Neutron Spectra Measurement Using Recoil Proton Method

Neutron spectrum measurement is the fundamental research in the field of physics.which plays an important part in the study of nuclear physics,particle physics,basic symmetry,astrophysics and cosmology,basic constants and so on.It's not only an important part of neutron detection,but also an important approach to solve problems of other areas,and it has a great effect on the nuclear physics research and development.This paper briefly introduces several main methods of neutron detection and its development history,as well as the working principle of scintillator detectors and other related content.Combining with project requirements and the research of neutron energy spectrum,we use the gas scintillator detector to obtaine the neutron spectrum with the recoil proton method and neutron spectrum unfolding programes.The unfolded neutron spectrum was then compared with the incident neutron spectrum and so the feasibility and effectiveness of the recoil proton method to measure neutron spectrum based on gas scintillator are discussed.We studied the effects of the thickness of the polyethylene target and the angle distribution of the outgoing recoil proton on the detection by Monte Carlo method.Thus the optimal thickness of the polyethylene target and the optimal placement of the detector are obtained.Monte Carlo method.is programmed to simulate the process of incident neutron into polyethylene target to produce recoil proton which deposit its energy in the gas scintillator detector.So three neutron energy spectra with different energy distributions were obtained and the relationship between the recoiled proton energy spectrum and the incident neutron spectrum is briefly discussed at the same time.Finally,we use MATLAB program to unfold the spectrum in three different ways,combining with the basic principle of neutron spectrum unfolding method and the detector response function.The unfolded spectrums were in agreement with the original neutron spectrums and the result shows that GRAVEL maintains a small error in the case of multiple incident neutron spectra,performing better than the other two.