No abstract available

[en] The investigation of hadronic physics with the electromagnetic probe receives nowadays increasing attention, as witnessed by the numerous electron accelerator projects that one hears about. The present experimental facilities, although powerful and productive, present limitations which the future insallations try to overcome. The next accelerators, whether planned or under construction, answer essentially the question of the duty cycle, which in all cases, will reach 100%

[en] Let us consider the simplest processes induced by the electromagnetic interaction, the emission or absorption of one photon. Their cross sections are unambiguously related to definite characteristics of the target, the charge and current form factors. In reality what is measured is different because higher order e.m. effects are unavoidable: (1) in photonuclear reactions, the radiative corrections, which are indeed negligible as long as the velocity imparted to the target or the emitted particles is small; (2) in contrast, the corrections to Born aproximation in electron scattering: distortion of the electron wave; two-photon exchange; radiative corrections, are far from negligible and pose eventually difficult problems. For the purpose of the following discussion, these will be considered as correctly handled, so that the final outcomes of the measurements are really form factors. At high energy, the so-called shadow effect comes into play. Whatever model is invoked to interpret it, the process is a one-photon and, as such, provides a form factor

No abstract available

[en] Current research in photoproduction of low energy charged and neutral pions on light nuclei is summarized

[en] The yield of conversion of negatons in positrons has been measured for different energies of incidents negatons (from 9 to 30 MeV) and different thickness of converter (from 0.5 to 6 mm of platinum). The spectra of positrons that have been obtained are compared to calculated spectra. The optimal thickness of converter is found equal to about a length of radiation of the incident negatons. (authors)

[en] A method for the production of photons with a narrow spectrum and of variable energy, based on the properties of the annihilation in flight of positrons, is examined in detail. The spectra of the photons produced and the yield of the process are given for various conditions. (author)

No abstract available

[en] A microscopic mechanics is constructed in order to incorporate the Planck constant while retaining the concept of particle location. In the one-dimensional stationary case, the first integral of the equation of motion can be solved explicitly with the help of the Schroedinger equation. It is thus shown that, in describing bound-state motions, this mechanics meets a serious difficulty. It can be overcome only by renouncing the classical concepts of trajectories and opting for quantum mechanics

[en] Contrary to a recent claim, the spreading of ultra-relativistic neutrino wave-packets results in time spreading much smaller than the duration of the observed bursts. (orig.)