Browsing by Author "Berg, G. P. A."

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    Indirect study of the stellar ³⁴ Ar(α,p) ³⁷K reaction rate through ⁴⁰Ca(p,t) ³⁸Ca reaction measurements
    (American Physical Society, 2017) Long, A. M.; Adachi, T.; Beard, M.; Berg, G. P. A.; Buthelezi, Z.; Carter, J.; Couder, M.; deBoer, R. J.; Fearick, R. W.; Fortsch, S. V.; Gorres, J.; Mira, J. P.; Murray, S. H. T.; Neveling, R.; Papka, P.; Smit, F. D.; Sideras-Haddad, E.; Swartz, J. A.; Talwar, R.; Usman, I. T.; Wiescher, M.; Van Zyl, J. J.; Volya, A.
    The ³⁴Ar(α,p)³⁷K reaction is believed to be one of the last in a sequence of (α,p) and (p,γ) reactions within the Tz=−1, sd-shell nuclei, known as the αp-process. This process is expected to influence the shape and rise times of luminosity curves coming from type I x-ray bursts (XRBs). With very little experimental information known on many of the reactions within the αp-process, stellar rates are calculated using a statistical model, such as Hauser-Feshbach. Questions on the applicability of a Hauser-Feshbach model for the ³⁴Ar(α,p) ³⁷K reaction arise due to level density considerations in the compound nucleus, 38Ca. We have performed high energy-resolution forward-angle ⁴⁰Ca(p,t)³⁸Ca measurements with the K=600 spectrograph at iThemba LABS in order to identify levels above the α-threshold in ³⁸Ca. States identified in this work were then used to determine the ³⁴Ar(α,p)³⁷K reaction rate based on a narrow-resonance formalism. Comparisons are made to two standard Hauser-Feshbach model predicted rates at XRB temperatures.