Delay and Offset Calibration Schemes for the INO ICAL Electronics

Abstract

Magnetised iron calorimeter (ICAL) is a detector to study the atmospheric neutrinos, proposed by the India-based Neutrino Observatory (INO) to be built using Resistive Plate Chambers (RPCs) which are interleaved between the iron plates. The neutrino interaction within the detector leaves tracks in the RPCs. A Global trigger, based on hit pattern, initiate RPCs to record hit information and their Time Of Flight (TOF). RPCs are spread geographically throughout the ICAL detector which measures about \(48\,{\text {m}} \times 16\,{\text {m}} \times 14.5\,{\text {m}}\), therefore the global signal paths and hence trigger delays to the RPCs will be unequal. Since each RPC records TOF on a trigger arrival, a calibration scheme is needed to measure and monitor the path delays of global trigger to each RPC or offsets of RPC timers. The local time measurements in the participating RPCs can then be translated to global values by applying the measured delays or offsets.