Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Koura, Hiroyuki; Yoshida, Tadashi*; Tachibana, Takahiro*; Chiba, Satoshi*
JAEA-Conf 2017-001, p.205 - 210, 2018/01
no abstracts in English
Koura, Hiroyuki; Yoshida, Tadashi*; Tachibana, Takahiro*; Chiba, Satoshi*
EPJ Web of Conferences, 146, p.12003_1 - 12003_4, 2017/09
Times Cited Count：3 Percentile：86.43(Nuclear Science & Technology)Koura, Hiroyuki; Katakura, Junichi*; Tachibana, Takahiro*; Minato, Futoshi
JAEA-Conf 2015-003, p.147 - 152, 2016/03
A chart of the nuclides 2014 version is now preparing to be published from JAEA. This will be the latest successive version of the chart since 1977, and continues every (approximately) four years until 2010. These charts include decay data of isotopes as half-lives, decay modes, and some isomeric states. In addition, the periodic table of elements, fundamental physical constants, thermal neutron capture and fission cross sections are tabulated. The latest version is now compiled with recent experimental data until the end of June in 2014. In the compilation process, we improved in the following parts: (1) Neutron or proton-unbound nuclei in the lighter region. (2) Drawing the neutron and proton-drip lines, and a boundary line of 
-delayed neutron emission. (3) 1- or 2-proton-emission theoretical half-lives are added for unmeasured nuclei in addition to original three partial half-lives of 
-decay, -decay and spontaneous fission. We compiled totally 3150 nuclides, which were experimental identified including 2914 life-measured nuclei. We will show overview of the chart with some statistics and examples.
Koura, Hiroyuki; Tachibana, Takahiro*; Chiba, Satoshi
JAEA-Conf 2009-004, p.135 - 140, 2009/10
We have developed an original model based on the macroscopic and mean-field models to describe the global features of nuclear masses, called the KTUY (Koura-Tachibana-Uno-Yamada) nuclear mass model. The standard deviation of this prediction from known masses is 0.67 MeV, and below 0.4 MeV from some separation energies. The calculated separation energies shows a change of magicities from 
=20 (or 14) to 16, =28 to 32 (or 34), =50 to 58 etc.
-decay, -decay, proton emission and spontaneous fission ranging from light nuclei to superheavy nuclei including unknown ones, and estimated the dominant nuclear decay modes. A file of these nuclear data is presented. The total number of nuclei having more than 1 ns is estimated to be approximately ten thousands.
-delayed fission and neutron emission probabilities with the use of gross theory and KTUY mass formulaTachibana, Takahiro*; Koura, Hiroyuki; Chiba, Satoshi
JAEA-Conf 2009-004, p.129 - 134, 2009/10
Probabilities of the -delayed neutron emission are important information for decay heat calculation and, recently, the effect of the -delayed fission to the r-process nucleosynthesis is a quite interesting topic. We make an improvement of the calculation of the probabilities of -delayed fission and neutron emission for nuclei in the region far from the experimentally known nuclides. The probabilities of -delayed fission and neutron emission are estimated by using the gross theory of nuclear -decay. This theory includes the allowed (Fermi and Gamow-Teller) and first-forbidden transitions. In order to estimate the decay width 
and 
, we improve the calculation of nuclear level density formula by Kawano et. al. to take into account the effects of collective motion. We adopted the KTUY mass model for obtaining 
-values, neutron separation energies and fission barrier heights. The shell and the paring energies are also obtained by KTUY mass model for the calculation of the nuclear level density. We will apply these data to an r-process network calculation and briefly discuss the effect of nuclear fission to the r-process abundance in the presentation.
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 -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 -decay rates (no emissive, neutron emission and -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.
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.
Koura, Hiroyuki; Tachibana, Takahiro*
RIKEN Accelerator Progress Report, Vol.39, P. 30, 2006/05
no abstracts in English
Koura, Hiroyuki; Tachibana, Takahiro*
Nihon Butsuri Gakkai-Shi, 60(9), p.717 - 724, 2005/09
no abstracts in English
Koura, Hiroyuki; Tachibana, Takahiro*; Uno, Masahiro*; Yamada, Masami*
Progress of Theoretical Physics, 113(2), p.305 - 325, 2005/02
Times Cited Count：397 Percentile：99.16(Physics, Multidisciplinary)A nuclidic mass formula composed of a gross term, an even-odd term and a shell term is presented as a revised version of the mass formula constructed by the present authors and published in 2000. The gross term has almost the same functional form as in the previous formula, but the parameter values in it are somewhat different. The even-odd term is treated more carefully, and a considerable improvement is brought about. The shell term is exactly the same as the previous one; it was obtained using spherical single-particle potentials and by treating the deformed nucleus as a superposition of spherical nuclei. The new mass formula is applicable to nuclei with 
1 and 
1. The root-mean-square deviation from experimental masses is 0.658 MeV, which is less than that of the previous mass formula, 0.680 MeV.
