MEASUREMENTS OF THE DIFFERENCES IN THE NUCLEAR-CHARGE RADII AMONG URANIUM ISOTOPES

Based on precise spectroscopic measurements of the x-ray transitions o f few-electron uranium ions, the difference in the nuclear charge radi i of U-235 and U-238 has been determined. The measurement makes use of the simplified atomic structure of highly charged ions, and it is sho wn that the spectroscopic data from few-electron ions are readily inte rpreted in terms of the variation in the mean nuclear radius. A value of delta(r(2))(235,238)= -0.250+/-0.032 fm(2) is found. Combining the results with data from earlier optical and x-ray measurements, values for delta(r(2))(A,238) with A =233, 234, 235, and 236 are derived that are of higher accuracy than previous values.