Electric Excitation ofAu197

Abstract

The gamma radiation emitted from ${\mathrm{Au}}^{197}$ following the electric excitation of the nucleus by protons of from 2 to 5 Mev has been studied. The angular distributions and absolute yields of the two intense gamma rays of the spectrum at 279 and 555 kev have been measured. The angular distributions of these two gamma rays were found to agree well with those calculated for $\frac{5}{2}\to \frac{3}{2}\mathrm{}(M1+E2\mathrm{})\mathrm{}$ and $\frac{7}{2}\to \frac{3}{2}\mathrm{}\left(E2\mathrm{}\right)\mathrm{}$ transitions, respectively, the excitation being $E2\mathrm{}$ in both cases. The yield from the 279-kev state was observed to increase with beam energy in the manner predicted by theory for electric quadrupole excitation. On the basis of the Bohr-Mottelson unified model of the nucleus the results indicate a larger than expected cross section for the formation of the 555-kev state. Values for the quadrupole moment and magnetic moment of the ground state of gold calculated from the cross section for the formation of the 279-kev state agree with spectroscopic values.