Moreira D S, Koskinas M F, Dias M S, Yamazaki I M
Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP), Centro do Reator de Pesquisas-CRPq, São Paulo, SP, Brazil.
Appl Radiat Isot. 2010 Jul-Aug;68(7-8):1566-70. doi: 10.1016/j.apradiso.2009.11.053. Epub 2009 Dec 16.
This work describes the measurements of the K X-ray and gamma-ray emission probabilities per decay of (198)Au performed at the Nuclear Metrology Laboratory (LMN) at the IPEN, São Paulo. The radioactive sample was obtained by means of (197)Au(n, gamma)(198)Au reaction irradiating an Au foil in a thermal neutron flux near the core of the IPEN 3.5 MW research reactor. The activity of samples was determined in a 4pibeta-gamma coincidence system, setting the gamma window at the 411.80 keV total energy absorption peak. The same samples were measured in two different spectrometers: a HPGe planar spectrometer with Be window, suitable for measurements in the low energy range and a coaxial REGe spectrometer. Both spectrometers were previously calibrated in a well defined geometry by means of standard sources calibrated in a 4pibeta-gamma coincidence system. MCNP4C Monte Carlo code was used for simulating the REGe spectrometer calibration curve, and a new version of code ESQUEMA was adopted for simulating the detection processes in the coincidence system, in order to predict the efficiency extrapolation curve.
这项工作描述了在圣保罗的IPEN核计量实验室（LMN）对（198）Au每次衰变的K X射线和γ射线发射概率的测量。放射性样品是通过（197）Au（n，γ）（198）Au反应获得的，该反应是在IPEN 3.5兆瓦研究堆堆芯附近的热中子通量中辐照金箔。在一个4πβ-γ符合系统中测定样品的活度，将γ窗设置在411.80 keV总能量吸收峰处。对相同的样品在两种不同的光谱仪中进行测量：一种是带有铍窗的HPGe平面光谱仪，适用于低能范围的测量；另一种是同轴REGe光谱仪。两种光谱仪之前都在定义明确的几何条件下，通过在4πβ-γ符合系统中校准的标准源进行了校准。使用MCNP4C蒙特卡罗代码模拟REGe光谱仪的校准曲线，并采用新版本的ESQUEMA代码模拟符合系统中的探测过程，以预测效率外推曲线。
