Mid Term Review

Auger electron spectroscopy of I-125 and the influence of electron beam damage in PVC using ERBS

Mr Bryan Tee
Department Nuclear Physics

Due to their high linear energy transfer (LET), low energy Auger electrons (< 1 keV) emitted in electron capture (EC) or internal conversion (IC) decay of radioisotopes have the potential to be used for targeted radiation treatment of cancer cells. To harness the potential of Auger electrons and to develop dosimetry simulations at the nanoscale the accurate knowledge of the emission rates are needed down to eV energies. To satisfy this requirement a new atomic relaxation model, BrIccEmis, was recently developed at the ANU to evaluate Auger and X-ray spectra for a range of radioactive isotopes based on calculations using a Monte Carlo method. In this talk I will report on the development of a new theoretical Auger and X-ray theoretical data base to be used for basic sciences and applications, including medical dosimetry simulations. I-125 is one of the most widely used medical isotopes and is known to be an effective Auger electron emitter. Here we report on our high-resolution electron measurements from the EC decay of I-125. The full electron spectra of I-125 will be presented and compared with the simulations from BrIccEmis and from Geant4. The so-called “penetration effect” caused by an overlap between atomic and nuclear fields was observed and characterised in our experiments.

Radiation damage in materials is an extensive field of research. Fast charged particles penetrating matter will interact with both the target and nuclei and electrons. The energy transferred to the system may result in breaking of chemical bonds and volatile species may escape. Often these effects are detrimental, e.g. for studying organic samples in an electron microscope and sometimes they are utilised on purpose, e.g. in lithography and charged-particle based cancer treatment. Here we report on our recent measurement of PVC using electron Rutherford backscattering (ERBS) technique to investigate the changes in structure/compositions of PVC due to electron beam damage.

Zoom meeting: https://anu.zoom.us/j/93469596997?pwd=aFRTWllhTVNVdUdBV2tpMzNKNmR6QT09

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