Coulomb excitation of 35Cl projectiles

Abstract

Coulomb excitation of the first two excited states in 35Cl was studied by bombarding thick foils of 24Mg and carbon with 35Cl ions of energies between 51 and 61 MeV. De-excitation gamma rays were observed in two 40 cm3 Ge(Li) detectors. From absolute cross-section measurements the following B(E2) values were obtained, B(E2, 0 → 1220) = (0.081 ± 0.009) × 10−50 e2 cm4 and B(E2, 0 → 1762) = (1.17 ± 0.09) × 10−50 e2 cm4. The mixing ratio δ(1762 → 0) was measured to be −2.95 ± 0.45 which can be combined with the corresponding B(E2) value to yield τ(1762) = (0.555 ± 0.050) ps. A Doppler shift attenuation method was employed to interpret the observed gamma-ray lineshapes in terms of nuclear lifetimes. The lineshape analysis yielded τ(1220) = (0.16 ± 0.05) ps and confirmed τ(1762) obtained from the absolute cross-section measurements. The results provide evidence that the three lowest states in 35Cl cannot be interpreted by a weak coupling model.