[en] Predictions from quantum chromodynamics and massive quark model for the quantity sigmasup(n)/sigmasup(p) as a function of Q² and X are studied vs. the experimental results so far available

[en] This paper describes the construction of a silicon tracker built to investigate how well silicon detectors can predict the position of particles in nuclear emulsions over a large area. The tracker consists of 72 single-sided silicon microstrip detectors with a total surface of 0.13 m² distributed over four layers, providing two x and two y coordinate measurements. The set-up was installed in a CERN PS pion beam in September 1997. (author)

[en] We have studied the achievable spatial resolution of a streamer tube chamber with pickup strips orthogonal to the signal wires and analog readout. The measurement has been performed in real experimental conditions with 135 GeV/c muons at CERN. Using a new algorithm to determine the center of the induced charge on the strips we have obtained for 1 cm wide strips a spatial resolution better than 50 μm after averaging over all strips. The intrinsic resolution averaged over a single strip is better than 350 μm. (orig.)

[en] The HARP experiment was designed to study hadron production in proton-nucleus collisions in the energy range of 1.5 GeV/c-15 GeV/c. The experiment was made of two spectrometers, a forward dipole spectrometer and a large-angle solenoid spectrometer. In the large-angle spectrometer the main tracking and particle identification is performed by a cylindrical Time Projection Chamber (TPC) which suffered a number of shortcomings later addressed in the analysis. In this paper we discuss the effects of time-dependent (dynamic) distortions of the position measurements in the TPC which are due to a build-up of ion charges in the chamber during the accelerator spill. These phenomena have been studied both by modelling and by experiment, and a correction procedure has been developed. The effects of the time-dependent distortions have been measured experimentally by means of recoil protons in elastic scattering reactions, where the track coordinates are precisely predictable from simple kinematical considerations. The dynamics of the positive ion cloud and of the electrostatics of the field-cage system have been modelled with a phenomenological approach providing an understanding of the features. Using the elastic scattering data a general correction procedure has been developed and applied to all data settings. After application of the corrections for dynamic distortions the corrected data have a performance equal to data where the dynamic distortions are absent. We describe the phenomenological model, the comparison with the measurements, the distortion correction method and the results obtained with experimental data.