The 7Li(p,alpha)4He bare nucleus reaction rate plays a crucial role in primordial nucleosynthesis and lithium depletion. But the measurement of the bare nucleus cross section is usually very difficult because of the presence of the Coulomb barrier and the electron screening effect. The Trojan Horse Method (THM) can be applied to extract the energy dependence of Sb(E) at very low energies without any extrapolation, by measuring the cross section of a proper three body process and has been applied to the 7Li(p,alpha )4He reaction. The value deduced from this experiment is Sb(0)=55 +/- 3 keV*b. From the obtained Sb(E) values it is also possible to measure U_e=330+/-40 eV. The astrophysical implications of these measurements are discussed in the case of solar lithium problem and primordial nucleosynthesis.
Improved cross section measurement for the 7Li(p,alpha)4He reaction and its importance for primordial nucleosynthesis and the lithium problem
DEGL'INNOCENTI, SCILLA;
2003-01-01
Abstract
The 7Li(p,alpha)4He bare nucleus reaction rate plays a crucial role in primordial nucleosynthesis and lithium depletion. But the measurement of the bare nucleus cross section is usually very difficult because of the presence of the Coulomb barrier and the electron screening effect. The Trojan Horse Method (THM) can be applied to extract the energy dependence of Sb(E) at very low energies without any extrapolation, by measuring the cross section of a proper three body process and has been applied to the 7Li(p,alpha )4He reaction. The value deduced from this experiment is Sb(0)=55 +/- 3 keV*b. From the obtained Sb(E) values it is also possible to measure U_e=330+/-40 eV. The astrophysical implications of these measurements are discussed in the case of solar lithium problem and primordial nucleosynthesis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
