text: For high energy photons it is useful to distinguish between small and large angle scattering. For large angles, where , the scatter ratio  is large and
  showing that the (large angle) differential cross section is inversely proportional to the photon energy.
  The differential cross section has a constant peak in the forward direction:
  independent of . From the large angle analysis it follows that this peak can only extend to about . The forward peak is thus confined to a small solid angle of approximately , and we may conclude that the total small angle cross section decreases with .