Experimental values of the relative heights of scintillation pulses generated in NaI(T1) crystals, by heavy ions ($Z>\mathrm{}5\mathrm{}$) of energy 1-10 MeV/amu, agree well with computed relative cross sections for photon production, from a theory based on the assumption of a one-hit response to the spatially distributed dose of ionization energy, and a characteristic dose of 4×${10}^7$ erg/${\mathrm{cm}}^3$ for this material. Discrepancies between theory and experiment for He bombardments arise from the theoretical neglect of the nonlinear dose variation over the sensitive volume surrounding each T1 atom. Similar discrepancies arising from the neglect of molecular volume occur in the theory of heavy-ion inactivation of dry enzymes and viruses, which forms the basis for the present work.

• Received 18 December 1967

DOI:https://doi.org/10.1103/PhysRev.170.397