To overcome the problem of inefficient computing time and unreliable results in MCNP5 calculation, a two-step method is adopted to calculate the energy deposition of prompt γ-rays in detectors for depleted uranium spherical shells under D-T neutron irradiation. In the first step, the γ-ray spectrum for energy below 7 MeV is calculated by MCNP5 code; secondly, the electron recoil spectrum in a BC501 A liquid scintillator detector is simulated based on EGSnrc Monte Carlo Code with the γ-ray spectrum from the first step as input. The comparison of calculated results with experimental ones shows that the simulations agree well with experiment in the energy region 0.4–3 MeV for the prompt γ-ray spectrum and below 4 MeVee for the electron recoil spectrum. The reliability of the two-step method in this work is validated.
The prompt T-ray spectrum from depleted uranium （DU） spherical shells induced by 14 MeV D-T neutrons is measured. Monte Carlo （MC） simulation gives the largest prompt 2/ flux with the optimal thickness of the DU spherical shells 3-5 cm and the optimal frequency of neutron pulse 1 MHz. The method of time of flight and pulse shape coincidence with energy （DC-TOF） is proposed, and the subtraction of the background y-rays discussed in detail. The electron recoil spectrum and time spectrum of the prompt γ-rays are obtained based on a 2＇＇ × 2＇＇ BC501A liquid scintillator detector. The energy spectrum and time spectrum of prompt γ-rays are obtained based on an iterative unfolding method that can remove the influence of γ-rays response matrix and pulsed neutron shape. The measured time spectrum and the calculated results are roughly consistent with each other. Experimental prompt γ-ray spectrum in the 0.4-3 MeV energy region agrees well with MC simulation based on the ENDF/BVI.5 library, and the discrepancies for the integral quantities ofγ-rays of energy 0.4-1 MeV and 1 3 MeV are 9.2% and 1.1%, respectively.
天然铀分解模拟装置中铀的相关反应率是研究混合堆包层设计宏观中子学的重要数据,采用活化法测量相应反应率的过程中必须对环状天然铀箔片的探测效率进行精确刻度。为了研究快速有效刻度HPGe探测器探测效率的方法,利用一系列标准伽马点源测量了轴线上6cm高度位置的点源探测效率曲线,在蒙特卡罗程序MCNP5中调整探测器内部结构参数,同时对HPGe探测器的探测效率进行模拟计算,在计算结果与实验结果能较好拟合的情况下推算探测器的死层厚度、冷指长度和半径等参数的实际尺寸。利用计算的尺寸模拟计算探测器对环状伽马源的探测效率,计算结果与实验结果在较宽能量区域（200-1 400 ke V）内在4%内符合。
