No abstract available

[en] This paper is an extension of a previous study of the pairing effects in the N=82 isotones. It is concerned with high-spin states in the nuclei from ¹⁴⁶Gd through the recently explored ¹⁵³Lu and ¹⁵⁴Hf. The results obtained confirm the importance of proton pairing correlations in the N=50--82 shell

[en] The structure of low-lying states in heavy odd-mass N=82 isotones (147≤A≤153) is investigated in terms of a number-projected one- and three-quasiparticle Tamm-Dancoff approximation. A surface-delta interaction is taken as the residual nucleon-nucleon interaction. Excitation energies, spin, and parity are calculated and compared with the experimental data. Some predictions about dipole and quadrupole moments are presented

[en] Using an on-line mass seperator the decay of ¹⁵³Lu was studied in ⁶⁴Zn bombardements of ⁹²Mo. The T_1/2 = 0.9±0.2 s activity was assigned to the β decay of the (11/2^-) isomer. (orig.)

[en] Experiments using the Daresbury Recoil Mass Separator have identified microsecond isomers in the exotic N = 82, 83 nuclei ¹⁵³Yb, ¹⁵³Lu, ¹⁵⁴Hf, and have established their decay schemes. The results for ¹⁵³Lu and ¹⁵⁴Hf, together with those for lighter N = 82 isotones, provide an outstanding illustration of the dependence of E2 transition rates between Jⁿ states on the subshell occupation, and demonstrate that half-filling of the πh_11/2 subshell in the N = 82 series occurs just below Z = 71 ¹⁵³Lu. The result of the isomer in the even-odd N = 83 nucleus ¹⁵³Yb shows that the isomerism is due to a low-energy E2 transition rather than an E3 transition as in lighter N = 83 even-odd isotones, which is another consequence of the πh_11/2 subshell being about half-filled. Furthermore, the long-lived isomer observed in the odd-odd N = 83 nucleus ¹⁵⁴Lu also reflects that the πh_11/2 subshell is close to being half-filled. 23 refs., 12 figs., 4 tabs

[en] The experimental results from the various reaction and decay studies leading to nuclides in the A = 153 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. This evaluation replaces that of Nuclear Data Sheets 83 (1998) 285 (1998He06)

[en] Microsecond isomers in the very proton-rich N=82 nuclei ¹⁵³Lu and ¹⁵⁴Hf have been identified by γ-ray spectroscopy following mass analysis of ¹⁰²Pd +245 MeV ⁵⁴Fe reaction products using the Daresbury Recoil Separator. The decays of the isomers, interpreted as (πh_11/2)ⁿ states, are characterized. Examination of reduced E2 transition rates between (πh_11/2)ⁿ states in the N=82 isotones indicates that the half-filling of the πh_11/2 subshell occurs just below Z=71

[en] Nuclides with A = 152 were produced in /sup 58/Ni bombardments of /sup 96/Ru and their decay properties were investigated following on-line mass separation. The isotope /sup 152/Lu (T/sub 1/2/ = 0.7 +- 0.1 s) was identified by γ rays in its β-decay daughter, /sup 152/Yb. Based on its decay characteristics, the parent state has a probable spin and parity assignment of (4,5,6^-). Several new transitions were observed to follow the β decays of /sup 152/Yb and the /sup 152/Tm low-spin isomer; they established previously unknown levels in both /sup 152/Tm and /sup 152/Er. The additional γ rays in /sup 152/Yb decay reduce from 100% to 88% the direct feeding to the one excited state in /sup 152/Tm that had been known earlier. Nevertheless, the corresponding logft value is calculated to be 3.5, indicating that this is an allowed β transition which connects the 0⁺ parent with a 1⁺ excited state in /sup 152/Tm. By comparing the β-decay rates of /sup 148/Dy and /sup 152/Ho, and the α- and β-decay rates of /sup 152/Er, an α branch of 90 +- 4 % was deduced for /sup 152/Er

[en] Eigenstates of the shell model are obtained by diagonalization of the Hamiltonian submatrix defined by a given shell model subspace. Matrix elements of the effective nuclear interaction can be determined from experiment in a consistent way. This approach was introduced in 1956 with the ³⁸Cl-⁴⁰K spectra, has been applied in many cases and its latest success is in the s, d shell. This way, general features of the effective interaction have been determined. The T=1 interaction is diagonal in the seniority scheme as clearly demonstrated in proton 1g_9/2ⁿ and 1h_11/2ⁿ configurations and in the description of semimagic nuclei by generalized seniority. Apart from a strong and attractive pairing term, T=1 interactions are repulsive on the average. The T=0 interaction is attractive and is the origin of the central potential well in which nucleons are bound. It breaks seniority in a major way leading to deformed nuclei and rotational spectra. Such an interaction may be approximated by a quadrupole-quadrupole interaction which is the basis of the interacting boson model. Identical nucleons with pairing and quadrupole interactions cannot be models of actual nuclei. Symmetry properties of states with maximum T are very different from those of ground states of actual nuclei. The T=1 interaction between identical nucleons cannot be approximated by pairing and quadrupole interactions. The rich variety of nuclear spectra is due to the competition between seniority conserving T=1 interactions and the T=0 quadrupole interaction between protons and neutrons. (orig.)

[en] Microsecond isomers in the exotic proton-rich N=82, 83 nuclei ¹⁵³Yb, ¹⁵³Lu, ¹⁵⁴Lu and ¹⁵⁴Hf have been identified by γ-ray spectroscopy following mass analysis of ¹⁰²Pd+245 MeV ⁵⁴Fe reaction products using the Daresbury Recoil Separator. The decays of the isomers, interpreted as πhⁿ_11/2 and πhⁿ_11/2νf_7/2 states, are characterized. The reduced E2 transition rates indicate that half-filling of the πh_11/2 subshell occurs just below Z=71, and results for the N=83 odd-odd isotones are also consistent with this finding. (orig.)