Fabrication and Characterisation of Oil-Free Large High Pressure Laminate Resistive Plate Chamber

TL;DR

This paper reports the development and characterization of a large, oil-free high pressure laminate resistive plate chamber, demonstrating high efficiency and good timing resolution for cosmic muon detection.

Contribution

It introduces a novel large-scale oil-free HPL RPC using locally available materials, with detailed fabrication, material characterization, and performance evaluation.

Findings

Efficiency >95% in muon detection

Timing resolution of ~0.83 ns at 9000V

Stable operation in streamer mode

Abstract

A large (240 cm $\times$ 120 cm $\times$ 0.2 cm) oil-free High Pressure Laminate (HPL), commonly referred as "bakelite", Resistive Plate Chamber (RPC) has been developed at VECC-Kolkata using locally available P-302 OLTC grade HPL. The chamber has been operated in streamer mode using Argon, Freon(R134a) and Iso-butane in a ratio of 34:57:9 by volume. The electrodes and glue samples have been characterised by measuring their electrical parameters like bulk resistivity and surface resistivity. The performance of the chamber has been studied by measuring the efficiency, its uniformity and stability in detection of cosmic muons. Timing measurement has been performed at a central location of the chamber. The chamber showed an efficiency $>$95$\%$ and time resolution ($\sigma$), at the point of measurement, $\sim$0.83 ns at 9000V. Details of the material characterisation, fabrication procedure and performance studies have been discussed.