# Physics Division

## Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics
related subjects. Usually these are held in the Building 6008
large Conference Room, at 3:00 pm on the chosen day, but times
and locations may vary. For more information, contact our seminar
chairman,

Alfredo Galindo-Uribarri

Tel (Office): (865) 574-6124 (FAX): (865) 574-1268

#### Thu., January 15, 2004, at 3:00 p.m.

### "Pairing correlations in fastly rotating nuclei"

*Philippe Quentin, Centre d'Etudes Nucleaires de Bordeaux Gradignan*

6008 Conference Room

By way of comparison with state of the art Routhian Hartree-Fock
Bogoliubov calculations, the dynamical effect of pairing correlations in
fastly rotating nuclei is shown to be equivalent to simple counter rotating
intrinsic vortical currents as encountered in classical fluid mechanics in
the Chandrasekhar S-type ellipsoids. Specifically it is shown that
calculations within two approaches : Routhian Hartree-Fock Bogoliubov and
Routhian Hartree-Fock (no pairing !) with a constraint on an operator
"measuring" these intrinsic currents (the so-called Kelvin circulation
operator) yield very similar results. Secondly, through calculations using
a very simple model ansatz again compared with the Routhian Hartree-Fock
Bogoliubov approach, the usual Mottelson-Valatin Coriolis antipairing
effect is quantitatively validated. Finally using a recently proposed fully
microscopic treatment of pairing correlations expilicitly conserving the
particle number while using current parametrisations of the effective
nucleon-nucleon interactions, one produces more realistic descriptions than
the usual quasiparticle approach in the regions of spuriously alleged
normal to superfluid transitions at very high spins. For all these points,
numerical examples are provided for various nuclear and deformation ranges
(SD states in the A~150 or 190 nuclei, ND in rare-earth or very heavy nuclei).