Thursday 12 April 2012, 3.15PM

**Speaker(s):** Dr Benjamin Kay, University of York

Determining the mass of the neutrino is arguably one of the major challenges of contemporary physics. An exciting prospect for determining the neutrino mass is through the hypothesised neutrinoless double-beta-decay process. A measurement of the half-life would lead to the neutrino mass if the nuclear matrix elements were known. These quantities cannot be probed experimentally, and as such rely on calculation, which are notoriously uncertain. However, various elements of these calculations can be benchmarked against measureable nuclear observables. Using the 76Ge➞76Se system, we have determined the occupancy of protons and neutrons in the ‘active orbitals’ of the respective 0+ ground states, and the difference between them, thus characterising the ground-state wave functions. The Fermi surface was found to be more diffuse than previous calculations suggested. Pairing properties have also been studied to test the validity of the BCS approximation used in QRPA, one of the major theoretical approaches to calculating the matrix elements. We are continuing this programme by studies of the 130Te➞130Xe and 100Mo➞100Ru systems, where each presents a different experimental challenge. An overview of the programme and its impact will be discussed.

**Location:** P/T111