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Journal Articles

Fission mechanism inferred from nuclear shape fluctuation by the Langevin equation

Aritomo, Yoshihiro*; Iwamoto, Akira*; Nishio, Katsuhisa; Ota, Masahisa*

Physical Review C, 105(3), p.034604_1 - 034604_8, 2022/03

Journal Articles

The r-process element abundance with a realistic fission fragment mass distribution

Chiba, Satoshi; Koura, Hiroyuki; Maruyama, Toshiki; Ota, Masahisa*; Tatsuda, Sayuki*; Wada, Takahiro*; Tachibana, Takahiro*; Sumiyoshi, Kosuke*; Otsuki, Kaori*; Kajino, Toshitaka*

AIP Conference Proceedings 1016, p.162 - 167, 2008/05

Effect of the $$beta$$-delayed fission in r-process abundance is investigated. The data base for the fission fragment mass distribution used in the r-process network calculation is constructed based on the 2-center shell model and Langevinequation. The $$beta$$-decay rates (no emissive, neutron emission and $$beta$$-delayed fission) are also newly calculated with the gross theory. The differences appeared in the final element abundance calculated with and without fission process are demonstrated and the mass region modified by the fission products is presented.

Journal Articles

Systematic study for the shell effect in the fission fragment mass distribution reptured from neutron rich nuclei

Ota, Masahisa*; Tatsuda, Sayuki*; Yamamoto, Kazuyuki*; Asano, Tomomasa*; Wada, Takahiro*; Hashizume, Kazuaki*; Sumiyoshi, Kosuke*; Otsuki, Kaori*; Kajino, Toshitaka*; Koura, Hiroyuki; et al.

Nuclear Physics A, 805(2), p.558 - 560, 2008/02

The data base for the fission fragment mass distribution used in the r-process network calculation is constructed. The differences appeared in the final element abundance calculated with and without fission process are demonstrated and the mass region modified by the fission products is presented.

Journal Articles

Fission fragment mass distribution for nuclei in the r-process region

Tatsuda, Sayuki*; Hashizume, Kazuaki*; Wada, Takahiro*; Ota, Masahisa*; Sumiyoshi, Kosuke*; Otsuki, Kaori*; Kajino, Toshitaka*; Koura, Hiroyuki; Chiba, Satoshi; Aritomo, Yoshihiro*

AIP Conference Proceedings 891, p.423 - 426, 2007/03

We investigate the fission-fragment mass distribution on about 2000 nuclides, which should have a critical impact on the r-process nucleosynthesis through fission ($$Z>85$$). The mass distribution of fission fragment is thought to be one of the most important elements on some astrophysical conditions for the theoretical estimation of the r-process abundance pattern. We calculated the potential energy surface (PES) by means of the liquid-drop model with the shell energy correction by the Two-Center shell model in 3-dimensional parameter space. We derive fission-fragment mass distribution by considering the location and the depth of the valley of PES near the saddle point and the scission point of nuclei with the use of the Langevin calculation. We determine the fission asymmetry by examining the valley depth and its location in the deformation parameter space. The consistency of our mass asymmetry with available experimental data is discussed.

Journal Articles

Photodisintegration cross section measurements on $$^{186}$$W, $$^{187}$$Re and $$^{188}$$Os; Implications for the Re-Os cosmochronology

Shizuma, Toshiyuki; Utsunomiya, Hiroaki*; Mohr, P.*; Hayakawa, Takehito; Goko, Shinji*; Makinaga, Ayano*; Akimune, Hidetoshi*; Yamagata, Tamio*; Ota, Masahisa*; Ogaki, Hideaki*; et al.

