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Journal Articles

Measurement of the $$^{77}$$Se($$gamma$$, n) cross section and uncertainty evaluation of the $$^{79}$$Se(n, $$gamma$$) cross section

Kitatani, Fumito; Harada, Hideo; Goko, Shinji*; Iwamoto, Nobuyuki; Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; Igashira, Masayuki*

Journal of Nuclear Science and Technology, 53(4), p.475 - 485, 2016/04

 Times Cited Count:2 Percentile:57.25(Nuclear Science & Technology)

Journal Articles

Cross section measurement for photo nuclear reaction using laser Compton-scattering $$gamma$$-ray

Kitatani, Fumito; Harada, Hideo; Goko, Shinji*; Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*

JAEA-Conf 2014-002, p.57 - 62, 2015/02

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

Analysis of nuclear resonance fluorescence excitation measured with LaBr$$_{3}$$(Ce) detectors near 2 MeV

Omer, M.*; Negm, H.*; Ogaki, Hideaki*; Daito, Izuru*; Hayakawa, Takehito; Bakr, M.*; Zen, H.*; Hori, Toshitada*; Kii, Toshiteru*; Masuda, Kai*; et al.

Nuclear Instruments and Methods in Physics Research A, 729, p.102 - 107, 2013/11

 Times Cited Count:4 Percentile:53.77(Instruments & Instrumentation)

The performance of LaBr$$_{3}$$ (Ce) to measure nuclear resonance fluorescence (NRF) excitations is discussedin terms of limits of detection and in comparison with high-purity germanium (HPGe)detectors near the 2 MeV region where many NRF excitation levels from special nuclear materials are located. The NRF experiment was performed at the High Intensity Gamma-ray Source (HIGS) facility of Duke University. The incident $$gamma$$-rays, of 2.12 MeV energy, hit a B$$_{4}$$C target to excite the $$^{11}$$B nuclei to the first excitation level. The statistical-sensitive non-linear peak clipping (SNIP) algorithm was implemented to eliminate theback ground and enhance the limits of detection for the spectra measured with LaBr$$_{3}$$ (Ce). Both detection and determination limits were deduced from the experimental data.

Journal Articles

Bulky averaged microscopic information for ECAP-processed Cu using Accelerator-based gamma-ray-Induced Positron Annihilation Spectroscopy and neutron diffraction

Ishibashi, Toshihiro*; Tomota, Yo*; Sugaya, Satoshi*; Toyokawa, Hiroyuki*; Hirade, Tetsuya; Horita, Zenji*; Suzuki, Hiroshi

Materials Transactions, 54(9), p.1562 - 1569, 2013/09

Bulky averaged microstructural parameters like vacancy density, texture, intergranular stress, etc. for 99.99% Cu subjected to Equal-Channel Angular Pressing (ECAP) were investigated using Accelerator-based gamma-ray-Induced Positron Annihilation Spectroscopy (AIPAS) and neutron diffraction. The Doppler-broadening parameter (S) for positron annihilation peaks of AIPAS increased by the first ECAP cycle and then decreased slightly with further ECAP cycles. Upon annealing, the S recovered at a lower temperature for the eight-cycle ECAP processed sample than for the one-cycle processed sample. The texture and intergranular stresses generated by ECAP are determined by neutron diffraction analyses. Changes in FWHM and intensity of neutron diffractions monitored in situ during annealing indicate the early onset of recrystallization in the eight-cycle ECAP sample. These bulky averaged data show good agreements qualitatively with local SEM/EBSD observations and the results of mechanical tests.

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

Dipole strength distributions in $$^{56}$$Fe

Shizuma, Toshiyuki; Hayakawa, Takehito; Ogaki, Hideaki; Toyokawa, Hiroyuki*; Komatsubara, Tetsuro*; Kikuzawa, Nobuhiro; Inakura, Tsunenori*; Homma, Michio*; Nakada, Hitoshi*

Physical Review C, 87(2), p.024301_1 - 024301_7, 2013/02

 Times Cited Count:10 Percentile:32.05(Physics, Nuclear)

Electro-magnetic dipole transitions in $$^{56}$$Fe were measured in photon scattering experiments with a linearly polarized photon beam. The parity quantum numbers of the excited dipole states were determined by the intensity asymmetry of resonantly scattered $$gamma$$-rays with respect to the polarization plane of the incident photon beam. While the summed magnetic dipole ($$M1$$) strength was determined as $$Sigma B(M1)!uparrow=3.52(17)$$ $$mu_N^2$$ at excitation energies between 7 and 10 MeV, the summed electric dipole ($$E1$$) strength below 10 MeV was obtained as $$Sigma B(E1)!uparrow=78.0(15)times10^{-3},e^2{rm fm}^2$$. The observed $$M1$$ strength was compared with shell-model predictions in the $$pf$$-shell using the GXPF1J and KB3G effective interactions. In addition, the $$E1$$ strength was compared with random-phase approximation calculations with the Skyrme interaction.

