Design study of a HPGe detector array for β-decay investigation in laboratory ECR plasmas

In the frame of PANDORA project, a new experimental approach aims at measuring in-plasma β-decay rate as function thermodynamical conditions environment, namely laboratory magnetized plasma able to mimic some stellar-like conditions. The decay rates (expected change dramatically ionization state) will be measured charge state distribution ions. correlating environment and rate. This can performed by simultaneously identifying discriminating—through an innovative multi-diagnostic system working synergically with γ -ray detection —the photons emitted -rays after isotope β -decay. this study, numerical simulations supporting design detector array, including statistical significance study check feasibility rates, are presented. Geant4 focused on array detectors evaluation total efficiency depending type optimal displacement around trap (including collimation systems shielding). simulation results showed that, due technical limitations in number apertures that created magnetic trap, best compromise is use 14 HPGe (70% relative efficiency) surrounding trap. were chosen for their excellent energy resolution (0.2% @ 1 MeV), since harsh (the background represented intense self-emission) strongly affects signal-to-background ratio. Once determined photopeak (0.1–0.2%), sensitivity experiment was checked “virtual run,” exploring measurability first three physical cases PANDORA: 176 Lu, 134 Cs 94 Nb. preliminary demonstrated measurement terms ratio it possible reach. indicated run durations could take from several days 3 months, under investigation, thus shedding light role weak interactions stellar nucleosynthesis.