Abstract
The variations of chemical and biological yields with radiation quality provide important clues for elucidating reaction mechanisms. Before attempting a detailed interpretation of such variations we require (1) a knowledge of the amounts of energy dissipated in the system by the different types of particle over their various kinetic energy ranges (in other words, the spectrum of energy dissipation versus kinetic energy for each type of particle), and (2) a model of the way in which energy is dissipated along the tracks of particles with particular emphasis on linear energy transfer. Both requirements involve the application of stopping-power formulas and are therefore not entirely independent of each other; however, they are to some extent separable, and this paper is concerned with the first aspect. At the 1955 International Conference of Radiobiology, calculations were given of certain energy-dissipation characteristics in water of 200-kvp total X-, 220-kvp primary X-, Co60 y-, and 25-Mvp betatron X-rays (1). Results were presented in terms of the relative amounts of local energy (QT AT) dissipated by electrons in kinetic energy ranges covering the complete spectrum. Local was taken to include all collisional energy transfers (excitation and ionization) up to 100 ev. Deltatracks or secondaries produced with an energy greater than 100 ev were treated separately, that is, as being distinct from the parent track. Mean linear energy transfer values were also calculated according to the following definition:
Published Version
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