"A symmetry of the CPHC model of odd-odd nuclei and its consequences for properties of M1 and E2 transitions"
Leszek Próchniak, Maria Curie-Sklodowska University, Lublin, Poland
(id #72)
Seminar: YesPoster: No
Invited talk: No
We studied energies and electromagnetic properties of odd-odd nuclei in the
frame of the Core Particle Hole Coupling (CPHC) model[1,2]. In the version
of the CPHC model used in the present work a core and unpaired nucleons
interact via separable quadrupole-quadrupole forces. Proton particle and
neutron hole occupy the same j level while the dynamics of the core is
described by the general Bohr Hamiltonian depending on the beta and gamma
deformation variables. Most calculations were done for the case of j=11/2
which is relevant for nuclei around A=130. We analysed several types of the
potential and kinetic energy entering the Hamiltonian of the core, including completely gamma independent ones and compare the results for the odd-odd nuclei with those obtained with the rigid rotor of the Davydov-Filippov model.
We focused our investigations on these properties of odd-odd nuclei which are often treated as a manifestation of the chiral symmetry[3], that is a presence of nearly degenerate partner bands with characteristic staggering seen in the M1 and E2 transitions between states with the total spin I and I-1. We found that such staggering can be explained by selections rules following a new, not discussed as yet, symmetry of the model. This symmetry is a combination of the parity operation in the five dimensional space of deformation of the core (we stress that it is not the parity in the ordinary space) and an exchange of states of the unpaired particles.
All eigenstates of the core Hamiltonian which is invariant against the
parity have mean value of the gamma deformation equal to 30 degs.
The considered symmetry is not fully preserved in the realistic cases, but
as our calculations show, small breaking of this symmetry does not destroy
staggering patterns in the M1 and E2 transition probabilities.
The present work was done in collaboration with Ch. Droste and S.G. Rohozinski (University of Warsaw) and K. Starosta (Simon Fraser University, Vancouver).
1. K. Starosta et al, Phys. Rev. C 65, 044328 (2002).
2. Ch. Droste et al, Eur. Phys. J. A 42, 79 (2009).
3. J. Meng et al, J. Phys. G 37, 064025 (2010).
frame of the Core Particle Hole Coupling (CPHC) model[1,2]. In the version
of the CPHC model used in the present work a core and unpaired nucleons
interact via separable quadrupole-quadrupole forces. Proton particle and
neutron hole occupy the same j level while the dynamics of the core is
described by the general Bohr Hamiltonian depending on the beta and gamma
deformation variables. Most calculations were done for the case of j=11/2
which is relevant for nuclei around A=130. We analysed several types of the
potential and kinetic energy entering the Hamiltonian of the core, including completely gamma independent ones and compare the results for the odd-odd nuclei with those obtained with the rigid rotor of the Davydov-Filippov model.
We focused our investigations on these properties of odd-odd nuclei which are often treated as a manifestation of the chiral symmetry[3], that is a presence of nearly degenerate partner bands with characteristic staggering seen in the M1 and E2 transitions between states with the total spin I and I-1. We found that such staggering can be explained by selections rules following a new, not discussed as yet, symmetry of the model. This symmetry is a combination of the parity operation in the five dimensional space of deformation of the core (we stress that it is not the parity in the ordinary space) and an exchange of states of the unpaired particles.
All eigenstates of the core Hamiltonian which is invariant against the
parity have mean value of the gamma deformation equal to 30 degs.
The considered symmetry is not fully preserved in the realistic cases, but
as our calculations show, small breaking of this symmetry does not destroy
staggering patterns in the M1 and E2 transition probabilities.
The present work was done in collaboration with Ch. Droste and S.G. Rohozinski (University of Warsaw) and K. Starosta (Simon Fraser University, Vancouver).
1. K. Starosta et al, Phys. Rev. C 65, 044328 (2002).
2. Ch. Droste et al, Eur. Phys. J. A 42, 79 (2009).
3. J. Meng et al, J. Phys. G 37, 064025 (2010).
