Near-yrast discrete line γ-ray spectroscopy of 159Er and 160Er to I≳40ℏ

J. Simpson, M. A. Riley, J. R. Cresswell, D. V. Elenkov, P. D. Forsyth, G. B. Hagemann, D. Howe, B. Nyakó, S. Ogaza, J. C. Lisle, J. F. Sharpey-Schafer

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Abstract

High-spin states in 159Er and 160Er have been populated using the 116Cd+48Ca reaction at a 48Ca bombarding energy of 210 MeV. Gamma rays were detected in an array (TESSA2) of six escape suppressed germanium spectrometers and a 50 element BGO multiplicity and summed energy detector. Decay scheme and angular correlation data for these nuclei were deduced from the gamma - gamma -BGO coincidence data. In 159Er the yrast band has been identified up to Ipi=89/2+ and three side bands have been observed to 69/2-(77/2-), 43/2+ and 51/2 -(59/2-). In 160Er the lowest energy positive-parity band has been observed up to 38+(40+) and the two lowest energy negative-parity side bands up to 40-(44 -) and 39-(41-). The ground state level sequence has been observed up to (28+). The spin and parity of the low-lying states (I160Er were established by measuring gamma -ray angular distributions and internal conversion coefficients following the 148Nd(16O, 4n) reaction at a beam energy of 80 MeV. The band structures can be understood in terms of aligning quasiparticles using the cranked shell model. The alignment of the first pair of h11/2 protons is observed in the three lowest energy bands in each nucleus. The increase in crossing frequency of this alignment with neutron number is further evidence for the increase in deformation for the light Er isotopes. Evidence is presented for the competition of favoured single-particle configurations with the collective structures at the highest spins.

Original languageEnglish
Article number013
Pages (from-to)847-881
Number of pages35
JournalJournal of Physics G: Nuclear Physics
Volume13
Issue number6
DOIs
Publication statusPublished - 1987

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rays
parity
spectroscopy
alignment
energy
gamma rays
nuclei
internal conversion
angular correlation
escape
energy bands
germanium
angular distribution
isotopes
spectrometers
neutrons
ground state
protons
detectors
decay

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Nuclear and High Energy Physics

Cite this

Simpson, J., Riley, M. A., Cresswell, J. R., Elenkov, D. V., Forsyth, P. D., Hagemann, G. B., ... Sharpey-Schafer, J. F. (1987). Near-yrast discrete line γ-ray spectroscopy of 159Er and 160Er to I≳40ℏ. Journal of Physics G: Nuclear Physics, 13(6), 847-881. [013]. https://doi.org/10.1088/0305-4616/13/6/013

Near-yrast discrete line γ-ray spectroscopy of 159Er and 160Er to I≳40ℏ. / Simpson, J.; Riley, M. A.; Cresswell, J. R.; Elenkov, D. V.; Forsyth, P. D.; Hagemann, G. B.; Howe, D.; Nyakó, B.; Ogaza, S.; Lisle, J. C.; Sharpey-Schafer, J. F.

In: Journal of Physics G: Nuclear Physics, Vol. 13, No. 6, 013, 1987, p. 847-881.

Research output: Contribution to journalArticle

Simpson, J, Riley, MA, Cresswell, JR, Elenkov, DV, Forsyth, PD, Hagemann, GB, Howe, D, Nyakó, B, Ogaza, S, Lisle, JC & Sharpey-Schafer, JF 1987, 'Near-yrast discrete line γ-ray spectroscopy of 159Er and 160Er to I≳40ℏ', Journal of Physics G: Nuclear Physics, vol. 13, no. 6, 013, pp. 847-881. https://doi.org/10.1088/0305-4616/13/6/013
Simpson J, Riley MA, Cresswell JR, Elenkov DV, Forsyth PD, Hagemann GB et al. Near-yrast discrete line γ-ray spectroscopy of 159Er and 160Er to I≳40ℏ. Journal of Physics G: Nuclear Physics. 1987;13(6):847-881. 013. https://doi.org/10.1088/0305-4616/13/6/013
Simpson, J. ; Riley, M. A. ; Cresswell, J. R. ; Elenkov, D. V. ; Forsyth, P. D. ; Hagemann, G. B. ; Howe, D. ; Nyakó, B. ; Ogaza, S. ; Lisle, J. C. ; Sharpey-Schafer, J. F. / Near-yrast discrete line γ-ray spectroscopy of 159Er and 160Er to I≳40ℏ. In: Journal of Physics G: Nuclear Physics. 1987 ; Vol. 13, No. 6. pp. 847-881.
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abstract = "High-spin states in 159Er and 160Er have been populated using the 116Cd+48Ca reaction at a 48Ca bombarding energy of 210 MeV. Gamma rays were detected in an array (TESSA2) of six escape suppressed germanium spectrometers and a 50 element BGO multiplicity and summed energy detector. Decay scheme and angular correlation data for these nuclei were deduced from the gamma - gamma -BGO coincidence data. In 159Er the yrast band has been identified up to Ipi=89/2+ and three side bands have been observed to 69/2-(77/2-), 43/2+ and 51/2 -(59/2-). In 160Er the lowest energy positive-parity band has been observed up to 38+(40+) and the two lowest energy negative-parity side bands up to 40-(44 -) and 39-(41-). The ground state level sequence has been observed up to (28+). The spin and parity of the low-lying states (I160Er were established by measuring gamma -ray angular distributions and internal conversion coefficients following the 148Nd(16O, 4n) reaction at a beam energy of 80 MeV. The band structures can be understood in terms of aligning quasiparticles using the cranked shell model. The alignment of the first pair of h11/2 protons is observed in the three lowest energy bands in each nucleus. The increase in crossing frequency of this alignment with neutron number is further evidence for the increase in deformation for the light Er isotopes. Evidence is presented for the competition of favoured single-particle configurations with the collective structures at the highest spins.",
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AU - Elenkov, D. V.

AU - Forsyth, P. D.

AU - Hagemann, G. B.

AU - Howe, D.

AU - Nyakó, B.

AU - Ogaza, S.

AU - Lisle, J. C.

AU - Sharpey-Schafer, J. F.

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