AFFECT OF ULTRASHORT ELECTRON BEAMS ON THE ESCHERICHEA COLI SURVIVAL

The paper represents the study of ultrashort electron beams impact on some Escherichia coliK-12strains with different radiosensitivity. The charged particle beams generated by ultrashort bunch accelerators differ by short duration of particle direct exposure, relatively long intervals between bunches and by high values of instantaneous dose rates. Because of these characteristics, the nature of ultrashort beams impact on biological objects may sufficiently differ from conventional sources of radiation. As a source of ultrashort beams linear electron accellerator AREAL of SichrotronResearcinstitut CANDLE (Yerevan, Armenia) was used. The dependence of E.coli cells survival from electron bunches repetition rate and irradiation media was investigated. It is shown that the dose dependence of the survival degree of microorganisms has a qualitatively different unusual concave shape. Such behavior of the survival curves does not depend on the ionic composition of the irradiation medium as well as on the time of preliminary incubation of microorganisms in this medium. To explain the observed phenomenon, it was assumed that the compensatory capacity of the irradiated object increases with an increase of the irradiation dose.The proposed mathematical model described well the behavior of the survival curves. It is assumed that this change of the compensatory capacity may be determined by oxygen.