Using a setup for testing a prototype for a satellite-borne cosmic-ray ion detector, we have operated a stack of scintillator and silicon detectors on top of the Princess Sirindhorn Neutron Monitor (PSNM), an NM64 detector at 2560-m altitude at Doi Inthanon, Thailand (18.59${}^{\circ }$N, 98.49${}^{\circ }$E). Monte Carlo simulations have indicated that about 15% of the neutron counts by PSNM are due to interactions (mostly in the lead producer) of GeV-range protons among the atmospheric secondary particles from cosmic ray showers, which can be detected by the scintillator and silicon detectors. Those detectors can provide a timing trigger for measurement of the propagation time distribution of such neutrons as they scatter and propagate through the NM64, processes that are similar whether the interaction was initiated by an energetic proton (for 15% of the count rate) or neutron (for 80% of the count rate). This propagation time distribution underlies the time delay distribution between successive neutron counts, from which we can determine the leader fraction (inverse multiplicity), which has been used to monitor Galactic cosmic ray spectral variations over $\sim$1-40 GV. Here we have measured and characterized the propagation time distribution from both the experimental setup and Monte Carlo simulations of atmospheric secondary particle detection. We confirm a known propagation time distribution with a peak (at $\approx$70 $\mathrm{\mu }$s) and tail over a few ms, dominated by neutron counts. We fit this distribution using an analytic model of neutron diffusion and absorption, for both experimental and Monte Carlo results. In addition we identify a group of prompt neutron monitor pulses that arrive within 20 $\mathrm{\mu }$s of the charged-particle trigger, of which a substantial fraction can be attributed to charged-particle ionization in a proportional counter, according to both experimental and Monte Carlo results. Prompt pulses, either due to neutrons or charged-particle ionization, are associated with much higher mean multiplicity than typical pulses. These results validate and point the way to some improvements in Monte Carlo simulations and the resulting yield functions used to interpret the neutron monitor count rate and leader fraction.

使用用于测试星载宇宙射线离子探测器原型的设置，我们在诗琳通公主中子监测器 (PSNM) 顶部运行了一堆闪烁体和硅探测器，这是一个位于 Doi 2560 米高度的 NM64 探测器泰国茵他侬 (18.59${}^{\circ }$否，98.49${}^{\circ }$E)。蒙特卡罗模拟表明，大约 15% 的 PSNM 中子计数是由于宇宙射线簇射的大气二次粒子之间 GeV 范围质子的相互作用（主要是在铅生产者中），这可以被闪烁体和硅探测到探测器。这些探测器可以为测量此类中子的传播时间分布提供定时触发，因为它们在 NM64 中散射和传播，无论相互作用是由高能质子（计数率的 15%）还是中子引发，过程都是相似的（对于 80% 的计数率）。这种传播时间分布是连续中子计数之间的时间延迟分布的基础，我们可以从中确定先导分数（逆多重性），$～$1-40 GV。在这里，我们测量并表征了大气二次粒子检测的实验设置和蒙特卡罗模拟的传播时间分布。我们确认一个已知的传播时间分布有一个峰值（在$\approx$70 $\mathrm{\mu }$s) 并拖尾数毫秒，以中子数为主。对于实验结果和蒙特卡罗结果，我们使用中子扩散和吸收的分析模型拟合该分布。此外，我们还确定了一组在 20 分钟内到达的瞬发中子监测脉冲。$\mathrm{\mu }$根据实验和蒙特卡罗结果，带电粒子触发器的 s ，其中很大一部分可归因于正比计数器中的带电粒子电离。由中子或带电粒子电离引起的瞬发脉冲与比典型脉冲高得多的平均多重性相关。这些结果验证了蒙特卡罗模拟的一些改进，并指出了用于解释中子监测计数率和先导率的产生的产量函数的方法。