China Spallation Neutron Source （CSNS）, one project of the 12th Five-Year-Plan scheme of China, is under construction in Guangdong province. Three neutron spectrometers will he installed during the first phase of the project, and two-dimensional position sensitive thermal neutron detectors are required. Before the construction of the neutron detectors, a prototype of a two-dimensional 200 mm^200 mm Multi-wire Proportional Chamber （MWPC） with Ar/CO2 （90/10） flowing gas has been constructed. In 2009, the prototype was tested with the 55Fe X-ray using part of the electronics, and performed well. Following the test in 2009, the neutron detector was constructed with the complete electronics and filled with the 6 atm. 3He^2.5 atm. C3Hs gas mixture in 2010. The neutron detector has been primarily tested with an Am-Be source. In this paper, new developments of the neutron detector including the design of the high pressure chamber, the optimization of the gas purifying system and the gas filling process will be reported. The results and discussion are also presented in this paper.
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. A detector with a single nTHGEM has been tested for 2-D imaging using a 252Cf neutron source. The key parameters of the performance of the nTHGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector.
