How do nuclei rotate 5 Appearance of bands

How do nuclei rotate? 5. Appearance of bands

Deformed mean field solutions This is clearly the case for a well deformed nucleus. Deformed nuclei show regular rotational bands. Spherical nuclei have irregular spectra.

E 2 radiation M 1 radiation

Magnetic rotation

Shears mechanism Most of interaction is due to polarization of the core. TAC calculations describe the phenomenon.

TAC Measurements confirmed the length of the parallel component of the magnetic moment.

Antimagnetic rotation Ferromagnet Magnetic rotor Anti-Ferromagnet Antimagnetic rotor

Magnetic rotor Antimagnetic rotor large B(M 1) (transversal magnetic moment ) no B(M 1) (transversal magnetic moment) decreases with I small B(E 2) (deformation) decreases with I Substantial moment of inertia

Band termination

termination

The nature of nuclear rotational bands The experimentalist’s definition of rotational bands: Requirements for the mean field:

Terminating bands deformation super axes ratio (d) 1: 2 mass D normal (0. 6) 1: 1. 5 weak (0. 3) 1: 1. 1 150 180 200 1 1/2 1/7 2 4 20 4 8 20 60 30 8 0. 005 0. 03 0. 05 (0. 1)

Classical periodic orbits in a deformed potential

Summary • Breaking of rotational symmetry does not always mean substantial deviation of the density distribution from sphericity. • Magnetic rotors have a non-spherical arrangement of current loops. They represent the quantized rotation of a magnetic dipole. • The angular momentum is generated by the shears mechanism. • Antimagnetic rotors are like magnetic ones, without a net magnetic moment and signature symmetry. • Bands terminate when all angular momentum of the valence nucleons is aligned. • The current loops of the valence orbits determine the current pattern and the moment of inertia.