Program - Brookhaven National Laboratory

and neutron multiplicity, information about the prompt neutron and γ-ray distributions as a function of
incident neutron energy is limited. Only a handful of data is available, mostly at thermal energies, on the
prompt γ-ray distributions. The prompt γ-ray and neutron distributions for the spontaneous fission of
252 Cf and neutron-induced fission of 235 U at incident energies of 1-20 MeV were measured simultaneously
[1] using an EJ301 liquid scintillator detector array [2] at the WNR/LANSCE facility. The feasibility of
exacting information about the prompt neutron and γ-ray distributions by using the same detector opens
up the opportunity to study γ-neutron correlations while simultaneously reducing amount of scattering
material. The first step in achieving this goal was to determine whether we could unfold the γ-ray and
neutron spectra. The prompt γ-ray spectra were unfolded using a simulated detector response matrix
validated using standard calibration sources. The γ-ray distributions obtained using the iterative Bayesian
and singular value decomposition unfolding techniques and comparisons to previous measurements will be
presented. This work benefited from the use of the LANSCE accelerator facility and was performed under
the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344 and LANL under Contract
DE-AC52-06NA25396.
[1] E. Kwan et al., Nucl. Instrum. Methods Phys. Res. A 688, 555 (2012). [2] D. Rochman et al., Nucl.
Instrum. Methods Phys. Res. A 523, 102 (2004).
GF 3 2:20 PM
Cross Section Measurements of the Radioactive 107 Pd and Stable 105,108 Pd nuclei
S. Nakamura, A. Kimura, F. Kitatani, M. Ohta, K. Furutaka, S. Goko, K.Y.Hara, H. Harada, T. Kin, M.
Koizumi, M. Oshima, and Y. Toh
Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun,
Ibaraki, 319-1195, Japan
K. Kino, F. Hiraga, T. Kamiyama, and Y. Kiyanagi
Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628,
Japan
T. Katabuchi, M. Mizumoto, and M. Igashira
Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku,
Tokyo 152-8550, Japan
J. Hori, T. Fujii, S. Fukutani,and K. Takamiya
Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka, 590-0404, Japan
Neutron-capture cross sections of Long-Lived Fission Products (LLFPs) are of great importance for predicting
long-term characteristics of nuclear reactors. Palladium-107 is one of the important LLFPs because of
its extremely long half-life (6.5x10 6 year) and fission yield (3% for 239 Pu). Some Pd isotopes among LLFPs,
e.g. 105,108 Pd, are also listed as important absorbers for thermal and fast reactors. From these points of view,
we have started the measurements of the neutron-capture cross sections for stable 105,108 Pd nuclei as well
as the radioactive 107 Pd. The neutron-capture cross-section measurements by the time-of-flight method
were performed using an apparatus called “Accurate Neutron-Nucleus Reaction measurement Instrument
(ANNRI)” installed at the neutron Beam Line No.4 of the Materials and Life science experimental Facility
(MLF) in the J-PARC. The neutron-capture cross sections of 107 Pd and 105,108 Pd have been measured in
the neutron energy range from thermal to 300 eV. Some new information was obtained for resonances of
these Pd nuclei. In this talk, we will present results of these measurements at J-PARC/MLF/ANNRI.
Present study is the result of “Study on nuclear data by using a high intensity pulsed neutron source for
advanced nuclear system” entrusted to Hokkaido University by the Ministry of Education, Culture, Sports,
Science and Technology of Japan (MEXT). This work was supported by JSPS KAKENHI Grant Number
22226016.
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