Current Status of Scintillating Bubble Chambers For Dark Matter Detection

The Scintillating Bubble Chamber (SBC) Collaboration aims to search for dark matter via low-energy nuclear recoils with strong electron recoil discrimination at a target threshold of 100 eV. We combine the excellent electron recoil discrimination by bubble chamber technology with the event-by-event energy resolution offered by liquid argon scintillation for possible detection of 1–10 GeV/c² WIMPs. Two functionally identical 10 kg detectors, SBC-Fermilab and SBC-SNOLAB are being developed. SBC-Fermilab is currently being assembled and commissioned at Fermi National Accelerator Laboratory for calibration of nuclear and electron recoil responses. SBC-SNOLAB is planned with an emphasis on radiopurity for low-background dark matter search and will be deployed deep underground at SNOLAB. If a background event rate of 0.1 ev/kg/yr is achieved, SBC-SNOLAB will be capable of competitive sensitivity of 2·10^-43–10^-44 cm², for a WIMP mass of 1–10 GeV/c² with 10 kg-yr exposure. We are exploring multiple background mitigation methods, including using scintillation in our hydraulic fluid CF₄ as a veto against neutrons and neutron producing interactions. In this talk, I will present the current progress on the SBC-Fermilab chamber, and characterization of scintillation in liquid CF₄ by gamma and alpha particles for background reduction.