Ionization and Scintillation from Argon Electron Recoils

The Aron Recoil Ionization and Scintillation (ARIS) Experiment measured the response of LAr to neutrons of a known energy. The response of LAr to low-energy interactions is still poorly understood, and the proposed Argon Recoil Ionization and Scintillation from Electron Recoils (ARIS-ER) experiment will characterize the LAr response to electron recoils down to a keV. The LAr in the ARIS-ER time projection chamber will be exposed to 511 keV gammas from a Na-22 source, which Compton scatter inside the detector. The energy of the scattered gammas will be measured by a Broad Energy Germanium (BEGe) detector and will determine the energy deposited. This information will be used to refine a GEANT-4 model describing ionization and scintillation processes in LAr, and will be useful for LAr-based dark matter searches. This talk will provide an overview of the ARIS-ER experiment's progress.