Etude de la réaction 18F(p,alpha)15O par réction de transfert pour application à l'émission gamma des novae

Abstract : The gamma-ray emission of novae at and below 511 keV is mainly due to the positron annihilation coming from the 18F beta+ decay. The interpretation from possible observations of this emision, with the INTEGRAL satellite for example, requieres a good knowledge of the 18F nucleosynthesis. In this context, the 18F(p,alpha)15O reaction rate is the most uncertain due to two resonances corresponding to 19Ne excited states of Ex = 6.419 and 6.449 MeV whose proton widths are totally unknown. We determined these proton widths using a one nucleon transfer reaction D(18F,p alpha)15N populating the 19F analog levels of the states of astrophysical interest. We used a 18F radioactive beam accelerated to 14 MeV at the "Centre de Recherche du Cyclotron" of Louvain--la--Neuve inpinging on a CD2 target in reverse kinematics as well as a the silicium multistrip detector LEDA. A DWBA analysis allowed to obtain the proton widths of the two resonances and showed that their contribution to the reaction rate could not be neglected. A carefull study of the remaining uncertainties on the reaction rate has been done, especially taking into account interferences between these two resonances and another one at higher energy in 19Ne. The reaction rate obtained only slightly differs from the previous one but is now established on a firmer basis. This will allow a better interpretation of futures gamma-ray observations and hence better constraints on astrophysical models.
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Contributor : Nicolas de Séréville <>
Submitted on : Monday, January 10, 2005 - 6:18:32 PM
Last modification on : Friday, March 15, 2019 - 2:28:05 PM
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  • HAL Id : tel-00007988, version 1



Nicolas de Séréville. Etude de la réaction 18F(p,alpha)15O par réction de transfert pour application à l'émission gamma des novae. Astrophysique [astro-ph]. Université Paris-Diderot - Paris VII, 2003. Français. ⟨tel-00007988⟩



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