Pulse shape discrimination studies with a Broad-Energy Germanium detector for signal identification and background suppression in the GERDA double beta decay experiment

First studies of event discrimination with a Broad-Energy Germanium (BEGe) detector are presented. A novel pulse shape method, exploiting the characteristic electrical field distribution inside BEGe detectors, allows to identify efficiently single-site events and to reject multi-site events. The first are typical for neutrinoless double beta decays (0νββ) and the latter for backgrounds from gamma-ray interactions. The obtained survival probabilities of back­grounds at energies close to Qββ(76Ge) = 2039 keV are (0.93 ± 0.08)% for events from 60Co, (21 ± 3)% from 226Ra and (40 ± 2)% from 228Th. This background suppression is achieved with (89 ± 1)% acceptance of 228Th double escape events, which are dominated by single site inter­actions. Approximately equal acceptance is expected for 0νββ-decay events. Collimated beam and Compton coincidence measurements demonstrate that the discrimination is largely inde­pendent of the interaction location inside the crystal and validate the pulse-shape cut in the energy range of Qββ. The application of BEGe detectors in the GERDA and the Majorana double beta decay experiments is under study

Data analysis of the internal background measurements of 40Ca100MoO4 scintillation crystals

The sensitivity of neutrinoless double beta (02) decay experiments is mainly dependent on the internal background of a detector which, in its turn, is defined by the purity of material and possibility for selection of background events. The AMoRE (Advanced Mo based Rare process Experiment) collaboration plans to use 40Ca100MoO4 scintillation crystals as a detector for search of 02 decay of 100Mo isotope. A purpose of this pa-per is further investigation of internal background of 40Ca100MoO4 scintillation elements with a low background setup at YangYang underground laboratory. We present new approaches for selection of background events from analyzing data and the latest updated values of background index of 40Ca100MoO4 crystals as a result of the new technique application

A Study of Radioactive Contamination of 40Ca100MoO4 Crystals for the AMoRE Experiment

A calcium molybdate (CaMoO4) crystal scintillator, with molybdenum enriched in 100Mo and calcium depleted in 48Ca (40Ca100MoO4), was developed by the Advanced Molybdenum based Rare process Experiment (AMoRE) collaboration to search for a neutrinoless double beta (0ν β β) decay of 100Mo. We are planning to use about 10 kg of 40Ca100MoO4 crystals as cryogenic bolometers for the first phase of the experiment (AMoRE-I) at the Yang Yang underground laboratory (Y2L) in Korea. This experiment calls for an extremely low level of radioactive contamination in detectors, particularly by thorium, uranium, and radium decay chains. We measured scintillation properties and radioactive contamination of CaMoO4 and 40Ca100MoO4 crystals at the Y2L. We also estimated the acceptable level of internal radioactive background using Monte Carlo simulation for the AMoRE-I. © 2016 IEEE1681Nsciescopu