Evolution of collectivity near mid-shell from excited-state lifetime measurements in rare earth nuclei

V. Werner, N. Cooper, J.-M. Régis, M. Rudigier, E. Williams, J. Jolie, R. B. Cakirli, R. F. Casten, T. Ahn, V. Anagnostatou, Z. Berant, M. Bonett-Matiz, M. Elvers, A. Heinz, G. Ilie, D. Radeck, D. Savran, and M. K. Smith

Phys. Rev. C 93, 034323 – Published 18 March 2016

Abstract

The $B (E 2)$ excitation strength of the first excited $2^{+}$ state in even-even nuclei should directly correlate with the size of the valence space and maximize at mid-shell. A previously found saturation of $B (E 2)$ strengths in well-deformed rotors at mid-shell is tested through high-precision measurements of the lifetimes of the lowest-lying $2^{+}$ states of the ${}^{168}{Hf}$ and ${}^{174}W$ rare earth isotopes. Measurements were performed using fast ${LaBr}_{3}$ scintillation detectors. Combined with the recently remeasured $B (E 2; 2_{1}^{+} \to 0_{1}^{+})$ values for Hf and W isotopes the new data remove discrepancies observed in the differentials of $B (E 2)$ values for these isotopes.

Received 3 August 2015
Revised 26 December 2015

DOI:https://doi.org/10.1103/PhysRevC.93.034323

Physics Subject Headings (PhySH)

Collective levels Electromagnetic transitions Energy levels Lifetimes & widths

150 ≤ A ≤ 189

Spectrometers & spectroscopic techniques

Nuclear Physics

Authors & Affiliations

V. Werner^1,2,*, N. Cooper¹, J.-M. Régis³, M. Rudigier^3,4, E. Williams^1,†, J. Jolie³, R. B. Cakirli⁵, R. F. Casten¹, T. Ahn^1,6, V. Anagnostatou^1,4, Z. Berant^1,7, M. Bonett-Matiz¹, M. Elvers^1,3, A. Heinz^1,8, G. Ilie¹, D. Radeck^1,3, D. Savran^1,9,10, and M. K. Smith^1,6

¹Wright Nuclear Structure Laboratory, Yale University, P.O. Box 208120, New Haven, Connecticut 06520, USA
²Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstr. 9, 64289 Darmstadt, Germany
³Institut für Kernphysik, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
⁴University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom
⁵Department of Physics, University of Istanbul, 34134 Istanbul, Turkey
⁶Physics Department, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, Indiana 46656
⁷Nuclear Research Center Negev, Beer-Sheva 84190, Israel
⁸Department of Fundamental Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
⁹ExtreMe Matter Institue EMMI and Research Division, GSI Helmholtzzentrum für Schwerionenforschung, D-64291 Darmstadt, Germany
¹⁰Frankfurt Institute for Advanced Studies (FIAS), D-60438 Frankfurt am Main, Germany

^*vw@ikp.tu-darmstadt.de
^†Present address: Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 2601, Australia.

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Vol. 93, Iss. 3 — March 2016

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