Fusion cross-section measurements in the Ne-Mg region to constrain pycnonuclear burning in the neutron star crust

Pycnonuclear reactions occur in a highly dense matter when nuclei are frozen in lattice structures. One such site is the crust of accreting neutron stars where the pycnonuclear reactions serve as an important heat source. Various studies have shown that the fusion of neutron-rich isotopes of Ne and Mg are most important among the pycnonuclear reactions in neutron star crusts. In the absence of any data on these fusion reaction cross-sections, theoretical cross-sections remain highly uncertain. A program has been initiated at the University of Notre Dame to measure the fusion cross-sections in the Ne-Mg region using the Notre Dame (ND)-Cube, a newly commissioned active-target Time Projection Chamber (TPC).  We will discuss the use of Ne-based gas mixtures as a target gas where the high gain has been achieved using the thick gas electron multipliers. Preliminary results from the first study of 20Ne+24Mg fusion cross-sections will be discussed. These measurements demonstrate the capabilities of TPCs as a highly efficient system to measure cross-sections below the fusion barrier and therefore provide a stringent test of theoretical model predictions. Future plans to measure the fusion cross-sections along the neon isotopic chain will be discussed.