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Journal Articles

Effects of multichance fission on isotope dependence of fission fragment mass distributions at high energies

Tanaka, Shoya; Aritomo, Yoshihiro*; Miyamoto, Yuya*; Hirose, Kentaro; Nishio, Katsuhisa

Physical Review C, 100(6), p.064605_1 - 064605_6, 2019/12

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

Fission fragment mass distributions of $$^{234-240}$$U, $$^{236-242}$$Np, and $$^{238-244}$$Pu are studied using the Langevin approach in the widely excitation energy range as $$E^{*}$$ = 15-55 MeV. In the present calculation, neutron emission before fission, so called multichance fission, was introduced. The calculated results well demonstrated the experimental data, which shows the double-peak structure up to the highest excitation energies and the clear dependence on the initial fissioning nuclides. The trend is nicely correlated with the neutron binding energy of the compound nucleus that dominates the neutron emission probability before fission.

Journal Articles

Origin of the dramatic change of fission mode in fermium isotopes investigated using Langevin equations

Miyamoto, Yuya*; Aritomo, Yoshihiro*; Tanaka, Shoya; Hirose, Kentaro; Nishio, Katsuhisa

Physical Review C, 99(5), p.051601_1 - 051601_7, 2019/05

 Times Cited Count:3 Percentile:15.55(Physics, Nuclear)

Journal Articles

Role of multichance fission in the description of fission-fragment mass distributions at high energies

Hirose, Kentaro; Nishio, Katsuhisa; Tanaka, Shoya*; L$'e$guillon, R.*; Makii, Hiroyuki; Nishinaka, Ichiro*; Orlandi, R.; Tsukada, Kazuaki; Smallcombe, J.*; Vermeulen, M. J.; et al.

Physical Review Letters, 119(22), p.222501_1 - 222501_6, 2017/12

 Times Cited Count:25 Percentile:7.49(Physics, Multidisciplinary)

Fission-fragment mass distributions were measured for $$^{237-240}$$U, $$^{239-242}$$Np and $$^{241-244}$$Pu populated in the excitation-energy range from 10 to 60 MeV by multi-nucleon transfer channels in the reaction $$^{18}$$O + $$^{238}$$U at the JAEA tandem facility. Among them, the data for $$^{240}$$U and $$^{240,241,242}$$Np were observed for the first time. It was found that the mass distributions for all the studied nuclides maintain a double-humped shape up to the highest measured energy in contrast to expectations of predominantly symmetric fission due to the washing out of nuclear shell effects. From a comparison with the dynamical calculation based on the fluctuation-dissipation model, this behavior of the mass distributions was unambiguously attributed to the effect of multi-chance fission.

Journal Articles

Study of fission using multi-nucleon transfer reactions

Nishio, Katsuhisa; Hirose, Kentaro; Vermeulen, M. J.; Makii, Hiroyuki; Orlandi, R.; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Sato, Tetsuya; Nagame, Yuichiro; et al.

EPJ Web of Conferences (Internet), 163, p.00041_1 - 00041_6, 2017/11

 Times Cited Count:0 Percentile:100

Journal Articles

Study of fission using multi-nucleon transfer reactions

Nishio, Katsuhisa; Hirose, Kentaro; L$'e$guillon, R.*; Makii, Hiroyuki; Orlandi, R.; Tsukada, Kazuaki; Smallcombe, J.*; Chiba, Satoshi*; Aritomo, Yoshihiro*; Tanaka, Shoya*; et al.

Proceedings of 6th International Conference on Fission and Properties of Neutron-rich Nuclei (ICFN-6), p.590 - 597, 2017/11

Journal Articles

Experimental fission study using multi-nucleon transfer reactions

Nishio, Katsuhisa; Hirose, Kentaro; L$'e$guillon, R.*; Makii, Hiroyuki; Orlandi, R.; Tsukada, Kazuaki; Smallcombe, J.*; Chiba, Satoshi*; Aritomo, Yoshihiro*; Tanaka, Shoya*; et al.

EPJ Web of Conferences (Internet), 146, p.04009_1 - 04009_6, 2017/09

 Times Cited Count:2 Percentile:7.87

Journal Articles

Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the $$^{18}$$O + $$^{232}$$Th reaction

L$'e$guillon, R.; Nishio, Katsuhisa; Hirose, Kentaro; Makii, Hiroyuki; Nishinaka, Ichiro*; Orlandi, R.; Tsukada, Kazuaki; Smallcombe, J.*; Chiba, Satoshi*; Aritomo, Yoshihiro*; et al.

