ALPHA-SCATTERING AND CAPTURE REACTIONS IN THE A = 7 SYSTEM AT LOW ENERGIES

Differential cross sections for He-3-alpha scattering were measured in the energy range up to 3 MeV. These data together with other availabl e experimental results for He-3 +alpha and H-3 +alpha scattering were analyzed in the framework of the optical model using double-folded pot entials. The optical potentials obtained were used to calculate the as trophysical S factors of the capture reactions He-3(alpha, gamma)Be-7 and H-3(alpha,gamma)Li-7, and the branching ratios for the transitions into the two final Be-7 and Li-7 bound states, respectively. For He-3 (alpha, gamma)Be-7 excellent agreement between calculated and experime ntal data is obtained. For H-3(alpha, gamma)Li-7 an S(0) value has bee n found which is a factor of about 1.5 larger than the adopted value. For both capture reactions a similar branching ratio of R = sigma(gamm a1)/sigma(gamma0) almost-equal-to 0.43 has been obtained.