Nuclear reactions among charged particles in stars take place at energies generally well below the Coulomb barrier, so its penetration factor exponentially suppresses the cross section down to values as small as few nanobarns or picobarns. Reaching astrophysical energies opens new challenges and calls for new approaches. In this work, the scope of nuclear astrophysics will be introduced and how experiments are usually conducted will be discussed. In particular, we will focus on the use of indirect methods as complementary approaches to direct measurements, introducing the asymptotic normalisation coefficient (ANC) technique and the Trojan Horse Method (THM), used to deduce the cross sections of reactions with photons and charged particles in the exit channel, respectively, with no need for extrapolation. Recent results of the application of the two methods will be exposed: the \(^6\mathrm {Li}({^3\mathrm {He}},d)^7\mathrm {Be}\) measurement used to deduced the ANCs of the \(^3\mathrm {He}+{^4\mathrm {He}}\to {^7\mathrm {Be}}\) and \(p+{^6\mathrm {Li}}\to {^7\mathrm {Be}}\) channels and the corresponding radiative capture cross sections. Then, the THM measurement of the \(^{27}\mathrm {Al}(p,\alpha )^{24}\mathrm {Mg}\) cross section through the \(^2\mathrm {H}(^{27}\mathrm {Al},\alpha {^{24}\mathrm {Mg}})n\) reaction will be reviewed, as well as the \(^{12}\mathrm {C}+{^{12}\mathrm {C}}\) fusion reaction cross section using \(^{14}\)N to transfer \(^{12}\)C and induce the reaction of astrophysical importance down to astrophysical energies. The indirect measurements made it possible to assess the occurrence of several resonances that are responsible for significant changes in the reaction rate at relevant temperatures. Abstract Published by the Jagiellonian University 2025 authors
Read more