Speaker
Mr
Alexander Long
(Universty of Notre Dame)
Description
Type 1 X-ray Bursts are identified as thermonuclear explosions on the surface of accreting neutron stars. These bursts can be observed and characterized through their bolometric luminosity curves. In a small number of type 1 X-ray bursts, a double peak structure in the light curve has been observed. This double peak structure lead Fisker et al to propose a nuclear waiting point impedance in the thermonuclear reaction flow of the αp-process, and conclude that uncertainties in (α,p) reactions rates on these potential waiting points can be directly observed in the structure of X-ray burst light curves [1]. (α,p) reaction rates on two possible waiting point nuclei, 26Si and 34Ar, were examined by investigating the level structure in the respective compound nucleus, 30S and 38Ca. This was done through high-precision measurements of 32S(p,t)30S and 40Ca(p,t)38Ca reactions utilizing the high energy-resolution zero-degree techniques with the K600 spectrometer at iThemba LABS [2]. States above the α-threshold have been identified and precise excitation energies were determined. These excitation energies, along with calculated level parameters were then used to determine the reaction rates for the 26Si(α,p) and 34Ar(α,p) reaction over stellar temperature ranges. Experimental excitation energies along with calculated reactions rates will be presented.
Ref.
[1] J L Fisker, F K Thielemann, and M Wiescher. The nuclear reaction waiting points: 22Mg, 26Si, 30S, and 34Ar and bolometrically double-peaked type I X-ray bursts. The Astrophysical Journal, 608(1):L61, 2008.
[2] R Neveling, H Fujita, F D Smit, T Adachi, G P A Berg, E Z Buthelezi, J Carter, J L Conradie, M Couder, R W Fearick, S V Fortsch, D T Fourie, Y Fujita, J Gorres, K Hatanaka, M Jingo, A M Krumbholz, C O Kureba, J P Mira, S H T Murray, P von Neumann-Cosel, S O'Brien, P Papka, I Poltoratska, A Richter, E Sideras-Haddad, J A Swartz, A Tamii, I T Usman, and J J van Zyl. High energy-resolution zero-degree facility for light-ion scattering and reactions at iThemba LABS. Nuclear Inst. and Methods in Physics Research, A, 654(1):29{39, October 2011.
Primary author
Mr
Alexander Long
(Universty of Notre Dame)
Co-authors
E. Sideras-Haddad
(Technische Universität Darmstadt)
E.Z. Buthelezi
(iThemba LABS)
F.D. Smit
(iThemba LABS)
G.P.A. Berg
(University of Notre Dame)
I. Usman
(iThemba LABS)
J. Carter
(University of Witwatersrand)
J. Görres
(University of Notre Dame)
J. Mira
(iThemba LABS)
J.A. Swartz
(iThemba LABS)
J.J. Van Zyl
(University of Witwatersrand)
M. Couder
(University of Notre Dame)
M. Weischer
(University of Notre Dame)
R. Fearick
(University of Cape Town)
R. Neveling
(iThemba LABS)
R. Talwar
(University of Notre Dame)
S. Murray
(iThemba LABS)
S. O’Brien
(University of Notre Dame)
S.V. Förtch
(iThemba LABS)
T. Adachi
(Tohoku University)
Y. Kheswa
(iThemba LABS)
