Coulomb excitation of 182, 184, 186W, 186, 188, 190, 192Os and 192, 194, 196, 198Pt with protons, 4He and 16O ions

Abstract

Coulomb excitation of the first 2+ states was produced in 186Os with 3 to MeV 4He ions, 188, 190, 192Os with 4.56–5.08 MeV protons, and 192–198Pt with 4.5 MeV protons and 43.75 MeV 16O ions. Values of B(E2, 0 → 2) have been extracted with an absolute uncertainty of ±9 % for 186Os, ±7% for 188–192Os and ± 5–6% for 192–198Pt. Coulomb excitation of second 2+ states was produced in 186-2192W with 5 MeV protons, 14 and 15 MeV 4He ions and 45.5 MeV 16O ions, and in 186–192Os with 5 MeV protons, 15 MeV 4He ions and 42, 45.1 and 45.5 MeV 16O ions. Excitation of higher 2+ states at 1257, 1386 and 1286 keV was effected in 182, 184, 186W with 15 MeV 4He ions. Values of B(E2, 0 → 2'), B(E2, → 2'), B(M1, 2 '→2), and δ = 〈2|́|E2|́|2'〉/〈2|́|M1|́|2'〉, and the transition branching ratio T(2' → 2)/T(2' → 0) are reported for second and higher 2+- states. Values of B(E2, 2 → 4) have been obtained for 182–186W and 186–192Os from direct Ge(Li) spectra using 15 MeV 4He ions and 42–45.5 MeV 16O ions and from 16O-γ coincident (NaI) spectra using 42–45.5 MeV 16O ions, and for 194, 196Pt from direct Ge(Li) spectra using 43.75 MeV 16O ions. Values of B(E2, 4→ 6) for 182, 184, 186W were also extracted from the 16O-γ data. Data analysis was carried out using first-order quantal perturbation theory in the case of proton and 4He ion experiments. First- and second-order semi-classical perturbation theory and the multipole Coulomb-excitation program of De Boer arid Winther as augmented by Sayer was used in analyzing the 16O ion data. The De Boer-Winther program was also used to estimate multiple excitation corrections for the 4He ion data. The results are compared to recent results of other workers and to the pairing-plus-quadrupole model calculations of Kumar and Baranger as well as to the predictions of the more simple phenomenological models.