Spectroscopy of ¹⁹Ne for the thermonuclear ¹⁵O(α ,γ )¹⁹Ne and ¹⁸F(p ,α )¹⁵O reaction rates

November 2015 • 2015PhRvC..92e5806P

Authors • Parikh, A. • Laird, A. M. • de Séréville, N. • Wimmer, K. • Faestermann, T. • Hertenberger, R. • Seiler, D. • Wirth, H. -F. • Adsley, P. • Fulton, B. R. • Hammache, F. • Kiener, J. • Stefan, I.

Abstract • Uncertainties in the thermonuclear rates of the ¹⁵O (α ,γ ) ¹⁹ Ne and ¹⁸ F(p ,α ) ¹⁵ O reactions affect model predictions of light curves from type I x-ray bursts and the amount of the observable radioisotope ¹⁸F produced in classical novae, respectively. To address these uncertainties, we have studied the nuclear structure of ¹⁹Ne over E_x=4.0 -5.1 and 6.1-7.3 MeV using the (³He¹⁹F,t )¹⁹Ne reaction. We find the J^π values of the 4.14- and 4.20-MeV levels to be consistent with 9 /2^- and 7 /2^- , respectively, in contrast to previous assumptions. We confirm the recently observed triplet of states around 6.4 MeV and find evidence that the state at 6.29 MeV, just below the proton threshold, is either broad or a doublet. Our data also suggest that predicted but yet unobserved levels may exist near the 6.86-MeV state. Higher resolution experiments are urgently needed to further clarify the structure of ¹⁹Ne around the proton threshold before a reliable ¹⁸ F(p ,α ) ¹⁵ O rate for nova models can be determined.

Links

• PREPRINT http://arxiv.org/abs/1511.00901
• ELECTR https://doi.org/10.1103%2FPhysRevC.92.055806