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Phys. Rev. C 69, 064314 (2004) [14 pages]

Collective excitations and shape changes in 80Y

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R. A. Kaye1,2, O. Grubor-Urosevic1, S. L. Tabor2, J. Döring3, Y. Sun4,5, R. Palit3, J. A. Sheikh6, T. Baldwin2,*, D. B. Campbell2, C. Chandler2,†, M. W. Cooper2,‡, S. M. Gerbick1, C. R. Hoffman2, J. Pavan2, L. A. Riley7,§, and M. Wiedeking2
1Department of Chemistry and Physics, Purdue University Calumet, Hammond, Indiana 46323, USA
2Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
3Gesellschaft für Schwerionenforschung (GSI), Planckstr. 1, D-64291 Darmstadt, Germany
4Department of Physics and Joint Institute of Nuclear Astrophysics, University of Notre Dame, Notre Dame, Indiana 46556, USA
5Department of Physics, Xuzhou Normal University, Xuzhou, Jiangsu 221009, People’s Republic of China
6Department of Physics, University of Kashmir, Hazrathbal, Srinagar, Kashmir 190 006, India
7Department of Physics and Astronomy, Earlham College, Richmond, Indiana 47374, USA

Received 24 January 2004; published 14 June 2004

Lifetimes of 30 high-spin levels in 80Y were measured using the Doppler-shift attenuation method. The high-spin states were populated using the 54Fe(28Si, pn) reaction at 90 MeV, with a thick 14 mg∕cm2 54Fe target used to stop all recoils. Prompt γ–γ coincidences were detected using a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. Lifetimes were determined from experimental line shapes measured at both 35° and 145° whenever possible. Transition quadrupole moments Qt inferred from the lifetimes in the lowest positive- and negative-parity bands are large (>3 eb) at low spin, but show a rather abrupt decrease at high spin. Results of calculations using the projected shell and cranked Woods-Saxon models in conjunction with the cranked-shell model suggest that these drops in Qt are due to quasiparticle alignment, which introduce shape changes in each band from nearly prolate below the alignment to triaxial above. Magnetic dipole transition strengths B(M1) in the yrast positive-parity band show a strong alternating pattern with spin, similar to that observed in other neighboring odd-odd nuclei.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevC.69.064314
DOI:
10.1103/PhysRevC.69.064314
PACS:
21.10.Tg, 21.10.Re, 23.20.Lv, 27.50.+e

*Present address: Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK.

†Present address: School of Chemistry and Physics, Keele University, Keele, Staffordshire, ST5 5BG, UK.

‡Present address: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824.

§Present address: Department of Physics and Astronomy, Ursinus College, Collegeville, PA 19426.

 
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