The Research On Tubular Neutron Detector Based On Charge Difference Position Reading Method

Neutron is an ideal probe for studying material structure.Neutron scattering technology has been widely used in the research of multidisciplinary fields such as condensed matter physics,chemistry,life sciences,and materials science.High-performance neutron detectors are key devices in neutron scattering experiments.For thermal neutrons,nuclear reaction methods are generally used for detection.Most of the traditional neutron scattering spectrometers use high-pressure ~3He gas detectors.The prices of ~3He gas have soared in recent years.To solve this problem,scientists began to search for a new neutron detector to replace ~3He.The scintillator neutron detector based on ~6Li F/Zn S(Ag)has the advantages of high neutron detection efficiency,good position resolution and low cost.It is widely used in practical applications.The tubular ~6Li F/Zn S(Ag)scintillator neutron detector is mainly composed of scintillator,WLSF,photoelectric readout device,electronics and data acquisition system.The sandwich structure consists of a double-layer crimped scintillator and winding WLSF arrays.Silicon photomultiplier tube(Si PM)reads out the optical signals at both ends of the fibers.By comparing the difference of the optical signals,we can calculate the neutron incident position.The crimped scintillator increases the neutron incident path,but the emission path remains unchanged.The average thermal neutron conversion efficiency of this structure can be more than twice that of the flat scintillator,almost equal to that of the commonly used ~3He tube.The winding fiber design greatly reduces the number of fibers needed by the detector,and the position resolution of the detector is comparable to the fiber spacing.Compared with traditional photomultiplier tubes,Si PM has the advantages of high integration,high gain,high quantum efficiency and low cost.A prototype of ~6Li F/Zn S(Ag)scintillator neutron detector was developed by studying the performance of key devices and the fabrication process of the detector.We tested the detector's performances at China Spallation Neutron Source.The neutron detection efficiency of the detector is about 78%and the position resolution is 4 mm.This neutron detector has the advantages of high neutron detection efficiency and high position resolution.The detector also has a small dead zone and can be quickly spliced.In the future,it can be widely used in neutron spectrometer,which can solve the urgent need of domestic neutron detectors for neutron spectrometer.