Isomers in neutron-rich A ≈ 190 nuclides from 208Pb fragmentation

Relativistic projectile fragmentation of ²⁰⁸Pb has been used to produce isomers in neutron-rich, A 190 nuclides. A forward-focusing spectrometer provided ion-by-ion mass and charge identification. The detection of -rays emitted by stopped ions has led to the assignment of isomers in ¹⁸⁸Ta, ¹⁹⁰W, ¹⁹²Re, ¹⁹³Re, ¹⁹⁵Os, ¹⁹⁷Ir, ¹⁹⁸Ir, ²⁰⁰Pt, ²⁰¹Pt, ²⁰²Pt and ²⁰³Au, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for ¹⁷⁴Er, ¹⁷⁵Er, ¹⁸⁵Hf, ¹⁹¹Re, ¹⁹⁴Re and ¹⁹⁹Ir. In most cases, time-correlated, singles -ray events provided the first spectroscopic data on excited states for each nuclide. In ²⁰⁰Pt and ²⁰¹Pt, the assignments are supported by - coincidences. Isomeric ratios provide additional information, such as half-life and transition energy constraints in particular cases. The level structures of the platinum isotopes are discussed, and comparisons are made with isomer systematics.     

E2 andE3 transition strengths in some rare-earth nuclei

Coulomb excitation byα-particles of vibrational-like states in even-mass rare-earth nuclei is used to determine the reduced transition probabilitiesB(E2; 0 _gs ⁺ →2 _γ ⁺ ),B(E2; 0 _gs ⁺ →2 _β ⁺ ),B(E2; 2 _gs ⁺ →0 _β ⁺ ) andB(E2; 0 _gs ⁺ →3 _oct ^? ) in¹⁵⁰Nd,^{152, 154}Sm,^{154, 158}Gd,¹⁶⁴Dy and¹⁶⁶Er. TheB(Eλ; 0 _gs ⁺ →I=λ)-values range from 2.4 to 6.5 single-particle units for transitions to the 2 _γ ⁺ -states, 0.8 single-particle units for the 2 _β ⁺ -states and from 14.1 to 21.7 single-particle units for the 3^?-states.