Physics Letters B, 761, p.125 - 130, 2016/10

 Times Cited Count:25 Percentile:6.7(Astronomy & Astrophysics)

Journal Articles

A Comprehensive approach to determination of nuclear data of unstable nuclei

Chiba, Satoshi*; Nishio, Katsuhisa; Aritomo, Yoshihiro*; Koura, Hiroyuki; Iwamoto, Osamu; Makii, Hiroyuki; Nishinaka, Ichiro*; Hirose, Kentaro

EPJ Web of Conferences (Internet), 106, p.04004_1 - 04004_9, 2016/02

 Times Cited Count:0 Percentile:100

Journal Articles

Surrogate reactions research at JAEA/Tokyo Tech

Chiba, Satoshi; Nishio, Katsuhisa; Makii, Hiroyuki; Aritomo, Yoshihiro*; Nishinaka, Ichiro; Ishii, Tetsuro; Tsukada, Kazuaki; Asai, Masato; Furutaka, Kazuyoshi; Hashimoto, Shintaro; et al.

Nuclear Data Sheets, 119, p.229 - 232, 2014/05

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

Journal Articles

In-beam fissio study at JAEA for heavy element synthesis

Nishio, Katsuhisa; Ikezoe, Hiroshi; Hofmann, S.*; Ackermann, D.*; Aritomo, Yoshihiro*; Comas, V. F.*; D$"u$llmann, Ch. E.*; Heinz, S.*; Heredia, J. A.*; He${ss}$berger, F. P.*; et al.

AIP Conference Proceedings 1524, p.68 - 72, 2013/04

 Times Cited Count:0 Percentile:100

Journal Articles

Fusion probabilities in the reactions $$^{40,48}$$Ca + $$^{238}$$U at energies around the Coulomb barrier

Nishio, Katsuhisa; Mitsuoka, Shinichi; Nishinaka, Ichiro; Makii, Hiroyuki; Wakabayashi, Yasuo*; Ikezoe, Hiroshi; Hirose, Kentaro*; Otsuki, Tsutomu*; Aritomo, Yoshihiro*; Hofmann, S.*

Physical Review C, 86(3), p.034608_1 - 034608_6, 2012/09

 Times Cited Count:52 Percentile:5.7(Physics, Nuclear)

Journal Articles

Dynamical approach to heavy-ion induced fission using actinide target nuclei at energies around the Coulomb barrier

Aritomo, Yoshihiro; Hagino, Koichi*; Nishio, Katsuhisa; Chiba, Satoshi

Physical Review C, 85(4), p.044614_1 - 044614_15, 2012/04

 Times Cited Count:45 Percentile:7.02(Physics, Nuclear)

In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. Fusion-fission, quasi-fission and deep quasi-fission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF) in the reactions of $$^{34,36}$$S+$$^{238}$$U and $$^{30}$$Si+$$^{238}$$U at several incident energies around the Coulomb barrier. We find that the time scale in the quasi-fission as well as the deformation of fission fragments at the scission point are different between the $$^{30}$$Si+$$^{238}$$U and $$^{36}$$S+$$^{238}$$U systems, causing different mass asymmetries of the quasi-fission.

Journal Articles

Spin-dependent observables in surrogate reactions

Chiba, Satoshi; Iwamoto, Osamu; Aritomo, Yoshihiro

Physical Review C, 84(5), p.054602_1 - 054602_5, 2011/11

 Times Cited Count:8 Percentile:44.71(Physics, Nuclear)

Observables emitted from various spin states in compound U nuclei are investigated to validate usefulness of the surrogate reaction method. It was found that energy spectrum of cascading $$gamma$$-rays and their multiplicities, spectrum of evaporated neutrons, and mass-distribution of fission fragments show clear dependence on the spin of decaying nuclei. The present results indicate that they can be used to infer populated spin distributions which significantly affect the decay branching ratio of the compound system produced by the surrogate reactions.

Journal Articles

Investigation of fission properties and evaporation residue measurement in the reactions using $$^{238}$$U target nucleus

Nishio, Katsuhisa; Ikezoe, Hiroshi; Hofmann, S.*; Ackermann, D.*; Antalic, S.*; Aritomo, Yoshihiro; Comas, V. F.*; D$"u$llmann, Ch. E.*; Gorshkov, A.*; Graeger, R.*; et al.

