First observation of excited states in $^{114}\mathrm{Cs}$: Spectroscopy of the yrast $\ensuremath{\nu}({h}_{11/2})\ensuremath{\bigotimes}\ensuremath{\pi}({h}_{11/2})$ band

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First observation of excited states in ${}^{114}{Cs}$ : Spectroscopy of the yrast $ν (h_{11 / 2}) \otimes π (h_{11 / 2})$ band

J. F. Smith, A. M. Fletcher, C. J. Chiara, M. P. Carpenter, H. J. Chantler, C. N. Davids, J. L. Durell, D. B. Fossan, S. J. Freeman, R. V. F. Janssens, T. Koike, F. G. Kondev, D. R. LaFosse, J. C. Lisle, D. Patel, E. S. Paul, W. Reviol, D. G. Sarantites, D. Seweryniak, K. Starosta, R. Wadsworth, and A. N. Wilson

Phys. Rev. C 73, 061303(R) – Published 8 June 2006

Abstract

Excited states have been observed for the first time in the very neutron-deficient $_{55}^{114} {Cs}_{59}$ nucleus. The assignment to ${}^{114}{Cs}$ was made by detecting $γ$ rays in coincidence with evaporated charged particles and with recoiling evaporation residues. A rotational band has been observed up to spin $21 ℏ$ (tentatively $25 ℏ$ ). Excitation-energy systematics and a study of quasiparticle alignments suggest that the band is based on the $ν (h_{11 / 2}) \otimes π (h_{11 / 2})$ configuration. Unlike bands based on this configuration in heavier cesium isotopes, only one signature partner is observed, and there is no evidence for signature inversion. These observations agree with theoretical calculations which predict that Coriolis-induced signature splitting should dominate at $N = 59$ .

Received 20 January 2006

DOI:https://doi.org/10.1103/PhysRevC.73.061303

Authors & Affiliations

J. F. Smith^1,*, A. M. Fletcher¹, C. J. Chiara^2,3, M. P. Carpenter⁴, H. J. Chantler⁵, C. N. Davids⁴, J. L. Durell¹, D. B. Fossan², S. J. Freeman¹, R. V. F. Janssens⁴, T. Koike², F. G. Kondev⁴, D. R. LaFosse², J. C. Lisle¹, D. Patel¹, E. S. Paul⁵, W. Reviol³, D. G. Sarantites³, D. Seweryniak⁴, K. Starosta^2,†, R. Wadsworth⁶, and A. N. Wilson^6,‡

¹Schuster Laboratory, University of Manchester, Manchester M13 9PL, United Kingdom
²Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York 11794-3800, USA
³Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA
⁴Argonne National Laboratory, Argonne, Illinois 60439, USA
⁵Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, United Kingdom
⁶Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom

^*Corresponding address: John. F. Smith@Manchester.ac.uk
^†Present address: NSCL, Michigan State University, East Lansing, Michigan 48824, USA.
^‡Present address: Department of Nuclear Physics, RSPhysSE, Australian National University, Canberra ACT 0200, Australia.

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Vol. 73, Iss. 6 — June 2006

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Figure 1
Gamma-ray spectra gated on various combinations of charged particles and $A = 114$ evaporation residues. The $γ$ -ray peaks in the spectra of panels (b) and (c) will be present the spectrum on panel (a) due to either a proton or an $α$ particle, respectively, going undetected. The spectrum shown in panel (d) is that of panel (a) with a fractions of the spectra of panels (b) [0.11] and (c) [0.91] subtracted. On panels (b) and (c), the most prominent peaks are marked with transition energies in keV, and the isotopic origin of the $γ$ ray in parentheses. On panel (d) the 229- and 443-keV $γ$ rays, assigned to ${}^{114}{Cs}$ , are marked.Reuse & Permissions
Figure 2
Representative $γ$ -ray spectra. Panel (a), projected from the $1 p$ -gated matrix, shows the spectrum in coincidence with the 443-keV $γ$ ray. The spectra shown in panels (b) to (e) are projected by double-gating in the $1 p$ -gated coincidence cube, as indicated. The peaks which are labeled, with $γ$ -ray energies in keV, correspond to $γ$ rays assigned to ${}^{114}{Cs}$ . The 663- and 825-keV $γ$ rays on panel (e) arise from coincidences with the low-energy tail of the more intense 443-keV $γ$ ray.Reuse & Permissions
Figure 3
The level scheme of ${}^{114}{Cs}$ deduced in this work, with transition energies given in keV. The uncertainties on the transition energies range from 0.1 to 0.4 keV. The spin assignments are tentative and are discussed in the text. Transitions with energies in parentheses are placed in the level scheme tentatively.Reuse & Permissions
Figure 4
Excitation-energy systematics of states in $ν (h_{11 / 2}) \otimes π (h_{11 / 2})$ bands. The data for ${}^{116 - 128}{Cs}$ are taken from Refs. 1, 3, 18, 19, 20, 21, 22. The spin assignments were discussed in Ref. 3. The excitation energies are given relative to the $10^{+}$ states in each of the bands. For ${}^{114}{Cs}$ , the two sets of data, given by open and filled circles, each represent the observed data. The open circles assume that lowest state observed is the $10^{+}$ state, and that the state at 229 keV is the $11^{+}$ state giving the band odd spins. The filled circles assume that the state at 229 keV is the $10^{+}$ state (with the lowest state observed having spin and parity $9^{+}$ ) and that the band has even spins. The open circles are thus offset from the filled circles by 229 keV.Reuse & Permissions
Figure 5
Aligned angular momenta in the $ν (h_{11 / 2}) \otimes π (h_{11 / 2})$ odd-spin bands in ${}^{114, 116, 118, 120}{Cs}$ . The data for ${}^{116, 118, 120}{Cs}$ are taken from Refs. 1, 3, 19. For all data points, a reference configuration with the Harris parameters [27] $J_{0} = 17.0$ MeV $^{- 1} ℏ^{2}$ and $J_{1} = 25.8$ MeV $^{- 3} ℏ^{4}$ [28] has been subtracted. A value of $K = 3$ has been assumed for all of the bands. The initial value of the aligned angular momentum (∼8ℏ) and the alignment frequency (0.47 MeV/ℏ) for ${}^{114}{Cs}$ are marked.Reuse & Permissions

Physical Review C

covering nuclear physics

First observation of excited states in ${}^{114}{Cs}$ : Spectroscopy of the yrast $ν (h_{11 / 2}) \otimes π (h_{11 / 2})$ band

Phys. Rev. C 73, 061303(R) – Published 8 June 2006

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Physical Review C

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First observation of excited states in Cs114: Spectroscopy of the yrast ν(h11/2)⊗π(h11/2) band

Phys. Rev. C 73, 061303(R) – Published 8 June 2006

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First observation of excited states in ${}^{114}{Cs}$ : Spectroscopy of the yrast $ν (h_{11 / 2}) \otimes π (h_{11 / 2})$ band