No abstract available

[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

[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] 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)

[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

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No abstract available

[en] Existing data for the 3₁⁺ state of ¹⁵²Sm present serious uncertainties for any collective interpretation of this nucleus. In this work the lifetime of the 3₁⁺ state in ¹⁵²Sm was remeasured, using the gamma ray induced Doppler technique in the (n,γ) capture reaction, and the E2/M1 mixing ratio of the 3₁⁺→2₃⁺ transition was obtained from linear polarization measurements of γ rays following the ε decay of ¹⁵²Eu. The results remove the previous potential discrepancies and are in agreement with the interpretation of ¹⁵²Sm as exhibiting phase coexistence near the critical point of a spherical-deformed phase transition

[en] The energy levels of ¹⁵⁹Er have been investigated from the decay of ¹⁵⁹Tm (T(1/2)=9mn). Samples were obtained by (p,xn) reaction and on-line separation through Isocele facility. A level scheme is proposed with 24 levels between 0 and 1.3MeV

[en] The mixing ratios (δ) and the internal conversion electron particle parameters (b₂) of the 121.8KeV transition in deformed ¹⁵²Sm nuclei were determined by comparing the γ-γ and γ-e angular correlation measurements made with the same source. The experimental apparatus was constructed with a surface barrier detector for electrons and two Ge(Li) detectors for gamma rays. The following results were obtained. 244.7 KeV - 121.8 KeV ; δ = -0.012±0.007 688.6 KeV - 121.8 KeV ; δ = 17.4±3.01 964.0 KeV - 121.8 KeV ; δ = 9.51±1.93 1112.0 KeV - 121.8 KeV ; δ = 12.30±2.05 1408.0 KeV - 121.8 KeV ; δ = 0.16±0.07 964.0 KeVγ - 121.8 keVe_k ; b₂ = 1.66±0.26 1408.0 KeVγ - 121.8 KeVe_k ; b₂ = 1.63±0.10 1408.0 KeVγ - 121.8 KeVe_L ; b₂ = 0.99±0.13 The results are compared with the theoretical values derived from the Pairing-Plus-Quadrupole model and from the Interacting-Boson-Approximation model, and an anomaly was found in the low-lying E2 transition for deformed ¹⁵²Sm nuclei. (Author)