Level structure of the Tz=-1 nucleus Ar 34 and its relevance for nucleosynthesis in ONe novae

The Mg24+C12 fusion reaction was used to perform a detailed γ-ray spectroscopy study of the astrophysically important nucleus Ar34. In particular, an experimental setup, coupling the advanced γ-ray tracking array GRETINA with the well-established Argonne fragment mass analyzer (FMA), was employed to obtain excitation energies and spin-parity assignments for excited states in Ar34, both above and below the proton separation energy. For the first time, an angular distribution analysis of in-beam γ rays from fusion-evaporation reactions, using a tracking array, has been performed and Coulomb energy differences of analog states in the T=1, A=34 mirror system, explored from 0 to 6 MeV. Furthermore, we present a comprehensive discussion of the astrophysical Cl33(p,γ) stellar reaction rate, together with implications for the identification of nova presolar grains from sulfur isotopic abundances.
This work was supported by the U. S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract No. DEAC02-06CH11357 and Grants No. DEFG02- 94-ER40834, No. DEFG02-97-ER41041, No. DEFG02- 97-ER41043, No. DEFG02-94-ER40848, and No. DESC0014231. United Kingdom personnel were supported by the Science and Technologies Facilities Council (STFC) and C.A. was supported by the Natural Sciences and Engineering Research Council of Canada. J.J. acknowledges support from Spanish MINECO Grant No. AYA2017-86274-P, the E.U. FEDER funds, and AGAUR/Generalitat de Catalunya Grant No. SGR-661/2017. This research uses resources of ANL’s ATLAS facility, which is a DOE Office of Science User facility