Clover探测器的效率刻度

【作者】 马金峰；

【导师】 夏海鸿；

【作者基本信息】 中国原子能科学研究院 ， 粒子物理与原子核物理， 2007， 硕士

【摘要】 HPGe探测器主要用于测量γ射线的能谱，其能量分辨一般为几个KeV，要比常用的NaI(T1)探测器好几十倍，使许多用NaI(T1)谱仪测量时无法分辨的谱线清楚地分开。因此，实际上绝大多数涉及复杂γ射线能谱的研究都是用高纯锗探测器进行的。Clover型HPGe探测器由四块相同的HPGe晶体模切加工组装而成，较常用的由单块HPGe晶体组成的探测器，在角分辨能力、最高计数率、探测效率和抑制多普勒展宽等方面具有明显优势。本论文在一个较宽的能量范围内对Clover探测器的γ射线探测效率利用通用蒙特卡罗程序MCNP4C进行了理论模拟，在低能部分进行了实验测量，并对理论模拟和实验测量的结果进行了比较，对Clover探测器的γ射线探测效率进行了刻度。Clover的外面包裹着8块反康BGO晶体。16路BGO反康信号的逻辑OR信号作为数据获取系统的门信号，控制着信号的取舍。实验利用Kmax多参数数据获取系统，以事件记录方式对Clover的四路输出信号同时进行记录。在离线数据处理中，对四路数据按事件方式进行处理，由对应于同一事件的各路能量相加，得出Clover的测试能谱和探测效率，并对由四块晶体间的cross-talk效应引起的事件探测效率增加做了分析。更多还原

【Abstract】 HPGe detector, of which the energy resolution is much better than the normally used NaI(Tl) detector, is widly used to detect theγ-ray. The HPGe detector can distinguish two spectrums of which the difference between the two energy information is not distinct. Therefor, the Ge detector is applied to most researches related to complexγ-ray spectrum.The Clover detector which contains four HPGe crystals has superiority in the aspects of angular resolution, the maximum count rate and energy resolution over the detector that contains only one crystal.The efficiency is calibrated over a large range of energy by means of theoretical simulation and experiment. MCNP4C, a general Monte Carlo program, is used in the process of theoretical simulation. The results of the theoretical simulation and experiment is compared.The Clover detector is surrounded by 8 crystals of BGO. Each crystal matches two photomultiplier tubes each of which generates an anti-compton signal. The logic OR of the 16 anti-compton signals is used to control the data acquisition system.Kmax, which is a multiple parameters data acquisition system based on CAMAC -BUS , records the data of four output channels of the Clover detector event by event on the computer disk. The efficiency and energy spectrum of the Clover detector is obtained by addition of energy information corresponding to the same event in the process of off lining data processing. The increase of the efficiency resulted from the effect of cross section among the four crystals in one Clover is illuminated in the paper.更多还原