Determination ofγSoftness inPt192,194,196from Coulomb Excitation withXe136Projectiles

The ${}_{}{}^{192,194,196}{}_{}{}^{}\mathrm{Pt}$ nuclei were Coulomb excited with ${}_{}{}^{136}{}_{}{}^{}\mathrm{Xe}$ projectiles. Strong excitation of the ground-state band (up to spin ${10}^{+}$) and the "$\gamma$" band (up to spin $8^{+}$) were observed. Excitation of the upper members of the $\gamma$ band is shown to be sensitive to the $\gamma$ softness. The observed Coulomb-excitation yields imply $B\left(E2\mathrm{}\right)\mathrm{}$ values which follow the rigid-triaxial-rotor relation. This contradicts current calculations which predict considerable $\gamma$ softness.