skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Unpaired band crossings in the A{approx}160 mass region

Abstract

Levels schemes for a number of low lying normally deformed bands in {sup 161,162}Er have been extended to significantly higher spins than hitherto using the EUROBALL Ge detector array sited at the Legnaro National Laboratory. In the case of one band in {sup 161}Er states have tentatively been observed to a spin in excess of 60({Dirac_h}/2{pi}). Evidence is found for a band crossing at high spin in the yrast even parity, positive signature (+, +1/2) band in {sup 161}Er. This can be explained in terms of a system in which the static pairing is quenched either involving a rearrangement of two neutrons into steeply aligning i{sub 13/2} orbitals or possibly an interchange of state of one proton and one neutron. A similar type of band crossing is tentatively identified in the lowest (-,-1/2) band of {sup 161}Er. Since a crossing involving the interchange of neutrons is blocked, this must involve protons. This, if confirmed, provides the first direct evidence for the quenching of static proton pairing at high spin in this mass region. Recent calculations [1] predict that such a crossing involving purely protons will occur in this band at I{approx}60({Dirac_h}/2{pi})

Authors:
; ; ;  [1];  [2];  [3]; ; ;  [4]; ;  [5];  [6];  [7]
  1. Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)
  2. CLRC, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom)
  3. School of Sciences, University of Stafford, Stoke-on-Trent ST4 2DE (United Kingdom)
  4. Department of Physics, University of Liverpool, Liverpool L69 3BX (United Kingdom)
  5. Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark)
  6. INFN, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy)
  7. Department of Physics, Florida State University, Tallahassee (United States)
Publication Date:
OSTI Identifier:
21208242
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 481; Journal Issue: 1; Conference: Nuclear structure 98 conference, Gatlinburg, TN (United States), 10-15 Aug 1998; Other Information: DOI: 10.1063/1.59525; (c) 1999 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; DEFORMED NUCLEI; ERBIUM 161; ERBIUM 162; GAMMA SPECTRA; GE SEMICONDUCTOR DETECTORS; NEUTRONS; NUCLEAR STRUCTURE; PAIRING INTERACTIONS; PARITY; PROTONS; SPIN; YRAST STATES

Citation Formats

Lisle, J. C., Bagshaw, A. P., Dagnall, P. J., Smith, A. G., Simpson, J., Bentley, M. A., Cullen, D. M., King, S. L., Shepherd, S., Hagemann, G. B., Tormanen, S., Napoli, D., and Riley, M. Unpaired band crossings in the A{approx}160 mass region. United States: N. p., 1999. Web. doi:10.1063/1.59525.
Lisle, J. C., Bagshaw, A. P., Dagnall, P. J., Smith, A. G., Simpson, J., Bentley, M. A., Cullen, D. M., King, S. L., Shepherd, S., Hagemann, G. B., Tormanen, S., Napoli, D., & Riley, M. Unpaired band crossings in the A{approx}160 mass region. United States. doi:10.1063/1.59525.
Lisle, J. C., Bagshaw, A. P., Dagnall, P. J., Smith, A. G., Simpson, J., Bentley, M. A., Cullen, D. M., King, S. L., Shepherd, S., Hagemann, G. B., Tormanen, S., Napoli, D., and Riley, M. Thu . "Unpaired band crossings in the A{approx}160 mass region". United States. doi:10.1063/1.59525.
@article{osti_21208242,
title = {Unpaired band crossings in the A{approx}160 mass region},
author = {Lisle, J. C. and Bagshaw, A. P. and Dagnall, P. J. and Smith, A. G. and Simpson, J. and Bentley, M. A. and Cullen, D. M. and King, S. L. and Shepherd, S. and Hagemann, G. B. and Tormanen, S. and Napoli, D. and Riley, M.},
abstractNote = {Levels schemes for a number of low lying normally deformed bands in {sup 161,162}Er have been extended to significantly higher spins than hitherto using the EUROBALL Ge detector array sited at the Legnaro National Laboratory. In the case of one band in {sup 161}Er states have tentatively been observed to a spin in excess of 60({Dirac_h}/2{pi}). Evidence is found for a band crossing at high spin in the yrast even parity, positive signature (+, +1/2) band in {sup 161}Er. This can be explained in terms of a system in which the static pairing is quenched either involving a rearrangement of two neutrons into steeply aligning i{sub 13/2} orbitals or possibly an interchange of state of one proton and one neutron. A similar type of band crossing is tentatively identified in the lowest (-,-1/2) band of {sup 161}Er. Since a crossing involving the interchange of neutrons is blocked, this must involve protons. This, if confirmed, provides the first direct evidence for the quenching of static proton pairing at high spin in this mass region. Recent calculations [1] predict that such a crossing involving purely protons will occur in this band at I{approx}60({Dirac_h}/2{pi})},
doi = {10.1063/1.59525},
journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 481,
place = {United States},
year = {1999},
month = {9}
}