[en] The systematics of excited states in the neutron-deficient even-mass Pt isotopes are shown to provide evidence that a strongly deformed configuration is present in the ground states of these isotopes. This configuration is proposed to be due to (πhsub(9/2))², based on proton intruder state systematics and the importance of valence neutrons and protons in producing deformation. It is suggested that this phenomenon is unprecedented and, for the present, unique to the neutron-deficient even-mass Pt isotopes. A simple test of this picture using the blocking effect of an hsub(9/2) proton coupled to the ¹⁸⁶Pt core, as observed in ¹⁸⁷Au, is discussed. The consequences of this intruder state structure in the neutron-deficient Pt isotopes on other observable quantities in this region are considered. (orig.)

[en] The changes of the mean-square charge radii have been measured for ¹⁹⁸Pt-¹⁸³Pt by means of resonance ionization mass spectroscopy (RIMS) at the new on-line isotope separator ISOLDE-3/CERN. As in the case of the neighbouring isotopes of Au and Hg, a strong nuclear deformation of vertical strokeβ₂vertical stroke≅0.24 is reached at the neutron mid-shell nucleus ¹⁸³Pt, but no indication for a sharp shape transition is observed from the study of the isotope shifts. (orig.)

[en] Short communication. 4 refs

[en] Angular distributions are presented for a number of states. The lowest excited 0⁺ and the 2⁺₃ states in the lighter Pt isotopes are close to the energies expected for the ''two-phonon'', K = 0 gamma vibrational band. 8 figures

No abstract available

[en] Isotope shift (IS) and hyperfine structure (HFS) measurements have been performed for ^{185,187,189,191,195}Pt using the PILIS (Post ISOCELE Laser Isobar Separation) apparatus installed at the ISOCELE facility. Magnetic and quadrupole moments have been deduced from the HFS results. The change radius changes determined for these odd nuclei from the IS results, added to the δ < r²> values of the even-A nuclei, are compared to the results of lattice Hartree-Fock + BCS calculations for asymmetric solutions. ¹⁸⁵Pt is confirmed to be prolate shaped whereas ^187,189,191Pt are likely triaxial in their ground states. (orig.)

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[en] The hyperfine structure splitting and the isotope shift in the λ=266 nm transition of Pt isotopes within the mass range 183≤A≤198 have been determined by Resonance Ionization Mass Spectroscopy (RIMS) in combination with Pulsed-Laser Induced Desorption (PLID). The Pt isotopes were obtained at the on-line isotope separator ISOLDE-3/CERN as daughters of the primarily produced Hg isotopes. Magnetic moments, quadrupole moments, and changes in the mean-square charge radii are deduced and compared with results of a particle-triaxial rotor model and mean field calculations. Good agreement with experimental data (including nuclear level schemes and transition probabilities) can only be obtained if triaxial shape is admitted. The calculations yield a smooth transition in the shape of odd-A Pt nuclei for a slightly deformed, nearly oblate ¹⁹⁵Pt via triaxial ^193-187Pt to a strongly deformed nearly prolate ¹⁷⁷Pt. (orig.)

No abstract available