Discovery of ^34g,mCl(p, γ)³⁵Ar Resonances Relevant for Classical Nova Nucleosynthesis

Abstract

Sulfur isotopic ratios have the potential to distinguish presolar grains of classical novae and type II supernovae origin. The current lack of experimentally determined 34g,m Cl(p, γ) 35 Ar reaction rates leads to large uncertainties in the production of 34 S in oxygen-neon classical nova models. As a first step toward determining these reaction rates, we have measured 35 Ar resonances up to 800 keV above the 35 Ar proton emission threshold. These resonances were populated using the 36 Ar(d, t) 35 Ar reaction, and the tritons were momentum analyzed by a high resolution quadrupole-dipole-dipole-dipole (Q3D) magnetic spectrograph. Seventeen new 35 Ar levels have been discovered, and uncertainties associated with the energies of the five previously known levels have been substantially reduced. Experimental level densities were then compared to calculated level densities, using the WBMB Hamiltonian within the sd − p f model space. This comparison indicates that most of the expected resonances in this region have been observed.