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Journal Articles

Inter-comparison of Hauser-Feshbach model codes toward better actinide evaluations

Capote, R.*; Hilaire, S.*; Iwamoto, Osamu; Kawano, Toshihiko*; Sin, M.*

EPJ Web of Conferences (Internet), 146, p.12034_1 - 12034_4, 2017/09

 Percentile:100

Journal Articles

Partial photoneutron cross sections for $$^{207,208}$$Pb

Kondo, Takeo*; Utsunomiya, Hiroaki*; Goriely, S.*; Iwamoto, Chihiro*; Akimune, Hidetoshi*; Yamagata, Tamio*; Toyokawa, Hiroyuki*; Harada, Hideo; Kitatani, Fumito; Lui, Y.-W.*; et al.

Nuclear Data Sheets, 119, p.310 - 313, 2014/05

 Times Cited Count:1 Percentile:85.28(Physics, Nuclear)

Journal Articles

Photoneutron cross sections for Mo isotopes; A Step toward a unified understanding of($$gamma$$,n) and (n,$$gamma$$)reactions

Utsunomiya, Hiroaki*; Goriely, S.*; Kondo, Takeo*; Iwamoto, Chihiro*; Akimune, Hidetoshi*; Yamagata, Tamio*; Toyokawa, Hiroyuki*; Harada, Hideo; Kitatani, Fumito; Lui, Y.-W.*; et al.

Physical Review C, 88(1), p.015805_1 - 015805_6, 2013/07

 Times Cited Count:38 Percentile:5.5(Physics, Nuclear)

Journal Articles

$$gamma$$-ray strength function method; A Way from photoneutron emission to radiative neutron capture

Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Yamagata, Tamio*; Iwamoto, Chihiro*; Goriely, S.*; Daoutidis, I.*; Toyokawa, Hiroyuki*; Harada, Hideo; Kitatani, Fumito; Iwamoto, Nobuyuki; et al.

Proceedings of 14th International Symposium on Capture $$gamma$$-Ray Spectroscopy and Related Topics, p.505 - 514, 2013/05

Journal Articles

Total and partial photoneutron cross sections for Pb isotopes

Kondo, Takeo*; Utsunomiya, Hiroaki*; Goriely, S.*; Daoutidis, I.*; Iwamoto, Chihiro*; Akimune, Hidetoshi*; Okamoto, Akiyuki*; Yamagata, Tamio*; Kamata, Masaki*; Ito, Osamu*; et al.

Physical Review C, 86(1), p.014316_1 - 014316_7, 2012/07

 Times Cited Count:26 Percentile:13.83(Physics, Nuclear)

Using quasi-monochromatic laser-Compton scattering $$gamma$$ rays, total photoneutron cross sections were measured for $$^{206,207,208}$$Pb near neutron threshold with a high-efficiency 4$$pi$$ neutron detector. Partial $$E$$1 and $$M$$1 photoneutron cross sections along with total cross sections were determined for $$^{207,208}$$Pb at four energies near threshold by measuring anisotropies in photoneutron emission with linearly-polarized $$gamma$$ rays. The $$E$$1 strength dominates over the $$M$$1 strength in the neutron channel where $$E$$1 photoneutron cross sections show extra strength of the pygmy dipole resonance in $$^{207,208}$$Pb near the neutron threshold corresponding to 0.32-0.42% of the Thomas-Reiche-Kuhn sum rule. Several $$mu$$$$_N^{2}$$ units of B($$M$$1)$$uparrow$$ strength were observed in $$^{207,208}$$Pb just above neutron threshold, which correspond to an $$M$$1 cross section less than 10% of the total photoneutron cross section.

Journal Articles

Photoneutron cross sections for $$^{118-124}$$Sn and the $$gamma$$-ray strength function method

Utsunomiya, Hiroaki*; Goriely, S.*; Kamata, Masaki*; Akimune, Hidetoshi*; Kondo, Takeo*; Ito, Osamu*; Iwamoto, Chihiro*; Yamagata, Tamio*; Toyokawa, Hiroyuki*; Lui, Y.-W.*; et al.

