H Nikjoo1, D Emfietzoglou, D E Charlton. 1. Radiation Biophysics Group, Medical Radiation Physics, Karolinska Institute, Stockholm, Sweden. hooshang.nikjoo@ki.se
Abstract
PURPOSE: The paper reports on progress in physics of radiationless transitions and new Auger spectra of (125)I and (124)I. We report progress in Monte Carlo track structure simulation of low energy electrons comprising majority electrons released in decay most Auger emitters. MATERIALS AND METHODS: The input data for electron capture (EC) and internal conversion(IC) were obtained from various physics data libraries. Monte Carlo technique was used for the simulation of Auger electron spectra. Similarly, electron tracks were generated using Monte Carlo track structure methods. RESULTS: Data are presented for the EC, IC and binding energy (BE) of radionuclides (124)I and (125)I. For each of the radionuclides (125)I and (124)I some examples of electron spectra of individual decays are given. Because most Auger electrons are low energy and short range, data and a short discussion are presented on recent Monte Carlo track structure development in condensed media and their accuracy. CONCLUSIONS: Accuracy of electron spectra calculated in the decay of electron shower by Auger emitting radionuclides depends on availability of accurate physics data. There are many gaps in these libraries and there is a need for detailed comparison between analytical method and Monte Carlo calculations to refine the method of calculations. On simulation of electron tracks, although improved models for sub-keV electron interaction cross sections for liquid water are now available, more experimental data are needed for benchmarking. In addition, it is desirable to make data and programs for calculations of Auger spectra available online for use by students and researchers.
PURPOSE: The paper reports on progress in physics of radiationless transitions and new Auger spectra of (125)I and (124)I. We report progress in Monte Carlo track structure simulation of low energy electrons comprising majority electrons released in decay most Auger emitters. MATERIALS AND METHODS: The input data for electron capture (EC) and internal conversion(IC) were obtained from various physics data libraries. Monte Carlo technique was used for the simulation of Auger electron spectra. Similarly, electron tracks were generated using Monte Carlo track structure methods. RESULTS: Data are presented for the EC, IC and binding energy (BE) of radionuclides (124)I and (125)I. For each of the radionuclides (125)I and (124)I some examples of electron spectra of individual decays are given. Because most Auger electrons are low energy and short range, data and a short discussion are presented on recent Monte Carlo track structure development in condensed media and their accuracy. CONCLUSIONS: Accuracy of electron spectra calculated in the decay of electron shower by Auger emitting radionuclides depends on availability of accurate physics data. There are many gaps in these libraries and there is a need for detailed comparison between analytical method and Monte Carlo calculations to refine the method of calculations. On simulation of electron tracks, although improved models for sub-keV electron interaction cross sections for liquid water are now available, more experimental data are needed for benchmarking. In addition, it is desirable to make data and programs for calculations of Auger spectra available online for use by students and researchers.