Splitting of the Dipole and Spin-Dipole Resonances

Cross sections for the 90,92,94Zr(p,n) reactions were measured at energies of 79.2 and 119.4 MeV. A phenomenological model was developed to describe the variation with bombarding energy of the position of the L=1 peak observed in these and other (p,n) reactions. The model yields the splitting between the giant dipole and giant spin dipole resonances. Values of these splittings are obtained for isotopes of Zr and Sn and for 208Pb.Comment: 14 pages, 4 figure

Mechanisms for reactions of α-particles on 28Si at Eα = 65 MeV leading to three-body final states

A kinematically complete measurement has been made of all charged particles produced by 65 MeV a-particles on Si. Singles, coincidence and projected energy spectra are presented. The following processes have been identified: (i) quasi-free projectile breakup; (ii) binary breakup due to the inelastic excitation of the projectile to an unbound excited state; (iii) charged particle decay of the residual nucleus following mass-transfer reactions; (iv) pickup processes to Li unbound states with the subsequent decay into a and either p, d or t; (v) coincident proton evaporation. The cross section for process (i) is at least one order of magnitude smaller than the corresponding process induced by 3He at the same beam velocity. It has been found that the selectivity for populating states in a final nucleus is almost independent of the reaction leading to that nucleus

Measurement of the g-factor and lifetime of the first-excited state of 20O

The g-factor and mean lifetime of the first-excited 2+ state at 1.67 MeV in 20O have been determined by means of a plunger set-up. The state was populated by the 3H(18O, pγ)20O reaction at E(18O) = 24.5 MeV. The analysis of p-γ anisotropies as a function of flight path of the recoiling ion in vacuum leads to a value for the g-factor of |g| = 0.352±0.015 and to a mean life of τ = 10.7±0.4 ps