High Spin Physics 2001 - Abstract 030

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

Abstract No: 030

Submitted on: 7 Jan 2001, 23:00 GMT

Title: Discrete Line Spectroscopy at $\sim$ 60 $\hbar$ in the Light Er Isotopes, and Global Lifetime Measurements of Highly-Deformed and Other Rotational Structures in the A $\sim$ 135 Light Rare-Earth Region.

Author(s): M.A.Riley¹, J.Simpson², A.P.Bagshaw³, J.C.Lisle³, A.Pipidis^1,4, R.W.Laird³, F.G. Kondev^1,5, D. Applebe², M.A.Bentley⁶, D. Campbell¹, D.M.Cullen³, P.J.Dagnall³, C. Fox⁷, G.B.Hagemann⁸, S.L.King⁷, V. Putnel², S.L. Shepherd⁷, A.G.Smith³, J. Smith³, S.Törmänen⁸, A. Afanasjev ^9,10,11, I. Ragnarsson¹¹, and D.E. Archer¹³, T.B. Brown¹, R.M. Clark¹², M. Devlin¹⁴, P. Fallon¹², D.J.Hartley¹⁶, I.M. Hibbert⁷, D.T. Joss¹⁵, D.R. LaFosse¹⁴, P.J. Nolan⁷,N.J. O'Brien¹⁵, J. Pfohl¹, E.S. Paul⁷, D.G. Sarantites¹⁴, R.K.Sheline¹, R. Wadsworth¹⁵, M.T. Matev ^16,18, J. Dobaczewski^17,18, G.A. Lalazissis⁹, W. Nazarewicz ^16,18,19, W. Satu $\l$ a¹⁸

Affiliation(s):
¹Florida State U.,USA. ²Daresbury Lab., UK. ³U. of Manchester, UK. ⁴U. of Surrey, UK. ⁵ANL, USA. ⁶Staffordshire U., UK. ⁷U. of Liverpool, UK. ⁸NBI, Denmark. ⁹Tech. Universität München, Germany. ¹⁰U. of Latvia, Latvia. ¹¹Lund Inst. of Tech., Sweden. ¹²LBNL, USA. ¹³LLNL, USA. ¹⁴Washington U., USA. ¹⁵U. of York, UK. ¹⁶U. of Tennessee, USA. ¹⁷CNRS-IN2P3, France. ¹⁸Warsaw U., Poland. ¹⁹ORNL, USA.

The quest to observe increasingly high angular momentum states in atomic nuclei has driven the field of high spin nuclear spectroscopy for many years. It is in the light mass A $\sim$ 160 Dy and Er nuclei that the highest spin states in normal deformed nuclei have been observed (spin I $\sim$ 60 $\hbar$ and E_excit $\sim$ 30 MeV) [1,2]. Aside from the question of the limiting spin at which discrete states in nuclei exist, other fundamental issues concern the effect of rotation on the nuclear equilibrium shape, on the nuclear pairing correlations and charting the correct single-particle spectrum of states at ultra-high spins. We have performed two recent experiments using the Euroball $\gamma$ -ray spectrometer to explore the N = 91 - 94 erbium isotopes ( ^159-162Er) in order to shed light on these important questions. Several key systematic trends have been identified and will be discussed.

GAMMASPHERE coupled with the Microball charged-particle detector has made possible a new class of nuclear lifetime measurements. For the first time, it has been possible to extract differential lifetime measurements free from common systematic errors for over 15 different nuclei (various isotopes of Ce, Pr, Nd, Pm, and Sm) at high spin from a single experiment [3]. This comprehensive study establishes Z, N, and configuration dependent quadrupole moment trends in the A $\sim$ 135 light rare-earth region. Detailed comparisons are made with theoretical calculations using the Cranked Skyrme Hartree-Fock framework which lead to theoretical estimates for the effective deformation parameters of the single-particle orbitals in this region.

Bibliography

1: J. Simpson et al., Phys. Rev. C62 (2000) 024321.
2: F.G. Kondev et al., Phys. Lett. B437 (1998) 35.
3: R.W. Laird et al., to be published.

$\fbox{ Invited talk. }$

High Spin Conference
2001-01-08

Abstract No:	030
Submitted on:	7 Jan 2001, 23:00 GMT
Title:	Discrete Line Spectroscopy at $\sim$ 60 $\hbar$ in the Light Er Isotopes, and Global Lifetime Measurements of Highly-Deformed and Other Rotational Structures in the A $\sim$ 135 Light Rare-Earth Region.
Author(s):	M.A.Riley¹, J.Simpson², A.P.Bagshaw³, J.C.Lisle³, A.Pipidis^1,4, R.W.Laird³, F.G. Kondev^1,5, D. Applebe², M.A.Bentley⁶, D. Campbell¹, D.M.Cullen³, P.J.Dagnall³, C. Fox⁷, G.B.Hagemann⁸, S.L.King⁷, V. Putnel², S.L. Shepherd⁷, A.G.Smith³, J. Smith³, S.Törmänen⁸, A. Afanasjev ^9,10,11, I. Ragnarsson¹¹, and D.E. Archer¹³, T.B. Brown¹, R.M. Clark¹², M. Devlin¹⁴, P. Fallon¹², D.J.Hartley¹⁶, I.M. Hibbert⁷, D.T. Joss¹⁵, D.R. LaFosse¹⁴, P.J. Nolan⁷,N.J. O'Brien¹⁵, J. Pfohl¹, E.S. Paul⁷, D.G. Sarantites¹⁴, R.K.Sheline¹, R. Wadsworth¹⁵, M.T. Matev ^16,18, J. Dobaczewski^17,18, G.A. Lalazissis⁹, W. Nazarewicz ^16,18,19, W. Satu $\l$ a¹⁸
Affiliation(s):	¹Florida State U.,USA. ²Daresbury Lab., UK. ³U. of Manchester, UK. ⁴U. of Surrey, UK. ⁵ANL, USA. ⁶Staffordshire U., UK. ⁷U. of Liverpool, UK. ⁸NBI, Denmark. ⁹Tech. Universität München, Germany. ¹⁰U. of Latvia, Latvia. ¹¹Lund Inst. of Tech., Sweden. ¹²LBNL, USA. ¹³LLNL, USA. ¹⁴Washington U., USA. ¹⁵U. of York, UK. ¹⁶U. of Tennessee, USA. ¹⁷CNRS-IN2P3, France. ¹⁸Warsaw U., Poland. ¹⁹ORNL, USA.