[en] A review of the high accuracy π⁺ threshold photoproduction cross-section determinations on deuterium and helium-3 is presented. These must be considered on the same footing as the data on electromagnetic observables, with reference to the important question of the description of the non nucleonic degrees of freedom in the nucleus. The π⁰ threshold photoproduction on very light nuclei which conveys information on the elementary nucleonic amplitudes in an energy region where one is sensitive to the break down of isospin symmetry as revealed by the π^+-, π⁰ and the n, p mass splittings is discussed

[en] The field of electromagnetic interactions on light nuclei is reviewed through a discussion of a few topics for which new experimental results have been obtained since the 1979 Vancouver Conference

[en] Discussion on the frame of interpretation of the experiments, try to explain the essential motivations of this investigation and to show that one can learn about basic pion photoproduction on nucleons, photoproduction mechanism in nuclei and nuclear matter distribution are presented. The experimental procedure utilized and the difficult problem of the absolute calibration of the measurements are discussed. In conclusion data on deuterium and ³He taken at the Saclay linac and on carbon and copper illustrate these points

[en] Pion photoproduction experiments are discussed in connection with experimental techniques used for the photon source and the pion detection. After presenting the physical motivations and the theoretical frame of interpretation, on a few significant experiments displaying different aspects of the field are reported

[en] Published in summary form only

No abstract available

[en] A special magnet designed to saturate at 2.2 T a 2.7 mm thick, 180 mm wide and 588 mm long rectangular iron foil has been built in Saclay for the CERN SMC experiment muon beam polarimeter. It consists of an H iron yoke equipped with two magnetizing copper coils operated in a pulsed mode in order to periodically invert the foil magnetization. The operation point and the demagnetizing factor influence are discussed. The measurements with a search coil of the resulting flux density and the influence of the eddy currents are presented. The magnet fringe field which affects particle trajectories has also been measured

[en] This paper discusses the absorption of transverse circularly polarized photons of squared mass q² = - Q², and lab energy ν, by a longitudinally polarized nucleon. There are two relative spin configurations, parallel or antiparallel, which correspond to the two transverse absorption cross-section σ_3/2^T and σ_1/2^T. The difference of these two cross-sections can be simply expressed in terms of the two polarized structure functions g₁ (ν Q²) and g₂(ν, Q²). Their sum, which is the non polarized transverse cross-section, is related to the F₁ structure function. In what follows we will specialize to two extreme cases: deep inelastic scattering and real photon absorption. In both cases the g₂ contribution vanishes, and σ_1/2 - σ_3/2 is expressed simply terms of g₁. The authors consider now the quantity I(Q²) which characterizes the absorption of the transverse photon of squared mass Q²

[en] The two- and three-nucleon systems offer the ground for a significant study of nuclear structures generated by the nucleon-nucleon interaction. A contribution to the knowledge of these systems is presented, based on the fact that charged pion photoproduction at threshold is a weak probe measuring the spin-flip form factor of the nuclear target. We have thus measured the cross-sections for reactions: γ+³He→³H+π⁺, and γ+²H→n+n+π⁺, at energies ranging from 1 to 5 MeV above threshold

[en] The photon total absorption cross-section has been measured using an positron annihilation in flight tagged photon beam and a very large acceptance 4π detector (with an overall efficiency of the order of 85%) in the energy range 133-531 MeV on carbone and lead. The measured cross-section varies linearly with A and is compared to other experiments and theoretical predictions