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Journal Articles

Orientation effects of deformed $$^{238}$$U target nuclei on the fusion probability for the heavy element synthesis

Nishio, Katsuhisa; Hofmann, S.*; Ikezoe, Hiroshi; He${ss}$berger, F. P.*; Ackermann, D.*; Antalic, S.*; Comas, V. F.*; Gan, Z.*; Heinz, S.*; Heredia, J. A.*; et al.

Nuclear Physics A, 805(1-4), p.516 - 518, 2008/06

Journal Articles

In-beam $$gamma$$-ray spectroscopy of neutron-rich nuclei in the uranium region through the heavy-ion transfer reaction

Ishii, Tetsuro; Makii, Hiroyuki; Asai, Masato; Koura, Hiroyuki; Shigematsu, Soichiro*; Tsukada, Kazuaki; Toyoshima, Atsushi; Matsuda, Makoto; Makishima, Akiyasu*; Shizuma, Toshiyuki; et al.

Nuclear Physics A, 805(1-4), p.257 - 259, 2008/06

https://doi.org/10.1016/j.nuclphysa.2008.02.090

no abstracts in English

Journal Articles

Photoneutron cross sections for $$^{80}$$Se; Implications for the s-process thermometer

Makinaga, Ayano*; Utsunomiya, Hiroaki*; Kaihori, Takeshi*; Yamagata, Tamio*; Akimune, Hidetoshi*; Goriely, S.*; Toyokawa, Hiroyuki*; Matsumoto, Tetsuro*; Harano, Hideki*; Harada, Hideo; et al.

Nuclear Physics A, 805(1-4), p.564 - 566, 2008/06

Photoneutron cross sections were measured for $$^{80}$$Se near the neutron threshold energy with quasi-monochromatic $$gamma$$ rays. Using the $$^{80}$$Se($$gamma$$,$$n$$) cross section as experimental constraints on the E1 $$gamma$$ strength function, we estimate the neutron capture rates for $$^{79}$$Se. The solar abundance ratio of s-only nuclides $$^{80}$$Kr and $$^{82}$$Kr are analyzed in terms of the s-process branching at $$^{79}$$Se within the local approximation. The corresponding temperature and neutron density regimes are discussed in the light of the s-process scenario in massive stars.

Journal Articles

Neutrino-nucleus reactions based on recent advances in shell-model calculations

Suzuki, Toshio*; Chiba, Satoshi; Yoshida, Takashi*; Higashijima, Koji*; Homma, Michio*; Kajino, Toshitaka*; Otsuka, Takaharu*

Nuclear Physics A, 805(2), p.579 - 581, 2008/02

Neutrino-nucleus reactions on $$^{12}$$C and $$^4$$He are studied based on new shell model Hamiltonians. The cross sections are found to be enhanced compared with those obtained by conventional Hamiltonians. The production yield of $$^7$$Li and $$^{11}$$B during supernova explosions are pointed out to be enhanced, and a possibility of determining the neutrino mixing angle $$theta_{13}$$ is discussed in case of neutrino oscillations. Neutrino induced reactions on Fe and Ni isotopes are also studied based on recent advances in shell model calculations in the $$fp$$-shell. The reaction crowds sections are found to be enhanced compared with those obtained by a modified KB3 Hamiltonian.

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

Excitation energy dependence of fragment mass and total kinetic energy distributions in proton-induced fission of uranium isotopes

Nishinaka, Ichiro; Tanikawa, Masashi*; Goto, Shinichi*; Nishio, Katsuhisa; Asai, Masato; Tsukada, Kazuaki; Nagame, Yuichiro; Kudo, Hisaaki*

Nuclear Physics A, 805, p.434 - 436, 2008/00

The aim of this work is to study how shell effects of fissioning nuclei and fission fragments are responsible for deformation and mass division during descent from the saddle point to scission. We studied in detail excitation energy dependence of mass and total kinetic energy distributions in the fission of $$p$$ + $$^{233,238}$$U at incident beam energies of 10.0, 11.5 and 13.0 MeV. For the asymmetric mass division in the fission for both uranium isotopes, the obtained yield at $$A$$ $$simeq$$ 132 with the spherical shell of $$N$$ = 82 increases more largely with increasing excitation energy than that at $$A$$ $$simeq$$ 143 with deformed shell of $$N$$ = 86-88. The present excitation energy dependence shows the opposite trend observed in the thermal neutron induced fission and cold fission of actinides. We will discuss the shell effects on excitation energy dependence of fragment mass and total kinetic energy distributions in fission.

