The Inconstancy of Mean Radii of Nuclear States in Rotational Bands

The difference, Δ , in the mean square radius of the first 2+ state with respect to the 0+ ground state of rotational bands has now been measured for a number of deformed nuclei using Mössbauer and muonic isomer shift techniques. The results of both types of measurements are reviewed. The derivation of Δ from Môssbauer data still contains up to 50% uncertainty in the evaluation of |ψ(0)|2. The muonic data are superficially more reliably analysed. There are, however, large corrections for energy shifts resulting from asymmetries in the decay of the magnetically split nuclear transition. And there are further ambiguities in evaluating polarization effects. Considering the overall uncertainties, the results of the two techniques are in good accord. On the other hand the theoretical predictions of Δ are Uniformly several times larger than the experimental values. Even more interesting is that recent experiments indicate that the mean radius of first 2+ states become smaller than the mean radius of the respective ground state in the W - Os region. (author)