Oxford University Press Acta Medica Okayama 2050-3911 2020 4 2020 Gamma-ray spectra from thermal neutron capture on gadolinium-155 and natural gadolinium 043D02 EN Tomoyuki Tanaka Department of Physics, Okayama University Kaito Hagiwara Department of Physics, Okayama University Enrico Gazzola Universitá di Padova and INFN, Dipartimento di Fisica Ajmi Ali Department of Physics, Okayama University Iwa Ou Department of Physics, Okayama University Takashi Sudo Department of Physics, Okayama University Pretam Kumar Das Department of Physics, Okayama University Mandeep Singh Reen Department of Physics, Okayama University Rohit Dhir Department of Physics, Okayama University Yusuke Koshio Department of Physics, Okayama University Makoto Sakuda Department of Physics, Okayama University Atsushi Kimura Japan Atomic Energy Agency Shoji Nakamura Japan Atomic Energy Agency Nobuyuki Iwamoto Japan Atomic Energy Agency Hideo Harada Japan Atomic Energy Agency Gianmaria Collazuol Universitá di Padova and INFN, Dipartimento di Fisica Sebastian Lorenz Institut für Physik, Johannes Gutenberg-Universität Mainz Michael Wurm Institut für Physik, Johannes Gutenberg-Universität Mainz William Focillon Département de Physique, École Polytechnique Michel Gonin Département de Physique, École Polytechnique Takatomi Yano Kamioka Observatory, ICRR, University of Tokyo Natural gadolinium is widely used for its excellent thermal neutron capture cross section, because of its two major isotopes: Gd-155 and Gd-157. We measured the gamma-ray spectra produced from the thermal neutron capture on targets comprising a natural gadolinium film and enriched Gd-155 (in Gd2O3 powder) in the energy range from 0.11 MeV to 8.0 MeV, using the ANNRI germanium spectrometer at MLF, J-PARC. The freshly analyzed data of the Gd-155(n,gamma) reaction are used to improve our previously developed model (ANNRI-Gd model) for the Gd-157(n,gamma) reaction [K. Hagiwara et al. [ANNRI-Gd Collaboration], Prog. Theor. Exp. Phys. 2019, 023D01 (2019)], and its performance confirmed with the independent data from the Gd-nat(n,gamma) reaction. This article completes the development of an efficient Monte Carlo model required to simulate and analyze particle interactions involving the thermal neutron captures on gadolinium in any relevant future experiments. No potential conflict of interest relevant to this article was reported.