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experiment
[Paper] Spectroscopic Quadrupole Moments in 96,98Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60
Spectroscopic Quadrupole Moments in Sr96,98: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60
E. Clément et al.
doi: 10.1103/PhysRevLett.116.022701
Neutron-rich 96,98Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N=60.
[Paper] Investigation into the semimagic nature of the tin isotopes through electromagnetic moments
Investigation into the semimagic nature of the tin isotopes through electromagnetic moments
J.M. Allmond et al.
DOI: 10.1103/PhysRevC.92.041303
A complete set of electromagnetic moments, B(E2;0+1→2+1),Q(2+1), and g(2+1), have been measured from Coulomb excitation of semi magic 112,114,116,118,120,122,124Sn (Z=50) on natural carbon and titanium targets. The magnitude of the B(E2) values, measured to a precision of ∼4%, disagree with a recent lifetime study [Phys. Lett. B 695, 110 (2011)] that employed the Doppler-shift attenuation method. The B(E2) values show an overall enhancement compared with recent theoretical calculations and a clear asymmetry about midshell, contrary to naive expectations. A new static electric quadrupole moment, Q(2+1), has been measured for 114Sn. The static quadrupole moments are generally consistent with zero but reveal an enhancement near midshell; this had not been previously observed. The magnetic dipole moments are consistent with previous measurements and show a near monotonic decrease in value with neutron number. The g-factor measurements in 112,114Sn establish the recoil-in-vacuum method for states with τ∼0.5 ps and hence demonstrate that this method can be used for future g-factor measurements on proton-rich isotopes toward 100Sn. Current theory calculations fail to reproduce the electromagnetic moments of the tin isotopes. The role of 2p-2h and 4p-4h intruders, which are lowest in energy at midshell and outside of current model spaces, needs to be investigated in the future.