0000000000157036
AUTHOR
M. A. Riley
showing 7 related works from this author
Global lifetime measurements of highly-deformed and other rotational structures in the a ∼135 light rare-earth region: probing the single-particle mo…
2001
It has been possible, using GAMMASPHERE plus Microball,to extract differential lifetime measurements free from common systematic errors for over 15 different nuclei (various isotopes of Ce, Pr, Nd, Pm, and Sm) at high spin within a single experiment. This comprehensive study establishes the effective single-particle quadrupole moments in the A~135 light rare-earth region. Detailed comparisons are made with calculations using the self-consistent cranked mean-field theory.
First candidates for γ vibrational bands built on the [505]11/2⁻ neutron orbital in odd-A Dy isotopes
2020
Rotational structures have been measured using the Jurogam II and GAMMASPHERE arrays at low spin following the 155Gd(α,2n)157Dy and 148Nd(12C,5n)155Dy reactions at 25 and 65 MeV, respectively. We report high-K bands, which are conjectured to be the first candidates of a Kπ=2+γ vibrational band, built on the [505]11/2− neutron orbital, in both odd-A155,157Dy isotopes. The coupling of the first excited K=0+ states or the so-called β vibrational bands at 661 and 676 keV in 154Dy and 156Dy to the [505]11/2− orbital, to produce a Kπ=11/2− band, was not observed in both 155Dy and 157Dy, respectively. The implication of these findings on the interpretation of the first excited 0+ states in the cor…
Spectroscopy of 161Hf from low to high spin
2014
Excited states in the neutron-deficient nucleus 161 72Hf89 have been populated using the 118Sn(48Ti,5n) 161Hf and 110Pd(56Fe,5n) 161Hf fusion-evaporation reactions at 240 and 270 MeV, respectively. The level scheme for 161Hf has been extended with the observation of new band structures and an I π = (13/2+) isomeric state with a half-life of 4.8(2) μs has been identified. The decay path from this isomer to the (7/2−) ground state is established. The yrast band, based on the (13/2+) isomeric state, is extended up to (73/2+) and side band structures are identified up to (69/2−) and (55/2−). Quasiparticle assignments for these rotational structures are made on the basis of their alignment prope…
Shell structure and shape coexistence in195Pb
1995
Pb-195 was investigated utilizing the reactions Dy-164(S-36, 5n)Pb-195 and Dy-164(S-34, 3n)Pb-195 at beam energies of 170 and 160MeV respectively. Two new dipole bands which feed into the yrast 25/2(+) state, were found in Pb-195. The connection between the bands and the spherical states was established and thus spins and energies of the involved collective states were determined. The deformation is understood as mainly due to excitations of protons across the Z = 82 shell gap. The observed backbends are interpreted as alignment of i(13/2) neutrons.
Discrete lineγ-ray spectroscopy in the(50–60)ħspin domain of161,162Er
2000
Very high spin states $(I=50--60\ensuremath{\Elzxh})$ have been observed in the transitional nuclei ${}^{161}\mathrm{Er}$ and ${}^{162}\mathrm{Er}$ using the Euroball $\ensuremath{\gamma}$-ray spectrometer. In ${}^{161}\mathrm{Er},$ three bands are observed well above spin $50\ensuremath{\Elzxh}.$ In the positive parity, positive signature $(+,+\frac{1}{2})$ band a discontinuity in the regular rotational behavior occurs at ${\frac{109}{2}}^{+}$ and a splitting into two branches occurs at ${\frac{97}{2}}^{\ensuremath{-}}$ in the negative parity, positive signature $(\ensuremath{-},+\frac{1}{2})$ band. The $(\ensuremath{-},\ensuremath{-}\frac{1}{2})$ band continues in a regular fashion to ${\…
Yrast structures in the light Pt isotopes169–173Pt
2005
The exploitation of the recoil-decay tagging (RDT) technique has reinvigorated experimental investigations of the shape coexistence phenomenon in heavy neutron-deficient nuclei. In a recent experiment using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator, excited states have been investigated in the light platinum isotopes. In addition to extending the yrast sequences in 170Pt and 172Pt, the first observation of excited states in the odd-N isotopes, 169Pt and 173Pt, is reported. The bands are discussed in terms of trends in level excitation energies as a function of neutron number.
β and γ bands in N = 88, 90, and 92 isotones investigated with a five-dimensional collective Hamiltonian based on covariant density functional theory…
2019
A comprehensive systematic study is made for the collective β and γ bands in even-even isotopes with neutron numbers N=88 to 92 and proton numbers Z=62(Sm) to 70 (Yb). Data, including excitation energies, B(E0) and B(E2) values, and branching ratios from previously published experiments are collated with new data presented for the first time in this study. The experimental data are compared to calculations using a five-dimensional collective Hamiltonian (5DCH) based on the covariant density functional theory (CDFT). A realistic potential in the quadrupole shape parameters V(β,γ) is determined from potential energy surfaces (PES) calculated using the CDFT. The parameters of the 5DCH are fixe…