  The results of computer simulation of the high-energy electrons passage
through thin layers of titanium (Ti) and polyimide Kapton$^\circledR$ in the
energy range from 3 to 20 MeV are presented. Simulation is carried out using
the Geant4 toolkit. The thickness of the Ti foil in the model experiment is 50
microns, the thickness of the Kapton$^\circledR$ film is 110 microns. The
purpose of the calculations is to reveal the possibility of using the
Kapton$^\circledR$ film in the output devices of linear electron accelerators.
It was necessary to calculate the probable values of the energy absorbed in a
Kapton$^\circledR$ film and in a Ti foil for each value of primary electrons
energy. Another important characteristic is the divergence radius of the
electron beam at a predetermined distance from the film, or the electron
scattering angle. As a result of calculations, the energy spectra of
bremsstrahlung gamma-quanta, formed during the passage of electrons through the
materials of the films, are obtained. The most probable values of the energy
absorbed in the Ti foil and in the Kapton$^\circledR$ film are calculated. The
scattering radii of an electron beam for the Kapton$^\circledR$ film and also
for the Ti foil at a distance of 20 cm are estimated. It is shown that the
ratio of the total amount of bremsstrahlung gamma quanta in the case of use the
Kapton$^\circledR$ film is approximately 0.56 of the total amount of
bremsstrahlung gamma quanta when using the Ti foil. The analysis of the
calculated data showed that the use of Kapton$^\circledR$ as a material for the
manufacture of output devices for high-energy electron beams is more preferable
in comparison to Ti films. The use of Kapton$^\circledR$ instead of Ti makes it
possible to significantly reduce the background of the generated bremsstrahlung
gamma quanta and reduce the scattering radius of the electron beam.
