Objective
Baryonic resonances are excited states of protons and neutrons. The proposed project envisages the study of the properties and production mechanisms in the nuclear medium of the two most prominent of those resonances, the Delta and the Roper resonances. The goals of the study are the following:
detailed experimental and theoretical investigation of the mechanisms of the Delta and Roper excitation resonances in free space and in nuclei in order to provide a reliable extraction of the resonance characteristics;
extraction of fundamental properties, like the width, coupling constants of the Roper resonance created by excitation of a free proton;
theoretical study of the polarization characteristics of the Delta and Roper resonances when excited in the nuclear medium;
experimental determination of the nucleon compressibility based on the results of the experimental and theoretical studies mentioned above.
To accomplish these goals four key experiments are proposed
:
coherent production of pions as signature of collective resonance excitations in nuclei using charge exchange reactions on various nuclei;
excitation of the Roper resonance as signature of the nucleon compressibility using the (alpha,alpha') inelastic scattering off protons;
polarization characteristics of the reactions with Roper resonance excitation off protons using polarized deuterons;
inclusive measurements of polarization observables in (d,d') scattering off protons.
The experiments will take place at two accelerator sites, the SATURNE II light ion accelerator at Saclay (France) and the Synchrophasotron at Dubna (Russia). The theoretical support of the experimental program will be provided in the following directions:
study of the mechanisms that play a role in (alpha,alpha') and (d,d') production of the Roper and Delta resonances;
study of mechanisms of excitation of baryonic resonances in nuclei, polarization characteristics of the production reactions and of the change of the resonance properties in the nuclear medium as compared to free space.
The results will take the form of articles, that will be submitted to peer-reviewed scientific journals. They will also be the subject of several Ph.D./Candidat theses and will be presented as contributions at international conferences.
Topic(s)
Call for proposal
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91191 Gif-sur-Yvette
France