Coulomb Excitation of the Second 2+ States in W, Os, and Pt Nuclei

The location of a second 2+ state has been established for six even-even nuclei by means of Coulomb excitation produced by 4- to 5-Mev protons. The relatively weak excitation of these states is detected by a measurement of the gamma-ray yields from singles spectra and from coincident measurements of the cascade gamma rays. The $B\left(E2\mathrm{}\right)\text{'}\mathrm{s}$ for decay of the second 2+ state to ground state by the crossover transition exhibit some uniformity for the even-even isotopes of W and Os, being about 6 times the single-particle value. The cascade/crossover ratio for the decay of the second 2+ state is known for these nuclei. The upper cascade $B\left(E2\mathrm{}\right)\text{'}\mathrm{s}$ exhibit enhancements of 10 to 60 times the single-particle value. The ratios of the $B\left(E2\mathrm{}\right)\text{'}\mathrm{s}$ for decay of the first and second 2+ states are compared to the predictions of several collective models. For five of these nuclei the $\frac{E2\mathrm{}}{M1\mathrm{}}$ ratio is known for the upper cascade transition. The $B\left(M1\mathrm{}\right)\mathrm{}$ values obtained are exceedingly small compared to the single-particle estimate. This result is in qualitative agreement with the collective models which predict that $M1\mathrm{}$ radiation is forbidden in the decay of vibrational excitations.