A. Paoloni

An RPC γ irradiation test

Abstract LHC muon trigger detectors are supposed to work for 10 yr under an intense flux of radiation. Therefore, in the framework of ATLAS, the performance of full and reduced size RPC prototypes, heavily irradiated with γ sources, were measured for variable incident fluxes. We introduce here a detector description in terms of the “global” parameters based on experimental data such as current, total counting rate and γ fluxes. In this test the ATLAS final front-end electronics was used for the first time.

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

Saturated logistic avalanche model

The search for an adequate avalanche RPC working model evidenced that the simple exponential growth can describe the electron multiplication phenomena in the gas with acceptable accuracy until the external electric field is not perturbed by the growing avalanche. We present here a model in which the saturated growth induced by the space charge effects is explained in a natural way by a constant coefficient non-linear differential equation, the Logistic equation, which was originally introduced to describe the evolution of a biological population in a limited resources environment. The RPCs, due to the uniform and intense field, proved to be an ideal device to test experimentally the presented model.

Response uniformity of a large size RPC

The response uniformity of a 90]290 cm2 RPC prototype working in avalanche mode has been tested using cosmic rays. The high statistics needed for the test has also been used for accurate e

Further advances in aging studies for RPCs

ciency studies. The intrinsic detector ine

RPC ageing studies

ciency free, from spacers e!ects has been measured. ( 2000 Elsevier Science B.V. All rights reserved.