Measurements of argon-scintillation and -electroluminescence properties for low mass WIMP dark matter search

It has been demonstrated that the liquid argon scintillation detector is an excellent particle detector for use in various physics experiments, particularly those seeking evidence of WIMPs dark matter. The detector observes primary scintillation signal (S1) and/or secondary electroluminescence signal (S2). It is crucial that the properties of the detector are understood comprehensively so that such projects reduce systematic uncertainty and improve sensitivity. This work covers the recent measurements, taken using the liquid argon test facility at Waseda University, of the liquid argon scintillation and ionization responses for nuclear and electronic recoils. Additionally, a basic study of the gaseous argon luminescence signal, which involves the S2 signal, is presented herein. The luminescence process of the S2 signal, based on this measurement, is then discussed along with a suggested new mechanism called neutral Bremsstrahlung.