[en] The present work constitutes an updating of the previous A = 155 data compilation, which appeared in the Nuclear Data Sheets in November 1963. All data available prior to August 1974 were considered for this compilation. Data are given for 10 nuclides, ¹⁵⁵Sm(Z = 62) through ¹⁵⁵Lu(Z = 71). The ground-state spins are now well established for the Z = 62 through Z = 67 members of this A-chain. More recent data on atomic masses have resulted in a change in the Q value for the epsilon decay of ¹⁵⁵Tb from 1 MeV in the earlier compilation to 817 keV. The bulk of the new data has come from single-nucleon transfer reactions and from semiconductor-detector studies of γ rays from radioactive decay and charged particle-induced reactions. The results have given a much more complete picture of the energy-level structure of these nuclei. ¹⁵⁵Sm, ¹⁵⁵Eu, ¹⁵⁵Gd, and ¹⁵⁵Tb are classified as deformed nuclei since they all exhibit well-developed rotational-band structure. The energy-level systematics of these nuclei are treated in terms of the Nilsson model including various well-established couplings. The N = 89 nuclide, ¹⁵⁵Dy, also exhibits rotational-band structure. However, since it is situated in a mass region where a transition from a deformed to a spherical equilibrium shape is found, the configuration assignments for the observed energy levels are somewhat tentative. Absolute β^--, 0000e)-, and epsilon(+β⁺)-branching ratios are given on the decay-scheme drawings. In all cases these quantities are based on a (γ+ce) intensity balance normalized to 100 percent decay to the ground state of the daughter nucleus. Specific details concerning the methods used to estimate the β- or epsilon-branching to the ground state of the daughter nucleus are discussed in connection with the individual nuclides. (U.S.)

[en] Using an on-line mass separator, the α-particle decays of ¹⁵⁵Lu and ¹⁵⁷Lu were investigated. A new α-emitting level in ¹⁵⁷Lu was identified [T_1/2=5.7(5) s, E_α=4924(20) keV]. In addition, a half-life of 140(20) ms was measured for the recently discovered second, low-lying, α-decaying level [E_α=5579(5) keV] in ¹⁵⁵Lu. (orig.)

[en] The α-decay properties of ¹⁵⁵Lu and ¹⁵⁷Lu show that their ground states are not πh_11/2 (as they are in ^153,155Tm, and ^151,153Ho) but either πd_3/2 or π_1/2. From single-particle level systematics the πd_3/2 assignment is favored. Calculations using the shell correction method predict the one-quasiparticle proton states based on the h_11/2, d_3/2, and s_1/2 subshells to appear very close in energy in Lu, Ta, and Re nuclei with N∼84, independently of equilibrium deformation

No abstract available

[en] This work represents an update of the previous evaluation of the nuclear data on the A = 155 nuclides (Nucl. Data Sheets 71 (1994) 709). The experimental data from reaction and decay studies leading to these nuclides have been reviewed. The elements included range from Ce (Z = 58) through Ta (Z = 73). These data are summarized and presented, together with the adopted level schemes and properties. In addition, data on the g. s. properties of those A = 159 nuclides whose α decays lead to final states in the A = 155 nuclides have been reconsidered

[en] Very neutron deficient isotopes below lead were produced with beams of ⁵⁸Ni, ⁹²Mo, and ¹⁰⁷Ag accelerated by the linear accelerator UNILAC. After separation from the projectile beam by the velocity filter SHIP, the fusion products were implanted with their full recoil energy into an array of position-sensitive detectors. This array is part of a detector system developed for investigation of decay modes of rare isotopes. In a compact geometry α, p, β, γ decay and fission can be observed. With a newly developed position and time correlation technique parent daughter relationships, half lives, and α branching ratios of a large number of isotopes could be determined. Two new α emitting isomeric states could be identified in ¹⁵⁵Lu and ¹⁵⁶Hf. The energies of the excited states are (1798 +- 12) keV in ¹⁵⁵Lu and (1977 +- 18) keV in ¹⁵⁶Hf, the half-lives are (2.60 +- 0.07) ms and (444 +- 17) μs, respectively. Compared to the ground state transitions, a hindrance of 10⁵ can be deduced for both transitions, possibly indicating orbital angular momenta of the order of 10 h for the α emitting states. The isomers are proposed to belong to shell model isomers beyond ¹⁴⁶Gd. A low energetic line at 1.19 MeV was found in the particle spectra taken in reactions of ⁵⁸Ni + ⁹⁶Ru → ¹⁵⁴Hf. It is tentatively assigned to a proton decay of the new isotope ¹⁵¹Lu. (orig.)

[en] This work represents an update of the previous evaluation of the nuclear data on the A=155 nuclides (2005Re01). The experimental data from reaction and decay studies leading to the following nuclides have been reviewed: ¹⁵⁵La, ¹⁵⁵Ce, ¹⁵⁵Pr, ¹⁵⁵Nd, ¹⁵⁵Pm, ¹⁵⁵Sm, ¹⁵⁵Eu, ¹⁵⁵Gd, ¹⁵⁵Tb, ¹⁵⁵Dy, ¹⁵⁵Ho, ¹⁵⁵Er, ¹⁵⁵Tm, ¹⁵⁵Yb, ¹⁵⁵Lu, ¹⁵⁵Hf, and ¹⁵⁵Ta. These data are presented, together with the adopted level schemes and their properties.

[en] Excited states in the proton rich nuclide ¹⁵⁶₇₂Hf₈₄ were observed for the first time using the ¹⁰²(⁵⁸Ni, 2p2n)¹⁵⁶Hf reaction at 270 MeV. Gamma rays were detected with the AYEBALL array of Compton suppressed Ge detectors, placed in front of the Fragment Mass Analyzer, and were assigned to individual reaction charmers using the Recoil-Decay Tagging Method. Prompt γ-ray cascades were associated with the alpha decay of both the ground state and the 8⁺ isomeric state in ¹⁵⁶Hf. The level scheme constructed for ¹⁵⁶Hf is compared with level schemes of lighter even-even N=84 isotones and is discussed within the framework of the Shell Model

[en] The decay properties of ¹⁵⁵Lu, ¹⁵⁵Yb, ¹⁵⁵Tm, and of the α-decay daughters ¹⁵¹Er and ¹⁵¹Ho were investigated following the on-line mass separation of A=155 nuclides produced in ⁶⁴Zn irradiations of ⁹⁵Mo. In the study, the half-life of the low-spin isomer in ¹⁵⁵Lu was measured to be 140±20 ms, the β-decay branch of ¹⁵⁵Yb was identified by observing daughter γ rays and Tm K x rays, and the existence in ¹⁵⁵Tm of an s_1/2 isomer (T_1/2=44±4 s), in addition to the h_11/2 ground state (T_1/2=21.6±0.2 s) was established. Schemes for the β decays of ¹⁵⁵Yb, ¹⁵⁵Tm, and ¹⁵¹Er are proposed. New information on ¹⁵¹Er decay establishes the s_1/2 isomer in ¹⁵¹Ho to be 41.1±0.2 keV above the h_11/2 ground state. Also, branchings of 90±5, 28±7, and 80_-20⁺¹⁵% were determined for the α decays of ¹⁵⁵Yb, ¹⁵¹Ho, and ¹⁵¹Ho^m, respectively

[en] The following article describes the experimental data on proton radioactivity known up to December 1st, 1992. The data are compared with results of proton-radioactivity theory aiming at a detailed understanding of the measured decay properties. (orig.)