Nuclear Seminar

Pycnonuclear Fusion in the Crust of Accreting Neutron Stars

Mary Beard
University of Notre Dame

Pycnonuclear fusion processes take place at extreme density conditions of rho >10e+10 g/cm3, anticipated for the core of white dwarfs or the crust of neutron stars. Formalism was developed for predicting pycnonuclear reaction rates for neutron rich nuclei in the carbon to magnesium range. The reaction rates have been used to simulate pycnonuclear burning in the deeper crust of an accreting neutron star. The pycnonuclear reaction rates will be presented and the results of the nucleosynthesis simulations will be discussed.

New Experimental Studies of ⁴⁴Ti Production

Daniel Robertson
University of Notre Dame

The main production reaction of ⁴⁴Ti observed in core collapse supernovae is the ⁴⁰Ca(a,g)⁴⁴Ti reaction. A number of different experimental studies have been performed over the last years to determine the stellar reaction rate. These measurements were based on in-beam gamma spectroscopy techniques, accelerator mass spectrometer (AMS) techniques, and inverse reaction techniques with a recoil separator for separating and detecting the reaction products. The experimental results showed drastic differences. New experiments have been performed at the DTL Bochum and at the NSL Notre Dame using gamma spectroscopy and the AMS techniques, respectively to investigate the reaction and the present discrepancies in the predictions. The results of the experiments will be presented and the impact on the reaction rate will be discussed.

Monday, October 5, 2009   4:00 p.m.   NSH 124
(Refreshments served prior to seminar in NSH 124)