The deformedN=60 nucleus 41 101 Nb

Abstract

The/~-decay of a~ has been investigated at the fission-product separators JOSEF and LOHENGRIN. The half-life of a~ has been determined to 2.5(1)s and a level scheme for t~ has been established from 7 ray singles as well as X-7 and 7-7 coincidence measurements. Conversion coefficients for transitions in l~ and level half-lives between 10 ps and 2 ns have been determined. Three rotational bands are identified among the low-lying levels with band heads at 0 keV, 206 keV and 208 keV. The bands are probably based on the Nilsson configurations [422 5/2+], [301 3/2-] and [303 5/2-], respectively. The deformation has been determined to /?q=0.40(4) and 0.41(8) for the ground state band and the band based on the 206 keV level from the half-lives of the first and second excited members of these bands. This shows that the rapid onset of deformation at N = 60 which is typical for the A = 100 region of neutron-rich nuclei, takes also place in the Nb isotopes. Nilsson model calculations describe the experimental data well, especially the several determined transition probabilities including those for E1 transitions from the 206 and 208 keV band heads to the ground state.

β-decay half-lives of neutron-rich nuclides in theA=100–110mass region

“…If a reference cited in the ENSDF file could not be obtained, the ENSDF file is cited along with the original reference. A previous measurement that does not contain any uncertainty will have no uncertainty in this The half-life of 101 Zr has been previously measured in fission-based experiments [34,[36][37][38]. Refs.…”

“…Refs. [36,38] both reported a large β-decay feeding intensity to levels in 101 Nb around 2 MeV. These measurements have been compiled in the decay scheme from ENSDF [35], which shows a group of nearby levels around 2 MeV (specifically, those levels between 1878.1 keV and 2030.65 keV, inclusive) that collectively have a relatively large β-decay feeding intensity.…”

Shape coexistence in the odd-odd neutron-rich nucleusY98studied in the interacting boson model

“…[27] but the position of a few levels has been adjusted to qualitatively reproduce the sequence of the levels discussed above. The order of the oddparity proton levels has been reversed and both have been slightly lowered ͑0.4 MeV͒ to more easily reproduce the 5/2 + ground state of 41 101 Nb [28]. The [422]3/2 and [404]9/2 neutron orbitals have been pushed upwards and downwards, respectively, by 1.5 MeV.…”

Structure of the highly deformed nucleus101Sr63 and evidence for identical K=3/2 bands

“…Thus, deformation parameters and moments of inertia show that the 98Sr 'core' [35] is not much affected by adding either a neutron in the u[41113/2 orbital or a proton in the ~r[42215/2 orbital. Accurate lifetimes of the first excited states of the [422]5/2 band are known for mlNb [25] and l~ [37]. However, since these bands show a tendency to decouple at I > 9/2 [17], the deduced deformations may be less reliable than for 99y and 99Sr.…”

“…This discrepancy may be attributed to a different normalisation. We used the more recent intensifies from l~ decay into l~ [25] instead of the 192keV isomeric transition in m]Tc. The new value for the feeding of the 5/2 + ground state in rely is important for the new interpretation of the ground-state spin and parity of 101Sr.…”