Evidence for direct reaction mechanism in at thermonuclear energies

New determination of proton spectroscopic factors and reduced widths forBe8states in the 16.5–18.0 MeV excitation energy region via the study of theLi7(Belhout1, Ouichaoui2, Beaumevieille3 et al. 2017Phys. Rev. C4000View full textAdd to dashboardCite

“…The corresponding results can be very helpful to obtain reliable informations on the abundance of lithium and beryllium isotopes in different astrophysical sites. On the other hand, these results strongly support existing clear experimental evidences for ( 8 Be) compound nucleus formation in the 7 Li(p,α) 4 He fusion reaction at thermonuclear energies, in contrast with previous indications [32] according to which a three-nucleon transfer reaction mechanism would dominate the proton sub-Coulomb energy regime of this reaction. [30] and to shell model calculated [13,54] counterparts.…”

“…Besides, Basak et al [30] have measured the 7 Li( − − → [9][10][11][12][28][29][30][31] and references therein), not only the corresponding spectroscopic information remains incomplete but the structures of these two special states steadily seem to be complex and not well elucidated. On the other hand concerning the reaction mechanism prevailing at thermonuclear temperatures in the 7 Li(p,α) 4 He proton capture reaction, a previous DWBA analysis [32] of precise cross section experimental data available for E p = (13 −10 3 ) keV proton energies [32,33] have led the authors to an apparently good agreement between theory and experiment, thus suggesting to interpret the data in terms of a dominant three-nucleon direct reaction transfer. However, this conclusion contradicts existing clear evidences for 8 Be compound nucleus formation in this reaction, as will be detailed later in Section III.…”

Astrophysical reaction rates forB10(p,α)7Rauscher1, Raimann2 1996Phys. Rev. CSelf Cite331250View full textAdd to dashboardCite

“…For example, the reactions of the ppchains in the Sun are known to be mainly dominated by such direct mechanisms [18,19]. Recent theoretical investigations of a number of sub-Coulomb transfer reactions [20,21,22,23,24] have also shown that they can be described by a direct reaction potential model like the distorted wave Born approximation (DWBA). Although "direct reaction" is often used synonymously with "non-resonant", the same potentials that describe the direct mechanism can give rise to resonances corresponding to energy levels in the projectile-target system.…”

“…In the sub-Coulomb energy range of (p,α) reactions the DWBA method has previously only been used to analyze non-resonant parts of the excitation functions [21,22]. We want to emphasize, though, that it is possible to reproduce resonance features in a DWBA calculation.…”

Reaction mechanism ofLi7(3Yamamoto1, Kajino2, Kubo3 1993Phys. Rev. C11010View full textAdd to dashboardCite

“…They demonstrated good agreement of the theoretical direct reaction cross section with the observed data at these energies without taking account of any resonance contribution. Recently the DWBA analyses have been applied to the Li(p, He) He [8] and ' F(p, He)' 0 [9) reactions of astrophysical interest, too. These studies have succeeded in describing the observed cross section at stellar energies, suggesting that the direct reaction process may contribute more than previously believed at low Li( H, n) Be at the low energies through careful comparison with the observed data for both reactions.…”