CAPTAIN-Mills: A Sterile Neutrino Search using ν_μ Disappearance at the Los Alamos Neutron Science Center

When combined with results from the Liquid Scintillator Neutrino Detector (LSND), the most recent MiniBooNE results confirm an excess of ν_e charged-current quasi-elastic events at the 6.1σ level. This could be explained by the existence of a fourth neutrino mass eigenstate. To test this hypothesis, the CAPTAIN-Mills (CCM) experiment has been funded to run at the Lujan Center at the Los Alamos Neutron Science Center. CCM will use a 7700 L liquid argon detector to observe coherent elastic neutrino-nucleus scattering (CEνNS) using scintillation light. MiniBooNE provides evidence for both ν_e and $\bar{\nu_e}$ appearance; however, experiments at the GeV and TeV energy scales have not yet observed ν_μ disappearance. CEνNS is a neutral current interaction with an order-of-magnitude enhanced cross section at lower neutrino energies over other ν-Ar interactions. Thus, the 30 MeV muon neutrinos from the stopped pion source at the Lujan Center will make CCM the first experiment sensitive to ν_μ disappearance at the LSND energy range. Further, the 6.0 × 10^-6 duty factor of the source will be essential in constraining neutron backgrounds.  This poster focuses on the motivation of CCM and the status of this Fall's commissioning run.