A new approach in simulating RPC and searching for the causes of large cluster size of RPC

Abstract

The prototype Resistive Plate Chamber (RPC) has been made for the ATLAS phase II upgrade. The beam-test results showed that its cluster size is larger than expected. To figure out the causes, we developed a new approach in simulating RPC which based on Computer Simulation Technology (CST) Suite. The influences from the surface resistivity of the graphite layer and other characteristics have been studied. Comparisons between the simulation data and the beam-tests results have also been performed. K: Detector modelling and simulations II (electric fields, charge transport, multiplication and induction, pulse formation, electron emission, etc); Resistive-plate chambers; Gaseous detectors 1Corresponding author.

Measuring attenuation in signal propagation in Resistive-Plate Chambers

“…After integrating signals of all strips, the total charge varied within 1% for different surface resistivities of the graphite layer and different propagation distances. This indicated that part of the signal was moving transversely outside the main strip and was collected by its neighbour strips which might increase the inefficiency of the detector as well as the cluster size [9]. Further studies concerned with measuring the cluster size as a function of the propagation distance were interesting topics, albeit beyond the scope of this work.…”

“…The simulations were based on the recently developed 3D partial-element equivalent circuit approach [9], in which the resistive graphite layers were involved in the processes of signal induction and propagation. In the simulations, the RPC model possessed a similar structure to that of a real RPC as shown in figure 1: five 25-mm-width and 1-m-long readout strips with a gap size between two adjoining strips of 2 mm, a 0.4-mm-thick PET (polyethylene terephthalate) film (𝜖 𝑟 = 2.9), a graphite layer featuring different surface resistivity and a 1.2-mm-thick bakelite electrode (𝜖 𝑟 = 4.8).…”

“…Two potential countermeasures to suppress signal attenuation have been studied using simulations [9]. One is to lower the strip-graphite capacitance per unit area 𝑐 𝑠 , by setting the relative permittivity of the PET film to 2.1 as opposed to 2.9.…”

A new layout about the graphite layers in RPC

“…The surface resistivity of the these layers is an important parameter which need to be tuned precisely. If the surface resistivity is lower than several hundreds kΩ/ , the induced signals will spread to a large area through the graphite layers and result in a large cluster size [3]. On the other hand, if the surface resistivity is too high, the large electric potential difference will be formed along the surface of detector.…”

Application of strip electrode in single-gap RPC

“…The surface resistivity of these layers is an important parameter which need to be tuned precisely. If the surface resistivity is lower than several hundreds kΩ/ , the induced signals will spread to a large area through the graphite layers and result in a large cluster size [4]. On the other hand, if the surface resistivity is too high, the large electric potential difference will be formed along the surface of detector.…”