1. Assuming that the energy relaxation of photoelectrons takes place by the spontaneous emission of acoustic phonons, the energy distribution of photoelectrons is obtained using the deformation potential scattering by acoustic phonons for the zero point lattice.

2. Photoelectrons released from the photocathode (40) are accelerated and directed to impinge the phosphor screen (42).

3. A theoretical study is made of the photoconductivity of hot photoelectrons interacting with acoustic phonons in n-type germanium at low temperature, T = 4 K, when the equipartition of the energy of phonons is not obeyed.