Physical Review C, 84(5), p.055805_1 - 055805_6, 2011/11

 Times Cited Count:31 Percentile:10.37(Physics, Nuclear)

Photoneutron cross sections were measured for $$^{118}$$Sn, $$^{119}$$Sn, $$^{120}$$Sn, $$^{122}$$Sn, and $$^{124}$$Sn near neutron threshold with quasi-monochromatic laser-Compton scattering $$gamma$$-rays. A systematic analysis of the present photoneutron data and existing neutron-capture data is made using the $$gamma$$-ray strength function on the basis of the HFB+QRPA model of E1 strength supplemented with a pygmy dipole resonance, which was deduced from a previous study on $$^{116}$$Sn and $$^{117}$$Sn. Radiative neutron capture cross sections for two radioactive nuclei, $$^{121}$$Sn and $$^{123}$$Sn, are deduced through the $$gamma$$-ray strength function method.

Journal Articles

The $$gamma$$SF method

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Yamagata, Tamio*; Kondo, Takeo*; Iwamoto, Chihiro*; Okamoto, Akiyuki*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; et al.

AIP Conference Proceedings 1377, p.255 - 259, 2011/10

 Percentile:100

Journal Articles

Application of the $$gamma$$SF method to palladium

Utsunomiya, Hiroaki*; Goriely, S.*; Arteaga, D. P.*; Daoutidis, I.*; Akimune, Hidetoshi*; Yamagata, Tamio*; Kondo, Takeo*; Iwamoto, Chihiro*; Kamata, Masaki*; Ito, Osamu*; et al.

AIP Conference Proceedings 1377, p.450 - 452, 2011/10

 Percentile:100

Journal Articles

$$gamma$$-ray strength function method and its application to $$^{107}$$Pd

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; Kondo, Takeo*; Ito, Osamu*; et al.

Physical Review C, 82(6), p.064610_1 - 064610_5, 2010/12

 Times Cited Count:30 Percentile:11.17(Physics, Nuclear)

The $$gamma$$-ray strength function method ($$gamma$$SF method) is devised to indirectly determine radiative neutron capture cross sections for radioactive nuclei. This method is applied here to the $$^{107}$$Pd case. Photoneutron cross sections were measured for $$^{105,106,108}$$Pd near neutron threshold with quasi-monochromatic laser-Compton-scattering $$gamma$$-ray beams. These photoneutron cross sections as well as the reverse radiative neutron capture cross sections for $$^{104,105}$$Pd are used to provide constraints on the $$^{107}$$Pd(n,$$gamma$$) $$^{108}$$Pd cross section.

Journal Articles

Photoneutron cross sections for $$^{96}$$Zr; A Systematic experimental study of photoneutron and radiative neutron capture cross sections for zirconium isotopes

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; Kondo, Takeo*; Ito, Osamu*; et al.

Physical Review C, 81(3), p.035801_1 - 035801_5, 2010/03

 Times Cited Count:32 Percentile:10.02(Physics, Nuclear)

This manuscript presents photoneutron cross sections for $$^{96}$$Zr. Combining the present data with the previously published Zr data, we investigated the $$gamma$$-ray strength function for zirconium isotopes systematically. We present a unified picture of the $$gamma$$-ray strength function that consists of the HFB + QRPA model of E1 strength accompanied by an extra M1 strength attributable to giant M1 resonance. It is shown that the $$gamma$$-ray strength function reproduces both (g,n) and (n,g) cross sections for Zr isotopes consistently.

