Giant $M1\mathrm{}$ Resonance in Pb

Highly polarized tagged photon were used to measure the distribution of $M1\mathrm{}$ transition strength in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ at excitations between 6.7 and 8.1 MeV. The observed $B\left(\uparrow M1\right)$ of about $19{\mu }_0^2$ can account for most of the isovector $M1\mathrm{}$ strength that is expected in the Pb nucleus. This result in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ is compared with the current experimental situation in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. The discrepancy between predicted and observed $M1\mathrm{}$ strengths in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ can probably be attributed to local fragmentation of the strength into states that are too weak to have yet all been identified.