EPJ Web of Conferences (Internet), 17, p.09005_1 - 09005_4, 2011/10

 Times Cited Count:1 Percentile:49.84

Journal Articles

Dynamical model of surrogate reactions

Aritomo, Yoshihiro; Chiba, Satoshi; Nishio, Katsuhisa

Physical Review C, 84(2), p.024602_1 - 024602_10, 2011/08

 Times Cited Count:6 Percentile:53.09(Physics, Nuclear)

A new dynamical model is developed to describe the whole process of surrogate reactions; the transfer of several nucleons at an initial stage, thermal equilibration of residues leading to washing out of shell effects and decay of populated compound nuclei are treated in a unified framework. Multi-dimensional Langevin equations are employed to describe time-evolution of the system. The new model is capable of calculating the spin distribution of the compound nuclei, one of the most important quantities in the surrogate technique. Furthermore, observable of surrogate reactions can be calculated. It is found that spin distributions of compound nuclei produced in $$^{18}$$O+$$^{238,236}$$U $$rightarrow ^{16}$$O+$$^{240,238*}$$U reactions are equivalent and much less than 10$$hbar$$, therefore satisfy conditions proposed by Chiba and Iwamoto if they are used as a pair in the surrogate ratio method.

Journal Articles

Nuclear orientation in the reaction $$^{34}$$S+$$^{238}$$U and synthesis of the new isotope $$^{268}$$Hs

Nishio, Katsuhisa; Hofmann, S.*; He${ss}$berger, F. P.*; Ackermann, D.*; Antalic, S.*; Aritomo, Yoshihiro; Comas, V. F.*; D$"u$llmann, Ch. E.*; Gorshkov, A.*; Graeger, R.*; et al.

Physical Review C, 82(2), p.024611_1 - 024611_9, 2010/08

 Times Cited Count:60 Percentile:4.42(Physics, Nuclear)

Journal Articles

Fusion-fission and quasi-fission processes in reactions using actinide target nuclei

Aritomo, Yoshihiro

International Journal of Modern Physics E, 19(5&6), p.813 - 824, 2010/06

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

We analyzed experimental data obtained for the mass distribution of fission fragments in the reactions $$^{36}$$S+$$^{238}$$U and $$^{30}$$Si+$$^{238}$$U at several incident energies, which were performed by the JAEA group. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. We also consider the fine structures in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has different features in the two reactions. The fusion cross sections are also estimated.

Journal Articles

Analysis of dynamical process with mass distribution of fission fragment in heavy ion reactions

Aritomo, Yoshihiro

EPJ Web of Conferences (Internet), 2, p.07004_1 - 07004_4, 2010/03

 Times Cited Count:0 Percentile:100

We analyzed experimental data obtained for the mass distribution of fission fragments in the reactions $$^{36}$$S+$$^{238}$$U and $$^{30}$$Si+$$^{238}$$U at several incident energies, which were performed by the JAEA group. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. We also consider the fine structures in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has different features in the two reactions. The fusion cross sections are also estimated.

Journal Articles

Evidence for quasifission in the sub-barrier reaction of $$^{30}$$Si+$$^{238}$$U

Nishio, Katsuhisa; Ikezoe, Hiroshi; Nishinaka, Ichiro; Mitsuoka, Shinichi; Hirose, Kentaro*; Otsuki, Tsutomu*; Watanabe, Yutaka*; Aritomo, Yoshihiro*; Hofmann, S.*

Physical Review C, 82(4), p.044604_1 - 044604_5, 2010/00

 Times Cited Count:39 Percentile:8.88(Physics, Nuclear)

Journal Articles

Analysis of dynamical processes using the mass distribution of fission fragments in heavy-ion reactions

Aritomo, Yoshihiro

Physical Review C, 80(6), p.064604_1 - 064604_12, 2009/12

 Times Cited Count:34 Percentile:10.76(Physics, Nuclear)

We analyzed experimental data obtained for the mass distribution of fission fragments in the reactions $$^{36}$$S+$$^{238}$$U and $$^{30}$$Si+$$^{238}$$U at several incident energies, which were performed by the JAEA group. The analysis of the mass distribution of fission fragments is a powerful tool for understanding the mechanism of the reaction in the heavy- and superheavy-mass regions. Using the dynamical model with the Langevin equation, we precisely investigate the incident energy dependence of the mass distribution of fission fragments. This study is the first attempt to treat such experimental data systematically. We also consider the fine structures in the mass distribution of fission fragments caused by the nuclear structure at a low incident energy. It is explained why the mass distribution of fission fragments has different features in the two reactions. The fusion cross sections are also estimated.

44 (Records 1-20 displayed on this page)