ElasticαAngular Distributions in the Sharp Cutoff Model

An analysis is made in terms of a semiclassical strong absorption model of all published angular distributions of intermediate energy alpha particles elastically scattered from heavy or medium weight nuclei as well as some examples of elastic proton and deuteron scattering. Moderately good agreement is found for radii obtained from different sets of data and also from analysis of fixed angle, variable energy experiments; there is some indication that the sharp cutoff radius increases as the bombarding energy is lowered to the Coulomb barrier. The connection between these results and optical model parameters is discussed. The best-fit critical angular momenta, $l^{\prime }$, are found to be essentially equivalent to the largest angular momenta, $l_m$, such that the $l_m\mathrm{th}$ potential barrier is classically surmounted by the bombarding particle when the most recent optical model parameters are used to represent the nuclear potential. It is suggested that, when the penetration depth is small, the most important "effective" parameter is $l_m$.