In Juin 1996, his finished the D.E.A French course (Diplome d'Études Approfondies de l'École Doctorale de l'INPG) in Signal,Image and Voice and carry out his stage at the ILL under the responsability of Dr. E. LELIEVRE-BERNA. The subject of this stage was : "Participation au développement d'un logiciel de calcul de carte de densité d'aimantation utilisant la méthode du maximum d'entropie" . You can read immediately the monograph (1.5 Mb) into your browser AdobePDF Viewer (french version).

September 99 he has finished the PhD thesis in Signal, Image and Voice processing. The subject of this Thesis was : "Optimization of Magnetization Distribution Determination". This work presents the study of new techniques for optimization of magnetization distribution determination by polarized neutron diffraction.

The polarized neutron diffraction technique applies to single crystals, which are magnetically ordered under an applied magnetic field. Assuming a good knowledge of nuclear structure, the dependence of the elastic scattering cross-section on the initial neutron polarization gives access to the Fourier components of the magnetization. One can retrieve the density after a simple Fourier inversion. A much better result can be obtained using the Bayesian maximum entropy method.

We present a search routine for the Bragg condition, which is based on the Brent´s algorithm and a new centering method that estimates the detector position by inverse Gaussian interpolation. The counting unit and the computation of the optimized counting time distribution on the peak and the background for flipping ratios determination was improved.

After the study of experiment progresses, we could define a strategy, which leads to a constant error bar distribution for the case of centric crystals. The first part of the experiment is done assuming a low magnetic contribution to the nuclear peaks. The prediction of the intensities takes into account the instrument resolution and geometry. During the next steps, the measuring time of the non-equivalent Bragg reflections is corrected after automatic data analysis.

In order to guarantee the optimized data collection, we have developed a new communication protocol called "Instrument Data Transfer Protocol" and a client/server application, which is instrument and computer independent.

You can read immediately this monograph (5 Mb) into your browser using the Adobe PDF Viewer (French version).