Abstract
We present a new set of 64 Ge(p , γ )65 As and 65 As(p , γ )66 Se reaction rates based on recently evaluated proton separation energies S p (65 As) and S p (66 Se), and nuclear structure data from large-scale shell model calculations. Our new 64Ge(p,g) rate differs from those available in REACLIB by up to two orders of magnitude at temperatures encountered within type I X-ray bursts. We used one-zone post-processing type-I x-ray burst model to test our new rates, and present the astrophysical impact of these rates.
Highlights
Type I x-ray burst (XRB) is generated in the accreted envelope of a neutron star in a close binary star system during thermonuclear explosion
We present a new set of 64Ge(p, γ)65As and 65As(p, γ)66Se reaction rates based on recently evaluated proton separation energies S p(65As) and S p(66Se), and nuclear structure data from large-scale shell model calculations
We have obtained new thermonuclear rates for the 64Ge(p,γ)65As and 65As(p,γ)66Se reactions based on large-scale shell model calculations and proton separation energies, S p(65As) and S p(66Se) derived from a recent mass measurement of the 65As [7] and AME2012 [12]
Summary
Type I x-ray burst (XRB) is generated in the accreted envelope of a neutron star in a close binary star system during thermonuclear explosion. In XRBs, beta decay of these waiting point nuclei may compete with the rate of proton capture. The energy levels of both 65As and 66Se nuclei up to 1 Ex 2 MeV are unmeasured In such missing important nuclear physics input, most of the XRB simulations use 64Ge(p,γ)65As and 65As(p,γ)66Se reaction rates derived from statistical-model. This suggestion is different from the previous expectations [3, 4, 9,10,11] This present work investigates the above controversy with a new set of thermonuclear 64Ge(p,γ)65As and 65As(p,γ)66Se reaction rates based on the updated S p(65As), newly evaluated S p(66Se), see Atomic Mass Evaluation (AME2012) [12], and the nuclear structure information from large-scale shell-model calculations. The astrophysical impact of our new rates and other available rates, e.g. rates from Van Wormer et al [13], from statistical-model (Hauser-Feshbach formalism) NON-SMOKER code [14], and from JINA REACLIB [15]1, has been checked using the post-processing one-zone XRB model
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