A Track Physics Retrospective

Many condensed matter dosimeters and detectors respond to the perspectives of track physics, a parametric model which relates their response to gamma rays to their response to heavy ions through the radial distribution of dose about a heavy ion’s path. Most dosimeters are treated as 1-hit detectors, a classification which includes emulsions, scintillators, TLDs, the Fricke dosimeter, alanine, and some biological substances: enzymes and Eschericia coli, among others. We have discovered many hit detectors. An extended model describes the killing, transformation, and mutation of biological cells after gamma and heavy ion irradiation. A detector is treated as a black box, in which the only relevant information is the nature of the incident radiation and the output response, although, at times, it is convenient to imagine some simple structure. Because the model is parametric it can be global, applying to many detectors. Once a set of numerical parameters is extracted from experimental findings, the equations of the model predict response to all radiation fields whose photon-particle energy spectrum is known. Finally, parameters of the model serve as a test of the validity of mechanistic theories, for these parameters summarize detector response to all ionizing radiations.