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Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ishii, Yasuo; Toyoshima, Atsushi; Ishii, Tetsuro; Nishinaka, Ichiro; Nagame, Yuichiro; et al.
Physical Review C, 87(1), p.014332_1 - 014332_6, 2013/01
Times Cited Count:6 Percentile:43.66(Physics, Nuclear)The spin-parity and neutron configuration of the ground state of No have been identified through -decay spectroscopy. The No is the nucleus with the largest neutron number whose spin-parities and single-particle configurations have ever been identified. The neutron 9/2[615] configuration was assigned to the ground state of No as well as to the 231.4 keV level in Fm. This allowed us to establish energy spacings and order of the neutron single-particle orbitals in such heaviest nuclear region. The appearance of the 9/2[615] ground state at =157 implies that the order of the neutron orbitals between the =152 and 162 deformed shell gaps should change considerably with increasing neutron number.
Asai, Masato; Tsukada, Kazuaki; Haba, Hiromitsu*; Ishii, Yasuo; Ichikawa, Takatoshi*; Toyoshima, Atsushi; Ishii, Tetsuro; Nagame, Yuichiro; Nishinaka, Ichiro; Kojima, Yasuaki*; et al.
Physical Review C, 83(1), p.014315_1 - 014315_12, 2011/01
Times Cited Count:24 Percentile:79.14(Physics, Nuclear)Excited states in Fm populated via the decay of No are studied in detail through - coincidence and fine structure measurements. Spin-parities and neutron configurations of the excited states in Fm as well as the ground state of No are definitely identified on the basis of deduced internal conversion coefficients, lifetimes of transitions, rotational-band energies built on one-quasiparticle states, and hindrance factors of transitions. It is found that the excitation energy of the 1/2[620] state in =151 isotones increases with the atomic number, especially at 100, while that of the 1/2[631] state decreases at =100. Energy systematics of the one-quasiparticle states in the =151 isotones are discussed in terms of the evolution of nuclear deformation involving the hexadecapole and hexacontatetrapole deformations.
Hayashi, Hiroaki*; Akita, Yukinori*; Suematsu, Osamu*; Shibata, Michihiro*; Asai, Masato; Sato, Tetsuya; Ichikawa, Shinichi; Nishinaka, Ichiro; Nagame, Yuichiro; Osa, Akihiko; et al.
European Physical Journal A, 34(4), p.363 - 370, 2007/12
Times Cited Count:16 Percentile:71.35(Physics, Nuclear)values of Eu and Gd were measured for the first time using a total absorption BGO detector, and the data of Pm, Sm, and Tb obtained previously were reanalyzed. These nuclei were produced by the proton-induced fission of U at the JAEA-Tokai tandem accelerator facility, and separated from the reaction products using an on-line isotope separator. The deduced mass excesses and two-neutron separation energies were compared with those of atomic mass evaluations and theoretical predictions.
Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Sakama, Minoru*; Haba, Hiromitsu*; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.
Physical Review C, 73(6), p.067301_1 - 067301_4, 2006/06
Times Cited Count:21 Percentile:76.1(Physics, Nuclear)no abstracts in English
Ichikawa, Shinichi; Asai, Masato; Tsukada, Kazuaki; Haba, Hiromitsu*; Nagame, Yuichiro; Shibata, Michihiro*; Sakama, Minoru*; Kojima, Yasuaki*
Physical Review C, 71(6), p.067302_1 - 067302_4, 2005/06
Times Cited Count:18 Percentile:74.03(Physics, Nuclear)The new neutron-rich raer-earth isotopes Pm, Sm, and Gd produced in the proton-induced fission of 238U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport sysetm. The half-lives of Pm, Sm, and Gd were determined to be 1.50.2s, 2.40.5s, and 4.81.0s, respectively. The partial decay scheme of Gd wes constructed for - coincidence data. The improved half-life values of 25.62.2s wes obtained for the previously identified isotope Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by the Audei and Wapstra.
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.
