Eur. Phys. J. Plus (2016) 131: 345
https://doi.org/10.1140/epjp/i2016-16345-6

Regular Article

Toward concordance of and values for proton unbound ³¹S states

¹ Departament de Física i Enginyeria Nuclear, EUETIB, Universitat Politècnica de Catalunya, E-08036, Barcelona, Spain
² Institut d’Estudis Espacials de Catalunya, E-08034, Barcelona, Spain
³ Department of Physics and Astronomy, Michigan State University, 48824, East Lansing, MI, USA
⁴ National Superconducting Cyclotron Laboratory, Michigan State University, 48824, East Lansing, MI, USA

^* e-mail: Wrede@nscl.msu.edu

Received: 12 June 2015
Accepted: 3 September 2016
Published online: 30 September 2016

Abstract

Nucleosynthesis in classical novae on oxygen-neon white dwarfs is sensitive to the poorly constrained thermonuclear rate of the ³⁰ P(p,)³¹ S reaction. In order to improve this situation, a variety of experiments have been performed over the past decade to determine the properties of proton unbound ³¹S levels up to an excitation energy of MeV. Inconsistencies in the energies and values for these levels have made it difficult to produce a useful ³⁰ P(p,)³¹ S reaction rate based on experimental information. In the present work, we revisit a subset of published data on the structure of ³¹S in order to shed light on these problems. First, we present an alternative calibration of ³¹ P(³ He, t)³¹ S spectra using newly available high-precision data in order to address discrepant ³¹S excitation energies. Second, we apply a similar method to a recently acquired ³² S(d, t)³¹ S spectrum. Third, for a different ³¹ P(³ He, t)³¹ S experiment in which angular distributions were acquired, we present alternative fits to the experimental data in order to address discrepant ³¹S values. Finally, we compare the values from ³¹ P(³ He, t)³¹ S to those reported from in beam -ray spectroscopy experiments in order to search for potential resolutions to the inconsistencies. Overall, viable new solutions to some of the problems emerge, but other problems persist.