F. Meddi

Two-particle rapidity correlations in proton-nucleus interactions at 300 GeV

Abstract The single- and two-particle inclusive rapidity distributions for proton-nucleus interactions at 300 GeV in nuclear emulsions are presented. The analysis of the data with the two-particle rapidity correlation function R ( ν 1 , ν 2 ) shows clear evidence of short range correlations. A remarkable asymmetry between projectile and target hemisphere is found.

Performance of the silicon ring counters for the helios experiment at cern

Abstract The construction and operation of silicon ring counters designed to measure multiplicity and pseudorapidity distributions of charged tracks in a high multiplicity environment are described. The detectors operated successfully in the HELIOS experiment during the CERN-SPS relativistic ion runs with 16 O projectiles in 1986 and with 32 S in 1987. They also provided a multiplicity trigger for the experiment.

An interactive system for emulsion data acquisition

We describe an interactive system, based on a micro-processor, for the acquisition and elaboration of nuclear emulsion measurements. The device consists of a Koritska R4 microscope coupled with a telecamera and with a motor driven stage for automatic displacement in the three directions. Both the pair of internal coordinates and the three external coordinates are digitized. The interactive management of the system is carried out with a PDP11/34.

Transverse mass spectra of strange and multiply—strange particles in Pb—Pb collisions at 158 A GeV/c

The WA97 experiment has measured the transverse mass (({m_{mathrm T}})) spectra for negative hadrons ((mathrm{h}^-)) and strange particles produced at mid–rapidity in Pb–Pb collisions. The increased statistics of analysed data samples allowed us to perform a study of the spectra of ({rm K_S^0}), (mathrm{Lambda}), (mathrm{Xi}), (mathrm{Omega}) and (mathrm{h}^-) as a function of the collision centrality. The data, which correspond to the most central 40% of the total inelastic cross section, have been divided into four centrality classes according to the estimated number of nucleons taking part in the collision. The (m_{mathrm T}) spectra, analysed separately for each centrality bin, exhibit only weak ((leq) 15%) centrality dependence. The deviation of the (mathrm{Omega}) inverse slope from the linear dependence on the particle mass is confirmed even for the most central Pb–Pb collisions.

Multicharged particle emission in the disintegration of aluminium induced by 800 mev electrons

Abstract The disintegration of aluminium nuclei by 800 MeV electrons is studied using plastic detectors. Angular and energy distributions of emitted Li, Be and B isotopes are presented. The compatibility of the results with a two-stage process (cascade and evaporation) is studied with the aid of a Monte Carlo calculation.

Hybrid silicon μstrip and GEM tracker for JLab hall-a high luminosity experiments

A new hybrid silicon μstrip and large area GEM (Gas Electron Multiplier) tracker is under development for the upcoming high luminosity (up to 1039 /s/cm2) experiments at the Hall-A of the JLab 12 GeV electron beam facility. The system consists of 2 small 10×20 cm2 silicon planes placed near the scattering chamber and 18 40×50 cm2 GEM modules that form larger chambers with variable active area depending on the experimental needs. Rather general purpose readout electronics has been designed for both detectors and can be adopted in other equipment. It consists of two active components: front-end cards, directly connected to the detector channels and a multi-purpose digitizer board (MPD). The front-end is based on existing 128 channels APV25-S1 chip developed in the framework of LHC experiments. The MPD handles 16 front-end cards (for a total of 2048 channels) and can be used in VME environments (also VME64x or VXS). It also provides: optical, Ethernet, USB. These resources permit to use MPD cards in different frameworks, ranging from small bench-top to large on-detector distributed systems. The GEM project is part of the CERN/RD51 collaboration activities. The system has been beam tested in late 2010 and 2011, some results are presented here.

Construction and test of modules of the CHORUS calorimeter

Abstract The CHORUS Collaboration is presently building a new detector for the search of ν μ - ν τ oscillations in the CERN neutrino beam, the experiment being sensitive to a mixing angle an order of magnitude smaller than the present limit. The basic components of the CHORUS “hybrid” detector are an active target made of nuclear emulsions, an air core spectrometer with scintillating fiber tracking, a high resolution calorimeter and a muon spectrometer. An account is given here of the design of the 110-tons compensating calorimeter, made of 1 mm diameter scintillating fibers embedded in a lead matrix, and of the test results from the first modules produced.

The high resolution calorimeter of the CHORUS experiment

The CHORUS Collaboration is presently building a new detector for the search of vμ−vτ oscillations on the CERN neutrino beam, this experiment being sensitive to a mixing angle an order of magnitude smaller than previous experiments. The basic components of the CHORUS “hybrid” detector are an active target made of nuclear emulsions (for the direct observation of the decay of τ-leptons), an air-core spectrometer with scintillating fiber tracking, a lead-scintillator (fibers and strips) calorimeter (with μ-tracking provided by planes of limited streamer tubes) and a muon spectrometer, consisting of iron toroids and drift chambers. We report here on the design of the calorimeter and on the tests performed on prototype modules.

Large area, high spatial resolution tracker for new generation of high luminosity experiments in Hall A at Jefferson Lab

In 2014 the CEBAF electron accelerator at Jefferson Lab (JLab) will deliver a longitudinally polarized (up to 85%), high intensity (up to 100 μA) beam with maximum energy of 12 GeV, twice the present value. To exploit the new opportunities that the energy upgrade will offer, a new spectrometer (Super BigBite — SBS) is under development, featuring very forward angle, large acceptance and ability to operate in high luminosity environment. The tracking system of SBS will consist of large area (40×150 cm2 and 50×200 cm2), high spatial resolution (better than 100 μm) chambers based on the GEM technology and 2 small (10×20 cm) Silicon Strip Detector planes. The design of the GEM chambers and its sub-components such as the readout electronics is resented here.

Track measurements on plastic sheets exposed to the CERN-SC carbon beam

ABSTRACT Track measurements on CR39 sheets exposed to the CERN-SC 86xA MeV Carbon beam are reported. The diameter of vertical tracks and the parameters of dipped tracks were measured. The p vs. REL trend is deduced. Charge discrimination for fully etched tracks is discussed.