Angular distribution of rays from neutron-induced compound states of La

中性子捕獲La複合核からの即発ガンマ線角度分布

奥平 琢也*; 高田 秀佐*; 広田 克也*; 木村 敦   ; 北口 雅暁*; 古賀 淳*; 長元 孝介*; 中尾 太郎*; 岡田 晏珠*; 酒井 健二 ; 清水 裕彦*; 山本 知樹*; 吉岡 瑞樹*

Okudaira, Takuya*; Takada, Shusuke*; Hirota, Katsuya*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Nagamoto, Kosuke*; Nakao, Taro*; Okada, Anju*; Sakai, Kenji; Shimizu, Hirohiko*; Yamamoto, Tomoki*; Yoshioka, Tamaki*

The angular distribution of individual rays, emitted from a neutron-induced compound-nuclear state via radiative capture reaction of La has been studied as a function of incident neutron energy in the epithermal region by using germanium detectors. An asymmetry was defined as , where and are integrals of low- and high-energy region of a neutron resonance respectively, and we found that has the angular dependence of , where is the emitted angle of rays, with and in 0.74-eV p-wave resonance. This angular distribution was analyzed within the framework of interference between s- and p-wave amplitudes in the entrance channel to the compound-nuclear state, and it is interpreted as the value of the partial p-wave neutron width corresponding to the total angular momentum of the incident neutron combined with the weak matrix element, in the context of the mechanism of enhanced parity-violating effects. Additionally, we use the result to quantify the possible enhancement of the breaking of time-reversal invariance in the vicinity of the p-wave resonance.