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At the CERN Proton Synchrotron (PS), the 24 GeV/c primary beam allows the operation of two new irradiation facilities. One is using directly the primary proton beam and the other one is using secondary particles (mainly /spl sim/1 MeV neutrons) produced in a cavity after a beam stopper. For both facilities, samples to be irradiated are brought to the irradiation positions by means of automatic shuttles. Designs, Monte Carlo simulations of particle spectra and background are presented as well as the performance achieved.

A laser polarimeter has been installed in LEP to measure the transverse beam polarization. The authors describe the layout, the production and the control of the polarization of the laser light, the photon detector, and the data acquisition philosophy. The commissioning experience in the first year of operation of the device is discussed together with recent results on the detection of transverse polarization. The behavior of the instrument was found to be in agreement with the predicted performance. The control and the optimization of the polarization states of the laser light were performed from the optical laboratory, and the quality of the circular light was adequate to produce observable effects on the mean-shift of the vertical distributions. >

A model describing the transport of charge carriers generated in silicon detectors (standard planar float zone and MESA diodes) by ionizing particles is presented. The current pulse response induced by /spl alpha/ and /spl beta/ particles in non-irradiated detectors and detectors irradiated up to fluences /spl Phi//spl ap/3/spl middot/10/sup 14/ particles/cm/sup 2/ is reproduced through this model: i) by adding a small n-type region 15 /spl mu/m deep on the p/sup +/ side for the standard planar float zone detectors at fluences beyond the n to p-type inversion and ii) for the MESA detectors, by considering one dead layer 14 /spl mu/m deep (observed experimentally) on each side, and introducing a second (delayed) component. For both types of detectors, the model gives mobilities decreasing linearity up to fluences of about 5/spl middot/10/sup 13/ particles/cm/sup 2/ and converging, beyond, to saturation values of about 1000 cm/sup 2//Vs and 455 cm/sup 2//Vs for electrons and holes, respectively. At a fluence /spl Phi//spl ap/10/sup 14/ particles/cm/sup 2/, charge collection deficits of about 13% for /spl beta/ particles, 25% for /spl alpha/ particles incident on the front and 35% for /spl alpha/ particles incident on the back of the detector are found for both type of diodes.

Future high energy physics experiments at CERN's Large Hadron Collider will use high precision silicon detectors for tracking purposes. The hadronic component of the radiation received threatens the lifetime of these detectors and it is vital to choose the silicon starting material to maximise the performance and lifetime. Ion-implanted silicon detectors with various initial resistivities and germanium concentrations have been irradiated with high energy protons up to a fluence of 10/sup 14/ cm/sup -2/. The change in leakage current and full depletion voltage have been studied both as a function of fluence and of time after irradiation. Measurements were made up to 100 days post-irradiation at room temperature and then using heating techniques to accelerate processes up to the equivalent of over 10 years at room temperature. The leakage-current damage constant is shown to be independent of the starting material while the conduction type inversion point and the long-term annealing of the depletion voltage are sensitive to the initial resistivity and impurity concentrations.