2024/10/24 by Bloch, Itay M., Botti, Ana M., Cababie, Mariano +27 · 3 citations
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)
paper · doi:10.48550/arxiv.2410.18716
We present results from data acquired by the SENSEI experiment at SNOLAB after a major upgrade in May 2023, which includes deploying 16 new sensors and replacing the copper trays that house the CCDs with a new light-tight design. We observe a single-electron event rate of (1.39 ± 0.11) × 10-5 e-/pix/day, corresponding to (39.8 ± 3.1) e-/gram/day. This is an order-of-magnitude improvement compared to the previous lowest single-electron rate in a silicon detector and the lowest for any photon detector in the near-infrared-ultraviolet range. We use these data to obtain a 90% confidence level upper bound of 1.53 × 10-5 e-/pix/day and to set constraints on sub-GeV dark matter candidates that produce single-electron events. We hypothesize that the data taken at SNOLAB in the previous run, with an older tray design for the sensors, contained a larger rate of single-electron events due to light leaks. We test this hypothesis using data from the SENSEI detector located in the MINOS cavern at Fermilab.