We demonstrate that polarized-proton radiative capture may be used to unambiguously identify concentrations of magnetic dipole strength. Three $M1\mathrm{}$ resonances are observed in the doubly magic ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ nucleus between $E_x=16\mathrm{} \mathrm{and} 20$ MeV, with a relatively large total ${\gamma }_0$-transition strength $B{\mathrm{}\left(M1\mathrm{}\right)\mathrm{}}_{\downarrow }>~0.24{{\mu }_0}^2$.

• Received 27 April 1979

DOI:https://doi.org/10.1103/PhysRevLett.43.117