A start trigger detector for the ALICE spectrometer

A fall-back option of the T0 start trigger detector was developed for the ALICE setup that was intended for the study of quark-gluon plasma with the LHC accelerator (CERN). The Monte Carlo simulation with the PYTHIA program was performed for a detector incorporating two symmetrical arrays of 12 Cerenkov counters, each composed of 26-mm- diameter Hamamatsu R5505 phototubes with fine-mesh dynodes and a quartz radiator 3 cm in length and 26 mm in diameter. Its simulated detection efficiency for p-p collisions exceeded 88%. A prototype Cerenkov counter, consisting of a R3432-01 (similar to R5505) phototube and a quartz radiator with dimensions of 25*30*12 mm, was tested in a beam of pions and protons with a 1.19-GeV/c-momentum. The time resolution in the 1-200 dynamic range was better than 50 ps. (3 refs)

Beam Tests of First Prototype of a Cherenkov Counter for the ALICE T0 Detector

Abstract The first prototype of a Cherenkov counter consisting of a quartz radiator of rectangular shape 25x30x12 mm (30 mm along the particles' trajectories) and/or PMTs Hamamatsu R3432-01 and FEU-187 have been tested at proton/pion beam with 1.19 GeV/c momenta. Time resolution better than 50 ps (sigma) has been obtained for both types of the PMTs at different voltages. The dynamic ranges of both types of PMTs was measured with a pulsed laser (500 ps FWHM). For both types of the PMTs the dynamic range, with a time resolution of better than 50 ps, exceeds 100, thus providing cover to the expected dynamic range for the ALICE experiment for p-p, Ca-Ca and Pb-Pb runs. </HTML