COLLEXCIT · Collective excitation in the ionization of atoms, in semiconductors and biological tissues
FP7 — People (Marie Curie Actions)
- Duration
- 2008-06-01 → 2012-05-31
- EU contribution
- €100,000
- Participants
- 1
- Scheme
- MC-IRG
Lines connect the coordinator with its partners.
Results in brief
Collective excitation in the ionization of atoms, in semiconductors and biological tissues
Except for closed shells, most atomic states exhibit some collective behavior. That is, the states cannot be described as a single product function, but superpositions of product states. In the description of the interaction of radiations with atoms, the independent particle approximation is used. Our angular distribution and angular correlation study, and in synchrotron photoionisation measurements there is a strong deviation from this model. Revisiting previous measurements with an open eye for the possibility of collective excitations, we can explain the majority of discrepancies by it. We have presented all the evidences in a paper and recommended best practices. We also give a critical review calling attention to the problem that theory laden experiments are used to verify theory. We have made on overview of the problems in determining the L shell fluorescence yields and Coster-Kronig transition probabilities. We have made a critical analysis of the experimental methods which are used to determine Coster-Kronig and fluorescence yield data. We have concluded that each of them has unrecognised systematic errors. We have recommended new approaches.
Data: CORDIS, © European Union
Project objective
Experimental determination of ionization and decay parameters of x-ray transitions, used in analytical applications, and basic physics research. Measurements are designed to establish the size of the many-body interactions in the excitation and decay processes. In this sub-field mainly single particle approaches have been used. The experimental data contradict basic conservation laws and arithmetic. Therefore, new methodological approaches are necessary. Improved detection techniques and quality assurance capable signal processors have emerged which allow new approaches to measuring these parameters. Energetic charged particles in x-ray and gamma ray solid state detectors lose their energy mainly by plasmon creation. Plasmons are collective excitations. Using a high energy electron spectrometer we will determine the plasmon creation probability in the energy range of 200 eV to 10 keV by a high energy photoelectron spectrometer. We will develop a deconvolution method, to analyze the photoelectron spectra. We intend to study semiconductor x-ray and gamma ray detectors’ response function as a function of the band gap and plasmon energy. We plan to develop a new signal processing approach based on the obtained information. We will study various surface modification of detectors, to reduce the surface plasmon creation probability. Collective excitations are also important in biological tissues. Many radioactive materials are used in medical imaging. Delocalized plasmons excited in biological tissue by energetic particles could be transferred to nearby molecules like DNA causing radiation damage. As a pilot study, we want to study what type of plasmon excitation is possible, measure the plasmon energy and the plasmon creation efficiency.
Original text from CORDIS.
Participants
- ATOMMAGKUTATO INTEZET · DebrecenCoordinatorHungary
Links
Data: CORDIS, © European Union