Chuong Huynh Dinh, Hung Nguyen Quoc, My Le Nguyen Thi, Nguyen Vo Hoang, Thanh Tran Thien
Nuclear Technique Laboratory, University of Science, VNU-HCM, Viet Nam.
Department of Nuclear Physics, Faculty of Physics and Engineering Physics, University of Science, VNU-HCM, Viet Nam.
Appl Radiat Isot. 2019 Jul;149:1-8. doi: 10.1016/j.apradiso.2019.04.009. Epub 2019 Apr 10.
The aim of this study is the validation of gamma scanning method for optimizing NaI(Tl) detector model in Monte Carlo simulation. The experimental procedure involved: scanning on front and lateral surfaces of the detector with collimated low-energy photon beam; calibrating the efficiency with energies between 31-1408 keV for point sources at distances of 0 cm and 30 cm from source to the detector. The Monte Carlo code used for the simulations was MCNP6. The diameter and the length of crystal were determined according to the measured results of gamma scanning with a collimated Am radioactive source. The distance from window to crystal was estimated using transmission measurement recorded on a second detector. The density of reflector was adjusted to obtain the match between measured and simulated values of efficiency ratio of 81 and 31 keV from a Ba radioactive source. The optimized model was applied in Monte Carlo simulations to determine the efficiency and energy spectrum response function of NaI(Tl) detector for point source measurements in two configurations. Good agreement was obtained between measured and simulated results.
本研究的目的是验证伽马扫描方法，以在蒙特卡罗模拟中优化碘化钠（铊）探测器模型。实验过程包括：用准直的低能光子束在探测器的前表面和侧面进行扫描；针对距离源0厘米和30厘米处的点源，在31 - 1408 keV能量范围内校准效率。用于模拟的蒙特卡罗代码是MCNP6。根据用准直的镅放射性源进行伽马扫描的测量结果确定晶体的直径和长度。使用在第二个探测器上记录的透射测量来估计窗口到晶体的距离。调整反射器的密度，以使来自钡放射性源的81 keV和31 keV效率比的测量值与模拟值相匹配。将优化后的模型应用于蒙特卡罗模拟，以确定两种配置下点源测量中碘化钠（铊）探测器的效率和能谱响应函数。测量结果与模拟结果取得了良好的一致性。
