Having collided with a relativistic electron, a photon is deflected through an angles `theta = 60^(@)` while the electron stops. Find the compton displacement of the wavelength of the scattered photon.

Explanation

This is the inverse of usual compton scattering.
When we write down the energy-momentum conservation equation for this process we find that are the same for the inverse process as they are for the usual process. If follows that the formula for compton shift is applicable except that the energy (frequency) of the photon is increased on scattering and the wavelength is shifted downward. With this understanding, we write
`Delta lambda = 2pi (cancel h)/(mc)(1-cos theta)`
`= 4pi((cancel h)/(mc)) sin^(2)((theta)/(2)) = 1.21 pm`