Measurement of the scintillation efficiency for low energy nuclear- and electronic-recoils in liquid argon detector for WIMP search

A liquid argon (LAr) scintillation detector is known to offer several attractive features to search for WIMP dark matter. A key quantity in this search is the conversion efficiencies of nuclear- and electronic-recoils (NR and ER) energy deposition into the scintillation signal. Two measurements are performed to study these properties: (1) scintillation efficiency for a few tens of keV NR under electric fields up to 3 kV/cm; (2) efficiency for ER ranging from a few keV to 1 MeV at null field. We present the results of these measurements and discuss the LAr response based on traditional models.