Sujet de stage / Master 2 Internship

Full digital detection spectroscopy will be installed on our Ion Beam Analysis setup. We propose a training period dedicated to performance evaluation of this new type of spectroscopy

Ion Beam Analysis is a panel of spectroscopies produced by the interaction of a light ion beam in the MeV/nucleon range with matter. The simultaneous combination of several of these spectroscopies allows, after simulation of the associated spectra, to reconstitute the chemical composition of the examined sample, laterally and in depth, for all the chemical elements present, whether they are major or trace elements.

The accuracy of these measurements depends largely on the quality of the signals collected and the counting statistics of the events giving rise to detectable radiation (charged particles, X-ray photons, γ). The detection chain usually used is based on the principles of nuclear spectroscopy, namely the association of a detector with a preamplifier followed by an analog amplifier producing a pseudo-Gaussian shaping and ending with an analog-digital converter. The coded signals are then used to construct the spectra and the lateral maps, the beam position being itself integrated in the coding process.

In order to improve the quality of the data produced, we are exploring the use of new electronic modules recently put on the market, which regroup the amplification and coding steps and which allow very fine adjustments of the different parameters affecting the conversion (rise time, type of shaping, zero pole, baseline restoration, stacking management...). The switch to this type of detection allows the production of better quality spectra by the possibility of discriminating the nature of the detected particle, allowed by the analyzis of the temporal profile of the signal, as well as by the control of count rates approximately 10 times higher than with analog chains.

The training course will take place according to the following plan:
• Handling of an "all digital" module with 16 input channels
• Tests using signal generators simulating the outputs of the detectors
• Study of the response of the module according to the nature of the detected particle
• Study of the behavior of the module at very high counting rate
• Qualification of the chain in analysis experiments

Within the framework of this internship, a collaboration is planned with a team of Sorbonne University which has implemented this type of detection.