Study of luminescence mechanism by neutral bremsstrahlung in gaseous argon

Abstract

Secondary scintillation light (S2 signal) has been used for direct dark matter search in two-phase detectors because of its appealing characters. In general, electrons extracted from the liquid phase of two-phase detectors produce excimers in the gaseous phase that emit a VUV (vacuum ultraviolet) S2 signal. However, recent research suggests that the S2 signal in argon has another luminescence mechanism called "neutral bremsstrahlung". In this work, detailed measurements of neutral-bremsstrahlung-induced -S2 -signal (and also VUV S2 signal) in argon are reported.