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Evolution of structure and shapes in Er 158 to ultrahigh spin

Simpson, J. ; Riley, M. A. ; Pipidis, A. ; Paul, E. S. ; Wang, X. ; Nolan, P. J. ; Sharpey-Schafer, J. F. ; Aguilar, A. ; Appelbe, D. E. and Ayangeakaa, A. D. , et al. (2023) In Physical Review C 107(5).
Abstract

The level structure of Er158 has been studied using the Gammasphere spectrometer via the Cd114(Ca48,4n) reaction at 215 MeV with both thin (self-supporting) and thick (backed) targets. The level scheme has been considerably extended with more than 200 new transitions and six new rotational structures, including two strongly coupled high-K bands. Configuration assignments for the new structures are based on their observed alignments, B(M1)/B(E2) ratios of reduced transition probabilities, excitation energies, and comparisons with neighboring nuclei and theoretical calculations. With increasing angular momentum, this nucleus exhibits Coriolis-induced alignments of both neutrons and protons before it then undergoes a rotation-induced... (More)

The level structure of Er158 has been studied using the Gammasphere spectrometer via the Cd114(Ca48,4n) reaction at 215 MeV with both thin (self-supporting) and thick (backed) targets. The level scheme has been considerably extended with more than 200 new transitions and six new rotational structures, including two strongly coupled high-K bands. Configuration assignments for the new structures are based on their observed alignments, B(M1)/B(E2) ratios of reduced transition probabilities, excitation energies, and comparisons with neighboring nuclei and theoretical calculations. With increasing angular momentum, this nucleus exhibits Coriolis-induced alignments of both neutrons and protons before it then undergoes a rotation-induced transition from near-prolate collective rotation to a noncollective oblate configuration. This transition occurs via the mechanism of band termination around spin 45ħ in three rotational structures. Two distinct lifetime branches, consistent with the crossing of a collective "fast"rotational structure by an energetically favored "slow"terminating sequence, are confirmed for the positive-parity states, and similar behavior is established in the negative-parity states. Weak-intensity, high-energy transitions are observed to feed into the terminating states. At the highest spins, three collective bands with high dynamic moments of inertia and large quadrupole moments were identified. These bands are interpreted as triaxial strongly deformed structures and mark a return to collectivity at ultrahigh spin.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review C
volume
107
issue
5
article number
054305
publisher
American Physical Society
external identifiers
  • scopus:85161271037
ISSN
2469-9985
DOI
10.1103/PhysRevC.107.054305
language
English
LU publication?
yes
id
8a9553f0-ae6f-4769-807f-d0164b03df6d
date added to LUP
2023-08-22 11:11:39
date last changed
2023-08-22 11:11:39
@article{8a9553f0-ae6f-4769-807f-d0164b03df6d,
  abstract     = {{<p>The level structure of Er158 has been studied using the Gammasphere spectrometer via the Cd114(Ca48,4n) reaction at 215 MeV with both thin (self-supporting) and thick (backed) targets. The level scheme has been considerably extended with more than 200 new transitions and six new rotational structures, including two strongly coupled high-K bands. Configuration assignments for the new structures are based on their observed alignments, B(M1)/B(E2) ratios of reduced transition probabilities, excitation energies, and comparisons with neighboring nuclei and theoretical calculations. With increasing angular momentum, this nucleus exhibits Coriolis-induced alignments of both neutrons and protons before it then undergoes a rotation-induced transition from near-prolate collective rotation to a noncollective oblate configuration. This transition occurs via the mechanism of band termination around spin 45ħ in three rotational structures. Two distinct lifetime branches, consistent with the crossing of a collective "fast"rotational structure by an energetically favored "slow"terminating sequence, are confirmed for the positive-parity states, and similar behavior is established in the negative-parity states. Weak-intensity, high-energy transitions are observed to feed into the terminating states. At the highest spins, three collective bands with high dynamic moments of inertia and large quadrupole moments were identified. These bands are interpreted as triaxial strongly deformed structures and mark a return to collectivity at ultrahigh spin.</p>}},
  author       = {{Simpson, J. and Riley, M. A. and Pipidis, A. and Paul, E. S. and Wang, X. and Nolan, P. J. and Sharpey-Schafer, J. F. and Aguilar, A. and Appelbe, D. E. and Ayangeakaa, A. D. and Boston, A. J. and Boston, H. C. and Campbell, D. B. and Carpenter, M. P. and Chiara, C. J. and Choy, P. T.W. and Clark, R. M. and Cromaz, M. and Evans, A. O. and Fallon, P. and Garg, U. and Görgen, A. and Hartley, D. J. and Janssens, R. V.F. and Joss, D. T. and Judson, D. S. and Kondev, F. G. and Lauritsen, T. and Lee, I. Y. and Macchiavelli, A. O. and Matta, J. T. and Ollier, J. and Petri, M. and Revill, J. P. and Riedinger, L. L. and Rigby, S. V. and Teal, C. and Twin, P. J. and Unsworth, C. and Ward, D. and Zhu, S. and Ragnarsson, I.}},
  issn         = {{2469-9985}},
  language     = {{eng}},
  number       = {{5}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review C}},
  title        = {{Evolution of structure and shapes in Er 158 to ultrahigh spin}},
  url          = {{http://dx.doi.org/10.1103/PhysRevC.107.054305}},
  doi          = {{10.1103/PhysRevC.107.054305}},
  volume       = {{107}},
  year         = {{2023}},
}