Indirect study of 11B(p,image)8Be and 10B(p,α)7Be reactions at astrophysical energies by means of the Trojan Horse Method: recent results Original Research Article

Nuclear (p,α) reactions destroying the so-called “light-elements” lithium, beryllium and boron have been largely studied in the past mainly because their role in understanding some astrophysical phenomena, i.e. mixing-phenomena occurring in young F-G stars [A.M. Boesgaard et al., Astr. Phys. J, 991, 2005, 621]. Such mechanisms transport the surface material down to the region close to the nuclear destruction zone, where typical temperatures of the order of ∼106 K are reached. The corresponding Gamow energy View the MathML source [C. Rolfs and W. Rodney, “Cauldrons in the Cosmos”, The Univ. of Chicago press, 1988] is about ∼10 keV if one considers the “boron-case” and replaces in the previous formula Zx=1, ZX=5 and T6=5. Direct measurements of the two 11B(p,α0)8Be and 10B(p,α)7Be reactions in correspondence of this energy region are difficult to perform mainly because the combined effects of Coulomb barrier penetrability and electron screening [H.J. Assenbaum, K. Langanke and C. Rolfs, Z. Phys., 327, 1987, 461]. The indirect method of the Trojan Horse (THM) [G. Baur et al., Phys. Lett. B, 178, 1986, 135; G. Calvi et al., Nucl. Phys. A, 621, 1997, 139; C. Spitaleri et al., Phys. Rev. C, 493, 1999, 206] allows one to extract the two-body reaction cross section of interest for astrophysics without the extrapolation-procedures. Due to the THM formalism, the extracted indirect data have to be normalized to the available direct ones at higher energies thus implying that the method is a complementary tool in solving some still open questions for both nuclear and astrophysical issues [S. Cherubini et al., Astr. Phys. J, 457, 1996, 855; C. Spitaleri et al., Phys. Rev. C, 63, 2001, 005801; C. Spitaleri et al., Phys. Rev. C, 63, 2004, 055806; A. Tumino et al., Phys. Rev. Lett., 98, 2007, 252502; M. La Cognata et al., Phys. Rev. Lett., 101, 2007, 152501; M.L. Sergi et al., AIPC, 1016, 2008, 433; H.W. Becker, Z. Phys. A, 327, 1987, 341; T. Rauscher and G. Raimann, Phys. Rev. C, 53, 1996, 5; F.C. Barker, Nucl. Phys. A, 707, 2002, 277; L. Lamia et al., Nuovo Cimento C, 31, 2008, 423; L. Lamia et al., Nucl. Phys. A, 787, 2007, 309c; M.G. Del Santo et al., Proc. of the 10th Symp. on Nuclei in the Cosmos, 2008; C. Angulo et al., Z. Phys. A, 345, 1993, 231].