ELFT HÍRADÓ

[Zoltan Mate <mate AT namafia.atomki.hu>]

Az MTA Atommagkutató Intézetének előadótermében
(Debrecen, Bem tér 18/c. 12. ép. III. em.)
2011. június 24-én, pénteken 11:00-kor


               J. F. Sharpey-Schafer
   (University of Western Cape, Belleville, South Africa)

        Collective Excitations of Deformed Nuclei
       and their Coupling to Single Particle States


címmel előadást tart.



                                        Máté Zoltán


Kivonat:
Traditionally [1] the collective excitations of deformed even-even nuclei, 
that give rise to intrinsic band heads within the pairing gap, have been 
regarded as beta(Kpi=0+), gamma (Kpi=2+) and octupole (Kpi=0- to 3-) 
vibrations. However the properties of the lowest excited 02+ states in
deformed nuclei do not generally have the properies of a beta vibration [2].
The low-lying 02+ states in transitional rare earth nuclei have been shown 
[3,4] to be 2p-2h, or 4qp, neutron states involving the [505]11/2- 
Nilsson orbit extruded by the deformation to the Fermi surface from the
filled h11/2 shell. This is demonstrated by the blocking of the the
coupling of [505]11/2- neutrons in odd-A nuclei to their core 02+ states
in N=88 and N=90 nuclei [4].
This experimental observation leaves gamma and octupole vibrations as the 
remaining collective states within the pairing gap. It demonstrates that 
nuclei, in general, are stiff to Kpi=0+ vibrations along the symmetry 
axis, even in transitional regions where the nuclear shape is changing 
rapidly. 
It also demonstrates the futility of expecting non-microscopic theories to 
be able to describe 02+ states if the effects of Pauli blocking cannot be 
included in the models.
In this presentation we will review the the experimental data on Kpi=2+ 
"gamma-bands" in deformed nuclei, built both on alignments in even-even 
nuclei and coupling to single particles in odd-A nuclei.

[1]  A. Bohr and B. R. Mottelson, "Nuclear Structure, Vol. II", Singapore: 
     World Scientific, 1998, pp. 363.
[2]  P. E. Garrett, J. Phys. G (London) 27, R1 (2001).
[3]  J. F. Sharpey-Schafer et al, Eu. Phys. J. A47 (2011) 5.
[4]  J. F. Sharpey-Schafer et al, Eu. Phys. J. A47 (2011) 6.