On the dependence of one-photon - two-electron differential cross sections on recoil momenta

We calculate the distributions in recoil momenta and their energy distributions for the high energy non-relativistic double photoionization of helium caused by the quasifree mechanism of the process. The distributions obtain local maxima at small values of the recoil momenta. This is in agreement with the earlier predictions and with recently obtained experimental data. We obtained also the angular correlations, which reach the largest value in the "back-to-back" configuration of the photoelectrons. Our analysis is valid in all high energy nonrelativistic region. Particular equations are true for the case when the wavelength of the photon exceeds strongly the size of the atom. We present numerical results for the photon energies in the region of 1 keV, employed in the recent experiments.