DNA Damage in Splenocytes of Mice Exposed to Secondary Radiation Created by 650 MeV Protons Bombarding a Concrete Shielding Barrier.

The proportion of splenocytes with a high level of DNA double-strand breaks was determined in mice exposed to primary and secondary radiation created by bombarding of a concrete barrier (thickness 20, 40, and 80 cm) by 650 MeV protons. The proportion of splenocytes with a high level of DNA double-strand breaks was assessed by flow cytometric analysis of γH2AX+ and TUNEL+ cells. It is shown that concrete barrier can significantly reduce primary proton radiation; the severity of negative biological effects in mice irradiated in the center of the proton beam decreased with increasing the thickness of this barrier. However, the spectrum of secondary radiation changes significantly with increasing the barrier thickness from 20 to 80 cm and the distance from central axis of the beam from 0 to 20 cm, and the proportion of the neutron component increases, which also causes negative biological effects manifesting in a significant (p<0.05) increase in the percentage of splenocytes with a high level of DNA damage in mice irradiated at a distance of 20 cm from the center of the proton beam and receiving relatively low doses (0.10-0.17 Gy).

A new type of ground-based simulator of radiation field inside a spacecraft in deep space.

The problem of full-scale ground-based modeling of cosmic radiation on heavy-ion accelerators for space radiobiology is very urgent. A new type of space radiation simulator at the 56Fe ion beam with energy 1 GeV/n is proposed. The simulator uses rotating converters consisting of segmented targets with varying thicknesses. When a flat uniform field of primary 56Fe ions is used, this design ensures the uniformity of the fields of all secondary particles behind the targets. The proposed setup with four replaceable converters makes it possible to simulate not only the distribution of linear energy transfers of cosmic radiation but also reproduce continuous energy spectra of all charged fragments of the projectile ion from protons to Co. The results of simulation of the internal radiation field inside the habitable module of a spacecraft with a shell of 15 g/cm2 Al, generated by particles of galactic cosmic rays in the solar activity range from 0 to 190 Wolf numbers, are presented.