ABSTRACT
Experience with optical changes in gel dosimeters has initiated a new realm in gel dosimetry, with dose measurement using optical techniques and image reconstruction in two and three dimensions. Most of the reactions involving the free radicals initially produced by the radiation are very rapid and essentially complete within a microsecond. However, subsequent reactions of non-radical products, or of large free radicals on polymer chains, may be quite slow. Nuclear magnetic resonance (NMR) methods have been very useful in the study of the structure, composition, and molecular dynamics of various materials. Of particular interest are NMR relaxation or relaxometry studies of radiation chemical dosimeters such as the ferrous sulfate-doped or Fricke gels and polymer gels. The formation of cross-linked polymers in the irradiated regions of the gel increases the NMR relaxation rates of neighboring water protons. NMR dose response models allow for the absorbed radiation dose to determine from fundamental physical variables rather than a calibration of the dosimeter's response.
