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 2021. The UCL group is a key player in LEGEND and has a number of leadership positions in the collaboration including Analysis Coordinator and Chair of the Institutional Board. 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.


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