Search

The lifetime of the second excited 2+ state of 94Zr at 1671 keV was determined with the Doppler-shift attenuation method (DSAM) following the (n, n'y) reaction on scattering samples of Zr metal and Zr02 of natural isotopic abundance. The measured lifetime, r = 368-23+2 fs, is considerably longer than the previous measurement, as are measured lifetimes of other levels in 94Zr. However, lifetimes of low-lying, low-spin states in 90,9l,92,96Zr were also determined and found to be in good agreement with measurements employing non-DSAM methods. Possible reasons for the discrepant lifetimes measured for 94Zr are discussed and focus on the chemical properties of the scattering sample, specifically, the effects of using amorphous materials, or those composed of small particles as scattering samples. These properties have been investigated by x-ray powder diffraction and scanning electron microscopy. The effects of using these materials for lifetime measurements were investigated by employing, as scattering samples, Zr(OH)4 (a known amorphous material) and Zr02 with various crystalline domain sizes. [ABSTRACT FROM AUTHOR]

New data have been obtained for 185Os following the 176Yb(13C,4n)185Os reaction, extending the pseudo-Nilsson &fracl;12-, -&frac;32- [&4tilde;&1tilde;&1tilde;] doublet structure and the &frac;72- [&4tilde;&0tilde;&4tilde; band to significantly higher spins. Gamma-ray branching ratio data have been analysed to obtain extensive B(M1) and B(E2) ratios for intraband and inter band transitions. The data are compared with particle-rotor calculations based on the pseudo-Nilsson potential and the Woods-Saxon potential. The results indicate that the pseudo-Nilsson approximation provides a good description of the &fracl;12-, -&frac;32-[&4tilde;&1tilde;&1tilde;] bands up to the first band crossing; the difference in magnitude between the model predictions and data for the &frac;72-[&4tilde;&0tilde;&4tilde;] band may be attributed to a lower deformation for the higher-K structure. [ABSTRACT FROM AUTHOR]