In order to fulfill the requirements of the engineering material diffraction spectrometer of China Spallation Neutron Source(CSNS), a new integrated and modular scintillator detector based on Silicon Photomultiplier(SiPM) readout is designed and constructed by the Neutron Detector Group of the CSNS. In this paper, the characteristics such as breakdown voltage, gain, temperature characteristics and dark count rate of Sensl MicroFJ-30035-TSV and Hamamatsu S13363-3050NE-16 model SiPM are tested. The results show that the performance of the two SiPM including the single-photon resolution, gain, dark count rate can meet the requirements of the scintillator detector. The gain of Sensl SiPM is higher than that of Hamamatsu SiPM in the same overbias and the latter is more sensitive to temperature. The temperature compensation coefficient of the Sensl and Hamamatsu SiPM are 22.0 and 53.6 mV/°C respectively, which will provide reference for the design of temperature compensation circuit of SiPM. The prototype of a scintillator detector based on the above two SiPM readout was developed and the detection efficiency of the detector has been tested on the BL09 of CSNS. The results show that the detection efficiency of detector equipped with Sensl SiPM or Hamamatsu SiPM is 76% and 68% for 2.8 Å neutrons, respectively. The results of this paper will provide reference for the selection of SiPM for the developed scintillator detector and other SiPM-based detectors.

Thermal neutron radiography is a powerful nondestructive detecting technique as an important complement to X-ray radiography. The miniaturized thermal neutron radiography system holds great potential in research and industrial applications. Based on the compact D-D neutron generator, a neutron moderator-collimator for thermal neutron radiography was designed and simulated by using Monte Carlo N-Particle Transport Code(MCNP-4C) to track neutrons and γ-rays. The aspect ratio of the moderator-collimator was about 3.58. The simulation results showed that the thermal neutron flux rate could reach and exceed 10³ n/(cm² · s) in the sample plane when the neutron yield of D-D neutron generator is greater than 5×10⁸ n/s. The proportion of thermal neutron in the collimated neutron beam was found to be over 74%. In a irradiation field with a diameter of 70 mm, the non-uniformity of thermal neutron flux was kept at 7.3%, which meets the imaging criteria of thermal neutron radiography.

Based on the influence "hydrogen bubbles" and "helium bubbles", which are produced by the neutron induced reactions on Fe, of the new nuclear energy utilization system, the ^56,54Fe(n, α)^53,51Cr, ^56,54Fe(n, p)^56,54Mn cross sections are calculated in this work. The physical model (including energy level density, Correction, nuclear temperature, optical potential parameters, etc.) parameters were adjusted according to the existing experimental data and evaluation data of ^56,54Fe(n, α)^53,51Cr, ^56,54Fe(n, p)^56,54Mn cross sections, and a set of universal parameters were obtained. Based on the adjusted parameters, the TALYS program is used for calculating ^56,54Fe(n, α)^53,51Cr, ^56,54Fe(n, p)^56,54Mn reaction datas, including energy differential cross section and double differential cross section. Furthermore, the results are all in good agreement with the experimental data and evaluation data in the region of incident neutron energy from 0 to 175 MeV. By obtaining the universal parameters, new method was added to our nuclear reaction theory and laid the foundation for the nuclear data evaluation.

In this paper, the energy spectrum and angular distribution data of neutron source of ⁹Be (d, xn) reaction accelerator with thick target are evaluated and calculated by using PHITS program. The applicability of JQMD, INCL and INCL/DWBA nuclear reaction physical models to calculate the neutron radiation field distribution of ⁹Be (d, xn) reaction with thick target is discussed. The results show that the energy spectrum and angular distribution data of the thick target ⁹Be(d, xn) reaction calculated by the PHITS program based on the INCL/DWBA nuclear reaction physical model are in good agreement with the experimental data, and can provide more accurate neutron radiation field data for the study and application of the characteristics of ⁹Be (d, xn) reaction neutron source with thick target. In addition, the scheme of water-cooled large-area rotating beryllium target is designed, and the simulation study of target surface temperature is carried out under the condition of 5~25 MeV/5 mA incident deuterium energy. The results show that the maximum temperature of target surface can be controlled below 100 ºC.