Measurement of Continuous Energy Neutron Incident Neutron Production Double Differential Cross Sections

点击翻译按钮获取中文摘要

Measurement of continuous-energy neutron-incident neutron-production double-differential cross sections were carried out for Al, Fe, In and Pb sample up to 400 MeV at the WNR facility of Los Alamos Neutron Science Center. It was difficult to adopt the time-of-flight method to obtain an emitted-neutron energy because it was unable to identify the time that an incident neutron was induced to a sample. The incident- and the emitted-neutron energy was obtained by the time-of-flight method and unfolding spectrum data of the deposited energy into a detector, respectively. The recoil proton method was adopted for higher-energy emitted-neutron detection above 100 MeV. The detector has phoswich configuration to separate full energy deposition events from partial energy deposition ones by pulse shape discrimination. This method needed much beam time because of low effective detection efficiency. Thick target neutron yields were measured to confirm availability of the recoil proton method on trial. Liquid organic scintillators were utilized for lower-energy emitted-neutron measurement below 100 MeV, Response functions of the detector were measured using low-intensity continuous-energy neutron at the WNR facility and compared with the results by the SCINFUL-QMD code. The emitted-neutron energy spectrum by the moving source model was assumed as desired neutron spectrum. Elastic scattering component was added to the moving source model because the detection system was unable to distinguish the elastic scattering events from all stored event data. The emitted-neutron spectra were obtained by unfolding the light output data from scintillators. It was found that the LA150 evaluated nuclear data library underestimated the backward experimental data for the incident energy above several tens MeV.