Due to the shortage and the rapidly increasing price of the 3He gas, seeking new types of position-sensitive neutron detectors is urgent. In order to fulfill the requirements of Chinese neutron spectrometers for neutron detectors, the research on neutron detector based on 6LiF/ZnS (Ag) scintillator and wavelength-shifting fiber (WLSF) structure neutron detectors was developed. It has the advantages of high neutron detection efficiency, good position resolution and the ability to splicing large areas. This paper proposed a tubular neutron detector structure. It consists of two layers of rolled 6LiF/ZnS(Ag) scintillators sandwich with two wavelength-shifting fibers, and two SiPMs (Silicon photomultipliers) for the photons readout. By MC simulation, we obtained the thermal neutron conversion efficiency of 6LiF/ZnS(Ag) scintillation screens with different thicknesses and rolled diameters, and optimized the detector structure. The characteristics of the key components are studied. A small detector prototype has been constructed. and been tested by the neutron beam. The preliminary test results showed that the detector can work well.
Chinese Spallation Neutron Source (CSNS) is under construction in Guangdong province since 2008. The investigation of the Neutron Scintillator Detector Arrays (NSDA) have been developed to fulfill the requirements of the General Purpose Power Diffractometer (GPPD). The detector module consists of 6LiF/ZnS (Ag) scintillators, crossed WLSF arrays, multi-anode photo multiplier tubes (MA-PMT), and the ASIC readout electronics. The position resolution of the detector module is 4mm×4mm, and the thermal neutron detect efficiency is better than 45%. 38 detector modules for phase I of the GPPD have been finished and been installed in GPPD in Aug., 2017. Joint debugging with neutron beam in the GPPD was started at the CSNS on November 1, 2017. During the 10-day joint debugging period, the NSDA successfully obtained diffraction data. The instrument resolution of the diffraction data for the standard Si powder for high angle banks is calculated to be 0.184%. It is better than that of the physical design.