Physical Review C, 72(2), p.025808_1 - 025808_9, 2005/08

 Times Cited Count:38 Percentile:88.71(Physics, Nuclear)

Cross sections of the $$^{186}$$W, $$^{187}$$Re, $$^{188}$$Os($$gamma,n$$) reactions were measured using quasi-monochromatic photon beams from laser Compton scattering (LCS) with average energies from 7.3 to 10.9 MeV. The results are compared with the predictions of Hauser-Feshbach statistical calculations using four different sets of input parameters. In addition, the inverse neutron capture cross sections were evaluated by constraining the model parameters, especially the $$E1$$ strength function, on the basis of the experimental data. The present experiment helps to further constrain the correction factor $$F_{sigma}$$ for the neutron capture on the 9.75 keV state in $$^{187}$$Os. Implications of $$F_{sigma}$$ to the Re-Os cosmochronology are discussed with a focus on the uncertainty in the estimate of the age of the Galaxy.

Journal Articles

Di-triton molecular structure in $$^{6}$$He

Akimune, Hidetoshi*; Yamagata, Tamio*; Nakayama, Shintaro*; Arimoto, Yasushi*; Fujiwara, Mamoru; Fushimi, Kenichi*; Hara, Keigo*; Ota, Masahisa*; Shiokawa, Atsuko*; Tanaka, Masayoshi*; et al.

Physical Review C, 67(5), p.051302_1 - 051302_4, 2003/05

 Times Cited Count:26 Percentile:79.94(Physics, Nuclear)

no abstracts in English

Oral presentation

Systematic study of fission fragment mass distribution by a semi-empirical model

Ota, Masahisa*; Tatsuda, Sayuki*; Wada, Takahiro*; Chiba, Satoshi; Koura, Hiroyuki; Maruyama, Toshiki; Kajino, Toshitaka*; Otsuki, Kaori*

no journal, , 

We propose a systematical method to calculate the fission fragment mass distribution (FFMD) for nuclear energy and astrophysical applications. The potential energy surface (PES) of fissionable nuclei is calculated by two-center shell model taking the mass-asymmetry, fragment deformation and distance of the fragments as parameters. Then, the ratio of symmetric and asymmetric fission modes is determined in a semi-empirical way. The present model can predict FFMD for a broad range of fissionable nuclei; Z=88 to 120. We compare the present results with measured data and systematics proposed by Katakura et al.

Oral presentation

Impact of fission fragment mass distribution on r-process nucleosynthesis pattern

Chiba, Satoshi; Koura, Hiroyuki; Maruyama, Toshiki; Ota, Masahisa*; Tatsuda, Sayuki*; Wada, Takahiro*; Tachibana, Takahiro*; Kajino, Toshitaka*; Sumiyoshi, Kosuke*; Otsuki, Kaori*

no journal, , 

We introduce $$beta$$-delayed fission in r-process calculation, and investigate the difference of the abundance pattern of synthesized nuclei depending on the model of fission fragment mass distribution. We further discuss the impact of it on nucleo-cosmochronometer and possibility to restrict the physical condition of r-process sites.

Oral presentation

Development of chemical separation of Sn from concrete matrices using TEVA resin

Do, V. K.; Furuse, Takahiro; Ota, Yuki; Sano, Yuichi; Iwahashi, Hiroyuki; Homma, Shunta; Ichijo, Yurina; Kurosawa, Kiyoko*; Endo, Tsubasa*; Motoki, Yoshiaki*; et al.

no journal, , 

This paper presents an HCl-free chemical separation procedure for Sn recovery from concretes. Two pretreatment methods of solution samples followed by a proposed solid-phase extraction on TEVA resin were examined. The obtained results show that Sn can be highly recovered by the developed separation scheme with good reproducibility. The developed method is aimed at practical application to purification of Sn from concrete rubble for quantification of $$^{126}$$Sn by mass spectrometer.

Oral presentation

Removal of interferences for ultrasensitive detection of $$^{126}$$Sn in radioactive rubbles by ICP-MS/MS

Ota, Yuki; Do, V. K.; Furuse, Takahiro; Sano, Yuichi; Iwahashi, Hiroyuki; Homma, Shunta; Ichijo, Yurina; Kurosawa, Kiyoko*; Endo, Tsubasa*; Motoki, Yoshiaki*; et al.

no journal, , 

no abstracts in English

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