Configuration interaction and rotational structure in 8Be

A configuration interaction calculation for ⁸Be is carried out in which $\text{0}\text{h}\text{?}\text{ω, 2}\text{h}\text{?}\text{ω}$ and $\text{4}\text{h}\text{?}\text{ω}$ configurations are taken into account. The results indicate a reordering of levels into new rotational bands and a grouping of bands into “families”.     

A study of the rotational side-bands in 162Dy

Rotational side-bands in ¹⁶²Dy have been studied using the ¹⁶⁰Gd(α, 2nγ)¹⁶²Dy reaction. Seven side-bands are observed, with K^π = 2⁺, 2^?, (0)^?, 0⁺, 5^?, 4⁺ and (6^?). Four of these bands have collective structure at low spin: the K^π = 2⁺γ-vibrational band, the K^π = 0⁺β-vibrational band, and the K^π = 2^? and (0)^? octupole vibrational bands. Of the remaining bands, the 4⁺ band is deformation coupled while the 5^? and (6^?) bands are rotation-aligned. Several bandcrossings are observed in this nucleus. The β and γ-bands are crossed at $\text{I = 6}\text{h}\text{?}\text{and}\text{12}\text{h}\text{?}$, respectively, by a highly aligned ($\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$)² S-band; extrapolation of this S-band to higher spin suggests that it crosses the g.s.b. between $\text{I = 18}\text{h}\text{?}\text{and}\text{20}\text{h}\text{?}$. The 2^? octupole band is crossed by the 5^? band at $\text{I = 9}\text{h}\text{?}$ and again by the (6^?) band at $\text{I = 12}\text{h}\text{?}$. The latter bandcrossings are discussed in terms of two-quasiparticle plus rotor calculations.     

The systematics of h112 proton alignment in 157, 158, 159Er

Rotational bands have been observed in ^{157, 158, 159}Er to very high spin ($\text{J ～ 41}\text{h}\text{?}$). Upbends are found, due to the alignment of two h_{$\text{11}\text{2}$} protons at $\text{0.40 ?}\text{h}\text{?}\text{ω ? 0.46}\text{MeV}$ in all bands. A systematic shift with neutron number of the band-crossing frequency is observed and is related to a change in quadrupole deformation ?₂.     

Structure of high-spin states in 232Th, 234U and 236U

Multiple Coulomb excitation of ²³²Th, ²³⁴U and ²³⁶U by 5.3 $\text{MeV}\text{u}$²⁰⁸Pb ions has been studied using γ-ray spectroscopy. Excitation of ground-band levels is observed up to spin I^π = 26⁺ (tentatively 28 ⁺) in ²³²Th and ²³⁴U and I^π = 28⁺ (tentatively 30⁺)in ²³⁶U. High-spin levels of the K^π = 0^? octupole-vibrational bands are also observed in these nuclei. The measured transition energies between ground-band levels suggest that at $\text{I≈ 28}\text{h}\text{?}$ several units of angular momentum are carried by single particles aligned with the rotation axis.This result can be understood in terms of a super band built on aligned two-quasiparticle configurations which crosses the ground-state rotational band at a rotational frequency of $\text{h}\text{?}\text{ω ? 0.25}\text{MeV}\text{(I ? 28}\text{h}\text{?}\text{)}$. The E2 transition-matrix elements deduced from the experimental γ-yields agree within their errors with the rigid-rotor predictions up to the highest spins observed.The experimental results are discussed using the concept of rotation alignment and are compared with predictions of the rotation-vibration model and the interacting-boson model.