Low-energy threshold demonstration for dark matter searches in TREX-DM with an $^{37}$Ar source produced at CNA HiSPANoS

physics.ins-det

/ Authors

J. Castel, S. Cebrián, T. Dafni, D. Díez-Ibáñez, A. Ezquerro, B. Fernández, J. Galán, J. A. García, C. Guerrero, I. G. Irastorza

and 9 more authors

G. Luzón, C. Margalejo, H. Mirallas, L. Obis, A. Ortiz de Solórzano, O. Pérez, J. Porrón, M. J. Puyuelo, A. Quintana

/ Abstract

We report on the successful implementation of an $^{37}$Ar calibration source in the TREX-DM detector, a high-pressure time projection chamber designed for low-mass dark matter searches. The $^{37}$Ar source was produced through fast neutron activation of CaO powder at the HiSPANoS facility of Centro Nacional de Aceleradores (CNA) in Spain, yielding $O(1)$ kBq of activity. Using a novel combined GEM-Micromegas readout system, we successfully detected both characteristic emissions from $^{37}$Ar decay (2.82 keV and 270 eV) and achieved unprecedented energy threshold performance in TREX-DM, approaching the single-electron ionization energy of argon.