Preliminary study of the criticality monitoring method based on the simulation for the activity ratio of short half-life noble-gas fission products from fuel debris

Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Kanno, Ikuo

Journal of Nuclear Science and Technology, 61(2), p.269 - 276, 2024/02

https://doi.org/10.1080/00223131.2023.2300773

Decay modes of heavy and superheavy nuclei

Koura, Hiroyuki

RIKEN Accelerator Progress Report, Vol.38, P. 9, 2005/05

We calculate proton-emission partial half lives and discuss dominant decay modes in the heavy and superheavy nuclidic region. The proton-emission partial half-lives are calculated from the one-dimensional WKB method with single-proton potentials and a mass formula that our group has developed. The calculated half lives well reproduce experimental ones in order of 100 or 1/100 which is similar predictability to other predictions as the alpha decay and the beta decay. We apply this result to calculation of branching ratios of nuclear decays considered the alpha decay, beta decay and spontaneous fission in the heavy and superheavy nuclide region. In this analysis we point out that proton-emitting nuclei are expected to be in the unknown proton-rich nuclidic region with . On the other hand, proton-rich nuclei with have much shorter spontaneous-fission half-lives than ones of proton emissions on this calculation, therefore we conclude that ground-state proton emissions would not occur in that region.

Measurement of the spontaneous fission half-life of Cm by absolute fission track counting

Usuda, Shigekazu; Umezawa, Hirokazu

Nucl. Tracks Radiat. Meas., 16(4), p.247 - 251, 1989/00

no abstracts in English

Depletion calculation of subcritical system with consideration of spontaneous fission reaction

Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi

no journal, , 

Spontaneous fission measurements for neutron-rich Fm isotopes using an Es target

Asai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi; Tomitsuka, Tomohiro; Chiera, N. M.; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro; Nishio, Katsuhisa; et al.

no journal, , 

Spontaneous fissions of neutron-rich heavy actinide isotopes Fm, Fm, and Lr have been measured at the JAEA Tandem accelerator facility. Fm and Fm were produced in a multinucleon transfer reaction with an O beam and an extremely rare Es target with a half-life of 276 days. Reaction products were mass-separated with an on-line isotope separator (ISOL). A transition between the typical asymmetric mass distribution and a very sharp symmetric one was clearly observed between Fm and Fm, while the spontaneous fission of Lr was found to exhibit mixture of three different fission modes.

New experimental results on the symmetric fission in neutron-rich transfermium nuclei

Asai, Masato

no journal, , 

New experimental results on the symmetric fission in neutron-rich transfermium nuclei are reported. Those nuclei were produced in the multi-nucleon transfer reactions with an Es target, and reaction products were mass-separated by a gas-jet coupled on-line isotope separator at the JAEA tandem accelerator facility. Spontaneous-fission fragments of those nuclei were measured with Si detectors, and fission-fragment mass and total-kinetic-energy distributions were deduced precisely. Details of the symmetric fission in neutron-rich transfermium nuclei were discussed based on the present experimental results.

Mass-TKE distributions for symmetric fission in neutron-rich Fm and transfermium nuclei

Asai, Masato

no journal, , 

Fission-fragment mass and total kinetic energy (TKE) distributions for the spontaneous fission (SF) of neutron-rich Fm and transfermium nuclei have been measured precisely. The deduced mass-TKE distributions for the SF of Fm, Md, and Lr revealed that the SF of these nuclei show mixture of three types of fission with different mechanisms: the high-TKE symmetric fission, low-TKE symmetric fission, and asymmetric fission.

Symmetric fission properties of neutron-rich transfermium nuclei

Asai, Masato

no journal, , 

Symmetric fission properties of neutron-rich transfermium nuclei have been studied through the measurements of spontaneous fission fragments of Fm, Md, and Lr. These nuclei were produced in the multinucleon transfer reactions with the O beam and the Es target, and in the fusion-evaporation reaction of Cm(N,4n)Lr at the JAEA tandem accelerator facility. The reaction products were mass-separated with the on-line isotope separator (ISOL), and the kinetic energies of spontaneous-fission fragments were measured with 4 pairs of Si semiconductor detectors. The deduced fission-fragment mass distributions and total kinetic energy distributions have revealed the detailed properties of symmetric fissions in this neutron-rich Fm and transfermium nuclei.