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; Ichikawa, Shinichi; Tsukada, Kazuaki; Osa, Akihiko; Nishinaka, Ichiro; Nagame, Yuichiro; Kojima, Yasuaki*; Shibata, Michihiro*
Fission and Properties of Neutron-Rich Nuclei; Proceedings of 3rd International Conference, p.227 - 232, 2003/10
Structure of neutron-rich A160-170 nuclei produced in the proton-induced fission has been studied through -ray spectroscopy using an on-line isotope separator. decays of Pm, Sm, and Gd have been observed for the first time, and their half-lives were determined. Excited states of their daughter nuclei were revealed. rays following the decay of Eu and Gd have been also observed. The results suggest that the ground state of Eu would have a spin 5 or 6.
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 .
Sakama, Minoru*; Tsukada, Kazuaki; Asai, Masato; Ichikawa, Shinichi; Haba, Hiromitsu; Goto, Shinichi*; Nishinaka, Ichiro; Nagame, Yuichiro; Oura, Yasuji*; Kojima, Yasuaki*; et al.
Journal of Nuclear Science and Technology, 39(Suppl.3), p.34 - 37, 2002/11
no abstracts in English
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.
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.
Shibata, Michihiro*; Shindo, Terumasa*; Taniguchi, Akihiro*; Kojima, Yasuaki*; Kawade, Kiyoshi*; Ichikawa, Shinichi; Kawase, Yoichi*
Journal of the Physical Society of Japan, 71(5), p.1401 - 1402, 2002/05
Times Cited Count:8 Percentile:49.91(Physics, Multidisciplinary)no abstracts in English
Ichikawa, Shinichi; Tsukada, Kazuaki; Asai, Masato; Haba, Hiromitsu; Sakama, Minoru*; Kojima, Yasuaki*; Shibata, Michihiro*; Nagame, Yuichiro; Oura, Yasuji*; Kawade, Kiyoshi*
Nuclear Instruments and Methods in Physics Research B, 187(4), p.548 - 554, 2002/04
Times Cited Count:14 Percentile:65.6(Instruments & Instrumentation)no abstracts in English
Asai, Masato*; Kawade, Kiyoshi*; Shibata, Michihiro*; Kojima, Yasuaki*; Osa, Akihiko; Koizumi, Mitsuo; Sekine, Toshiaki
Nuclear Instruments and Methods in Physics Research A, 463(1-2), p.205 - 212, 2001/05
Times Cited Count:3 Percentile:28.27(Instruments & Instrumentation)no abstracts in English
Shibata, Michihiro*; Kojima, Yasuaki*; Uno, H.*; Kawade, Kiyoshi*; Taniguchi, Akihiro*; Kawase, Yoichi*; Ichikawa, Shinichi; Maekawa, Fujio; Ikeda, Yujiro
Nuclear Instruments and Methods in Physics Research A, 459(3), p.581 - 585, 2001/03
Times Cited Count:8 Percentile:87.21(Instruments & Instrumentation)no abstracts in English
Sakama, Minoru*; Tsukada, Kazuaki; Asai, Masato; Ichikawa, Shinichi; Haba, Hiromitsu; Goto, Shinichi*; Oura, Yasuji*; Nishinaka, Ichiro; Nagame, Yuichiro; Shibata, Michihiro*; et al.
European Physical Journal A, 9(3), p.303 - 306, 2000/11
Times Cited Count:17 Percentile:66.14(Physics, Nuclear)no abstracts in English
Asai, Masato; Sakama, Minoru*; Tsukada, Kazuaki; Ichikawa, Shinichi; Haba, Hiromitsu; Nishinaka, Ichiro; Nagame, Yuichiro; Goto, Shinichi*; Kojima, Yasuaki*; Oura, Yasuji*; et al.
AIP Conference Proceedings 561, p.358 - 367, 2000/09
no abstracts in English
Ichikawa, Shinichi; Asai, Masato*; Tsukada, Kazuaki; Nishinaka, Ichiro; Nagame, Yuichiro; Osa, Akihiko; Shibata, Michihiro*; Kawade, Kiyoshi*; Kojima, Yasuaki*; Sakama, Minoru*; et al.
Proceedings of 2nd International Conference on Fission and Neutron-rich Nuclei, p.203 - 205, 2000/03
no abstracts in English