Journal Articles

Neutron capture cross sections of $$^{186}$$Os, $$^{187}$$Os, and $$^{189}$$Os for the Re-Os chronology

Segawa, Mariko; Masaki, Tomohiro*; Nagai, Yasuki*; Temma, Yasuyuki*; Shima, Tatsushi*; Mishima, Kenji*; Igashira, Masayuki*; Goriely, S.*; Koning, A.*; Hilaire, S.*

Physical Review C, 76(2), p.022802_1 - 022802_5, 2007/08

 Times Cited Count:15 Percentile:25.53(Physics, Nuclear)

Discrete as well as continuum $$gamma$$-ray energy spectra from the neutron capture by $$^{186}$$Os, $$^{187}$$Os, and $$^{189}$$Os have been taken for the first time at 5 $$leq$$ En $$leq$$ 90 keV by an anti-Compton NaI(Tl) spectrometer. The detection of a weak discrete $$gamma$$-ray, about 0.5% of total $$gamma$$-ray strength, demonstrates the high sensitivity of the present measurement. The energy spectra enabled us to accurately determine the reaction cross sections with a small systematic uncertainty. Based on the new cross sections, we re-estimate on the basis of a careful reaction cross section calculation the correction factor F$$_{sigma}$$ for the neutron capture on the 9.75-keV first excited state in $$^{187}$$Os as a function of stellar temperature, as required to derive the age of the Galaxy within the Re-Os chronology.

Oral presentation

Nuclear astrophysics study with pulsed neutrons

Segawa, Mariko; Nagai, Yasuki*; Masaki, Tomohiro*; Temma, Yasuyuki*; Shima, Tatsushi*; Mishima, Kenji*; Igashira, Masayuki*; Goriely, S.*; Koning, A.*; Hilaire, S.*

no journal, , 

The $$^{187}$$Re nucleus is known to be a good chronometer to derive the stellar duration of the r-process nuceosyntheis and deduce the age of universe. However, there are several problems inherent to this chronometer. In order to solve these problems, one must know both the production and depletion rates (via the excited state as well as the ground state) of $$^{187}$$Os and inelastic scattering cross section off the ground state (J$$^{pi}$$= 1/2$$^{-}$$) of $$^{187}$$Os to its excited 10 keV state (J$$^{pi}$$= 3/2$$^{-}$$) are needed. Hence, in the present study we aimed to accurately measure the neutron capture cross sections of $$^{186}$$Os, $$^{187}$$Os and $$^{189}$$Os, and the inelastic scattering cross section for $$^{187}$$Os for neutrons between 10 and 90 keV by developing a new experimental method.

Oral presentation

Neutron induced reaction and Re/Os chronometer

Segawa, Mariko; Nagai, Yasuki*; Masaki, Tomohiro*; Temma, Yasuyuki*; Shima, Tatsushi*; Makii, Hiroyuki*; Mishima, Kenji*; Ueda, Hitoshi*; Nakayoshi, Akira*; Ota, Takeshi*; et al.

no journal, , 

$$^{187}$$Re-$$^{187}$$Os pair is known as the most promising nuclear cosmochronometer with considerable potential. However, there remains non-trivial problems related to an excited neutron capture reaction of $$^{187}$$Os at a stellar temperature. Firstly, $$^{187}$$Os is produced and depleted by the slow process nucleosynthesis. Hence, it is necessary to obtain both the production and depletion rates of $$^{187}$$Os. Secondly, $$^{187}$$Os is depleted not only by its ground state neutron capture reaction but also by an excited state neutron capture reaction of $$^{187}$$Os in a stellar temperature. In the present study, we have measured the neutron capture reaction cross sections for $$^{186}$$Os, $$^{187}$$Os and $$^{189}$$Os accurately and neutron inelastic scattering reaction cross section for $$^{187}$$Os off the ground state of 1$$^{187}$$Os to its 9.75-keV first excited statein the neutron energy range from 10 to 100 keV. The measurements of the neutron capture reactions have been carried out by detecting a prompt $gamma$-ray by means fan anti-Compton NaI(Tl) spectrometer. The (n, n') reaction cross section for $^{187}$$Os has been measured with use of four 6Li-glass scintillation detectors. Based on these new capture cross sections, we reestimate on the basis of a careful reaction cross section calculation the correction factor F for the neutron capture on the 9.75-keV first excited state in $$^{187}$$Os as a function of stellar temperature, as required to derive the age of the galaxy within the Re-Os chronology.

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