India-based Neutrino Observatory (INO) has proposed a 50kton magnetised Iron Calorimeter (ICAL) in an underground laboratory to be constructed near Madurai. Main aims of this project are to precisely study the atmospheric neutrino oscillation parameters and to determine the ordering of neutrino masses. The detector will deploy about 28,800 glass Resistive Plate Chambers (RPCs) of approximately 2m$\times$2m in area. About 3.6million detector channels are required to be instrumented.
A detector stack comprising of 12 layers of 2m$\times$2m RPCs was designed and commissioned in Madurai. These RPCs are readout through 60 pickup strips (of pitch 3cm) on the X-plane and 63 on orthogonal Y-plane. The signals which are induced on strips due to passage of charged particles through RPC detectors are processed by a series of electronic elements such as Analog-Front End (AFE), Digital-Front End (DFE) and back-end data acquisition (DAQ) system. On an event trigger mostly caused by passage of atmospheric muon through the detector stack, the coordinates of all strip hits and their timing with reference to the global trigger signal are recorded by the DAQ system. The entire electronics, data acquisition and trigger systems were developed in-house using preamplifier, discriminator and TDC ASICs as well as high-end FPGAs.
Apart from characterising and long term performance of RPC detectors and electronics, this stack was utilised even to study a few physics problems such as integrated muon flux, polar and azimuthal distribution of incident cosmic ray muons as well as multiplicity of muons passing through the stack.