Measurement of the 30S+α system for type I X-ray bursts

Abstract

The 30S(α, p) reaction is considered to be important in the nuclear trajectory to higher mass in type I X-ray bursts. The reaction flow encounters a bottle-neck at 30S, owing to the competition of photo-disintegration with further proton capture, and because the half-life of this isotope is on the order of the burst rise timescale. Different burst simulations by various researchers indicate the (α,p) reaction may by-pass this waiting point, depending on the stellar reaction rate, which has not previously been measured experimentally, and the structure of the compound nucleus 34Ar is not well understood above the alpha-threshold. The 30S(α, p) reaction could explain rare bolometrically double-peaked burst profiles, appears to make a considerable contribution to the overall energy generation, and affects the neutron star crustal composition for the recurrent inertia required in burst models to reproduce astronomical observations. Using a low-energy 30S radioactive ion beam and an active target technique (a helium gas mixture serves as both a target gas and a detector fill gas), we acquired data on both alpha elastic scattering of 30S as well as the 30S(α, p) reaction simultaneously at relevant energies for X-ray bursts. We present for the first time the status of the data analysis and the preliminary results of this research. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.