No abstract available

[en] Results from a spectroscopic study of high spin states in ¹⁷⁴Os is presented. The ground state band has an i_13/2 neutron alignment at ℎω_c = 0.30 MeV with a strong interaction. Possible assignments for the negative parity sidebands are discussed in terms of both neutron and proton i_13/2 alignments. (author)

[en] The yrast bands of the neutron deficient isotopes ¹⁷²Os and ¹⁷⁴Os have been identified to spins of about 24 h/2π. The yrast band in ¹⁷⁴Os shows no bandcrossing anomalies, confirming the shell effect observed in other N=98 nuclei. In contrast, a strong backbend is observed at a frequency of about 0.26 MeV in ¹⁷²Os and is attributed to the s-band crossing. A weaker bandcrossing is also observed at a lower frequency, about 0.24 MeV, in ¹⁷²Os. This unexpected anomaly may be due to either a deformation effect, or to a change in the s-band structure

No abstract available

[en] Data are presented which indicate the existence of F-spin multiplets for the shape-coexistent intruder states of sequences of nuclei differing by an α particle. We argue that these intruder F-spin multiplets, or, equivalently, F-spin analog states, occur because of their larger and more nearly equal values of N_πNν

[en] A γ-rigid version (with γ = 0) of the X(5) critical point symmetry is constructed. The model, to be called X(3) since it is proved to contain three degrees of freedom, utilizes an infinite well potential, is based on exact separation of variables, and leads to parameter free (up to overall scale factors) predictions for spectra and B(E2) transition rates, which are in good agreement with existing experimental data for "1"7"2Os and "1"8"6Pt. The predictions of X(3) are furthermore compared to two-parameter calculations in the framework of the Interacting Boson Approximation (IBA) model. The results show that X(3) coincides with IBA parameters consistent with the phase/shape transition region of the IBA. The same turns out to hold also for the parameter independent (up to overall scale factors) predictions of the X(5)-β2 and X(5)-β4 models, which are variants of the X(5) critical point symmetry developed within the framework of the geometric collective model, manifested experimentally in "1"4"6Ce, "1"7"4Os, and "1"5"8Er, "1"7"6Os respectively.

[en] The parameter-independent (up to overall scale factors) predictions of the X(5)-β²,X(5)-β⁴, and X(3) models, which are variants of the X(5) critical point symmetry developed within the framework of the geometric collective model, are compared to two-parameter calculations in the framework of the interacting boson approximation (IBA) model. The results show that these geometric models coincide with IBA parameters consistent with the phase/shape transition region of the IBA for boson numbers of physical interest (close to 10). ¹⁸⁶Pt and ¹⁷²Os are identified as good examples of X(3), while ¹⁴⁶Ce, ¹⁷⁴Os, and ¹⁵⁸Er, ¹⁷⁶Os are identified as good examples of X(5)-β₂ and X(5)-β⁴ behavior, respectively

[en] The yrast bands of ¹⁷²Os (N = 96) and ¹⁷⁴Os (N = 98) have been observed to spins of about 26 h/2π using (²⁸Si, xn) reactions and γ-ray techniques. The yrast band of ¹⁷⁴Os shows no anomalies, confirming the neutron shell effect at N = 98. Backbending is observed in ¹⁷²Os, and the presence of a second anomaly at low frequency is also suggested. This low frequency anomaly might be due to a change in deformation. Preliminary results for ¹⁶⁸W, which sould also be soft to deformation, do not show an equivalent effect. (author)

No abstract available

[en] Abstract only. 3 refs