Deep-underground dark matter search with a COSINUS detector prototype
G. Angloher, M. R. Bharadwaj, I. Dafinei, N. Di Marco, L. Einfalt, F. Ferroni, S. Fichtinger, A. Filipponi, T. Frank, M. Friedl, A. Fuss, Z. W. Ge, Matti Heikinheimo, Martin Hughes, Katri Huitu, Moritz Kellermann, R. Maji, M. Mancuso, L. Pagnanini, F. Petricca, S. Pirro, F. Pröbst, G. Profeta, A. Puiu, F. Reindl, K. Schäffner, J. Schieck, D. Schmiedmayer, C. Schwertner, K. Shera, M. Stahlberg, A. Stendahl, M. Stukel, Cesare Tresca, F. Wagner, Shijing Yue, V. Zema, Y. Zhu
Abstract
Sodium iodide (NaI)-based cryogenic scintillating calorimeters using quantum sensors for signal readout have shown promising first results toward a model-independent test of the annually modulating signal detected by the DAMA/LIBRA dark matter experiment. The COSINUS Collaboration has previously reported on the first above-ground measurements using a dual-channel readout of phonons and light based on transition edge sensors (TESs) that allows for particle discrimination on an event-by-event basis. In this article, we outline the first underground measurement of a NaI cryogenic calorimeter readout via the novel remoTES scheme. A 3.67 g NaI absorber with an improved silicon light detector design was operated at the Laboratori Nazionali del Gran Sasso, Italy. A significant improvement in the discrimination power of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msup><a:mrow><a:mi>e</a:mi></a:mrow><a:mrow><a:mo>−</a:mo></a:mrow></a:msup><a:mo>/</a:mo><a:mi>γ</a:mi></a:mrow></a:math> events to nuclear recoils was observed with a fivefold improvement in the nuclear recoil baseline resolution, achieving <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>σ</c:mi><c:mo>=</c:mo><c:mn>441</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:mi>eV</c:mi></c:math>. Furthermore, we present a limit on the spin-independent dark matter nucleon elastic scattering cross section, achieving a sensitivity of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi mathvariant="script">O</e:mi><e:mo stretchy="false">(</e:mo><e:mi>pb</e:mi><e:mo stretchy="false">)</e:mo></e:math> with an exposure of only 11.6 g d. Published by the American Physical Society 2024