Pair Transfer Reactions and Nuclear Matrix Elements for Neutrinoless Double Beta Decay

We test the validity of using the Quasiparticle Random Phase Approximation incalculating the nuclear matrix elements for neutrinoless double beta decay of 136Xe. The approximation is tested by measuring the transition strengths to the ground state and to excited 0` states in the residual nucleus via the (3He, n) two proton dropoff reaction. In this thesis, we describe the experimental techniques and data analysis methods developed and used to perform cross-section measurements of the (3He, n) reaction on 134Xe and 136Xe. We report our cross-section results as a differential cross section at a 3He lab energy of 26 MeV and a neutron scattering angle of 0 degrees. The cross section for the reaction on 134Xe was measured to be 355 ̆ 33 μb/sr, and the cross section for the reaction on 136Xe was measured to be 205 ̆ 19 μb/sr. In both reactions, strong transitions to 0` excited states were observed, though these transitions were much stronger for 136Xe. These results indicate a failure of the BCS approximation (commonly used as part of the QRPA) to describe the ground state of the 136Xe isotope and a possible failure for the 134Xe isotope as well.