Collectivity of neutron-rich magnesium isotopes investigated by projected shell model calculations
Dong, G. X., Wang, X., Liu, H. L., & Xu, F. R. (2013). Collectivity of neutron-rich magnesium isotopes investigated by projected shell model calculations. Physical Review C, 88 (2), 024328. doi:10.1103/PhysRevC.88.024328 Retrieved from http://link.aps.org/doi/10.1103/PhysRevC.88.024328
Published in
Physical Review CDate
2013Discipline
FysiikkaCopyright
© 2013 American Physical Society. Published in this repository with the kind permission of the publisher.
The abnormally large collectivity of neutron-rich magnesium isotopes in the “island of inversion” has not been
well understood. It has been commented that the unexpectedly large deformations observed in the magnesium
isotopes are attributed to the neutron f7/2 intruder orbits involved remarkably even in the ground states, which
points to nuclear force directly. Recently, a new isospin-dependent Nilsson potential was suggested to improve
the calculations of the ground states of magnesium isotopes. With the improved Nilsson potential, in the present
work we investigate the collectivity of excited states by using the projected shell model. To avoid the collapse of
the BCS pairing, which occurs in weak pairing, we improved pairing calculations by using the Lipkin-Nogami
approach. The collectivity and the erosion of the N = 20 shell in neutron-rich magnesium isotopes are discussed
by calculating spectra and electric quadrupole transitions. The gyromagnetic factors are calculated and compared
with existing data to get insight into the configurations of collective states at different spins. A two-quasineutron
Kπ = 6+ state in 38Mg is predicted to be a possible isomer with an excitation energy lower than the I π = 6+
member of the ground-state band.
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