Lifetime measurements of some rotational levels by a new recoil method

Lifetime measurements of some rotational levels were carried out by observing the decay of the excited nuclei along the recoil path, following Coulomb excitation with backscattered oxygen ions. Mean lives were determined for levels in ¹⁵³Eu and ¹⁶³Dy and also, as a check, for the 2⁺ levels is ¹⁵²Sm and ¹⁸⁸Os. As a consequence of these measurements the ratio of the M1 strengths of the transitions 9 2⁺ → 7 2⁺ and 7 2⁺ → 5 2⁺ in ¹⁵³Eu was found to agree with the rotational value. The E2 strength of the 9 2⁺ → 7 2⁺ transition was on the other hand found to be reduced by a factor of two relative to the pure rotational value.