means of -ray spectroscopy. Excited states in Pu have been established for the first time, and tentative spin-parity and Nilsson assignments were given to these levels. The ground state of Am was evaluated to be the state from the experimental results. It was found that the state in Np is located at 15~keV, which allowed us to determine the value of Am as 6569~keV, in combination with the measured -particle energy.
Sakama, Minoru*; Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Nishinaka, Ichiro; Nagame, Yuichiro; Haba, Hiromitsu*; Goto, Shinichi*; Shibata, Michihiro*; Kawade, Kiyoshi*; et al.
Physical Review C, 69(1), p.014308_1 - 014308_11, 2004/01
Times Cited Count:21 Percentile:73.68(Physics, Nuclear)no abstracts in English
Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Sakama, Minoru*; Haba, Hiromitsu*; Nagame, Yuichiro; Nishinaka, Ichiro; Akiyama, Kazuhiko; Toyoshima, Atsushi; Kaneko, Tetsuya*; et al.
European Physical Journal A, 16(1), p.17 - 19, 2003/01
Times Cited Count:8 Percentile:50.24(Physics, Nuclear)The new isotope Bk has been identified for the first time using a gas-jet coupled on-line isotope separator at the JAERI tandem accelerator facility. Characteristic X rays and three transitions associated with the EC decay of Bk have been observed, and the half-life was determined to be 4.6 min. The half-life value and the observed -ray energies and intensities can be consistently explained as a consequence of the allowed EC transition of .
Asai, Masato; Sakama, Minoru; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi; Kojima, Yasuaki*; Oura, Yasuji*; et al.
Journal of Nuclear Science and Technology, 39(Suppl.2), p.474 - 477, 2002/08
Neutron-deficient americium and curium isotopes with half-lives 10 min have been produced with the tandem accelerator, and their EC and weak decays have been successfully measured through an on-line isotope separation. Decay schemes of Am have been established, and proton-neutron configurations in the parent and daughter nuclei have been determined. Observed transitions in Am were found to be the favored transitions between the Nilsson states. Information on nuclear structure, deformation, and atomic masses in this region were obtained.
Haba, Hiromitsu; Kasaoka, Makoto*; Igarashi, Manabu*; Washiyama, Koshin*; Matsumura, Hiroshi*; Oura, Yasuji*; Shibata, Seiichi*; Sakamoto, Ko*; Furukawa, Michiaki*; Fujiwara, Ichiro*
Radiochimica Acta, 90(7), p.371 - 382, 2002/08
Times Cited Count:2 Percentile:17.03(Chemistry, Inorganic & Nuclear)The reaction yields of 63 radionuclides with the mass number A = 56-135 produced in the photofission of Bi by bremsstrahlung of end-point energies (E) from 450 to 1100 MeV have been measured using a catcher foil technique. The charge distribution was well reproduced by a Gaussian function with the most probable charge (Z) expressed by Z = RA + S, and with the A-independent FWHME. The charge distribution parameters R, S and FWHM were independent of E above 600 MeV. The weighted mean values at E 600 MeV were R = 0.421 0.001, S = 0.6 0.1 and FWHM = 2.1 0.1 charge unit (c.u.). Based on the charge distribution parameters, the symmetric mass yield distributions with the most probable mass A of 96 1 mass unit (m.u.) and the width FWHM of 33 1 m.u. were also obtained. The characteristics of the charge and mass yield distributions are discussed by referring to those for Au based on the results of calculations using PICA3/GEM.
Asai, Masato; Sakama, Minoru*; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Akiyama, Kazuhiko; Toyoshima, Atsushi; et al.
Journal of Nuclear and Radiochemical Sciences, 3(1), p.187 - 190, 2002/06
EC and decays of neutron-deficient americium, curium, and berkelium nuclei have been studied using the JAERI on-line isotope separator. Decay schemes of Am have been established for the first time, and proton-neutron configurations in Am and Pu have been determined. transitions observed in Am were found to be the favored transitions between the Nilsson states. values of Cm have been determined. Nuclear structure, deformation, and atomic masses for these nuclei were discussed.
Akiyama, Kazuhiko; Sueki, Keisuke*; Tsukada, Kazuaki; Yaita, Tsuyoshi; Miyake, Yoko*; Haba, Hiromitsu*; Asai, Masato; Kodama, Takeshi*; Kikuchi, Koichi*; Otsuki, Tsutomu*; et al.
Journal of Nuclear and Radiochemical Sciences, 3(1), p.151 - 154, 2002/06
The oxidation state of actinide elements encapsulated in fullerenes is studied. HPLC elution behavior of actinide-fullerenes is classified into two groups; the elution behavior of the first group, encapsulating U, Np, and Am, is similar to that of the light lanthanide-fullerenes, such as La, Ce, Pr, and Nd, while the behavior of the second group, encapsulating Th and Pa, is quite different from that of any lanthanide-fullerenes. The chemical species in the main HPLC elution peak of each group were identified as M@C82 and M@C84 (M = metal atom) from the mass of the U and Th fullerenes, respectively. The oxidation states of the U and Th atoms in the fullerenes were deduced to be 3+ and 4+, respectively, from the UV/vis/NIR absorption and XANES spectroscopy.
Nishinaka, Ichiro; Tanikawa, Masashi*; Nagame, Yuichiro; Nakahara, Hiromichi*
no journal, ,
In the 12 MeV proton-induced fission of Th and U, primary and secondary fragment mass yields as well as the average neutron multiplicity have been studied with a double time-of-flight technique. From these experimental data of fission fragments and the literature data of fission products, the nuclear-charge polarization at scission was derived. It was found that the nuclear charge polarization is characterized by the liquid-drop properties of nuclei and the proton shell effects = 50 of heavy fragments. The fragment mass dependence of the nuclear-charge polarization in the present systems agrees with that in the thermal-neutron-induced fission of U, indicating that the nuclear-charge polarization is practically insensitive to mass and excitation energy of the fissioning nucleus for the asymmetric fission in the region of light actinides.
Ishitobi, Takayuki; Hattori, Kazumasa*
no journal, ,
no abstracts in English
Ishitobi, Takayuki; Hattori, Kazumasa*
no journal, ,
no abstracts in English