The Relative Biological Effectiveness of Different Kinds of Radiations on Chromosome Aberrations in Nigella Damascena Seed

Summary

In Nigella damascena the relative biological effectiveness (RBE) of different kinds of radiations was measured for chromosome breaks induced in G₁ and scored at first mitosis after germination of seeds. The effects of γ-rays from ¹³⁷Cs were used for reference to compute RBE's for 2·8 GeV protons, mono-energetic neutrons, fission neutrons, and α-particles from the reactions ¹⁰B(n, α)⁷Li and ⁶Li(n, α)³H following irradiation with thermal neutrons. For 2·8 GeV protons the RBE was 2·1 for total aberrations. The RBE's for mono-energetic neutrons ranged from 44 (1·8 MeV) to 84 (0·43 MeV) for one-break, and 79 (1·8 MeV) to 154 (0·43 MeV) for two-break aberrations: for fission neutrons the RBE was 78 for total aberrations. The low RBE for α-particles from thermal neutron irradiation of seeds enriched with ¹⁰B and ⁶Li was attributed in part to the non-homogeneous distribution of these atoms in the seeds.