Coherent Bremsstrahlung applied to photonucler reactions

• Grant number: 98/01088-7
• Support Opportunities: Scholarships abroad - Research
• Start date: October 12, 1998
• End date: October 11, 1999
• Field of knowledge: Physical Sciences and Mathematics - Physics - Nuclear Physics
• Principal Investigator: Sebastião Simionatto
• Grantee: Sebastião Simionatto
• Host Investigator: Barry Louis Berman
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: George Washington University, United States

Abstract

In support of four research program in experimental nuclear physics, we seek funding to develop and construct a Coherent Bremsstrahlung Facility that will enable the production of energetic beams of linearly polarized photons. This facility will be installed in Hall B of the Thomas Jefferson National Accelerator Facility (TJNAF, formerly known as CEBAF) at Newport News, Virginia. The coherent-bremsstrahlung facility, in combination with the Hall-B photon tagger and the CEBAF Large-Acceptance Spectrometer (CLAS), will provide an extremely powerful tool to explore and to quantify experimentally the spin-dependent properties of the photon-nucleon interaction in the few-GeV energy regime. The first experiment to make use of this facility will be our measurement of the Photoproduction of the Meson from the Proton with Linearly Polarized Photons. The main goal of this approved experiment is to identify and extract information on baryon resonances that have a significant decay probability in the ρN channel. Quark-based models of the nucleon predict a number of such resonances which have yet to be discovered. We expect the additional degree of freedom provided by the use of a polarized beam to enhance our chances considerably to extract small resonant amplitudes Photoproduction of Pions and Photoreactions on 3He, will also benefit considerably from the use of a polarized beam; delineation both of resonance effects in the π-N channels and of three-bidy effects in the photodisintegration of 3He will be much more sharply drawn in the exclusive polarized-photon channels. The envisaged facility will be installed permanently in the Hall-B beamline, and thus be available as a source of linearly polarized photons for the entire Collaboration. (AU)