PhD project: The Legend experiment

Supervisor: Prof. Ruben Saakyan

LEGEND is an experiment designed to search for neutrinoless double beta decay (0vbb) with an unprecedented sensitivity and discovery potential. The observation of this process will have the most profound implications for particle physics. It is the only realistic way to determine the Majorana or Dirac nature of the neutrino, which may shed light on the mechanism behind the dominance of matter over anti-matter in the universe. LEGEND will search for 0vbb of the Ge76 isotope using an array of enriched high purity germanium (HPGe) detectors operated in liquid argon that is used as an active shield. Recent technological breakthroughs have made it possible to operate these detectors as “solid state” time-projection chambers combining an excellent energy resolution of HPGe detectors with particle identification capabilities. This opens up the possibility to search for 0vbb in a background free regime. LEGEND will have two phases: LEGEND-200 with HPGe detectors hosting 200 kg of Ge76, and LEGEND-1000 employing 1000kg of enriched HPGe detectors. LEGEND-200 is currently under construction at the Gran Sasso underground laboratory in Italy with physics data taking commencing in late 2021/early 2022. LEGEND-1000 recently came up as the winner in an international review of the next generation 0vbb experiments.

The UCL group is a key player in LEGEND providing leading contributions to simulations and data analysis, low background technologies and HPGe detector development. A PhD project on the LEGEND experiment will include:
  • Data analysis from LEGEND-200 which will have a record sensitivity to 0vbb with an unrivalled discovery potential.
  • Background model building with a focus on cosmogenic Ar42, one of the most challenging backgrounds that must be mitigated to reach the LEGEND ultimate sensitivity.
  • Technological developments for LEGEND-1000 and beyond including ultra-low background radio assays and next generation HPGe detectors.

    More details on Legend at UCL can be found here.

    For more details please contact r.saakyan at ucl.ac.uk