The elastic scattering of 60Co gamma rays from lead

The elastic scattering of 60Co gamma rays from lead has been remeasured using a lithium-drifted germanium detector. For angles less than 90°, there is satisfactory agreement between the measured and calculated values. For angles greater than 90°, the measured values are significantly smaller. The discrepancy is too large to be attributed to destructive interference from Delbrück scattering. An explanation can be found in the possibility that there are phase shifts between the Rayleigh and nuclear Thomson components.