Particle Physics in Birmingham

Particle Physics Seminar

Wednesday 14th June 2023 at 13:30

(coffee served at 1315)

The Status and Prospects for LEGEND

Giuseppe Salamanna (Roma3 University)


If neutrinos were the one (and only) instance of elementary particles of the Majorana type, they could undergo a hypothetical process violating lepton number, the so-called Neutrinoless double-beta decay. If indeed it were observed, that would be enough to claim the Majorana nature of neutrinos. Several experiments have been conceived, which search for this mode in a handful of isotopes, baring a favourable energy-momentum configuration. A variety of experimental techniques are being employed in the quest. So far the best statistical sensitivity on the half-life for the process occurrence is of around 10^{26} yr and belongs to experiments employing Ge76 (germanium) both as source and as semi-conducting detector. It comes from an experiment called GERDA, based at the Italian underground Laboratori Nazionali del Gran Sasso (LNGS). In this seminar I will focus on the child born of GERDA and its US counterpart, the "MAJORANA Demonstrator": LEGEND. Using a two-stage approach with about 200 kg first and then 1000 kg of germanium diodes enriched in Ge76, LEGEND aims to attain a sensitivity around 10^{28} years in half-life, probing the inverted-ordering of the neutrino masses. I will review the general concept and design of LEGEND; describe the detectors and their current performance in the present LEGEND-200 phase, after several months of commissioning and physics data taking at LNGS. I will also illustrate how the backgrounds can have a dramatic effect on the search; and in which way this can be mitigated, with some emphasis on the use of the liquid-argon detector. Finally, I will provide an expected timeline to get LEGEND-1000 up and running and the related R&D activities.