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

Nondestructive identification of isotopes using nuclear resonance fluorescence

Shizuma, Toshiyuki; Hayakawa, Takehito; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Ogaki, Hideaki; Toyokawa, Hiroyuki*

Review of Scientific Instruments, 83(1), p.015103_1 - 015103_4, 2012/01

 Times Cited Count:5 Percentile:62.5(Instruments & Instrumentation)

Nondestructive identification of heavy isotopes concealed in a thick iron box has been demonstrated by using nuclear resonance fluorescence. A quasi-monochromatic photon beam produced by the collision of laser quanta with high energy electrons was used for resonant excitation of nuclear levels in $$^{206}$$Pb and $$^{208}$$Pb. By measuring the resonant $$gamma$$ rays emitted from $$^{206}$$Pb and $$^{208}$$Pb, each of these isotopes were clearly identified. The ratio of the effective thickness, i.e., concentration distribution, of these isotopes was deduced from the relative intensities of the measured NRF strengths.

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

Photoneutron cross sections for Au

Ito, Osamu*; Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Yamagata, Tamio*; Kondo, Takeo*; Kamata, Masaki*; Toyokawa, Hiroyuki*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; et al.

AIP Conference Proceedings 1377, p.362 - 364, 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

Measurement of ($$gamma$$,$$n$$) cross sections of Se isotopes using laser-Compton scattering $$gamma$$-rays

Kitatani, Fumito; Harada, Hideo; Goko, Shinji*; Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*

Journal of the Korean Physical Society, 59(2), p.1836 - 1839, 2011/08

 Times Cited Count:1 Percentile:86.08(Physics, Multidisciplinary)

The photo-nuclear cross section of Se isotopes ($$^{80}$$Se, $$^{78}$$Se, $$^{77}$$Se, $$^{76}$$Se) were measured with laser-Compton scattering (LCS) $$gamma$$-rays to supply fundamental data for the estimation of the inverse reaction cross sections, i.e., the $$^{79}$$Se($$n$$,$$gamma$$) $$^{80}$$Se cross section. An enriched Se isotope samples were irradiated with LCS $$gamma$$-rays whose maximum energy was varied from each near neutron separation energy to 16.0 MeV. The energy distributions of LCS $$gamma$$-rays were precisely determined using a high-resolution high-energy photon spectrometer (HHS). Emitted neutrons were detected by a high efficiency 4$$pi$$-$$^{3}$$He detector. The excitation function of the photo-nuclear cross section of Se isotopes were determined for the energy range form each near neutron separation energy to near 16.0 MeV. The energy point corresponding to each cross section was deduced using the accurately determined energy distribution of LCS $$gamma$$-rays.

Journal Articles

The $$gamma$$SF method; Determination of radiative neutron-capture cross section for unstable nuclei

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*; Lui, Y.-W.*

Journal of the Korean Physical Society, 59(2), p.1713 - 1716, 2011/08

 Times Cited Count:2 Percentile:75.59(Physics, Multidisciplinary)

Journal Articles

Measurement of $$^{76}$$Se and $$^{78}$$Se ($$gamma$$, n) cross sections

Kitatani, Fumito; Harada, Hideo; Goko, Shinji*; Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Toyokawa, Hiroyuki*; Yamada, Kawakatsu*

Journal of Nuclear Science and Technology, 48(7), p.1017 - 1024, 2011/07

Journal Articles

Photoneutron cross sections for Au revisited; Measurements with laser Compton scattering $$gamma$$-rays and data reduction by a least-squares method

Ito, Osamu*; Utsunomiya, Hiroaki*; Akimune, Hidetoshi*; Kondo, Takeo*; Kamata, Masaki*; Yamagata, Tamio*; Toyokawa, Hiroyuki*; Harada, Hideo; Kitatani, Fumito; Goko, Shinji*; et al.

Journal of Nuclear Science and Technology, 48(5), p.834 - 840, 2011/05

Photoneutron cross section measurements were made for Au in the entire energy range of the ($$gamma$$,n) channel based on a direct neutron-counting technique with quasi-monochromatic $$gamma$$-rays produced in inverse Compton-scattering of laser photons with relativistic electrons. The data were analyzed with a least-squares method to deduce photoneutron cross sections. The analysis significantly reduced experimental uncertainties compared with those resulted from the photon difference method. The result is compared with the previous data by direct neutron-counting with $$gamma$$-rays produced in positron annihilation in flight and by photoactivation with bremsstrahlung. The present data are in good agreement with the previous data near neutron threshold, while there remain some discrepancies between the present and the previous data above 10 MeV.

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

Striking behavior of photoneutron cross sections for $$^{90}$$Zr near threshold

Utsunomiya, Hiroaki*; Goriely, S.*; Akimune, Hidetoshi*; Yamagata, Tamio*; Kondo, Takeo*; Iwamoto, Chihiro*; Ito, Osamu*; Kamata, Masaki*; Io, Masanori*; Kususe, Koichi*; et al.

AIP Conference Proceedings 1377, p.447 - 449, 2010/10

 Percentile:100

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