Journal Articles

Hyperon-Quark mixed phase in compact stars

Maruyama, Toshiki; Chiba, Satoshi; Schulze, H.-J.*; Tatsumi, Toshitaka*

Nuclear Physics A, 805, p.588 - 590, 2008/00

no abstracts in English

Oral presentation

Nuclear cosmic clock of neutrino induced-reaction process

Hayakawa, Takehito; Shizuma, Toshiyuki; Kajino, Toshitaka*; Ogawa, Kengo*; Nakada, Hitoshi*

no journal, , 

no abstracts in English

Oral presentation

Universality of photodisintegration reaction nucleosynthesis in supernovae

Hayakawa, Takehito; Iwamoto, Nobuyuki; Kajino, Toshitaka*; Shizuma, Toshiyuki; Umeda, Hideyuki*; Nomoto, Kenichi*

no journal, , 

no abstracts in English

Oral presentation

A Systematic study of astrophysical nuclear reaction rates via $$^8$$Li

Miyatake, Hiroari; Ishiyama, Hironobu*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Tanaka, Masahiko*; Yoshikawa, Nobuharu*; Jeong, S.-C.*; Fuchi, Yoshihide*; Nomura, Toru*; et al.

no journal, , 

A systematic study of astrophysical reaction rates on light neutron-rich nuclei using low-energy radioactive nuclear beams (RNB) is in progress at the tandem facility of Japan Atomic Energy Agency (JAEA). Direct measurements of reaction rates of $$^8$$Li($$alpha$$, n)$$^{11}$$B, $$^{12}$$B($$alpha$$, n)$$^{15}$$N and, $$^8$$Li(d, p), (d, t), (d, $$alpha$$), (p, $$alpha$$) have been carried out. Measured excitation functions and obtained reaction rates will be presented. Possible r-process path via $$^8$$Li at each temperature during r-process and the influence of r-process abundance will be discussed.

Oral presentation

Spectroscopy of neutron-rich $$^{187,188}$$W produced in $$^{18}$$O-induced transferreactions

Shizuma, Toshiyuki; Ishii, Tetsuro; Makii, Hiroyuki; Hayakawa, Takehito; Shigematsu, Soichiro*; Matsuda, Makoto; Ideguchi, Eiji*; Zheng, Y.*; Liu, M.*; Morikawa, Tsuneyasu*; et al.

no journal, , 

Neutron-rich W-Os nuclei with $$Aapprox190$$ exhibit the various signature of nuclear collective motions such as $$gamma$$-softness, triaxiality, and a prolate-oblate shape transition. In addition, the emergence of high-$$K$$ isomers, where $$K$$ is the angular momentum projection on the nuclear symmetry axis, based on multi-quasiparticle excitation is a characteristic of nuclei in this region. The recent experimental and theoretical studies of the neutron-rich W nuclei have revealed the existence of high-$$K$$ multi-quasiparticle isomers. Here we report results from the in-beam $$gamma$$-ray spectroscopic experiments on neutron-rich $$^{187}$$W and $$^{188}$$W.

Oral presentation

Nuclear moments of the radioactive isotope $$^{131}$$La determined by collinear fast-beam laser spectroscopy

Iimura, Hideki; Schuessler, H. A.*; Buchinger, F.*; Cocolios, T.*; Crawford, J. E.*; Gulick, S.*; Lee, J. K. P.*; Levy, C. D. P.*; Pearson, M.*; Lioubimov, V.*; et al.

no journal, , 

We report measurements of the hyperfine structure constants of $$^{131}$$La (N=74) as an initial step to further exploring the neutron deficient rare-earth region where a sudden onset of nuclear deformation is predicted theoretically around N=74. This work is an extension of our earlier off-line experiments on $$^{135,137-139}$$La to on-line laser spectroscopy. The radioactive isotope $$^{131}$$La (T$$_{1/2}$$=59 min) was produced by means of a spallation reaction using a proton beam from TRIUMF cyclotron. The hyperfine spectra were observed by using the method of collinear fast-beam laser spectroscopy. From the obtained hyperfine constants, the nuclear moments of $$^{131}$$La were derived. In order to arrive at an understanding of the nuclear structure of $$^{131}$$La, we have carried out particle triaxial-rotor calculations. The results from the calculation reproduce well the experimental values when a triaxial shape is assumed for $$^{131}$$La.

Oral presentation

Neutron capture measurements using the 4$$pi$$ Ge detector for Au and Ag

Harada, Hideo; Kitatani, Fumito; Toh, Yosuke; Kimura, Atsushi; Nakamura, Shoji; Furutaka, Kazuyoshi; Koizumi, Mitsuo; Oshima, Masumi; Mizumoto, Motoharu*; Igashira, Masayuki*; et al.

no journal, , 

The $$gamma$$ rays produced by neutron capture reactions for Au and Ag samples were measured using the 4$$pi$$ Ge spectrometer in the resonance region in a time-of-flight (TOF) mode. Two dimensional matrices for TOF and summed Ge pulse heights were produced to analyze the data. From the analyses of the matrices, the origin of each resonance peak is identified. For example, the resonance of Ag-107 and Ag-109 were clearly separated in the measurement of Ag-nat sample by gating at the neutron separation energy for each isotope. Furthermore, the $$gamma$$-ray spectrum for each resonance is deduced from the matrices. The potential of the 4$$pi$$ Ge detector as the high-energy-resolution total energy absorption detector is demonstrated using the TOF data obtained for Au and Ag.

