[en] Published in summary form only

[en] The physic program at CEBAF Hall A includes several experiments using 4 GeV polarized electron beam: parity violation in electron elastic scattering from proton and ⁴He, electric form factor of the proton by recoil polarization, neutron spin structure function at low Q². Some of these experiments will need beam polarization measurement and monitoring with an accuracy close to 4%, for beam currents ranging from 100 nA to 100 microA. A project of a Compton Polarimeter that will meet these requirements is presented. It will comprise four dipoles and a symmetric cavity consisting of two identical mirrors. 1 fig., 10 refs

[en] The high quality of the tagged photon beam of the MAMI accelerator in Mainz (Germany) coupled with the large acceptance tracking detector DAPHNE, allowed for the first time high precision measurements of N-body final state interactions ³He(γ,pd) and ³He(γ,ppn)

[en] Virtual Compton scattering (VCS) is the electron scattering on a proton which radiates a real photon before being detected, i.e., the exclusive reaction γ^*p → γ' p' with gamma^* denoting a virtual photon, provides new insights on the internal structure of the proton. The new observables, called generalized polarizabilities (GP), extracted from this VCS at threshold can be understood as the deformation of the charge and current distribution of the proton. These GP are functions of the mass of the virtual photon Q², in real compton scattering (Q² =0). The reaction p(e,e'p')γ was performed in two high resolution spectrometers at the Mainz Microtron MAMI for Q² = 0.33 GeV². Preliminary results of five differential cross sections as a function of the angle between the two photons for fixed photon energy (q) and for five different values of 'q' are presented. The VCS experiment demonstrated that it is possible to measure 2 linear combinations: P_LL - 1/εP_TT and P_LT of five generalized polarizabilities. Refs. 9, figs. 2, tab. 1 (nevyjel)

[en] Several developments were made in the GATE simulation platform to allow accurate modeling of the count rate performances of PET scanners over a wide range of activity concentrations. A background noise module, a dead time and limited bandwidth modeling for the coincidences, and a delayed coincidence builder were added in the code. The results obtained for the modeling of the ECAT HRRT and Focus 220 scanners with the newly developed modules are discussed. They show that GATE can be used to accurately simulate the single event, prompt coincidence and delayed coincidence rates, from very low activity levels in the field of view up to levels that saturate the acquisition system. The new developments were committed into the public release of GATE, making them available for the whole community, thanks to the open source license under Which GATE is published (LGPL). (authors)

[en] A new Compton polarimeter is built on the CEBAF Hall A electron beam line. Performances of 10% resolution and 1% calibration are required for the photon calorimeter of this polarimeter. This calorimeter is built with lead tungstate scintillators coming from the CMS electromagnetic calorimeter R and D. Beam tests of this detector have been made using the tagged photon beam line at MAMI, Mainz, and a resolution of 1.76%+2.75%/√E+0.41%/E has been measured

[en] A new Compton polarimeter is built on the CEBAF Hall A electron beam line. Performances of 10% resolution and 1% calibration are required for the photon calorimeter of this polarimeter. This calorimeter is built with lead tungstate scintillators coming from the CMS electromagnetic calorimeter R and D. Beam tests of this detector have been made using the tagged photon beam line at MAMI, Mainz, and a resolution of 1.76%+2.75%/v+0.41%/E has been measured

[en] The virtual Compton scattering (VCS) is the electron scattering on a proton which radiates a real photon before being detected. The new observables, called generalized polarizabilities (GP), extracted from this VCS at the threshold can be understock as the deformation of the charge and current distributions of the proton. These GP are functions of the mass of the nucleon are real Compton scattering (Q² = 0), some polarizabilities of the nucleon are already measured. With the VCS, we will generalized these observables by measuring them at different values of Q². The Virtual Compton Scattering at Mainz demonstrates that it is possible to measure 2 linear combinations: P_LL - 1/ε P_TT and P_LT of 5 Generalized Polarizabilities. (authors)

[en] The total and the differential cross sections for the D(γ,p)n reaction have been measured over the photon energy range 100-800 MeV at the 855 MeV MAMI Microtron in Mainz. Using the large acceptance detector DAPHNE in conjunction with the Glasgow tagging spectrometer, high precision results with small systematic errors were obtained. The data are presented in the form of thirty-five angular distributions at c.m. proton angles between 30 ^circle -160 ^circle in 10 ^circle intervals and at photon energies in steps of 20 MeV. Previous experimental work is reassessed in the light of the present results and comparison with some recent theoretical calculations. (orig.)

[en] We present an analysis technique (''range method'') that optimizes particle discrimination and enables energy reconstruction using a sampling detector. The method is a powerful extension of the well known dE/dx - E technique in which the energy loss rate measured by several scintillator layers is fitted on the theoretical energy-range curves. The general features of the method will be discussed and its application to nuclear physics investigations at intermediate energies with the DAPHNE detector. Momentum reconstruction for protons with a resolution of ΔP/P = 2.5-10% (FWHM) in the range P = 300-900 MeV/c has been obtained. (orig.)