title: Calculations of charged-particle recoils, slowing-down spectra, LET and event-size distributions for fast neutrons and comparisons with measurements.
abstract: A rapid system has been developed for computing charged-particle distributions generated in tissue by any neutron spectra less than 4 MeV. Oxygen and carbon recoils are derived form R-matrix theory, and hydrogen recoils are obtained from cross-section evaluation. Application to two quite different fission-neutron spectra demonstrates the flexibility of this method for providing spectral details of the different types of charged-particle recoils. Comparisons are made between calculations and measurements of event-size distributions for a sphere of tissue 1 micrometer in diameter irradiated by these two neutron spectra. LET distributions have been calculated from computed charged-particle recoils and also derived from measurements using the conventional approximation that all charged particles traverse the chamber. The limitations of the approximation for these neutron spectra are discussed.
mesh_terms: D002244:Carbon / Q000528:radiation effects; D004735:Energy Transfer; D005214:Fast Neutrons; D009502:Neutrons; D010100:Oxygen / Q000528:radiation effects; D011522:Protons; D011829:Radiation Dosage; D012542:Scattering, Radiation
chemical_list: D011522:Protons; D002244:Carbon; D010100:Oxygen