液体闪烁体探测器中α粒子Geant4模拟的详细研究

中文摘要 AI 辅助

目的：来自$^{214}$Po、$^{212}$Po和$^{210}$Po的α粒子越来越多地用于校准大型液体闪烁体探测器，但其能量沉积的Geant4模拟需要详细验证。方法：我们使用Geant4 4.11.4.2在4 m LAB基液体闪烁体立方体中模拟α粒子，并逐步应用Birks淬灭。我们研究了步长、产生阈值、Birks常数和电磁模型依赖性，并使用Geant4-DNA检查keV尺度电子径迹结构。结果：δ电子相关涨落主导模拟响应。在测试的显式δ设置中，次级径迹的淬灭响应贡献方差是总方差的1.01--1.12倍；负的主-次级协方差减少了总方差。模拟淬灭曲线形状与SNO+数据在当前不确定性内兼容，对于$k_B=0.007$--$0.010$ g cm$^{-2}$ MeV$^{-1}$，$\chi^2/\mathrm{ndf}\simeq0.14$--$0.17$。Geant4-DNA给出强电子径迹曲率，曲折度从200 eV时的约6降至10 keV时的1.6。结论：在测试配置中，δ电子涨落是固有分辨率的主要贡献。产生阈值的影响大于电磁模型：Penelope和Livermore在L/E方面一致在约3%以内，而Standard给出更高的L/E，尤其是在低阈值下。

英文摘要

Purpose: Alpha particles from $^{214}$Po, $^{212}$Po, and $^{210}$Po are increasingly used to calibrate large liquid scintillator detectors, but Geant4 simulations of their energy deposition require detailed validation. Methods: We simulate alpha particles in a 4 m cube of LAB-based liquid scintillator with Geant4 11.4.2 and apply Birks quenching per step. We study step-size, production-threshold, Birks-constant, and electromagnetic-model dependence, and use Geant4-DNA to examine keV-scale electron track structure. Results: Delta-electron-associated fluctuations dominate the simulated response. Across the tested explicit-delta settings, the variance of the quenched-response contribution from secondary tracks is 1.01--1.12 times the total variance; a negative primary--secondary covariance reduces the total. The simulated quenching-curve shape is compatible with SNO+ data within current uncertainties, with $χ^2/\mathrm{ndf}\simeq0.14$--$0.17$ for $k_B=0.007$--$0.010$ g cm$^{-2}$ MeV$^{-1}$. Geant4-DNA gives strong electron-track curvature, with tortuosity decreasing from about 6 at 200 eV to 1.6 at 10 keV. Conclusion: Delta-electron fluctuations are the dominant contribution to the intrinsic resolution in the tested configurations. The production threshold has a larger effect than the electromagnetic model: Penelope and Livermore agree within about 3% in L/E, whereas Standard gives higher L/E, especially at low thresholds.

发表机构

• Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）
• University of Chinese Academy of Sciences（中国科学院大学）

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