The MCNP Simulation Of HPGe Detector Efficiency

HPGe is a high rapid development semiconductor detector in last few years. It overcomes the GE detectors (LI) detector long production cycle time and low temperatures storage, and so on disadvantage. It leads complex quantitative analysis of gamma spectrum radioisotope to realization. Immensely help the development of nuclear annihilation.In nuclear physics research and applied research in nuclear technology HPGe detector is primarily used to detect energy and strength of rays. As with higher resolution, high energy efficiency and greater detection of x-ray detection range (a few keV to several MeV), HPGe detector has been widely applied to all kinds of ventures measuring. Most crucial metrics for HPGe are energy efficiency resolution and detection efficiency, detect efficiency is directly related to the physical measurement accuracy, HPGE with significant meaning for the study of detection efficiency .For different measurement purpose the detector has different definitions. Laboratory HPGe has high detection efficiency and energy resolution, it is used for testing high precision gamma ray measurement of the totipotency vrukh very sharp, even if more complicated rays or more of the nuclein issued by the rays incident, the majority of the totipotency vrukh have been able to separate in isolation, totipotency vrukh easily recognized, and a full spectrum of often occupy a lot of road and totipotency vrukh, the number of factors affecting relatively few, troposcatter and other interference radiation pulse to a lesser extent does not affect to the totipotency peak counts.totipotency vrukh, symmetricmatrices also easily distinguished peak area easier. Based on tot potency peak such characteristics, the article main study tot potency peak detection efficiency.Firstly, this article did much investigation and research work for HPGE detector and its detecting efficiency, then did related experiment and simulation calculation, Experiment using 133ba, 152Eu series standard gamma rays source radiate HPGE detectors to measure gamma spectrum. At meanwhile, by changing ray source energy and detector distance to study the relationship between detection efficiency and them.Meanwhile, the article introduce MCNP4C program to simulate advanced HPGE detector testing experiment process..MCNP4C Monte-Carlo Los-Alamos program is developed by the United States National Laboratory ,which is MCNP new version of the Monte-Carlo program, it is widely used in a variety of particle transport simulation. MCNP has flexible, versatile and easy for application and so on features. The article is try to display HPGe detector test standard source efficiency at laboratory environmental and experimental conditions in MCNP program. Initially simulate HPGe detector testing process for detection efficiency of standard source at experiment condition, and compared simulation data to experimental results, the result show simulation result with much error with experiment result .Through research and analysis, reading reference documents, we can find, when using Monte Carlo method to calculate the semiconductor detector for detecting efficiency, the geometric dimensions of each component ,especially length of Crystal, RADIUS and cold refers size, dead layer thickness, has much error with actual size, So it affect the evaluates the accuracy significantly. Dad layer has obvious influence for low energy part ; Cold refer has much influence for high energy part. In order to make sure calculated results consistent with measuring results, it needs to build accurate modeling detector. Adjust thickness of dead layer and cold refer dimension for detector.Firstly, establish initials physical simulation model depending on manufacturers parameter, Simulate HPGE detecting efficiency at lab environment and conditions, in the simulation process, consider the different dead layers affection for result, and compare and analyze experimental results with calculate result to determine the size of the micro pattering of smell volume and layer thickness, then compare simulation result to experiment data , they are nearly consistent with each other. Using series of standards rays source (133Ba and 152Eu) irradiate semiconductor device model to do simulation and measurement, specific investigate how radioactive sources energy, distance between source and detector head, as well as distance of source to detector axial to affect detecting efficiency. Compare and analyze experiment result with simulation result, they are consistent .It verify that HPGE detecting efficiency experiment and simulation are correct and the data is reliable, so this calculations method can be used to simulate HPGe detector for detecting gamma spectrum efficiency. The simulation method can be used to calculate the efficiency distribution ofγrays, which radiate by any point sources in space, it is the foundations of no source efficiency scale method. Any arbitrary distribution of energy, sources of radiation measurements can apply Monte Carlo program to simulate.