High resolution spectroscopy of 19Ne to determine the production of 18F in novae

by Laurie Dienis, 1st year Phd student at GANIL

Gamma-rays emitted by the decay of radioactive isotopes are clues to understanding the nucleosynthesis and dynamics of stars. Classical novae, the second most frequent stellar explosions in the Galaxy, can be investigated with the annihilation line from β+ decay of 18F that should generate the most intense flux. Yet, this is currently very difficult to bring accurate estimations of the production of 18F. Its main destruction path, via the reaction 18F(p, α)15O, is to this day highly uncertain because of a lack of spectroscopic data for the compound nucleus 19Ne in the Gamow window.  

The goal of the experiment of my PhD is to reduce these uncertainties by measuring the excitation energies, spins and α partial widths of the levels in 19Ne which are located near the proton threshold. To this end, the approach using elastic scatterings α(15O, α)15O will be used to probe the aimed levels. Depending on the 19Ne measured properties in this experiment, the reaction rate can change the amount of 18F produced during classical novae by a factor 3.5.