Search for Daily Modulation of MeV Dark Matter Signals with DAMIC-M
I. J. Arnquist, N. Ávalos, D. Baxter, X. Bertou, N. Castelló-Mor, Á. Chavarría, J. Cuevas-Zepeda, A. Dastgheibi-Fard, C. De Dominicis, Olivier Deligny, J. Duarte-Campderros, E. Estrada, N. Gadola, R. Gaïor, T. W. Hossbach, L. Iddir, Bradley J. Kavanagh, B. Kilminster, A. Lantero-Barreda, I. Lawson, S. Lee, A. Letessier‐Selvon, P. Loaiza, A. Lopez-Virto, Kellie McGuire, P. Mitra, Sravan Munagavalasa, D. Norcini, S. Paul, A. Piers, Paolo Privitera, P. Robmann, S. Scorza, M. Settimo, R. Smida, M. Traina, R. Vilar Cortabitarte, G. Warot, R. Yajur, J. P. Zopounidis
Abstract
Dark matter (DM) particles with sufficiently large cross sections may scatter as they travel through Earth's bulk. The corresponding changes in the DM flux give rise to a characteristic daily modulation signal in detectors sensitive to DM-electron interactions. Here, we report results obtained from the first underground operation of the DAMIC-M prototype detector searching for such a signal from DM with MeV-scale mass. A model-independent analysis finds no modulation in the rate of 1 e^{-} events with sidereal period, where a DM signal would appear. We then use these data to place exclusion limits on DM in the mass range [0.53,2.7] MeV/c^{2} interacting with electrons via a dark photon mediator. Taking advantage of the time-dependent signal we improve by ∼2 orders of magnitude on our previous limit obtained from the total rate of 1 e^{-} events, using the same dataset. This daily modulation search represents the current strongest limit on DM-electron scattering via ultralight mediators for DM masses around 1 MeV/c^{2}.