M. Gallio

Measurement of the pp→ppη total cross section between 1.265 and 1.50 GeV

Abstract The total cross section of the pp→ pp η reaction has been measured at incident proton energies of 1.265, 1.3, 1.4 and 1.5 GeV by detecting the two photons from the η decay in the PINOT spectrometer. The data are compared with other near-threshold measurements and with the predictions of existing theoretical calculations.

η-meson production in pd and pp collisions

Abstract The doubly-differential cross sections for the pp → ppη and pd → ηX reactions have been measured at incident proton energies of 1.3 and 1.5 GeV. The ratio of the pd to pp -induced cross sections varies from about 8–10 at 1.3 GeV to 4.5–6 at 1.5 GeV in the η kinetic energy interval 100 MeV ⩽ T η ⩽220 MeV. Information on the pn → ηX reaction has been extracted from these measurements within the framework of a simple folding model.

Measurement of the Annihilation Cross-Section for Antineutrons on Fe from 100 to 531 MeV/c

The cross-section for annihilation on Fe from 100 to 531 MeV/c was measured by means of a layered absorption detector. The cross-sections are related to the free N annihilation cross-sections by a simple A2/3 scaling law, indicating a surface process.

An experimental study of antineutron detection

Abstract The main features of a new type of antineutron detector are described. It consists of modules of scintillators, limited streamer tube planes and iron converters. The energy of the antineutrons is measured by time of flight with a resolution of 800 ps FWHM. The vertex of annihilation is reconstructed with a precision of 8 cm FWHM. The trigger conditions can be selected following the chosen topology of the events.

A Study of the bar n Production on Nuclei by bar p of 550 MeV/c

Inclusive spectra produced at 0° by the interaction of 550 MeV/c s on C, Al, Cu and Pb targets were measured. The results are discussed in the framework of simple models on incoherent particle production by complex nuclei.

Front-end electronics for the RPCs of the ALICE dimuon trigger

A dedicated front-end electronics has been developed for the trigger chambers of the ALICE muon spectrometer under construction at the future LHC at CERN. This trigger detector is based on RPCs (Resistive Plate Chambers) working in streamer mode. The number of electronics channels (about 21000) and the fact that RPC signals have specific characteristics have led to the design of an 8 channel front-end ASIC using a new discrimination technique. The principle of the ASIC is described and the radiation hardness is discussed. Special emphasis is put on production characteristics of about 4000 ASICs.

Study of the resistive plate chambers for the ALICE Dimuon Arm

Abstract The trigger system for the ALICE Dimuon Arm will be based on Resistive Plate Chambers (RPC). A RPC prototype, with electrodes made of low-resistivity bakelite ( ρ∼3×10 9 Ω cm ) has been tested both at the SPS and at the Gamma Irradiation Facility. The results for the operation in the streamer mode are presented here.

Experimental evidence for the p6Li to eta 7Be reaction at threshold

The p6Li to eta 7Be reaction has been investigated at Tp=683 MeV using the Saturne synchrotron. eta mesons were detected with the high-resolution light neutral meson spectrometer PINOT. The small-angle CM differential cross section for the production of the sum of the first few levels of 7Be was found to be 4.6+or-3.8 nb Sr-1. This value is about one order of magnitude less than that for the Pd to eta 3He reaction at the same eta CM momentum.

The ALICE dimuon trigger: overview and electronics prototypes

Abstract ALICE is the LHC experiment (2005) dedicated to the study of heavy ion collisions. Amongst the ALICE sub-detectors, the muon spectrometer will investigate the dimuon production from heavy resonance (J/ ψ , ϒ ) decays, which is believed to be a promising signature of the Quark Gluon Plasma (QGP) formation. For maximum efficiency of the spectrometer, a dedicated dimuon trigger is presently built. The detector part itself is based on resistive plate chambers (RPCs) operated in streamer mode and is the topic of another contribution to this conference. This paper gives the principle and the simulated performances of the trigger and is also focussed on the description of the electronics prototypes and future developments. The RPCs are read-out by X and Y orthogonal strips: the front-end chips are presently developed. The signals are sent to the trigger electronics which basically performs a p t cut on the tracks to reduce the background. A prototype of fast (decision time 200 ns) programmable electronics working in a pipelined mode at 40 MHz has been built and tested. This prototype handles simultaneously 160 digital information from the strips. The tests of the trigger card have required the construction of a pattern generator (160 bits at 40 MHz).

A simple model for particle reabsorption in nuclei at intermediate energies

SummaryA simple semi-classical model for particle reabsorption in nuclei is presented. The model is well suited for evaluating the number of effective nucleons for inclusive particle production on nuclei at intermediate energies, where both the direct and the two-step elementary production mechanisms play a role and particle production at large angles occurs. The number of effective nucleons predicted for the (p, π+) and (p, K+) reactions turns out to be in agreement with the experimental data. Finally a first indication about the value of the % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfKttLearuqr1ngBPrgarmqr1ngBPrgitL% xBI9gBamXvP5wqSXMqHnxAJn0BKvguHDwzZbqegm0B1jxALjhiov2D% aeHbuLwBLnhiov2DGi1BTfMBaebbfv3ySLgzGueE0jxyaibaiyc9qr% pepeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFfea0dXdc9LqpGe9% FjuP0-is0dXdbba9pGe9xq-Jbba9suk9fr-xfr-xfrpeWZqaaeaabi% GaciaacaqabeaadaabauaaaOqaaGGaaiab-D7aOnrr1ngBPrwtHrhA% XaqehuuDJXwAKbstHrhAG8KBLbacgaGae4xdX7eaaa!4F8C!