Neutron Capture Cross Section Measurement on ⁹¹Zr at J-PARC/MLF/ANNRI

¹ Kyoto University, Research Reactor Institute, 590-0494 Kumatori-cho, Osaka, Japan
² Japan Atomic Energy Agency, Nuclear Science and Engineering Center, 319-1195 Tokai-mura, Ibaraki, Japan
³ Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, 152-8550 O-okayama, Tokyo, Japan
⁴ Hokkaido University, Faculty of Engineering, 060-8628 Sapporo, Hokkaido, Japan
⁵ Nagoya University, Graduate school of Engineering, 464-8603 Furo-cho, Chikusa-ku, Nagoya, Japan

^a Corresponding author: hori@rri.kyoto-u.ac.jp

Published online: 28 May 2015

Abstract

The neutron capture cross section measurement on ⁹¹Zr was performed at neutron TOF beam line ANNRI installed at J-PARC/MLF. Prompt capture gamma rays from the sample were detected with an array of large Ge detectors at a distance of 21.5 m from the spallation neutron source by the time-of-fligh (TOF) method. The neutron capture gamma-ray pulse-height spectra from the 182-eV p-wave resonance and the 292-eV s-wave resonance were obtained by gating on the TOF regions, respectively. Though the decay patterns of primary transitions from the capture state were quite different between resonances, the prominent characteristics common to both resonances was the very strong ground-state transition from the 935-keV state. Therefore, a ground-state transition method was applied to obtain the capture yield, so that the background components due to impurities were successfully eliminated. The preliminary result of the neutron capture cross section for ⁹¹Zr up to 5 keV is presented.