An attenuation technique has been used to measure the total reaction cross section ${\sigma }_R$ for the systems $p+{}_{}{}^3{}_{}{}^{}\mathrm{He}$ and $p+{}_{}{}^4{}_{}{}^{}\mathrm{He}$ at 10 and 16 incident proton energies, respectively, between 18 and 48 MeV. The attenuations were measured to about 2% and the elastic corrections are known to about 2%. This results in the ${\sigma }_R$ values being determined to about 8%, with smaller errors than this at the high energies and larger errors than this at the low energies. The data are compared with results from elastic scattering analyses using phase shifts, the optical model, and the resonating-group method.

NUCLEAR REACTIONS $p+{}_{}{}^{3,4}{}_{}{}^{}\mathrm{He}$, $E_p=18\mathrm{}-48$ MeV; measured ${\sigma }_R$; anticoincidence beam-attenuation technique.

• Received 25 August 1975

DOI:https://doi.org/10.1103/PhysRevC.13.451