EPJ Web Conf.
Volume 219, 2019International Workshop on Particle Physics at Neutron Sources (PPNS 2018)
|Number of page(s)||6|
|Section||Searches for Time-Reversal-Violation in Nuclei|
|Published online||12 December 2019|
Measurement of the angular distribution of γ-rays after neutron capture by 139La for a T-violation search
1 J-PARC center, Japan Atomic Energy Agency, Tokai, Ibaraki 319–1184, Japan
2 Department of Physics, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464–8601, Japan
3 Kobayashi-Maskawa Institute, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464–8601, Japan
4 National Institute of Standards and Technology, 100 Bureau Dr, Gaithersburg, MD 20899, USA
5 Department of Physics, Kyushu University, 744 Motooka, Nishi, Fukuoka, Fukuoka 819–0395, Japan
6 Research Center of Advanced Particle Physics, Kyushu University, 744 Motooka, Nishi, Fukuoka, Fukuoka 819–0395, Japan
7 Institute of Material Structure Science, High Energy Accelerator Organization (KEK), Oho 1–1, Tsukuba, Ibaraki 305–0801, Japan
8 Department of Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro, Tokyo 152–8551, Japan
9 Department of Chemistry, UBC Faculty of Science, University of British Columbia, Vancouver, British Columbia V6R1Z1, Canada
10 Department of Earth and Environmental Sciences, Yamagata University, 1-4-12 Kojirakawa, Yamagata 990–8560, Japan
11 Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Japan
12 Research Reactor Institute, Kyoto University, 2 Asashiro-nishi, Kumatoricho, Senngan-gun, Osaka 590–0494, Japan
13 Research Center for Nuclear Physics, Osaka University, 10–1 Mihogaoka, ibaraki, Osaka 567–0047, Japan
14 RIKEN Center for Advanced Photonics, RIKEN, Hirosawa 2–1, Wako, Saitama 351–0198, Japan
a e-mail: email@example.com
Published online: 12 December 2019
Parity violating effects enhanced by up to 106 times compared to proton-proton scattering have been observed in several neutron capture induced compound nuclei. This enhancement is explained as an interference between an s-wave and a p-wave amplitude (s-p mixing). Theory predicts that this mechanism can also enhance T-violating effects. For estimation of this enhancement in a promising candidate nucleus, we measured the angular distribution of γ-rays in the (n,γ) reaction induced in a 139La target. Experiments were performed at J-PARC, using a germanium detector array at an intense neutron beam. Analysis of the observed angular dependence around the 0.74 eV p-wave resonance allowed us to determine the ratio of the partial p-wave neutron width to the total neutron width in the entrance channel of the compound nucleus. We also report our development of a 3He spin filter needed as an epithermal-neutron polarizer for the T-violation search.
© The Authors, published by EDP Sciences, 2019
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