Studies of the dependence on energy of the biological effects of fast neutrons. I. Growth reduction and chromosome aberrations of Hordeum vulgare and Vicia faba

Abstract

The effects of 3·4-meV and 14·7-MeV neutrons on seeds of Hordeum vulgare and Vicia faba were compared. The neutrons were produced by the reactions 2 H(d,n) 3 He and 3 H(d,n) 4 He using a 600-keV cascade accelerator. Biological response was measured in terms of growth inhibition and frequency of chromosome aberrations. We use as measure of effectiveness R ( E ) ( E = neutron energy in MeV) in the case of growth inhibition the constant reactivity of the exponential part of the dose effect curve, and in the case of aberration induction the aberration frequency per unit dose. The ratio R (14·7)/ R (3·4) of the effectivenesses for the two neutron energies is: 1·0, 0·93, 0·92, 1·1, 0·93 in the case of growth inhibition of the first leaf of barley, frequency of double bridges in barley root tips, growth inhibition of the main root of Vicia faba , frequency of double breaks, and fraction of aberrant cells in Vicia faba root tips respectively. The ratio is almost independent of the observed effect and about equal to the ratio 0·85 of quality factors. Therefore, an estimation of the energy dependence of the fast neutron effects should be possible by means of these factors.