Nonscissorsmode behaviour of isovector magnetic dipole orbital transitions involving isospin transfer
Abstract
We study the response of isovector orbital magnetic dipole (IOMD) transitions to the quadrupolequadrupole ( Q· Q) interaction, to the isospinconserving pairing interaction (ICP) and to combinations of both. We find qualitatively different behaviours for transitions in which the final isospin differs from the initial isospin versus cases where the two isospins are the same. For N= Z eveneven nuclei with J^{π}=0 ^{+}, T=0 ground states such as ^{8}Be and ^{20}Ne, the summed T=0→ T=1 IOMD from the ground state to all the J=1, T=1 states in the 0ℏ ω space does not vanish when the Q· Q interaction is turned off. The pairing interaction (ICP) alone leads to a finite transition rate. For nuclei with J=0 ^{+}, T=1 ground states such as ^{10}Be and ^{22} Ne, the summed T=1→ T=1 IOMD does vanish when the Q· Q interaction is turned off, as is expected in a good scissorsmode behaviour. However this is not the case for the corresponding sum of the T=1→ T=2 IOMD transitions. In ^{22}Ne (but not in ^{10}Be) the sum of the T=1→ T=2 IOMD transitions is remarkably insensitive to the strengths of both the Q· Q and the ICP interactions. In ^{22}Ne an energyweighted sum is similarly insensitive. All our calculations were carried out in the 0ℏ ω space.
 Publication:

Nuclear Physics A
 Pub Date:
 December 2003
 DOI:
 10.1016/j.nuclphysa.2003.08.023
 arXiv:
 arXiv:nuclth/0305016
 Bibcode:
 2003NuPhA.728...96A
 Keywords:

 Nuclear Theory
 EPrint:
 19 pages (including 5 figures). submitted to Nucl. Phys. A