Yoshida, Tadashi*; Okajima, Shigeaki; Sakurai, Takeshi; Nakajima, Ken; Yamane, Tsuyoshi; Katakura, Junichi; Tahara, Yoshihisa*; Zukeran, Atsushi*; Oyamatsu, Kazuhiro*; Osawa, Takaaki*; et al.
Journal of Nuclear Science and Technology, 39(Suppl.2), p.136 - 139, 2002/08
no abstracts in English
Katakura, Junichi; Yoshida, Tadashi*; Oyamatsu, Kazuhiro*; Tachibana, Takahiro*
JAERI 1343, 79 Pages, 2001/07
no abstracts in English
- and 
-ray spectra for JENDL FP decay data fileKatakura, Junichi; Yoshida, Tadashi*; Oyamatsu, Kazuhiro*; Tachibana, Takahiro*
Journal of Nuclear Science and Technology, 38(7), p.470 - 476, 2001/07
Times Cited Count：5 Percentile：38.97(Nuclear Science & Technology)no abstracts in English
-decay half-lives of new neutron-rich isotopes 
Tb and levels in DyAsai, Masato*; Ichikawa, Shinichi; Tsukada, Kazuaki; Sakama, Minoru*; Shibata, M.*; *; Osa, Akihiko; Nishinaka, Ichiro; Nagame, Yuichiro; Kawade, Kiyoshi*; et al.
Physical Review C, 59(6), p.3060 - 3065, 1999/06
Times Cited Count：33 Percentile：82.85(Physics, Nuclear)no abstracts in English
measurements of 
LaKojima, Yasuaki*; Asai, Masato*; Osa, Akihiko; Koizumi, Mitsuo; Sekine, Toshiaki; Shibata, M.*; *; Kawade, Kiyoshi*; Tachibana, Takahiro*
Journal of the Physical Society of Japan, 67(10), p.3405 - 3413, 1998/10
Times Cited Count：10 Percentile：58.6(Physics, Multidisciplinary)no abstracts in English
Tachibana, Takahiro*; *
JAERI-M 87-122, 56 Pages, 1987/08
no abstracts in English
Koura, Hiroyuki; Tachibana, Takahiro*; Chiba, Satoshi
no journal, ,
no abstracts in English
Koura, Hiroyuki; Tachibana, Takahiro*; Chiba, Satoshi
no journal, ,
Based on the KUTY nuclear mass formula, we calculate spontaneous-fission, proton-emission and alpha-decay half-lives in the super-heavy nuclidic region and discuss the limit of existence of nuclei. Regarding the spontaneous fission, we prepare potential energy surfaces (PES) by using the spherical-basis method we have developed, and then calculate the WKB penetration probabilities on the energy surfaces with a penetrating particle having a variable mass parameter. We show some predictions of decay modes of unknown super-heavy nuclei. In the superheavy, neutron-rich region, a border of existence of nuclei is given by the spontaneous fission instead of the proton emission. If we choose the minimum half-lives of 10
s, the upper limit of the proton number is obtained as 
for 
, 
for 
, and 
for 
. Furthermore, a line of the spontaneous-fission half-lines of 10 second crosses the neutron-drip line around 
. The total number of nuclides in this region is estimated to be approximately 11,000.
Takano, Masatoshi*; Tachibana, Takahiro*; Koura, Hiroyuki
no journal, ,
We discuss the synthesis of superheavy elements, heavier than the iron, in the cosmos from a viewpoint of the study for nuclear data. Estimation of nuclear reactions in the synthesis of the superheavy elements requires nuclear data as nuclear masses, beta-decay rates, nuclear reaction rates, etc. Especially, almost the nuclear data related to the r-process are absent in the current experiment, therefore many theoretical predictions of these nuclei are required. Some typical nuclear mass models, however, give different predictions in the unknown neutron-rich nuclei; therefore the result of the r-process calculations fully depends on the mass models adopted. We review the properties of the various mass models and discuss the dependencies of them. Furthermore, we present our theoretical estimation of existence of doubly magic superheavy nucleus with Z=114 and N=184 producing by the r-process nucleosynthesis, and discuss the possibility of observation of the nucleus in the cosmic-ray.
Koura, Hiroyuki; Tachibana, Takahiro*; Chiba, Satoshi
no journal, ,
We have developed an original nuclear mass model based on the macroscopic and mean-field models to describe the global features, called the KTUY (Koura-Tachibana-Uno-Yamada) model. By using the KTUY model, we have studied decay modes for -decay, -decay, proton emission and spontaneous fission ranging from light nuclei to superheavy nuclei including unknown ones. In this calculation we find that various decay modes coexist and a kind of a periodic structure of the closed shell with =126, 184 and 228 near the proton-drip line in the superheavy region. We also calculate total half-lives for nuclei in the "island of stability for the superheavy nuclei" and find a nucleus with the longest half-life on the -stability line in the order of 100 years. Furthermore, we also investigate much heavier nuclei beyond the superheavy ones and estimate the next "island of stability" and the limit of existence of nuclei which is given not by proton emission, but by fission.
