[en] Some recent figures which indicate the excellent performance of PETRA are given. (W.D.L.).

[en] The authors have studied quantum-mechanical suppression of bremsstrahlung of low-energy 1-500 MeV photons from high-energy 25 GeV electrons. They have measured the LPM effect, where multiple scattering of the radiating electron destroys coherence required for the emission of low-energy photons, and the dielectric effect, where the emitted photon traveling in the radiator medium interferes with itself. For the experiment, the collaboration developed a novel method of extracting a parasitic low-intensity high-energy electron beam into the fixed target area during normal SLC operation of the accelerator. The results agree quantitatively with Migdal's calculation of the LPM effect. Surface effects, for which there is no satisfactory theoretical prediction, are visible at low photon energies. For very thin targets, the suppression disappears, as expected. Preliminary results on dielectric suppression of bremsstrahlung are in qualitative agreement with the expectation

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[en] The question of where the next quark flavor n should occur is discussed. It is guessed that it will have a mass of 14 to 15 GeV by extrapolating from lower heavy quark mass ratios. The corresponding anti nn vector meson would have a mass of 30 GeV. The excitation spectrum of quarks is contrasted with that of the hydrogen atom. The possibility of regarding flavor as an excitation of some new degree of freedom in the system is discussed

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[en] The present status of the 50-GeV Proton Synchrotron Project (J-PARC) in Japan is described

[en] This paper presents a first investigation of the planarity effect in inelastic hadronic reactions at 70 GeV/c with the help of principal axis variables. It has been observed from the analysis of emulsion data of proton-nucleon interactions at 70 GeV/c that the planarity effect is prominent in the case of low multiplicity events and this effect decreases with the increase of multiplicity. (auth)

[en] The University of Chicago balloon telescope for cosmic ray electrons has been substantially modified and improved, and has been exposed in another successful balloon flight in 1980. The combination of a transition radiation detector with a deep lead-scintillator shower detector makes possible excellent discrimination between electrons, and nuclear background, high overall efficiency, and very good energy resolution. We shall present preliminary results from this flight, over the energy range 5 to 200 GeV. Our data indicates an electron flux of .27+-.04 (m²sec sr GeV)^-1 at 10 GeV, and a spectral shape consistent with a power law Esup(-3.0) at low energies, but steepening further, probably due to radiative energy losses, with increasing energy

No abstract available