[en] The level structures of the N = 89 ¹⁵⁷Er and N = 87 ¹⁵⁵Er nuclei have been investigated through the decay of ¹⁵⁷Tm (Tsub(1/2) = 3.3 min) and ¹⁵⁵Tm (Tsub(1/2) = 25 s). Mass separated samples were obtained from the ISOCELE 1 on-line separator. Gamma ray spectra, conversion electron spectra and γ-γ bi-dimensional coincidences were examined, and lead to proposed level schemes for these transitional nuclei

No abstract available

[en] The (7/2)[523] and (7/2)[404] bands are observed in ¹⁵⁹Tm to I = (61/2) and (43/2), respectively, well beyond the i/sub 13/2/ neutron backbend. Before the backbend, the (7/2)[523] band exhibits large signature splitting, the (7/2)[404] none, which is interpreted as resulting from the very different driving influences of the K = (7/2) h/sub 11/2/, and g/sub 7/2/ orbits, respectively, on the core triaxiality. The i/sub 13/2/ neutron alignment changes the signature splitting in each band as a result of its dominant driving force to positive values of γ. Measured B(M1;I→I-1)/B(E2;I→I-2) values increase dramatically after the backbend, and this is explained in terms of calculated increases in the M1 transition rates and decreases in the E2 rates

[en] Two methods have been used to obtain values of the effective moment of inertia of very-high-spin (20h-bar--50h-bar) states populated in heavy-ion compound-nucleus reactions. The ¹⁶²Yb nucleus studied has effective moments of inertia smaller than, but approaching, the rigid-body estimate

[en] The existance of the 4.8+-0.2 min ¹⁶⁰Yb activity has been established. Five gamma-transitions with energies (in keV) and their relative intensities (in parentheses):132.23(9.9), 140.35(16.6), 173.76(77.4), 215.78(32.0), and 372.24(3.5) were found and assigned to decay of this isotope. (author)

No abstract available

No abstract available

[en] High resolution interference and intermodulated optogalvanic saturation spectroscopy has been applied for isotope shift (IS) studies in the ground-configuration 4f¹²6s² of Er I. For the isotope pairs ^170-166Er and ^168-166Er the results confirm a strong J- and term dependence of the IS caused through crossed-second-order (CSO) effects. We performed a parametric analysis to evaluate the CSO-parameters z_4f for the interpretation of the J-dependence and T(³H), T(³F), T(¹G) to describe the term dependence. The following parameter values (in MHz) were determined, for ^170-166Er: z_4f=40.1(0.6), T(³F)=-153(5), T(³H)=-220(6), and T(¹G)=-79(4); for ^168-166Er: z_4f=20.1(0.7), T(³F)=-77(6), T(³H)=-111(7), and T(¹G)=-43(5). The normalization of these parameters with the corresponding nuclear parameters λ for both isotope pairs leads to almost identical parameter values indicating a dominant influence of the field shift effect in second-order for the z_4f parameter and in third-order for the parameters T(³F), T(³H), and T(¹G). (orig.)

[en] The hyperfine structure of 21 lines in the Gd-II spectrum was measured with a photoelectric Fabry-Perot-spectrometer. From these results tje electric quadrupole moment of ¹⁵⁷Gd was determined. (WL)

[en] The hfs of the 6¹P₁ state of ¹⁷³Yb has been investigated by level-crossing and anticrossing spectroscopy. From an optimal fit of experimental and calculated signal curves the authors obtain the hfs coupling constants: A = 58.45(80) MHz, B = 589.6(13.0) MHz. (Auth.)