Thermal-neutron capture cross sections and resonance integrals of the Se(,)Se reactions

Se(,)Se反応の熱中性子捕獲断面積及び共鳴積分

中村 詔司  ; 古高 和禎  ; 原田 秀郎   ; 加藤 敏郎*

Nakamura, Shoji; Furutaka, Kazuyoshi; Harada, Hideo; Kato, Toshio*

放射化法を用いて、Seの中性子捕獲によりSeのアイソマー及び基底状態の生成にかかわる、熱中性子断面積及び共鳴積分を測定した。高純度の酸化セレン試料を、立教大原子炉の回転試料棚にて照射した。共鳴積分を求めるために、Cd遮蔽を用いた照射も行った。照射試料位置での中性子束をモニタするために、金,コバルトのアルミ合金線を用いた。高純度Geを用いて、照射済み試料からの線を測定し、その線の強度から生成放射能及び反応率を求めた。Westcott's conventionに基づき及びを求めた。Se(,)Se反応について、0.0570.003b, 0.1860.014b、またSe(,)Se反応について、0.5360.046b, 0.8670.102bと、それぞれ求められた。

Thermal-neutron capture cross-sections () and resonance integrals () leading to ground and isomeric states of Se were measured by the activation method. Samples of high purity (99.99%) selenium oxide were irradiated in a rotary specimen rack at the research reactor of Rikkyo University. The irradiation of a cadmium-shielded sample was also conducted to obtain . Wires of Co/Al and Au/Al alloys, which have different sensitivities to neutrons in thermal and epithermal energy regions, were irradiated to monitor thermal neutron fluxes and epithermal components at the same position of one of the rack. A high purity Ge detector was used to measure the rays emitted from the irradiated samples and wires, and reaction rates were calculated from -ray yields. On the basis of Westcott's convention, the cross-sections were obtained as follows: = 0.0570.003 b and =0.186 0.014 b leading to Se, = 0.536 0.046 b and = 0.867 0.102 b leading to Se.