[en] Nuclear structure data for mass-166 nuclei are compiled, and adopted level and gamma-ray properties are presented. The adopted values are based on all data received before May 1974. All published data received between May and August 1974 were also considered in arriving at adopted values. (U.S.)

[en] In order to check theoretical models, the measurement of ¹⁶⁶Ta (Z 73, N = 93) is a subsequent study on this problem. The structure of yrast band in ¹⁶⁶Ta shows an expected larger amplitude of M1 transition zig-zag behavior before signature inversion and a desired higher angular momentum (∼20.5 ℎ) of the signature inversion point compared with these of ¹⁶⁴Lu, ¹⁶²Tm and ¹⁶⁰Ho

[en] High-spin states in the odd-odd nucleus ¹⁶⁶Ta are investigated through the 5n channel of the ⁵¹V+¹²⁰Sn reaction. Four new bands are observed and linked into the previous level scheme. Configurations for the bands are proposed, based on measured alignments and B(M1)/B(E2) transition strength ratios.

[en] Excited states in ¹⁶⁶Hf were populated in the β⁺/ε decay of ¹⁶⁶Ta and studied through off-beam γ-ray spectroscopy at the Yale moving tape collector. New coincidence data found no support for two previously reported excited 0⁺ states and led to a substantially revised level scheme. Similarities between the revised level scheme of ¹⁶⁶Hf and the X(5) critical point symmetry are discussed, and the extent of X(5) behavior in this mass region is explored through the W and Os isotopes. Among X(5) candidates with N>90, good agreement is observed for most energies and interband B(E2) strengths, while all exhibit similar disagreements with other key observables, in particular, yrast B(E2) values and spacing in the excited K = 0⁺ sequence

[en] The yrast band in ¹⁶⁶Ta at high-spin states is established for the first time through the ¹⁴¹Pr(²⁸Si, 3n)¹⁶⁶Ta reaction at a beam energy of 127 MeV. Excitation function, residual radioactivity, and x-γ, γ-γ coincidences were measured. Signature inversion features of ¹⁶⁶Ta and neighbouring isotones are discussed. (author)

[en] Short communication

[en] γ-rays from the decay of a new isotope ¹⁶6>Ta(Tsub(1/2) = 32 +- 3 sec) have been studied singly and in two-parameter coincidence. Sources of ¹⁶⁶Ta were prepared by the thermalization and transport of recoil products from the ¹⁵⁹Tb(¹⁶O, 9n)¹⁶⁶Ta reaction by means of a helium-jet system. Spectrum multiscaling spectroscopy provided accurate half-life information. Rotational levels of the ground-state, β- and γ-vibrational bands of ¹⁶⁶Hf have been observed and a decay scheme with deduced branching ratios and log ft values is proposed. (author)

[en] Tantalum 164 to 167, Zirconium 82 to 84 and Strontium 78 have been selectively observed at the ISOCELE-2 on-line mass separator in the TaF₄⁺, ZrF₃ and SrF⁺ compound form. New isotopes have been identified: ¹⁶⁵Ta (31.0 +- 1.5 s), ¹⁶⁴Ta (13.7 +- 0.6 s), ⁸²Zr, (32 +- 5 s) and ⁷⁸Sr (2.5 +- 0.3 mn). (orig.)

[en] Short communication

[en] The retention behavior of volatile bromide molecules of short-lived isotopes of tantalum and element 105 in KCl coated quartz columns was studied using continuous isothermal gas chromatography. HBr and HBr saturated with BBr₃ vapor were used as reactive gases. The isotopes were produced in the fusion reactions ²⁰Ne+^nat.Eu and ¹⁸O+²⁴⁹Bk, respectively. The reaction products were transported from the accelerator to the chromatography set-up with a gas-jet system using an aerosol with He as carrier gas and KCl as transporting particles. The measured retention times are compared to those of ^99gNb bromides from a previous study. The retention times of niobium and tantalum bromides are very similar, in agreement with expectations based on the nearly identical sublimation enthalpes of NbBr₅ and TaBr₅. For the bromides of element 105, higher retention times are found, indicating a lower volatility of 105Br₅ than of NbBr₅ and TaBr₅. On the basis of empirical systematics, a sublimation enthalpy of 138±15 kJ/mol can be estimated for 105 Br₅ from the experimental data. (orig.)