0000000000810287
AUTHOR
A. Siivola
Low-energy rotational bands in the nucleus155Eu
Excited states in the nucleus155Eu have been produced during in-beam bombardments of a154Sm target with3He beams at 22 and 27 MeV. Decay gamma rays were detected using coincidence equipment optimized for low-energy photons. The level scheme is based on the observedγγ-coincidence relationships combined with the information on relative intensities. Tentatively suggested spin assignments follow from the apparent rotational character of the nucleus. Experimental observations are compared with predictions calculated from a particle-rotor model with a nonspheroidal Woods-Saxon potential.
Low-lying excitations in the odd-odd nucleus154Eu
The doubly odd nucleus154Eu was produced during in-beam bombardments of a154Sm target with3He and deuteron beams at 27 and 10 MeV. The resulting gamma-rays were investigated using prompt and delayed gamma-gamma-coincidence equipment. The half-life of the isomeric 2+ level was determined as 2.2±0.1 μs. The partial level scheme, including numerous previously unidentified excitations, can be divided into two separate groups of levels. The results provide evidence for the existence of a very regular ground band and two rather regularK=3 level structures, whose configurations are closely related to it. In addition, several rotational sequences built on the band heads with otherK values have been…
Remeasurement of the Lifetime of the Isomeric 9/2+State in155Dy
The isomeric 9/2+ state at 132.2 keV in the nucleus 155Dy has been populated through 3He bombardment (E = 27 MeV) of a 155Gd target. The half-life of the the 9/2+ level has been determined as 51 ± 3 ns. The decay modes of the 11/2-, 234.2 keV level have been confirmed. For both levels the hindrance factors calculated with the particle-rotor model have been compared with other predictions available.
The Isomeric 9/2+and the Lowest 7/2-State in the Weakly Deformed N = 89 Nuclei
The decays of the isomeric 9/2+ states which have been produced by (d, pγ) and (3He, xnγ) reactions, have been investigated in three N = 89 nuclei. The half-lives have been determined to be 5.1 ± 0.3 ns in 149Nd and 3.5 ± 0.4 μs in 153Gd. In 155Dy a 5.5 ns half-life was found, but we were unable to assign it to the 9/2+ state. The calculated E1 transition probability from the 9/2+ state has been used as a probe in suggesting the following main components for the lowest-lying 7/2- state: 7/2 5/2-[523] in 149Nd, 7/2 3/2-[521] in 153Gd and 7/2 3/2-[521] in 155Dy. The corresponding 7/2- state in 151Sm is proposed to be 7/2{1}3/2-[532] + 5/2-[523]{1}. All calculations have been performed using a…
Low-lying levels in the nuclei151Nd and155Sm
Decay properties of excited states in the151Nd and155Sm nuclei produced by 10 MeV douterons have been investigated with in-beam gamma-gamma-coincidence equipment during bombardment of the150Nd and154Sm targets. The results largely confirm the data obtained earlier for these nuclei. The (d, p γ) reaction channel favors population of odd-parity low-spin levels, whose energies follow the rule of regular band structure for well-deformed nuclei. The level schemes are interpreted with calculations using an axial particle-rotor model with a Woods-Saxon potential.