hrvatski

Raspodjela frekvencija ionskih parova u ozračenom tkivu

The statistical distribution of the number of ion pairs per ionizing event in a small volume simulating a tissue sphere was obtained by applying an iterative deconvolution method to experimental spectra measured by exposing a Rossi-type spherical proportional counter to gamma radiation. The spectrum obtained by a proportional counter is determined by two independent ionization processes: (a) the ionization along the primary track in the counter gas and (b) the multiplication of these primary electrons by the counter. The resulting spectrum, R(E), representing the distribution of the total number of electrons per event, can be represented in a matrix form as R=Q ˇ P. It is a weighted sum of single, double, triple, etc. convolutions of the single electron spectrum [Q(n,E), n=1,2,3...], where the weighting factors P(n) are discrete functions of the primary distribution. The single-electron spectrum which represents the multiplication process follows the Gamma distribution. The primary distribution was obtained by an iterative deconvolution process which discriminates against negative weighting factors (which have no physical meaning). A number of distribution spectra showing the relative frequency of primary ion pairs per event is presented for simulated tissue spheres exposed to 60Co gamma radiation.

mikrodozimetrija; broj ionskih parova; proporcionalni brojač; primarna raspodjela; dekonvolucija; tkivu-ekvivalentni brojač

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