Orateur
M.
Florent Boulay
(PhD student Ganil)
Description
Classical novae occur in close binary star systems consisting of white dwarf accreting matter from its companion, main sequence or red giant star. The accreting material provides fuel and the conditions necessary to initiate a thermonuclear explosion on the White Dwarf surface, leading to the synthesis of some heavier types of nuclei and the ejection of material into space.
Among else, novae produce radioactive isotopes, such as 18F, that could be detected by their gamma–ray emission (one of the scientific objective of the INTEGRAL satellite). Why do we focus on 18F? Because the annihilation of positrons generated by its β+ decay is the dominant source of gamma rays during the first hours of a nova explosion. So, The knowledge of the abundance of the 18F in novae is essential because its gamma presentationrays (≤511 keV) are one of the observables, which give insight into nuclear processes of novae.
Depending on the temperature, the β+ decay and two nuclear reactions are in competition for the destruction of 18F : 18F(p,α)15O and 18F(p,γ)19Ne. Unfortunately, present radioactive beams intensities are not sufficient for a direct measurement of those reactions. Nevertheless, these two reactions rates strongly depend on the structure of 19Ne. In particular, the energies, spins, and decay widths of important 19Ne resonances must be determined in order to reduce their uncertainty. Today, only a few intrinsic properties of states have been measured yet experimentally in the excitation energy range of astrophysical interest (commonly called the Gamow window).
Based on the success of the experiment performed at Louvain-La-Neuve (Belgium) in the past, we will realize on November 2013 at GANIL a new and accurate spectroscopy of 19Ne inside the Gamow window via an improved (p,p') inelastic scattering reaction. The experimental setup combines an annular silicon detector and the magnetic spectrometer VAMOS. The latter will be used for the first time to detect protons at zero degree, on the spectrograph mode, thus it will be required to configurate it.
In the talk I will remind the motivations and present for first time the preliminary results from the experiment.
