First Bubbles in the SBC-LAr10 Detector at Fermilab

The Scintillating Bubble Chamber (SBC) Collaboration develops liquid-noble bubble chambers for the detection of low-mass (GeV-scale) particle dark matter and coherent neutrino scattering (CEvNS) at nuclear reactors. Like other bubble chamber dark matter detection efforts, SBC relies on the intrinsic background discrimination seen in superheated fluids: nuclear recoils from WIMP and neutrino interactions in the superheated target of the bubble chamber nucleate a single bubble, while electronic recoils from background beta decays and gamma rays do not. By using a liquid-noble target, SBC extends this discrimination to much lower thresholds than achievable in other bubble chambers while also adding a scintillation signal for event-by-event energy reconstruction. SBC-LAr10 is the collaboration's first physics-scale device, operating in the MINOS underground area at Fermilab and designed to superheat a 10-kg argon target to bubble nucleation thresholds as low as 40 eV. SBC-LAr10 saw its first bubbles in October 2025, beginning a year-long calibration campaign to evaluate the physics potential of this new detector technology. This talk will report on the early successes and challenges in this campaign, showing detector performance and preliminary results from the thermodynamic states explored thus far.