POSSIBLE CONSERVATION OF THE K-QUANTUM NUMBER IN EXCITED ROTATING NUCLEI

The gamma cascades feeding into low-K and high-K bands in Er-163 are i nvestigated analyzing variances and covariance of the spectrum fluctua tions. From a large data set of 10(9) triple coincidences, gamma-gamma coincidence spectra gated by resolved low-lying rotational bands are analyzed. Low-it bands are found to be fed by a much larger effective number of cascades than high-K bands. The covariance between pairs of gated spectra shows that the cascades feeding low-It bands are differe nt from those feeding the high-it bands. The persistence of the It-sel ection rules for the excited rotational bands within the angular momen tum region 30h less than or equal to I less than or equal to 40h is su ggested as explanation.