In-situ production of radioisotopes by cosmic muon interactions may generate a non-negligible background for deep underground rare event searches. Previous Monte Carlo studies for the GERDA experiment at LNGS identified the delayed decays of Ge-77 and its metastable state( 77m)Ge as dominant cosmogenic background in the search for neutrinoless double beta decay of 76 Ge. This might limit the sensitivity of next generation experiments aiming for increased( 76)Ge mass at background-free conditions and thereby define a minimum depth requirement. A re-evaluation of the( 77(m))Ge background for the GERDA experiment has been carried out by a set of Monte Carlo simulations. The obtained Ge-77(m) production rate is (0.21 +/- 0.01 ) nuclei/(kg.year). After application of state-of-the-art active background suppression techniques and simple delayed coincidence cuts this corresponds to a background contribution of (2.7 +/- 0.3) x 10(-6) cts/(keV.kg.year). The suppression achieved by this strategy equals an effective muon flux reduction of more than one order of magnitude. This virtual depth increase opens the way for next generation rare event searches.
Virtual depth by active background suppression: revisiting the cosmic muon induced background of GERDA Phase II
Pandola, Luciano;
2018-01-01
Abstract
In-situ production of radioisotopes by cosmic muon interactions may generate a non-negligible background for deep underground rare event searches. Previous Monte Carlo studies for the GERDA experiment at LNGS identified the delayed decays of Ge-77 and its metastable state( 77m)Ge as dominant cosmogenic background in the search for neutrinoless double beta decay of 76 Ge. This might limit the sensitivity of next generation experiments aiming for increased( 76)Ge mass at background-free conditions and thereby define a minimum depth requirement. A re-evaluation of the( 77(m))Ge background for the GERDA experiment has been carried out by a set of Monte Carlo simulations. The obtained Ge-77(m) production rate is (0.21 +/- 0.01 ) nuclei/(kg.year). After application of state-of-the-art active background suppression techniques and simple delayed coincidence cuts this corresponds to a background contribution of (2.7 +/- 0.3) x 10(-6) cts/(keV.kg.year). The suppression achieved by this strategy equals an effective muon flux reduction of more than one order of magnitude. This virtual depth increase opens the way for next generation rare event searches.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
