标题： 1 AU处的太阳高能粒子径迹产生率：比较原位粒子通量与月球样品-derived径迹密度 显示英文标题

标题： Solar-Energetic-Particle Track-Production Rates at 1 au: Comparing In-situ Particle Fluxes with Lunar Sample-Derived Track Densities

摘要： 高能（Z>26）太阳高能粒子（SEPs），其能量约为1 MeV/核子，在陨石材料中已知会留下可见的损伤轨迹。 在月球和小行星样本中这种太阳耀斑轨迹的密度已被用作衡量样本暴露于太空的时间，从而提供了关于行星空间风化速率、星际尘粒的动力学和寿命以及太阳粒子流量长期历史的关键信息。 了解1天文单位处行星材料中的SEP轨迹累积率对于正确解释观测到的轨迹密度至关重要。 在这里，我们使用NASA高级成分探测器（ACE）获得的0.50-3.0 MeV/nuc铁族SEP通量的原位粒子观测数据，计算出1天文单位处诱导轨迹粒子的通量为6.0×10^5/cm2/yr/立体角。 利用铁族SEPs的观测能量谱，我们发现从ACE测量推断的SEP诱发损伤轨迹深度分布与最近在月球样本64455中测量的结果非常吻合；然而，ACE推断的速率比在月球样本中观察到的高出约25倍。 我们讨论了导致这一差异的几种假设，包括轨迹形成效率低下、月球样本的热退火效应、通过空间风化过程的侵蚀以及月球附近SEP流量的变化，但未能找到令人满意的解释。 我们鼓励进一步研究陨石材料中SEP轨迹形成性质以及地质时期月球表面铁族SEPs的流量，以解决这一分歧。 显示英文摘要

摘要： Heavy (Z>26) solar energetic particles (SEPs) with energies ~1 MeV/nucleon are known to leave visible damage tracks in meteoritic materials. The density of such solar flare tracks in lunar and asteroidal samples has been used as a measure of a sample's exposure time to space, yielding critical information on planetary space weathering rates, the dynamics and lifetimes of interplanetary dust grains, and the long-term history of solar particle fluxes. Knowledge of the SEP track accumulation rate in planetary materials at 1 au is critical for properly interpreting observed track densities. Here, we use in-situ particle observations of the 0.50-3.0 MeV/nuc Fe-group SEP flux taken by NASA's Advanced Composition Explorer (ACE) to calculate a flux of track-inducing particles at 1 au of 6.0x10^5 /cm2/yr/str. Using the observed energy spectrum of Fe-group SEPs, we find that the depth distribution of SEP-induced damage tracks inferred from ACE measurements matches closely to that recently measured in lunar sample 64455; however, the magnitude of the ACE-inferred rate is approximately 25x higher than that observed in the lunar sample. We discuss several hypotheses for the nature of this discrepancy, including inefficiencies in track formation, thermal annealing of lunar samples, erosion via space weathering processing, and variations in the SEP flux at the Moon, yet find no satisfactory explanation. We encourage further research on both the nature of SEP track formation in meteoritic materials and the flux of Fe-group SEPs at the lunar surface in recent and geologic times to resolve this discrepancy.