Lifetimes of $2^{+}$ Rotational States

The mean lives of the rotational $2^{+}$ states of nuclei in the region $150<~A<~186$ have been measured with a pulsed proton beam timing device. The presence of prompt proton bremsstrahlung requires more elaborate analysis of the time distributions than the customary determination of center of gravity shift. In order to achieve the necessary accuracy and freedom from drift, a beam switching procedure was introduced, alternating the beam between two targets and therefore allowing accurate comparisons to be made. A measurement of the mean life of ${\mathrm{B}}^{10}$, carried out as a check, yielded results in good agreement with previous measurements. A method for utilizing the lifetime measurements for accurate determinations of $B\left(E2\mathrm{}\right)\mathrm{}$ values is discussed.