Nicolaou G
Demokritus University of Thrace, School of Engineering, Department of Electrical and Computer Engineering, Laboratory of Nuclear Technology, Kimmeria Campus, Xanthi, Greece.
Appl Radiat Isot. 2013 Apr;74:9-12. doi: 10.1016/j.apradiso.2012.12.012. Epub 2012 Dec 27.
A Monte Carlo approach, based on total variance reduction, was presented in order to evaluate the solid angle subtended between a well-type NaI detector and a cylindrical source within the well. The results obtained, in the form of the geometrical efficiency εg, were within 0.7% of those in the literature, for a point and a volumetric radioactive source within the well. The effect of self-absorption on the geometrical efficiency was investigated for different gamma-ray energies emitted by the volumetric source, different source matrices and radii. Self-absorption is found to be particularly significant for gamma-ray energies below 300keV regardless the source matrix and radius. Furthermore, self-absorption becomes significant, in the case of the larger radius volumetric source, for the gamma-ray energies up to 1MeV considered. Hence, the effect of self-absorption on the geometrical factor should be considered in the absolute quantification of radioactivity of volumetric sources.
为了评估井型碘化钠探测器与井内圆柱形源之间所张的立体角，提出了一种基于总方差减少的蒙特卡罗方法。对于井内的点源和体积放射源，以几何效率εg的形式获得的结果与文献中的结果相差在0.7%以内。研究了体积源发射的不同伽马射线能量、不同源基体和半径对几何效率的自吸收效应。发现无论源基体和半径如何，自吸收对于低于300keV的伽马射线能量尤为显著。此外，对于所考虑的高达1MeV的伽马射线能量，在较大半径体积源的情况下，自吸收也变得显著。因此，在体积源放射性的绝对定量中应考虑自吸收对几何因子的影响。
