Measurement of a novel scintillation mechanism in xenon-doped liquid argon

The Xenon-Argon Technology (X-ArT) collaboration presents a new study on the scintillation properties of liquid argon (LAr) in both pure and xenon-doped systems. Our experimental setup has allowed us to identify an additional radiative mechanism in xenon-doped LAr that significantly enhances light and ionization yields. This newly recognized mechanism complements the traditional collisional energy transfer process in xenon-doped systems. We offer a comprehensive model of the Xe-Ar scintillation mechanism, incorporating both collisional and radiative processes. By analyzing data from silicon photomultipliers (SiPMs) with and without quartz windows, which are sensitive to different wavelength ranges, we demonstrate the existence of a long-lived scintillation component. This component is present in both pure and Xe-doped LAr, with its effects becoming more pronounced as xenon concentration increases. Additionally, we explore how Xe-doping influences scintillation light yield and pulse shape discrimination. These findings have important implications for next-generation neutrino and dark matter detectors. Understanding the scintillation dynamics in Xe-doped LAr can optimize detector performance, and this work advances our knowledge of the fundamental physics of noble liquid scintillators, providing key insights for enhancing the design and sensitivity of future large-scale particle detectors.