The Dynamic Albedo of Neutrons (DAN) instrument onboard Mars Science Laboratory uses neutron die‐away, an active nuclear spectroscopy technique, to measure the abundance and depth distribution of hydrogen and neutron‐absorbing elements (e.g., Fe and Cl) in the top ∼0.5 m of the Mars subsurface. We examined the intrinsic variability in neutron die‐away data using simulated DAN measurements with a range of compositions relevant to equatorial and high‐latitude environments on Mars. Our analysis shows that the total neutron counts and timing of neutron arrival explain most variability in thermal neutron die‐away curves for a DAN‐like instrument configuration over homogeneous subsurfaces. We analyzed the variability in thermal neutron die‐away across a variety of elemental compositions that might be observed by DAN or future instruments. We found that when H concentration is low (e.g., in equatorial regions including Gale crater), neutron die‐away is most sensitive to variations in H. Conversely, when H concentration is high (e.g., in poleward regions of Mars or icy bodies), neutron die‐away is most sensitive to variations in neutron absorbers. We estimated that the H and neutron absorber concentrations in DAN measurements acquired Sols 1–2080 in Gale crater and found that most measurements had low H and moderate absorber content. We presented an outlier analysis of these measurements to identify targets with high potential scientific impact and found that most outliers along the traverse corresponded with abnormally low or high neutron absorber content measurements, some of which may be associated with high‐silica fracture‐associated halos and felsic igneous material.

中文翻译：

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来自火星科学实验室中子仪器动态反照率的主动中子测量分析：内在变异性，离群值及其对未来研究的启示

火星科学实验室机载的动态中子反照率（DAN）仪器使用主动核能谱技术中子死亡，测量顶部氢和中子吸收元素（例如铁和氯）的丰度和深度分布。火星地下0.5 m。我们使用模拟DAN测量以及与火星赤道和高纬度环境有关的一系列成分，研究了中子死亡数据的内在变异性。我们的分析表明，中子的总数和中子到达的时间解释了在均质次表面上类似DAN的仪器配置中热中子消亡曲线的最大变化。我们分析了DAN或未来仪器可能观测到的各种元素组成中热中子消失的变化。我们发现，当H浓度低时（例如，在包括大风火山口的赤道地区），中子死亡对H的变化最敏感。相反，当H浓度高时（例如，在火星的极地区域或冰冷的体中） ，中子消亡对中子吸收体的变化最敏感。我们估计DAN测量中的H和中子吸收剂浓度获得了Gale陨石坑中的Sols 1-2080，发现大多数测量结果中H和中子的含量较低。我们对这些测量值进行了离群分析，以发现具有潜在潜在科学影响的目标，并发现沿导线的大多数离群值与异常低或高的中子吸收剂含量测量值相对应，其中一些可能与高硅石断裂相关的光晕和长丝状火成岩物质。