Description of the ballistic dependance in triple-to-double coincidence ratio (TDCR) method using a surrogate optical model

IF 1.8 3区工程技术 Q3 CHEMISTRY, INORGANIC & NUCLEAR

Applied Radiation and Isotopes Pub Date : 2025-09-20 DOI:10.1016/j.apradiso.2025.112200

Romain Coulon , Camille Queruel , Christophe Bobin , Cheick Thiam , Haoran Liu , Zihao Fan , Eric Macedo , Tiphaine Choteau

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引用次数: 0

Abstract

The Triple-to-Double Coincidence Ratio (TDCR) method is a widely used technique for absolute activity measurements in liquid scintillation counting. While the standard TDCR model assumes statistical independence in photon detection across photomultiplier tubes (PMTs), this study investigates the impact of ballistic dependence, where photon detection probabilities are influenced by the spatial origin of decay events within the scintillator. Using a surrogate bidimensional optical model, the probability distribution of scintillation photon flux among PMTs is sampled and integrated into a Poisson-Multinomial-Binomial hierarchical model of TDCR optics simulation. The results reveal that ballistic dependence leads to a reduction in both double and triple coincidence count rates, causing a corresponding decrease in the TDCR value—particularly for emitters of low energy ionizing radiations such as ⁵⁵Fe or ⁵¹Cr. This effect diminishes with increasing optical diffusion, which effectively decouples photon detection probabilities from the emission site. These results highlight the critical role of maximizing photon diffusion in TDCR counters and underscore the need for refined TDCR models incorporating Monte Carlo-based optical transport to enhance measurement accuracy.

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用替代光学模型描述三倍-两倍符合比（TDCR）方法的弹道相关性。

三双符合比（TDCR）法是液体闪烁计数中广泛使用的绝对活度测量技术。虽然标准的TDCR模型假设光子探测在光电倍增管（pmt）中的统计独立性，但本研究调查了弹道依赖性的影响，其中光子探测概率受到闪烁体内衰变事件的空间起源的影响。利用替代二维光学模型，对pmt间闪烁光子通量的概率分布进行采样，并将其集成到TDCR光学仿真的泊松-多项-二项分层模型中。结果表明，弹道依赖导致双重和三重符合计数率的降低，从而导致TDCR值的相应降低，特别是对于低能量电离辐射的发射体，如55Fe或51Cr。这种效应随着光扩散的增加而减弱，这有效地将光子探测概率与发射点解耦。这些结果强调了在TDCR计数器中最大化光子扩散的关键作用，并强调了采用基于蒙特卡罗的光输运的改进TDCR模型以提高测量精度的必要性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Applied Radiation and Isotopes 工程技术-核科学技术

CiteScore

3.00

自引率

12.50%

发文量

406

审稿时长

13.5 months

期刊介绍： Applied Radiation and Isotopes provides a high quality medium for the publication of substantial, original and scientific and technological papers on the development and peaceful application of nuclear, radiation and radionuclide techniques in chemistry, physics, biochemistry, biology, medicine, security, engineering and in the earth, planetary and environmental sciences, all including dosimetry. Nuclear techniques are defined in the broadest sense and both experimental and theoretical papers are welcome. They include the development and use of α- and β-particles, X-rays and γ-rays, neutrons and other nuclear particles and radiations from all sources, including radionuclides, synchrotron sources, cyclotrons and reactors and from the natural environment. The journal aims to publish papers with significance to an international audience, containing substantial novelty and scientific impact. The Editors reserve the rights to reject, with or without external review, papers that do not meet these criteria. Papers dealing with radiation processing, i.e., where radiation is used to bring about a biological, chemical or physical change in a material, should be directed to our sister journal Radiation Physics and Chemistry.