发表机构
INFN Cagliari; Physics Department, Università degli Studi di Cagliari; CIEMAT, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas; Savannah River National Laboratory; Centro de Astropartículas y Física de Altas Energías (CAPA), Universidad de Zaragoza; INFN Laboratori Nazionali del Gran Sasso; Department of Physics, University of California, Davis; University of Oxford; Department of Physics, Carleton University; AstroCeNT, Nicolaus Copernicus Astronomical Center of the Polish（意大利核物理研究所卡利亚里分部; 卡利亚里大学物理系; 能源、环境和技术研究中央中心; 萨凡纳河国家实验室; 萨拉戈萨大学高能天体粒子与物理学中心; 意大利核物理研究所格兰萨索国家实验室; 加州大学戴维斯分校物理系; 牛津大学; 卡尔顿大学物理系; 波兰科学院尼古拉·哥白尼天文学中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用DArT探测器在坎弗兰克地下实验室测量大气氩中$^{39}$Ar比活度，通过切割计数和最大似然拟合获得最精确结果，并验证了DArT在DArTInArDM实验中的关键作用。
AI 中文摘要
我们报告了在西班牙坎弗兰克地下实验室（LSC）使用DArT对大气氩中$^{39}$Ar比活度的测量。DArT是一种由低温硅光电倍增管读出的低本底单相液氩探测器。DArT首先充入大气氩，然后充入来自DarkSide-50实验的已知放射性的地下氩样品。地下氩在本测量中作为本底参考，使得结果稳健，因为我们不依赖本底模拟。我们分别用切割计数法和分箱最大似然拟合测量$^{39}$Ar比活度，得到一致的结果。我们得到$a_{\text{AAr}}= 0.955 \pm 0.008~\text{Bq}/\text{kg}$。该结果与先前其他实验的测量一致，并提供了迄今为止对大气氩中$^{39}$Ar比活度的最精确测定。它还验证了DArT作为LSC处DArTInArDM实验的关键组成部分，该实验旨在测量从美国科罗拉多州深层地下井中提取的氩中$^{39}$Ar活度，这些氩用于意大利格兰萨索国家实验室的Darkside-20k和LEGEND-1000实验。
英文摘要
We report the measurement of the $^{39}$Ar specific activity of atmospheric argon using DArT, a low-background single-phase liquid-argon detector read out by cryogenic silicon photomultipliers, at the Canfranc Underground Laboratory (LSC) in Spain. DArT was first filled with atmospheric argon and then with a sample of underground argon of known radioactivity from the DarkSide-50 experiment. The underground argon serves as a background reference in this measurement, making the result robust because we do not rely on background simulations. We measure the $^{39}$Ar specific activity with both a cut-and-count method and a binned maximum-likelihood fit, yielding consistent results. We obtain $a_{\text{AAr}}= 0.955 \pm 0.008~\text{Bq}/\text{kg}$. This result agrees with previous measurements from other experiments and provides the most precise determination of the $^{39}$Ar specific activity in atmospheric argon to date. It also validates DArT as a key component of the DArTInArDM experiment at LSC, which aims to measure the $^{39}$Ar activity of the argon extracted from deep underground wells in Colorado (USA) for the Darkside-20k and LEGEND-1000 experiments at Laboratori Nazionali del Gran Sasso in Italy.
