Experimental analysis of neutron and background gamma-ray energy spectra of 80-400 MeV ⁷Li(p,n) reactions under the quasi-monoenergetic neutron field at RCNP, Osaka University

¹ Japan Atomic Energy Agency (JAEA), 2-4 Shirakata,Tokai, Naka, Ibaraki 319-1195, Japan
² High Energy Accelerator Research Organization (KEK), 1-1Oho, Tsukuba, Ibaraki 305-0801, Japan
³ Department of Accelerator Science, Graduate University for Advanced Studies (SOKENDAI), 1-1Oho, Tsukuba, Ibaraki 305-0801, Japan
⁴ Research Reactor Institute, Kyoto University, 2-1010 Asashiro-nishi, Kumatori, Sennan, Osaka 590-0494, Japan
⁵ National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
⁶ Research Center for Nuclear Physics (RCNP), Osaka University, 10-1Mihogaoka, Ibaraki, Osaka 567-0047, Japan
⁷ Shimizu Corporation, Etchujima 3-4-17, Koto-ku, Tokyo 135-8530, Japan
⁸ Cyclotron and Radioisotope Center, Tohoku University, 6-3 Aramaki, Aoba, Sendai 980-8578, Japan

^a Corresponding author: iwamoto.yosuke@jaea.go.jp

Published online: 25 September 2017

Abstract

To develop the 100-400 MeV quasi-monoenergetic neutron field, we measured neutron and unexpected gamma-ray energy spectra of the ⁷Li(p,n) reaction with 80-389 MeV protons in the 100-m time-of-flight (TOF) tunnel at the Research Center for Nuclear Physics (RCNP) cyclotron facility. Neutron energy spectra with energies above 3 MeV were measured by the TOF method, which had been reported in our previous papers, and photon energy spectra with energies above 0.1 MeV were measured by the automatic unfolding function of the radiation dose monitor DARWIN. For neutron spectra, the contribution of peak intensity to the total intensity integrated with energies above 3 MeV varied between 0.38 and 0.48 in the proton energy range of 80–389 MeV. For gamma-ray spectra, highenergetic gamma-rays at around 70 MeV originated from the decay of π⁰ were observed with proton energies higher than 200 MeV. For the 246-MeV proton incident reaction, the contribution of gamma-ray dose to neutron dose is negligible because the ratio of gamma-ray dose to neutron dose is 0.014.