New 32Cl(p,γ)33Ar reaction rate for astrophysical rp-process calculations

H. Schatz, C. A. Bertulani, B. A. Brown, R. R. C. Clement, A. A. Sakharuk, B. M. Sherrill

Submitted on 22 November 2005


The 32Cl(p,γ)33Ar reaction rate is of potential importance in the rp-process powering type I X-ray bursts. Recently Clement et al. \cite{CBB04} presented new data on excitation energies for low lying proton unbound states in 33Ar obtained with a new method developed at the National Superconducting Cyclotron Laboratory. We use their data, together with a direct capture model and a USD shell model calculation to derive a new reaction rate for use in astrophysical model calculations. In particular, we take into account capture on the first excited state in 32Cl, and also present a realistic estimate of the remaining uncertainties. We find that the 32Cl(p,γ)33Ar reaction rate is dominated entirely by capture on the first excited state in 32Cl over the whole temperature range relevant in X-ray bursts. In the temperature range from 0.2 to 1 GK the rate is up to a factor of 70 larger than the previously recommended rate based on shell model calculations only. The uncertainty is now reduced from up to a factor of 1000 to a factor of 3 at 0.3-0.7 GK and a factor of 6 at 1.5 GK.


Comment: To be published in Phys. Rev. C

Subjects: Nuclear Experiment; Astrophysics; Nuclear Theory