Germanium is the detector material of choice in many rare-event searches looking for low-energy nuclear recoils induced by dark matter particles or neutrinos. We perform a systematic exploration of its quenching factor for sub-keV nuclear recoils, using multiple techniques: photoneutron sources, recoils from gamma-emission following thermal neutron capture, and a monochromatic filtered neutron beam. Our results point to a marked deviation from the predictions of the Lindhard model in this mostly unexplored energy range. We comment on the compatibility of our data with low-energy processes such as the Migdal effect, and on the impact of our measurements on upcoming searches.

中文翻译：

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锗对亚 keV 核反冲的响应：多管齐下的实验表征

在寻找由暗物质粒子或中微子引起的低能核反冲的许多稀有事件搜索中，锗是首选的探测器材料。我们使用多种技术对其亚 keV 核反冲的猝灭因子进行了系统的探索：光中子源、热中子捕获后伽马发射的反冲和单色过滤中子束。我们的结果表明，在这个几乎未开发的能量范围内，与 Lindhard 模型的预测存在明显偏差。我们评论我们的数据与低能量过程（例如 Migdal 效应）的兼容性，以及我们的测量对即将进行的搜索的影响。