E. Pastori

Performance of RPCs and diamond detectors using a new very fast low noise preamplifier

The new high energy high luminosity experiments require an improvement in both the counting rate and the space resolution for the detectors. This improvement can be achieved by reducing the charge per count, however this implies a need for a better signal to noise ratio in the signal processing. In this article we will show the performances of diamond detectors and RPCs using a new preamplifier with low noise (500–1000 electrons RMS), fast shaping (about 10 ns) and large input capacitance.

RPC operation at high temperature

Abstract The resistive electrodes of RPCs utilised in several current experiments (ATLAS, CMS, ALICE, BABAR and ARGO) are made of phenolic/melaminic polymers, with room temperature resistivities ranging from 10 10 Ω cm , for high rate operation in avalanche mode, to 5×10 11 Ω cm , for streamer mode operation at low rate. The resistivity has however a strong temperature dependence, decreasing exponentially with increasing temperature. We have tested several RPCs with different electrode resistivities in avalanche as well as in streamer mode operation. The behaviours of the operating current and of the counting rate have been studied at different temperatures. Long-term operation has also been studied at T=45°C and 35°C, respectively, for high and low resistivity electrodes RPCs.

SF6 quenched gas mixtures for streamer mode operation of RPCs at very low voltages

In the present paper we describe a search for gases that allow to reduce the energy of the electrical discharge produced in Resistive Plate Chambers (RPCs) operated in streamer mode, by reducing both the operating voltage and the released charge. This can be achieved, with current gas mixtures of argon, tetrafluoroethane (TFE) and isobutane, by reducing the total amount of quenching components (TFE+isobutane) down to 10–15% and compensating for the lower gas quenching power with the addition of small amounts of SF6: We show here that SF6; even for concentrations as low as 1% or less, has a strong effect in reducing the delivered charge in low quenched gases and allows to achieve a proper working mode of the RPC even at voltages as low as 4–5kV over a 2 mm gas gap. r 2002 Elsevier Science B.V. All rights reserved. PACS: 29.40.Cs

New RPC gas mixtures for large area apparatuses

The working gas choise has always been a crucial topic for RPC. The optimization of the gas mixture, for different purposes, allowed the RPC detector to be successful in many experiments of today physics [1,2]. Both running and future experiments however could profit from new gases with low environmental impact, low cost and good behavior with respect to ageing and RPC performances. We present here the first results in the search for this new gas.

The RPC space resolution with the charge centroid method

RPC detectors were originally developed to exploit the very good intrinsic time resolution of the plane geometry and have been used as muon trigger in most of their high energy physics applications, disregarding the detector space resolution. Due to the high luminosity of future colliders, new experiments will be very demanding in terms of momentum selection of the muon spectrometer. For this reason, trigger detectors will be required to have a sub-millimeter space resolution as well as a sub-nanosecond time resolution. RPCs are good candidates for these applications, as it can be shown that they have excellent intrinsic space resolution, while the actual results depend mostly on the front-end electronics performance. Here we present a beam test carried out on a small size RPC. The results are consistent with a space resolution of ~ 130 μm.

Test for upgrading RPCs at very high counting rate

Very large systems of RPCs with 2 mm gas gap are presently working at LHC as muon trigger detectors. In order to conceive a new generation of RPCs, fully adequate to the needs of the high luminosity super-colliders of the next future, two aspects have to be reconsidered: the gap width which determines the amount of charge delivered in the gas per detected avalanche and the front end electronics which determines the minimum charge that can be discriminated from the noise. Both aspects have a crucial effect on the rate capability. We present here the results of a cosmic ray test carried out on small size RPCs of gap width 2.0, 1.0 and 0.5 mm respectively. The wave forms of both the prompt signal due to the fast drifting electrons and the signal generated in the HV circuit, which is dominated by the slow ion drift, are recorded for each detected cosmic muon. The analysis of these signals is crucial to understand the RPC working features. XI workshop on Resistive Plate Chambers and Related Detectors (RPC2012) INFN-Laboratori Nazionali di Frascati, Italy February 5-10, 2011 P o S ( R P C 2 0 1 2 ) 0 6 5  Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it

The ATLAS RPC Test Stand at INFN Roma Tor Vergata

The ATLAS experiment at the LHC uses plastic laminates RPCs as first level trigger detectors in the barrel up to pseudorapidity |eta| < 1. A set of quality controls are performed on the RPC chambers before they are sent to CERN for integration and installation on the experiment. Three test stands were installed for this purpose in INFN Divisions of Lecce, Napoli and Roma Tor Vergata. The results of the BOL-type chambers tested in Rome are presented.

Performance of RPCs with phenolic glass electrodes

This paper shows the results of a Cosmic Ray test carried out on small size RPCs, built with electrodes of phenolic glass, a new promising material for RPC applications. The tested chambers, of area 10 × 57 cm2, are characterized by both thin gas gaps, 1.0 and 0.5 mm, and thin electrode plates, 0.8, 0.5 and 0.17 mm. The good performance of these RPCs, in spite of their very thin electrodes, is due to the excellent mechanical properties of the new material, which looks well suitable for the RPC electrodes.

Improving the RPC rate capability

This paper has the purpose to study the rate capability of the Resistive Plate Chamber, RPC, starting from the basic physics of this detector. The effect of different working parameters determining the rate capability is analysed in detail, in order to optimize a new family of RPCs for applications to heavy irradiation environments and in particular to the LHC phase 2. A special emphasis is given to the improvement achievable by minimizing the avalanche charge delivered in the gas. The paper shows experimental results of Cosmic Ray tests, performed to study the avalanche features for different gas gap sizes, with particular attention to the overall delivered charge. For this purpose, the paper studies, in parallel to the prompt electronic signal, also the ionic signal which gives the main contribution to the delivered charge. Whenever possible the test results are interpreted on the base of the RPC detector physics and are intended to extend and reinforce our physical understanding of this detector.

Corrigendum to The ATLAS RPC detector control system: Problems, solutions and new opportunities [Nucl. Instr. and Methods in Physics Research, A 602/3(2009) 796-800]

Corrigendum to ‘‘The ATLAS RPC detector control system: Problems, solutions and new opportunities’’ [Nucl. Instr. and Methods in Physics Research, A 602/3(2009) 796–800] G. Aielli a,c, , P. Camarri , R. Cardarelli , A. Di Ciaccio , L. Di Stante , B. Liberti , F. Marchese , E. Pastori , A. Polini , A. Salamon , R. Santonico c,b a E.N.E.A. Frascati, Via Enrico Fermi 45, 00044 Frascati (RM), Italy b Physics Department, University of Rome ‘‘Tor Vergata’’, Via della Ricerca Scientifica 1, 00195 Roma, Italy c I.N.F.N. Sec. of Roma ‘‘Tor Vergata’’, Via della Ricerca Scientifica 1, 00195 Roma, Italy d I.N.F.N. Sec. of Bologna, Via Irnerio 46, 40126 Bologna, Italy