Gamma-ray spectrum from thermal neutron capture on gadolinium-157

Kaito Hagiwara, Takatomi Yano, Tomoyuki Tanaka, Mandeep Singh Reen, Pretam Kumar Das, Sebastian Lorenz, Iwa Ou, Takashi Sudo, Yoshiyuki Yamada, Takaaki Mori, Tsubasa Kayano, Rohit Dhir, Yusuke Koshio, Makoto Sakuda, Atsushi Kimura, Shoji Nakamura, Nobuyuki Iwamoto, Hideo Harada, Michael Wurm, William FocillonMichel Gonin, Ajmi Ali, Gianmaria Collazuol

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We have measured the $\gamma$-ray energy spectrum from the thermal neutron capture, ${}{157}$Gd$(n,\gamma)$, on an enriched ${157}$Gd target (Gd$ {2}$O$ {3}$) in the energy range from 0.11 MeV up to about 8 MeV. The target was placed inside the germanium spectrometer of the ANNRI detector at J-PARC and exposed to a neutron beam from the Japan Spallation Neutron Source (JSNS). Radioactive sources (${60}$Co, ${137}$Cs, and ${152}$Eu) and the ${35}$Cl($n$,$\gamma$) reaction were used to determine the spectrometer's detection efficiency for $\gamma$ rays at energies from 0.3 to 8.5 MeV. Using a Geant4-based Monte Carlo simulation of the detector and based on our data, we have developed a model to describe the $\gamma$-ray spectrum from the thermal ${}{157}$Gd($n$,$\gamma$) reaction. While we include the strength information of 15 prominent peaks above 5 MeV and associated peaks below 1.6 MeV from our data directly into the model, we rely on the theoretical inputs of nuclear level density and the photon strength function of ${}{158}$Gd to describe the continuum $\gamma$-ray spectrum from the ${}{157}$Gd($n$,$\gamma$) reaction. Our model combines these two components. The results of the comparison between the observed $\gamma$-ray spectra from the reaction and the model are reported in detail.

Original languageEnglish
Article number023D01
JournalProgress of Theoretical and Experimental Physics
Issue number2
Publication statusPublished - Feb 1 2019

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Hagiwara, K., Yano, T., Tanaka, T., Reen, M. S., Das, P. K., Lorenz, S., Ou, I., Sudo, T., Yamada, Y., Mori, T., Kayano, T., Dhir, R., Koshio, Y., Sakuda, M., Kimura, A., Nakamura, S., Iwamoto, N., Harada, H., Wurm, M., ... Collazuol, G. (2019). Gamma-ray spectrum from thermal neutron capture on gadolinium-157. Progress of Theoretical and Experimental Physics, 2019(2), [023D01].