engleski

The ^7Li(P, alpha)^4He fusion reaction studied via the Trojan Horse Method and its astrophysical implications

The ^7Li(p, alpha)4He bare nucleus S(E)-factor, S, (E) plays a key role in the lithium problem. The presence of the Coulomb barrier and elec- tron screening effect makes this measurement at astrophysical energies very hard to perform. Thus experimental S(E)-factors are usually corrected for the electron screening enhancement factor and then extrapolated to nearly zero energies. The Trojan Horse Method [l] can be applied to ex- tract the energy dependence of &, (E), at very low energies without any extrapolation, by mea- suring the cross section of a suitable three body process. We have applied the THM to study the 7Li(p, o)4He reaction through the 7Li(d, o:cy)n three body process and the value deduced from this experiment, using the DWBA approach, is $(0)x55 f 3 keV.b [2], slightly different from the value reported in the NACRE compilation. It is also possible to measure the electron screening potential U, which in this case is 330f40 eV. The FRANEC code was then used to calculate the sur- face lithium abundance during the Sun lifetime ; the two calculations, with rates derived from [2] and from NACRE, are shown in fig. 1.

Trojan horse method; fusion reactions

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