A Neutrino Disappearance Search for Sterile Neutrinos with the CAPTAIN-Mills Detector at the Los Alamos Neutron Science Center

MiniBooNE and LSND have shown compelling evidence for sterile neutrinos at Δm² ∼1 eV² in short baseline neutrino oscillations experiments. In these experiments, a pure muon neutrino beam is used to search for electron neutrino appearance, but muon neutrino disappearance searches have shown no anomalies. This talk will describe the CAPTAIN-Mills experiment which will use a 10-ton liquid argon scintillation detector to leverage the enhanced cross section from coherent elastic neutrino-nucleus scattering (CEvNS) to measure muon neutrino disappearance at the Lujan Center at the Los Alamos Neutron Science Center. Lujan is a 100-kW stopped pion source that nominally delivers a 290-ns wide, 800-MeV proton beam onto a tungsten target at 20 Hz, but the beam width can be significantly narrowed to 30 ns. Fast pulsing is critical for isolating the monoenergetic muon neutrino from the other neutrino flavors and neutron backgrounds. In this talk, I will describe the CAPTAIN-Mills detector, the Lujan neutrino source, the expected sensitivities for sterile neutrinos, and show results from the summer neutrino test run.