[en] High P_T photoproduction offers a unique opportunity to observe the interplay between VDM-like and point-like interactions of the photon. The relative strength of these two phenomena strongly depends of the selected final state: high P_T photon, high P_T hadron or J/Ψ. The results obtained by the NA14 experiment at the CERN-SPS concerning the inclusive cross-section for such reactions as well as detailed properties of the associated final state are reported here

[en] The study of an accelerating structure, without cylindrical symmetry, by means of a 3-D electromagnetic code gives a better knowledge of the electromagnetic properties of the structure. In particular its allows to computer some important RF characteristics for comparison with either analytical method or prototype measurement. (authors). 3 refs., 3 figs., 4 tabs

[en] The Final Focus Test Beam, to be constructed at SLAC, will focus a 50 GeV electron beam to a 1 x .06 μm² spot size. The line optics, the magnets, their alignment and stabilization, and the instrumentation are described

[en] Fast neutron irradiation has been performed at liquid argon temperature as a realistic evaluation test for experiments at the LHC Collider at CERN, Early results presented in this note have been obtained with fast charge preamplifiers SiJfet and GaAs Mesfet for white noise and 1/f noise increase with neutron fluence. We have observed a degradation of the transconductance in the case of SiJfet, but a smaller effect on GaAs Mesfet. Optical devices were also studied for light emission with unsatisfactory results, and optical fibres for light transmission showing a remarkable stability. (author). 7 refs., 4 figs

[en] The upgraded UA2 detector has collected data corresponding to an integrated luminosity of 7.8 pb^-1 at a center of mass energy of 630 GeV during the 88 and 89 runs of the CERN pantip collider. A search was performed for the production of new particles: top quark (t) and heavy quark from a hypothetical fourth family (b'), and supersymmetric particles (squarks, and gluinos, and also selectrons and winos through Z decays). No such particles were found, and lower limits on their masses were obtained: mt > 69 GeV/c², mb' > 54 GeV/c² at 95% CL, m squarks > 74 GeV/c², m gluinos > 79 GeV/c², m selectrons > 40 GeV/c², mwinos > 45 GeV/c² at 90% CL. In the first section the search for squarks and gluinos will be discussed and in the second section the search for top and b' will be described

[en] This paper describes an optimal design of a simple and compact ECR ion source of coaxial shape which belongs to the antenna type ion sources at 2.45 GHz. Avoidance of dielectric pieces in the microwave plasma and careful dimensioning of the antenna as well as the use of a radially magnetized split ring rare earth magnet allowing the localization of the ECR zone near the fire end of the antenna are the main characteristics of this design. A 30 mm in diameter ion beam with current density of 2.3±0.1 mA/cm² over a 18 mm diameter was produced under a mass flow rate of 1 sccm, a microwave power of 75 W and an extraction voltage of 1 kV. It was observed that, according to the mass flow rate and amount of microwave power, a high energy tail or peak in the energy distribution was present or not in the extracted beam. An outstanding feature of this source was its ability to be operated without any microwave tuning element and without a cooling circuitry. (orig.)

[en] X-ray diffraction using anomalous scattering yields to partial interference functions and radial distribution functions for an amorphous Fe₉₀Zr₁₀ alloy. These results are compared with icosahedral models obtained from the curved space approach. A good agreement is observed which supports both X-ray results and theoretical results

[en] The possibility of transition radiation application in the area of particle beam diagnostics is examined. The experiments are limited to the optical part of transition radiation (from 2800 A up to 6000 A) produced by electron beams with Lorentz factors in the range γ=100, essentially on the AL at Saclay and also with higher γ on the LAL at Orsay

[en] A chemical procedure has been developed for the production, separation and purification of ²³⁶Pu and ²³⁵Np from ²³⁸U targets irradiated with 34 MeV protons. An intense (74 MBq) and carrier-free source of ²³⁶Pu has been prepared by ion exchange chromatography. This source is intended for the investigation of the ²³⁶Pu decay by emission of α particles and ²⁸Mg clusters. (orig.)

No abstract available