Electric quadrupole moment of the 211Rn (63/2)- isomer: Absence of core deformation at very high spins.

The electric quadrupole moments of /sup 211/Rn isomers were determined as Q((17/2)/sup -/) = 19(2) exfm/sup 2/ and Q((63/2)/sup -/) = 160(22) exfm/sup 2/ via measurements of the quadrupole interaction in a Bi single-crystal host. The results indicate that the spherical shape is preserved in the lead region even at the core-excited very high-spin regime, in contradiction to theoretical predictions.