Studies on liquid argon S1 and S2 properties for low mass WIMP search experiments

Liquid argon is known as an excellent target material for WIMP dark matter direct search experiment. Relatively small atomic mass (A=40) gives high nuclear recoil energy for WIMP-Ar nuclear scattering, thus it potentially has high sensitivity for low mass WIMP (<10 GeV/c(2)). There are two crucial R&D topics for the liquid argon detector to explore such low mass WIMP signal, namely, deep understanding the liquid argon scintillation and ionization process for low energy deposition (<10 keV), and increasing the signal light yield by improving the argon scintillation light collection efficiency. In this paper, we report recent results from Waseda university liquid argon test facility.