0.57、1.0和1.5MeV中子诱发^235U裂变时^95Zr、^140Ba和^147Nd产额的绝对测量

^(95)Zr,^(140)Ba,and ^(147)Nd Yields From 0.57,1.0,and 1.5MeV Neutrons Induced Fission of ^(235)U

用HPGeγ能谱法绝对测量0.57、1.0和1.5 MeV中子诱发235U裂变的裂变产物95Zr、140Ba和147Nd的产额。P型同轴HPGe探测器的体积为110 cm3,对60Co 1 332.5 keVγ射线的分辨率为1.8 keV。使用双裂变电离室监测裂变率,应用SPAN程序解析γ谱。对影响产额测量的主要因素进行了分析,并用MCNPIVB程序模拟计算了非主中子的影响。实验测得0.57 MeV中子诱发时,95Zr、140Ba、147Nd的产额分别为(6.64±0.21)%、(6.37±0.22)%、(2.37±0.08)%;1.0 MeV中子诱发时,95Zr、140Ba、147Nd的产额分别为(6.49±0.19)%、(6.35±0.18)%、(2.25±0.07)%;1.5 MeV中子诱发时,95Zr、140Ba、147Nd的产额分别为(6.59±0.19)%、(6.25±0.18)%、(2.37±0.07)%。对95Zr、140Ba、147Nd的产额随入射中子能量的变化趋势作了简要分析与讨论。

The yields of fission products（Y） 95Zr,140Ba,and 147Nd were absolutely determined using γ-spectrum method for the 235U fission induced by 0.57,1.0,and 1.5 MeV neutrons,respectively.The γ-spectra were measured by a P-type coaxial HPGe detector with the volume of 110 cm3 and the resolution of 1.8 keV at 1 332.5 keV,and the acquired γ-spectra were analyzed by the SPAN code.The fission rate in the fission process was monitored with a double-fission ionization chamber.The impacts of some factors on the fission yield data were analyzed,specially.The neutron spectrum in the uranium sample was simulated with MCNP IVB code,and the effects from other secondary neutrons were also analyzed.Finally,the determined fission yields are given as following： the Y（95Zr）=（6.64±0.21）%,Y（140Ba）=（6.37±0.22）%,Y（147Nd）=（2.37±0.08）% for 0.57 MeV neutron;Y（95Zr）=（6.49±0.19）%,Y（140Ba）=（6.35±0.18）%,Y（147Nd）=（2.25±0.07）% for 1.0 MeV neutron;Y（95Zr）=（6.59±0.19）%,Y（140Ba）=（6.25±0.18）%,Y（147Nd）=（2.37±0.07）% for 1.5 MeV neutron.The variations of Y（95Zr/140Ba/147Nd） with neutron energy were analyzed and discussed.