Inelastic Scattering of 20-MeV Tritons fromZr90

Abstract

The inelastic scattering of tritons from ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ was studied at a beam energy of 20 MeV, and angular distributions of states up to 5.22 MeV of excitation were obtained. The data are compared with distorted-wave calculations, employing both collective and shell-model form factors. Both calculations reproduce the shapes of the experimental angular distributions quite well. Values of deformation parameters obtained from the collective-model form-factor calculation are in good agreement with the results of inelastic scattering experiments employing beams of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ ions, but are in poor agreement with the results of proton inelastic scattering measurements. The shell-model analysis assumed an effective two-body interaction between the triton projectile and the target nucleons, and the form-factor calculation employed a Yukawa well with a 1.0-F range. Under these conditions, an effective interaction strength averaging 660 MeV was obtained for the excitation of the well-known pure proton-configuration states. This value is approximately three times the strength obtained in the previous study of proton inelastic scattering from these states. This result supports the assumption that the optical potential has a real well depth approximately three times as great for the triton as for the single nucleon. The strengths of the transitions to the other observed states are also discussed in terms of configurations expected to contribute to the states. Characteristics of the ($t,t^{\prime }$) reaction are compared with those of the ($p,p^{\prime }$) reaction.