Speaker
Daniel Galaviz
(Centro de F´ısica Nuclear da Univ. de Lisboa, 1649-003 Lisbon, Portugal)
Description
Type I X-ray bursts are thermonuclear runaways that occur on the surface of neutron stars in binary systems with low-mass companions. These systems, in some cases, host the so-called rapid proton capture process (rp–process) [1,2]. Under high temperature (T ~2 GK) and density (rho> 1E5 g/cm3) conditions in the burning layer, the nuclear reaction network of the rp- process runs close to the proton drip-line via series of (alpha,p) and (p,gamma) reactions, and subsequent beta+ decays, thus creating proton-rich nuclei. The modeling of these astrophysical objects and the correct description of their observables (i.e. light emission curves) relies on correct nuclear physics input.
Concerning the mass region A >40, proton capture rates are often dominated by a few resonances and therefore statistical methods can not be applied. In order to reduce the uncertainties in the calculation of resonant proton capture rates, neutron removal experiments on exotic beams have been performed at the National Superconducting Cyclotron Laboratory at Michigan State University to precisely determine the excitation energy levels of nuclei located along the rp–process path [3,4,5].
This contribution presents the results obtained from those experiments.
[1] R. K. Wallace, S. E. Woosley, Astrophys. J. Suppl. 45 (1981) 389.
[2] H. Schatz et al., Phys. Rep. 294 (1998) 167.
[3] R. R. C. Clement et al., Phys. Rev. Lett. 92 (2004) 172502.
[4] D. Galaviz et al., to be submitted
[5] A. M. Amthor, Ph. D. Thesis, Michigan State University, 2008
Author
Daniel Galaviz
(Centro de F´ısica Nuclear da Univ. de Lisboa, 1649-003 Lisbon, Portugal)