[en] Short communication. 1 fig

[en] Polarization observables in the photoproduction of pseudoscalar mesons are discussed. Particularly, those single and double polarization observables are analyzed which the best suited might be to advance the knowledge of elementary photoproduction of pions, kaons and etas. For pion photoproduction the process γp → π^p, for eta photoproduction the reaction γp → ηp, and for kaon photoproduction the process γp → Κ⁺Λ was considered with polarization observables. (R.P.) 12 refs., 6 figs., 2 tabs

[en] A status report is presented on the polarized ³He target development work at the University of Mainz. It is based on the optical pumping of the ³S₁ state of ³He with subsequent metastability spin exchange to the ground state atoms. This pumping scheme is very efficient at ³He pressures of about 1 Torr; for high density targets, however, a mechanical compression of the polarized gas is needed in a second step. First results with a Toepler compression pump look promising and will be discussed in the following. (author) 10 refs., 4 figs

[en] Very few results exist in the study of spin observables with electromagnetic probes, contrary to hadronic probes. Recent progress in handling polarized beams of electrons and photons allow to undertake the systematic study of the spin observables in hadronic matter. Spin can be used to select the part of the cross-section which is directly proportional to the interference between the Coulomb and the transverse part of the transition amplitude. The main axes are given. (R.P.) 4 refs., 2 tabs

[en] In the proceedings of the workshop, held at the Institut de Physique Nucleaire in Orsay, France, full texts of 20 contributions are presented. The two main topics were polarized electrons and polarized photons. It has been reported that significant processes have been made recently in the science and technology of polarized electron sources, polarized targets and polarimeters. The relevant tools are therefore now available to complete extensive experimental programs. The 20 papers are indexed and abstracted separately for the INIS database. (R.P.)

[en] The advantages of pulsed electron accelerators which feed a stretcher ring, such as in the ELSA facility, are considered. Two types of resonances were observed, the imperfection resonances and the intrinsic resonances, causing depolarization. The polarized electron beam has been applied for experiments to study the Drell-Hearn-Gerassimov sum rule, and to examine neutron electric form factor. (R.P.) 4 refs

[en] An intense source of spin-polarized electrons with the highest possible figure of merit was decided to be constructed. Its aim is to apply it at an existing European electron synchrotron like NIKHEF during 1993. The electron source uses optically pumped flowing helium afterglow, similarly to the design of the Rice University Source. The design and operation of the polarized electron source is described, its status, preliminary results and future perspectives are discussed. (R.P.) 5 refs., 6 figs

[en] The Argon cluster-beam, with maximum thickness of 1.5x10¹⁴ atoms/cm², installed at Frascati on the ADONE storage ring, is described. The cluster-beam works at room temperature and is used as a radiator to produce an intense tagged photon beam with energy up to 1.2 GeV. The Argon beam properties were measured using electrons stored in ADONE. The results are in good agreement with the expected values. The effects of the target on the circulating electrons were studied. The apparatus can produce cluster-beams of higher thickness and work with different gases. It is suitable for internal target experiments with the 1.5 GeV stored electrons. (author) 23 refs., 5 figs., 1 tab

[en] The possibilities of recoil detection for some interesting physics questions are discussed, and some examples are presented. After the description of recoil detectors for the detection of p, d, t, ³He and ⁴He particles to study ⁴He(e,e'n)³He type reactions, some particular experiments including the (virtual) photon-neutron coupling, two-nucleon knockout, electro-pion production and polarization studies are presented. (R.P.) 12 refs., 6 figs

[en] The advent of high duty cycle machines has opened up the area of coincidence experiments, both in and out-of-plane, allowing the measurement of four exclusive structure functions with a corresponding gain of information. MAMI B has successfully produced a 855 MeV electron beam in august 1990. The first two polarization experiments will be devoted to the measurement of the electric formfactor G_E,n of the neutron in a range of momentum transfer Q² = 5 - 15 fm^-2 using ²D(e,e'n) and ³H e(e,e'n). The necessary e-source, spin rotator, e-polarimeter, ³H e-target and n-polarimeter are under construction. (author) 14 refs., 1 fig., 1 tab