Abstract
In this work we investigate fusion induced by a radioactive 8 Li projectile on a 4 He gas target, at center-of-mass energies between 0.6 and 5 MeV. The main result is the tendency of the dimensionless fusion cross section σπλ2 to form well visible plateaus alternated to steep rises. This is likely to be the most genuine consequence of the discrete nature of the intervening angular momenta observed so far in fusion reactions right above the Coulomb barrier. A partial-wave analysis, exclusively based on a pure quantal penetration fusion model, identifies a remarkably low-height barrier. Indeed, these plateaus allow enhanced experimental sensitivity to the fusion barrier given that the most barrier-sensitive lowest partial waves are well separated. We expect that the present results for 8 Li+4 He will promote further investigations of the fusion reaction mechanism between very light ions at energies much below the interaction barrier. For the moment, we believe that understanding the plateau origin in the cross section above the barrier will almost certainly be useful to corroborate the extrapolation to the important astrophysical region below the Coulomb barrier, not only in the case of the 8 Li+4 He fusion but also for other systems, such as the 12 C+12 C.
Highlights
IntroductionThe 8Li + α fusion has important astrophysical applications in explosive scenarios such as the big bang nucleosynthesis and the heavy-element production through the r-process
Fusion between light ions plays an important role in many astrophysical sites such as, for instance, quiescent-burning stars, including massive stars beyond H-burning, type Ia supernovae and surface explosions of neutron stars
In this work we investigate the low energy trend of the 8Li + α fusion reaction
Summary
The 8Li + α fusion has important astrophysical applications in explosive scenarios such as the big bang nucleosynthesis and the heavy-element production through the r-process. In neutron rich environments where r-process can take place [13, 14], seed nuclei eventually burnt to heavier elements in the fast neutron captures could be obtained through α-capture reactions, in particular on 8Li. Fig.1a) displays the 8Li + α concordant data set as established in [7]. In Figs.1c) and d) exhibit the same data expressed in the form of dimensionless cross section in units of π 2 Both figures indicate the existence of nearly horizontal plateaus clearly
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