Method for virtual source position determination of high energy homogeneous electron beams

The beams of electrons accelerated in the cyclic accelerators have special rectangular rparallel, rperpendicular ) distribution at the accelerator exit window. To determine the absorbed dose in the irradiated medium located at other distances than the standard ones where these absorbed doses were measured, it is important to know the distance of a virtual source (svir,parallel , svir,perpendicular ) corresponding to the electron beam as to the entrance field into the irradiated medium. This paper presents the method to determine the position of the virtual source for 10.95, 16.60, 21.76 and 28.8 MeV nominal energy electron beams, homogenized by means of some special formation geometry in the 40 MeV medical betatron. (Author)