Conversion electron measurement of isomeric primary transitions in196, 198, 199, 200, 201Pb

The transition energies of nine low energy primary transitions from high spin isomers in^{196, 198, 199, 200, 201}Pb have been measured with conversion electron spectroscopy usinge ^? e ^? ande ^? γ coincidences.B(E2) values as deduced from the measured lifetimes and transition energies are discussed in terms of seniority shell model configurations and of a quasiparticle Tamm-Dancoff approach using the surface delta interaction. A revised discussion of the effectiveE2 charge in neutron deficient Pb isotopes is presented.     

Lifetime measurements of highly excited Rydberg states of strontium I

Lifetimes of Rydberg states of the triplet-series 5s ns ³ S ₁ withn = 19–23, 35 and 5s nd ³ D ₃ withn = 18–20, 23–28 in the spectrum of neutral strontium have been determined. Observation of the exponential decay after excitation by a pulsed laser in a fast atomic beam and subsequent state-selective field ionization was employed. The lifetimes of the states of the³ S ₁-series show the expectedn*³ dependence on the effective principal quantum number, while the³ D ₃-series is disturbed by configuration mixing. Furthermore, state re-populations induced by black-body radiation have been observed.     

Ground-state properties of neutron-deficient platinum isotopes

The hyperfine structure splitting and the isotope shift in the =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 daugthers 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 from a slightly deformed, nearly oblate¹⁹⁵Pt via triaxial^197-187Pt to a strongly deformed nearly prolate¹⁷⁷Pt.Dedicated to P. Armbruster on the occasion of his 60th birthday     

Evidence for a two-phonon octupole vibrational state in208Pb

Collective properties of^206,208Pb have been investigated with gamma-ray spectroscopy using nuclear and electromagnetic excitation by²⁰⁸Pb projectiles. From the measurement of particle-particle- and particle-particle- coincidences a new energy level in²⁰⁸Pb at 5.683 MeV was observed and the data suggest an interpretation as a 2-phonon octupole vibrational state with spin 4⁺ or 6⁺. For this state one finds the same dynamical deformation parameter ₃ as for the first-excited collective 3^– state. The results are compared to predictions of models which consider, in particular, the aspects of the quadrupole interaction and the interaction of the 2-particle pairing vibration with the 2-phonon octupole vibration. For the²⁰⁶Pb+²⁰⁸Pb system at 6.2 MeV/u the nuclear potential could be determined from the measured inelastic cross sections.Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday