Enriched high purity germanium detectors for the LEGEND-200 experiment: purification and characterization by quadrupole and high resolution inductively coupled plasma mass spectrometry (ICP-MS)

Abstract

LEGEND-200 (Large Enriched Germanium Experiment for Neutrinoless ββ Decay) is a physics experiment at the Gran Sasso National Laboratories (LNGS) in Italy searching for neutrinoless double beta (0υββ) decay of ⁷⁶Ge using enriched high purity germanium (HPGe) detectors with a total mass of about 200 kg. During the production of germanium crystals, especially during the crystal cutting, a fraction of the enriched germanium remains as metal residues. To reuse these residual materials again for crystal growing, they must be efficiently purified. A special plant was built to purify and convert Ge metal to GeO₂. Quadrupole ICP-MS (Q-ICP-MS) and High Resolution ICP-MS (HR-ICP-MS) were used to characterize the starting materials, reaction and final products. The results of the analyses are presented here.

Keywords: Germanium; Germanium oxide; Inductively coupled plasma mass spectrometry; Neutrinoless double beta decay; Purification.