Angular distribution measurements of photo-neutron yields produced by 2.0 GeV electrons incident on thick targets

厚いターゲットへの2.0GeV電子入射による光中性子生成角度分布の測定

Lee, H.-S.*; 伴 秀一*; 佐波 俊哉*; 高橋 一俊*; 佐藤 達彦   ; 秦 和夫*; Chung, C. W.*

Lee, H.-S.*; Ban, Shuichi*; Sanami, Toshiya*; Takahashi, Kazutoshi*; Sato, Tatsuhiko; Shin, Kazuo*; Chung, C. W.*

厚いターゲットへの2GeV電子入射による光中性子生成角度分布を測定した。本測定では、以前測定した90度方向だけでなく、48及び140度方向に対する光中性子生成率の測定も行い、角度分布に関するより詳細な情報を得た。測定対象とした中性子のエネルギー範囲は8250MeVで、ターゲットは、それぞれ10放射長の銅,スズ,タングステン及び鉛とした。測定値をMCNPX2.5及びEGS4とPICA3を組合せた計算値と比較した結果、計算値は、測定値を過小評価する傾向にあることが判明した。

A study of differential photo-neutron yields by irradiation with 2 GeV electrons has been carried out. In this extension of a previous study in which measurements were made at an angle of 90 degrees. Relative to incident electrons, the differential photoneutron yield was obtained at two other angles, 48 and 140 degrees, to study its angular characteristics. Photo-neutron spectra were measured using a pulsed beam time-of-flight method and a BC418 plastic scintillator. The reliable range of neutron energy measurement was 8-250 MeV. The neutron spectra were measured for 10 Xo-thick Cu, Sn, W and Pb targets. The angular distribution characteristics, together with the previous results for 90, are presented in the study. The experimental results are compared with Monte Carlo calculation results. The yields predicted by MCNPX 2.5 tend to underestimate the measured ones. The same trend holds for the comparison results using the EGS4 and PICA3 codes.