New NEMESIS Results

Abstract

Preliminary results from a 349-day run (live time) with a 565 kg Pb target and a 166-day background measurement are presented. Three minor anomalies were detected in muon-suppressed neutron multiplicity spectra. The multiplicities of these one-sigma excesses match the outcome of an earlier, similar but independent measurement. The nature of the anomalies remains unclear, but, in principle, they may be a signature of self-annihilation of a Weakly Interacting Massive Particle (WIMP) with a mass around 10 GeV/c 2 . The expected cross section would be around 10 -42 cm 2 for Spin Dependent and 10 -46 cm 2 for Spin Independent interactions. Analysis of the event rate, based on the statistical uncertainty, indicates that cross-section limits for Dark Matter (DM) mass range of approximately 3-40 GeV/c 2 can be investigated with an upgraded NEMESIS setup.

New Evidence for DM-like Anomalies in neutron multiplicity spectra

“…The first NEMESIS 0.1 results were presented at ICRC 2021 [4], TAUP 2021 [5], VCI 2022 [6], and NDM 2022 [7]. Since then, we have conducted detailed Monte Carlo studies [8] for the NMDS setup used for measurements at 0.2 km (583 m.w.e) and 0.4 km (1166 m.w.e.).…”