Experimental Study Of Thermal Neutron Detector Based On NTHGEM

With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in 3He gas supply, research on new types of neutron detector as an alternative to 3He is a research hotspot in the field of particle detection. GEM(Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors.In this paper, the physical process of neutron detection is simulated with Geant4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic nTHGEM(neutron THick GEM) for neutron detection. The performance of the nTHGEM working in different Ar/CO2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. And also test its performance working in a 252 Cf neutron source environment. A thermal neutron detector prototype with a single nTHGEM has been tested on the time of flight polarized neutron reflectometer in China Mianyang Research Reactor(CMRR), including measurements of the neutron beam spot imaging, time of flight spectroscopy of thermal and cold neutron. Meanwhile, for neutron detection environment, the key components of the detector system such as signal readout board and high voltage power supply made the appropriate improvements.Traditional GEM detectors work in gas-flow environment. Because of the gas supply system, limiting the scope of application of the detectors. We improved the traditional GEM detectors, made a preliminary study of the seal. By improving the detector cavity structure design, improved sealing performance, and replace internal components of the detector in order to reduce the release of impurity gases, created the conditions for the detector to achieve seal.