Photon Scattering by the Giant Magnetic Dipole States inC12,Mg24, andSi28

Photons, defined in energy to about 1% with the aid of a bremsstrahlung monochromator, were scattered by isolated energy levels in C, Mg, and Si. Parameters for the six observed levels are: The 15.11-MeV level in ${\mathrm{C}}^{12}$, the 9.92- and 10.66-MeV levels in ${\mathrm{Mg}}^{24}$, and the 11.42-MeV level in ${\mathrm{Si}}^{28}$ are $T=1\mathrm{}$, $T_z=0\mathrm{}$ analogs of low-lying 1 + states in the neighboring odd-odd nuclei. These levels exhaust most of of the magnetic dipole transition strength of the respective nuclei, and therefore give information about the expectation value of 1·s in the ground state.