Oral presentation

Measurement of total $$gamma$$ absorption for high energy $$gamma$$ rays

Kitatani, Fumito; Harada, Hideo; Hara, Kaoru; Utsunomiya, Hiroaki*; Goko, Shinji*; Kaihori, Takeshi*; Toyokawa, Hiroyuki*

no journal, , 

Oral presentation

Innovative method for nuclear level construction using measured multiple prompt $$gamma$$-rays

Kin, Tadahiro; Oshima, Masumi; Kimura, Atsushi; Furutaka, Kazuyoshi

no journal, , 

MA and LLFP neutron capture cross sections are important for nuclear transmutation. Measurements of prompt $$gamma$$ are useful method for improvement of accuracy of the data. For the method, ground-state transition $$gamma$$ have to be known. We developed an innovative method for identification of nuclear levels using measured multiple prompt $$gamma$$-ray. For demonstration of the method, we calculated a existing-probability of $$^{15}$$N nuclear levels with measurement of $$^{14}$$N(n,$$gamma$$)$$^{15}$$N reaction with 4$$pi$$ Ge spectrometer at JRR-3. With this demonstration, we verified that the method is useful.

Oral presentation

Development of an innovative $$gamma$$-ray spectrometer for neutron capture experiments

Oshima, Masumi; Furutaka, Kazuyoshi; Kin, Tadahiro; Kimura, Atsushi; Toh, Yosuke; Koizumi, Mitsuo; Goto, Jun*

no journal, , 

Oral presentation

Electric quadrupole moment measurement using a new RF-application system

Nagae, Daisuke; Takemuara, Makoto*; Ueno, Hideki*; Kameda, Daisuke*; Asahi, Koichiro*; Yoshimi, Akihiro*; Sugimoto, Takashi*; Nagatomo, Takashi*; Kobayashi, Yoshio*; Uchida, Makoto*; et al.

no journal, , 

An electric quadrupole moment ($$Q$$ moment) is sensitive to collective aspects of nuclear structure. In the $$Q$$-moment measurement for unstable nuclei, we employ the $$beta$$-detected nuclear-quadrupole resonance method. In this method, we need to supply $$2I$$ resonance frequencies, where $$I$$ denotes the nuclear spin. We have developed a new RF-application system to induced all of the $$2I$$ transitions. The application of the $$2I$$ frequencies may be pursued in two different ways; the sequential RF pulse method and the mixed-wave RF pulse method. We confirmed the reversal of polarization for the both methods, from measurements of $$beta$$-ray asymmetry change for polarized $$^{12}$$B. Using this system, the $$Q$$ moments of $$^{31,32}$$Al have been measured to be $$|Q(^{31}{rm Al})| = 104(9)$$ $$e$$$$cdot$$mb and $$|Q(^{32}{rm Al})| = 24(2)$$ $$e$$$$cdot$$mb by the sequential RF pulse method.

Oral presentation

Systematical study of nuclear decay modes and a limit of existence of nuclei

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 $$alpha$$-decay, $$beta$$-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 $$N$$=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 $$beta$$-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.

Oral presentation

Photonuclear reaction cross sections of Cl-37 and Sm-152

Hara, Kaoru; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; Hohara, Shinya*; Kaihori, Takeshi*; Makinaga, Ayano*; Utsunomiya, Hiroaki*; Toyokawa, Hiroyuki*; Watanabe, Yukinobu*

no journal, , 

Neutron capture cross sections of the unstable nuclei $$^{36}$$Cl (t$$_{1/2}$$=3.0$$times$$10$$^{5}$$ yr) and $$^{151}$$Sm (t$$_{1/2}$$=90 yr) are the fundamental data for the nuclear transmutation. The cross sections of the inverse $$^{37}$$Cl($$gamma$$,n)$$^{36}$$Cl and $$^{152} $$Sm($$gamma$$,n)$$^{151}$$Sm reaction were measured with the laser-Compton scattering (LCS) $$gamma$$ rays at 10.4-12.0 MeV and 8.3-12.4 MeV, respectively. Quasi-monochromatic beams of LCS photons irradiated a natural NaCl sample and an enriched $$^{152}$$Sm$$_2$$O$$_3$$ sample. The emitted neutrons were detected with a 4$$pi$$ neutron detector. The energy distribution of LCS $$gamma$$ beam was measured with a 120 $$%$$ Ge detector or the high-resolution high-energy photon spectrometer (HHS). The present data for $$^{37}$$Cl, $$^{152}$$Sm, and $$^{197}$$Au are compared with the previous data compiled in the IAEA document and the calculation with a nuclear reaction code TALYS.

Oral presentation

Bulk properties of kaonic nuclei in the mean-field calculation

Maruyama, Toshiki; Chiba, Satoshi; Tatsumi, Toshitaka*

no journal, , 

no abstracts in English

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