The gamma-ray radiation from a 178m2Hf source with an activity of Bq was measured for the first time with two ultra-low-background HPGe spectrometers over a cumulative 1170 h deep underground at the Gran Sasso National Laboratory (LNGS) of the INFN. The aim of the measurements was the search for deexcitations of the 178m2Hf isomer induced by inelastic Dark Matter candidates. The process would lead to -ray emission from the excited levels of the 178Hf that are not populated in the spontaneous decay of the 178m2Hf. In this way improved limits on the half-life of eighteen inelastic-dark-matter-induced transitions, at the level of limT1/2∼4×10^5–6×10^6 yr are derived. The parameters’ space of such inelastic candidates is also derived for some given model assumptions. Elements towards progress in sensitivity are briefly mentioned.
Belli, P., Bernabei, R., Cappella, F., Caracciolo, V., Cerulli, R., Danevich, F.a., et al. (2025). Search for deexcitations of 178m2Hf isomer induced by inelastic Dark Matter candidates in ultra-low-background conditions. PHYSICS OF THE DARK UNIVERSE, 50 [10.1016/j.dark.2025.102113].
Search for deexcitations of 178m2Hf isomer induced by inelastic Dark Matter candidates in ultra-low-background conditions
Caracciolo, V.;Leoncini, A.;
2025-10-01
Abstract
The gamma-ray radiation from a 178m2Hf source with an activity of Bq was measured for the first time with two ultra-low-background HPGe spectrometers over a cumulative 1170 h deep underground at the Gran Sasso National Laboratory (LNGS) of the INFN. The aim of the measurements was the search for deexcitations of the 178m2Hf isomer induced by inelastic Dark Matter candidates. The process would lead to -ray emission from the excited levels of the 178Hf that are not populated in the spontaneous decay of the 178m2Hf. In this way improved limits on the half-life of eighteen inelastic-dark-matter-induced transitions, at the level of limT1/2∼4×10^5–6×10^6 yr are derived. The parameters’ space of such inelastic candidates is also derived for some given model assumptions. Elements towards progress in sensitivity are briefly mentioned.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
