Measurement of the transverse asymmetry of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math> rays in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Sn</mml:mi><mml:mprescripts/><mml:none/><mml:mn>117</mml:mn></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mi>n</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo>)</mml:mo><mml:mmultiscripts><mml:mi>Sn</mml:mi><mml:mprescripts/><mml:none/><mml:mn>118</mml:mn></mml:mmultiscripts></mml:mrow></mml:math> reaction
Shunsuke Endo, Takuya Okudaira, Rihei Abe, Hiroyuki Fujioka, K. Hirota, A. Kimura, Masaaki Kitaguchi, Takayuki Oku, K. Sakai, Tatsushi Shima, Hirohiko M. Shimizu, S. Takada, S. Takahashi, Tomoki Yamamoto, H. Yoshikawa, T. Yoshioka
Abstract
Largely enhanced parity-violating effects observed in compound resonances induced by epithermal neutrons are currently attributed to the mixing of parity-unfavored partial amplitudes in the entrance channel of the compound states. Furthermore, it is proposed that the same mechanism that enhances the parity violation also enhances the breaking of time-reversal invariance in the compound nucleus. The entrance-channel mixing induces energy-dependent spin-angular correlations of individual $\ensuremath{\gamma}$ rays emitted from the compound nuclear state. For a detailed study of the mixing model, the $\ensuremath{\gamma}$-ray yield in the reaction of $^{117}\mathrm{Sn}(n,\ensuremath{\gamma})^{118}\mathrm{Sn}$ was measured using a pulsed beam of polarized epithermal neutrons and Ge detectors. An angular dependence of asymmetric $\ensuremath{\gamma}$-ray yields for the orientation of the neutron polarization was observed.