High Spin Physics 2001 - Abstract 006

High Spin Physics 2001, Warsaw, February 6-10, 2001

Abstract No: 006

Submitted on: 19 Dec 2000, 17:37 GMT

Title: Measurements of spectroscopic quadrupole moments at high spins: test of the Tilted Axis Cranking (TAC) model

Author(s): D.L. Balabanski,^1,2 K. Vyvey,¹ G. Neyens,¹ D. Boremans,¹ N. Coulier,¹ W. De Clercq,¹ R. Coussement,¹, G. Georgiev,^1,2 A. Lèpine-Szily,^1,3 S. Ternier,¹ S. Teughels,¹ M. Mineva,⁴ P.M. Walker,⁵ H. Hubel,⁶ S. Chmel,⁶ N. Nenoff,⁶ D. Rossbach,⁶ R.Schwengener,⁷ P. Blaha,⁸ D. Almehed⁷ and S. Frauendorf^7,9

Affiliation(s): ¹IKS, University of Leuven, B-3001 Leuven, Belgium, ²Faculty of Physics, University of Sofia, BG-1164 Sofia, Bulgaria, ³IFU, Sao Paulo, CP 20156, Sao Paulo, Brazil, ⁴Department of Physics, Lund University, S-221 00 Lund, Sweden, ⁵Department of Physics, University of Surrey, Guilford GU2 7XH, UK, ⁶ISKP, University of Bonn, D-53115 Bonn, Germany, ⁷IKHP, Forschungszentrum Rossendorf, D-01314 Dresden, Germany, ⁸IPTC, Technical University Vienna, A-1060 vienna, Austria, ⁹Department of Physics, University of Notre Dame, Indiana 46556, USA

Several measurements of spectroscopic quadrupole moments of high-spin isomers ware carried out recently at the CYCLONE facility at Louvain-la-Neuve, using the $\underline{Le}$ vel $\underline{M}$ ixing $\underline{S}$ pectroscopy (LEMS) technique [1]. All of them aimed to test the predictions of the $\underline{T}$ ilted $\underline{A}$ xis $\underline{C}$ ranking (TAC) model [2]

The spectroscopic quadrupole moment of the high-spin, high-K five-quasiparticle isomer ( $K^\pi=\frac{35}{2}^-$ , $T_{1/2}=750\pm80$ ns, E_i=3349 keV) in ¹⁷⁹W was found to be Q_s=4.00(^+0.83_-1.06) eb, which corresponds to an intrinsic quadrupole moment Q₀=4.73(^+0.98_-1.25) eb and to a quadrupole deformation $\beta_2=0.185(^{+0.038}_{-0.049})$ . These values differ significantly from the deduced ground-state quadrupole moments and deformations and are in disagreement with the current theoretical predictions in this mass region [3].

In another experiment we have measured the spectroscopic quadrupole moment of the $I^\pi=11^-$ isomer in ¹⁹⁶Pb. This isomer has the same proton $\pi(s^{-2}_{1/2}h_{9/2}i_{13/2})$ configuration as the $I^\pi=16^{(-)}$ bandhead of the magnetic band in ¹⁹⁶Pb, which allows to deduce the quadrupole moment of the 16^(-) state as Q_s=-0.316(97) eb. This is the first experimental determination of the quadrupole moment of a magnetic rotational bandhead. Its small value proves the nearly sphericity of the magnetic bandhead [4].

Bibliography

1

F. Hardeman et al., Phys. Rev. C43, 130 (1991).

2

S. Frauendorf, Nucl. Phys. A557, 259c (1993).

3

D.L. Balabanski et al., Phys. Rev. Lett. (in print).

4

K. Vyvey et al., in preparation for Phys. Rev. Lett.

$\fbox{ Preferred presentation of the contribution: in the oral session. }$

High Spin Conference
2000-12-19

Abstract No:	006
Submitted on:	19 Dec 2000, 17:37 GMT
Title:	Measurements of spectroscopic quadrupole moments at high spins: test of the Tilted Axis Cranking (TAC) model
Author(s):	D.L. Balabanski,^1,2 K. Vyvey,¹ G. Neyens,¹ D. Boremans,¹ N. Coulier,¹ W. De Clercq,¹ R. Coussement,¹, G. Georgiev,^1,2 A. Lèpine-Szily,^1,3 S. Ternier,¹ S. Teughels,¹ M. Mineva,⁴ P.M. Walker,⁵ H. Hubel,⁶ S. Chmel,⁶ N. Nenoff,⁶ D. Rossbach,⁶ R.Schwengener,⁷ P. Blaha,⁸ D. Almehed⁷ and S. Frauendorf^7,9
Affiliation(s):	¹IKS, University of Leuven, B-3001 Leuven, Belgium, ²Faculty of Physics, University of Sofia, BG-1164 Sofia, Bulgaria, ³IFU, Sao Paulo, CP 20156, Sao Paulo, Brazil, ⁴Department of Physics, Lund University, S-221 00 Lund, Sweden, ⁵Department of Physics, University of Surrey, Guilford GU2 7XH, UK, ⁶ISKP, University of Bonn, D-53115 Bonn, Germany, ⁷IKHP, Forschungszentrum Rossendorf, D-01314 Dresden, Germany, ⁸IPTC, Technical University Vienna, A-1060 vienna, Austria, ⁹Department of Physics, University of Notre Dame, Indiana 46556, USA