Indirect ${}^7\mathrm{Li}(p,\alpha {)}^4\mathrm{He}$ reaction at astrophysical energies

Information on the ${}^7\mathrm{Li}(p,\alpha {)}^4\mathrm{He}$ reaction cross section at energies relevant for astrophysics has been obtained by means of the indirect Trojan-horse method applied to the three-body ${}^2\mathrm{H}{(}^7\mathrm{Li},\alpha \alpha )n$ reaction. Measurements at ${}^7\mathrm{Li}$-beam energies of 19, 19.5, 20, and 21 MeV have been carried out. The results are reported in terms of the astrophysical $S\left(E\right)\mathrm{}$ factor. The value $S\left(0\right)\mathrm{}$ measured in the present experiment is compared with that extrapolated from a direct measurement.