Trojan Horse method and radioactive ion beams: study of 18F(p,α)15O reaction at astrophysical energies, M. Gulino, INFN, LNS and Univesita' degli Studi di Enna Kore, Italy − For the first time, the Trojan Horse Method (THM) was applied to study a reaction induced by a radioactive ion beam. In particular, the 18F(p,α)15O process was investigated at low energies relevant for astrophysics via the 18F(d,α15O)n reaction.

 

The γ-ray emission from classical novae is dominated by positron annihilation resulting from the beta decay of radioactive nuclei, and especially of 18F (τ=110 min).  Consequently, the knowledge of the nuclear reaction rate of production and destruction of 18F is mandatory to calculate the amount of 18F synthesized in novae and the resulting γ-ray radiation intensity.

 

The 18F destruction channel given by the 18F(p,α)15O reaction was in particular investigated by many recent experiments.  Despite significant progress, the cross section in the range of the low energies covering novae temperatures is still unknown.  Moreover, the population of several resonances of the 19Ne compound nucleus makes extremely difficult the extrapolation of the reaction rate down to low energies.

 

In this framework, the 18F(p,α)15O reaction cross section has been for the first time investigated in the energy range from 0 up to 700 keV by applying the THM to the 18F(d,α15O)n reaction.  The 18F beam produced at the CRIB facility at RIKEN, Japan, was focused onto a CD2 target and the ejected particles were detected using a new designed experimental set-up covering a large solid angle.  The obtained results and their implication on astrophysics will be discussed.