Geant4 simulation is used to calculate peak efficiency and correct the effect of coincidence summing in detecting volumetric gamma-ray sources; this simulation was applied to a standard 152Eu source with different volumes as a test case. The source is a liquid cylindrical shape of various volumes. Peak efficiency was calculated using two tracks in the Geant4 simulation: single-energy track and "monoenergetic Track" without coincidence summing. Here, the energy of the source is known, and the track of radionuclides, including the coincidence summing, depends on the decay scheme of the radioactive source. The ratio between the peak efficiency of the two tracks gives us the correction factor (CF). The experimental method was used to calculate the peak efficiency and was amended by the correction factor computed with Geant4 tracks. The results showed a good agreement between experimental efficiency after correction and free-summing simulated efficiency. The comparison indicated that the present method is valid and useful for voluminous gamma-ray sources.

中文翻译：

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使用 Geant4 仿真计算不同圆柱形源的 NaI 探测器峰值效率和重合求和因子。

使用Geant4模拟计算峰值效率并修正重合求和在探测体积伽玛射线源中的影响；该模拟应用于不同体积的标准 152Eu 源作为测试用例。源是不同体积的液体圆柱形。使用 Geant4 模拟中的两个轨迹计算峰值效率：单能量轨迹和无重合求和的“单能量轨迹”。这里，源的能量是已知的，并且放射性核素的轨迹（包括符合总和）取决于放射源的衰变方案。两条轨道的峰值效率之间的比率为我们提供了校正因子（CF）。采用实验方法计算峰值效率，并通过Geant4轨迹计算的校正因子进行修正。结果表明，校正后的实验效率与自由求和模拟效率之间具有良好的一致性。比较表明，该方法对于大量伽玛射线源是有效且有用的。