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Title: Medium-spin {gamma}-ray spectroscopy of the transitional nucleus {sup 160}Er

Abstract

The nucleus {sup 160}Er, with the structural parameter R{sub 4/2}=E(4{sub 1}{sup +})/E(2{sub 1}{sup +})=3.10, falls on the transition path between the critical point of the vibrator-rotor shape phase transition and the rigid rotor limit, thus serving as a critical test of the CBS rotor model, which describes this transition region. Medium-spin states of {sup 160}Er have been populated via the reaction {sup 159}Tb({sup 6}Li,5n) and new levels have been identified and interpreted as the even-spin members of the {gamma} band and members of the {beta} vibrational band. Level energies and branching ratios are compared to the CBS rotor model predictions.

Authors:
; ; ; ; ; ; ; ; ;  [1];  [2]
  1. Department of Physics and Astronomy, State University of New York, Stony Brook, New York 11794-3800 (United States)
  2. Institut fuer Kernphysik, Universitaet zu Koeln, D-50937 Cologne (Germany)
Publication Date:
OSTI Identifier:
20771195
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 73; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevC.73.014317; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BRANCHING RATIO; COLLECTIVE MODEL; ENERGY-LEVEL TRANSITIONS; ERBIUM 160; GAMMA SPECTRA; GAMMA SPECTROSCOPY; LITHIUM 6 REACTIONS; PARTICLE-CORE COUPLING MODEL; PHASE TRANSFORMATIONS; SPIN; TERBIUM 159 TARGET; VIBRATIONAL STATES

Citation Formats

Dusling, K., Pietralla, N., Rainovski, G., Ahn, T., Bochev, B., Costin, A., Koike, T., Li, T.C., Pontillo, S., Vaman, C., and Linnemann, A. Medium-spin {gamma}-ray spectroscopy of the transitional nucleus {sup 160}Er. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.73.014317.
Dusling, K., Pietralla, N., Rainovski, G., Ahn, T., Bochev, B., Costin, A., Koike, T., Li, T.C., Pontillo, S., Vaman, C., & Linnemann, A. Medium-spin {gamma}-ray spectroscopy of the transitional nucleus {sup 160}Er. United States. doi:10.1103/PhysRevC.73.014317.
Dusling, K., Pietralla, N., Rainovski, G., Ahn, T., Bochev, B., Costin, A., Koike, T., Li, T.C., Pontillo, S., Vaman, C., and Linnemann, A. Sun . "Medium-spin {gamma}-ray spectroscopy of the transitional nucleus {sup 160}Er". United States. doi:10.1103/PhysRevC.73.014317.
@article{osti_20771195,
title = {Medium-spin {gamma}-ray spectroscopy of the transitional nucleus {sup 160}Er},
author = {Dusling, K. and Pietralla, N. and Rainovski, G. and Ahn, T. and Bochev, B. and Costin, A. and Koike, T. and Li, T.C. and Pontillo, S. and Vaman, C. and Linnemann, A.},
abstractNote = {The nucleus {sup 160}Er, with the structural parameter R{sub 4/2}=E(4{sub 1}{sup +})/E(2{sub 1}{sup +})=3.10, falls on the transition path between the critical point of the vibrator-rotor shape phase transition and the rigid rotor limit, thus serving as a critical test of the CBS rotor model, which describes this transition region. Medium-spin states of {sup 160}Er have been populated via the reaction {sup 159}Tb({sup 6}Li,5n) and new levels have been identified and interpreted as the even-spin members of the {gamma} band and members of the {beta} vibrational band. Level energies and branching ratios are compared to the CBS rotor model predictions.},
doi = {10.1103/PhysRevC.73.014317},
journal = {Physical Review. C, Nuclear Physics},
number = 1,
volume = 73,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • High-spin states in /sup 156/Er were populated using the ( alpha ,8n) and (/sup 16/O,/sup 4/n) reactions. In the ground state band a strong back bending effect was observed at I/sup pi / = 12/sup +/. Four states of a second K = 0 band spins 9, 11, 13, and 15 were found. This second band depopulates completely into the 8/sup +/ and 10/sup +/ members of the ground state band. This is explained by the fact that the upper states of this second band are yrast states and that this band crosses the (gsb)-line at I approximately 11. (GE)
  • The {sup 114}Cd({sup 48}Ca,6n{gamma}) reaction at 215 MeV has been investigated using the Gammasphere spectrometer to study the high-spin structure of the nucleus {sub 68}{sup 156}Er{sub 88}. Many new transitions have been established along with definitive spin-parity level assignments from a high-fold angular-distribution analysis. In addition, absolute B(M1) and B(E1) strengths have been inferred from measured {gamma}-ray branching ratios. Strong B(E1) strength (10{sup -3} W.u.) is discussed in terms of possible octupole collectivity at low spin. At high spin, this nucleus undergoes a Coriolis-induced shape transition from a prolate state of collective rotation to a noncollective, triaxial-oblate configuration. The yrastmore » positive-parity structure ultimately terminates in an energetically favored oblate state at I{sup {pi}}=42{sup +}. Several weak high-energy {gamma}-ray transitions have been discovered that feed this favored state. State-of-the-art cranked Nilsson-Strutinsky calculations are used to interpret the high-spin behavior of {sup 156}Er and comparisons are made with other N=88 isotones.« less
  • We have measured the intensities and feeding times and also the lifetimes of the yrast levels of the isotopes /sup 156,160//sub 68/Er. The reactions /sup 120,124//sub 50/Sn(/sup 40//sub 18/Ar,4n) /sup 156,160//sub 68/Er were used, and the Doppler method of determining recoil distances was used. For the isotope /sup 160//sub 68/Er the lifetimes of the levels have the same tendency of a weak deviation from the model of a rigid rotator as in the known cases of /sub 70/Yb and /sub 72/Hf, but the data for the transition-region nucleus /sup 156//sub 68/Er indicate an appreciable hindrance of transitions in the backbendingmore » region. The intensities and feeding times were measured at two energies for each isotope, which has permitted conclusions to be drawn regarding the feeding mechanism.« less
  • The g factors of the I/sup ..pi../ = 11/sup -/ isomer in /sup 154/Er and I/sup ..pi../ = (13/2)/sup +/ isomers in /sup 155/Er and /sup 157/Yb were measured using the technique of time-dependent perturbed angular distributions. The value obtained for /sup 154/Er, g = +0.0154(12), indicates a predominant configuration of ..nu..(i/sub 13/2/,h/sub 9/2/)/sub 10//sup -/, 11/sup -/ for the isomeric state. The results for /sup 155/Er and /sup 157/Yb, g = -0.085(5) and g = -0.116(12), respectively, are explained in terms of Pauli blocking of the 3/sup -/ core excitation component in the wave function of the (13/2)/sup +/more » state.« less
  • Excited states in 186Re with spins up to J = 12~ were investigated in two separate experiments using 186W(d, 2n) reactions at beam energies of 12.5 MeV and 14.5 MeV. Two- and three-fold γ-ray coincidence data were collected using the CAESAR and CAGRA spectrometers, respectively, each composed of Compton-suppressed HpGe detectors. Analysis of the data revealed rotational bands built on several two-quasiparticle intrinsic states, including a long-lived Kπ = (8+) isomer. Configuration assignments were supported by an analysis of in-band properties, such as |gK - gR| values. The excitation energies of the observed intrinsic states were compared with results frommore » multiquasiparticle blocking calculations, based on the Lipkin-Nogami pairing approach, that included contributions from the residual proton-neutron interactions.« less