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Ab initio calculations of Auger transition rates and applications to nuclear physics and medecine

Vendredi 14 novembre 2014 11:00 - Duree : 1 heure
Lieu : ILL 1 - Seminar Room, 71 avenue des Martyrs - Grenoble

Orateur : B. Q. LEE (Australian National University, Canberra)

Radioisotopes that emit Auger electrons have been of particular interest as therapeutic agents. Their biological impact is localised within the immediate vicinity of the decay site due to the short range of Auger electrons, making them ideal tools for precise targeting of cancer cells. Detailed knowledge of Auger energy spectra is needed to study the radiobiological effects of Auger-electron emitters. Besides medical applications, calculations of Auger yields could be useful in nuclear physics to describe the charge-state distribution of radioisotopes following nuclear reactions.

A pilot Monte Carlo Auger-cascade model, which takes account of spectator vacancies, has been developed to study the yields and energy spectra, as well as the charge-state distributions following the decays of commonly used medical radioisotopes. It is important to note that the pilot model can be applied to any other radioisotopes within 6 < Z < 100. Ab initio calculations of atomic transition energies are performed at every propagation step of the Auger cascade using a relativistic Dirac-Fock (DF) method. Reasonably good agreement with experimental results have been achieved. However, the pilot model is restricted by the overestimations of binding energies in the adopted DF method. Furthermore, atomic transition probabilities from the Evaluated Atomic Data Library (EADL) are found to be inaccurate, especially for elements Z < 60.

The multiconfiguration Dirac-Hartree-Fock (MCDHF) method has been found to be a reliable and versatile tool for ab initio calculations of a variety of atomic properties including atomic transition energies and probabilities. One of the advantages that the MCDHF method can offer is the treatment of QED and electron-correlation effects. The computer codes GRASP2K and RATIP, based on the MCDHF method are being adapted to overcome the limitations of the pilot model. Comparison of preliminary MCDHF calculations with recent experimental data for several radioisotopes will be presented. The calculated results for K Auger transitions are generally in much better agreement with experiment.

Future directions of the project will also be discussed.

Contact : blanc@ill.fr

Discipline évènement : (Physique)
Entité organisatrice : (ILL)
Nature évènement : (Séminaire)
Evènement répétitif : (General ILL Seminar - College 3)
Site de l'évènement : Polygone scientifique

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