M.N. Saraf

Delay and Offset Calibration Schemes for the INO ICAL Electronics

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.

Development of a ±6 kV Bias Supply for ICAL Detectors of INO

The Iron-CALorimeter detector of India-based Neutrino Observatory is designed to use 28,800 single gap Resistive Plate Chambers (RPCs) of 2 m \(\times \) 2 m size as its active detector elements. Each RPC requires a variable High Voltage (HV) supply of up to 12 kV for generation of the operating electric field in the detector gas medium. Considering the large number of supplies needed for the ICAL detector, the location of HV supplies has significant importance in system design in terms of overall cost and space requirement. External generation of HV and its distribution to so many RPC has the disadvantage of requiring bulky HV connectors and cables. In order to avoid HV distribution problem, an indigenous development of a programmable, ± 6 kV HV supply has been carried out. The supply has been developed in a very compact form factor as the space available for it is very limited inside the RPC. In order to achieve low switching noise, the HV inverters have been designed with quasi-sinusoidal waveforms. The developed supply has HV output voltage and current read back facility with two control ports (SPI and RS-232) for remote programming and monitoring purposes. This paper will discuss salient design features, performances and test results of the developed prototype.

Ethernet Scheme for Command and Data Acquisition for the INO ICAL Detector

Over 28,800 Resistive Plate Chambers (RPCs) are going to be deployed in the INO ICAL detector. To control and acquire data from these detectors, a digital front-end (DFE) module will be mounted on each of the RPCs. The DFE modules are provided with an Ethernet interface and hence each of them will function as a network node with an unique IP address. ICAL will use Local Area Network (LAN) topology with a basic TCP/IP communication protocol. Thousands of DFE modules will be grouped together and controlled by a common back-end Command Server, which will use a customized UDP protocol.Each RPC is readout on 128 channels which are connected to corresponding DFE module. This paper describes an efficient solution for transfer of raw data from RPCs in the front end to a permanent storage at the BackEnd in a packaged format, and to communicate with RPCs from the control room.

Calibration and Auxiliary Unit for INO’s ICAL Data Acquisition System

Magnetised iron calorimeter is a detector to study atmospheric neutrinos, proposed by the India based Neutrino Observatory. It will be built using 30 k Resistive Plate Chambers interleaved between iron plates. The neutrino interaction within the detector creates Muon tracks. The position information and TOF w.r.t trigger arrival of an interaction in RPC is recorded locally in each of participating DAQ nodes. CAU is a common interface between all ICAL subsystems for control, calibration and time synchronization. CAU caters global service signals over various electrical path length as per geographical position of RPC. The Global trigger delay offset at each RPC is computed by measuring the round path delay using calibration signals to translate local TOF w.r.t a global reference.

Soft-Core Processor Based Data Acquisition Module for ICAL RPCs with Network Interface

The India-based Neutrino Observatory (INO) collaboration is planning to set up a magnetised Iron-CALorimeter (ICAL) detector to study atmospheric neutrino oscillations. ICAL detector will deploy 28,800 single gap Resistive Plate Chambers (RPCs) of about \(2\,{\text {m}} \times 2\,{\text {m}}\) in area as its active detector elements. Particles produced in the neutrino interactions within the detector volume pass through alternating layers of iron plates and the RPCs, thus leaving tracks in the latter. Signals from each RPC are acquired using 128 pickup strips—64 each on X- and Y-orthogonal planes. These signals are amplified and converted to logic signals by the analog front-end modules, which are mounted on the RPC unit. Major functions of the digital front-end module, which is also mounted at one corner of the RPC unit are to collect and process the event data on trigger, package it and transmit it to the back-end via the built in TCP/IP based network interface.

Glass RPC detector R&D for a mega neutrino detector

India-based Neutrino Observatory (INO) collaboration has proposed a 50 kTons magnetised iron calorimeter (ICAL), whose primary goals are to precisely determine oscillation parameters of the atmospheric neutrinos, to study matter effects on the oscillations and finally to use it as a long baseline detector for the neutrino beams. Good tracking and energy resolutions, good directionality (translating to a time resolution of better than a ns) and charge identification of the detecting particles are the essential requirements of ICAL detector. The ICAL detector will cover an area of about 100,000 m2 and will use about 30,000 glass Resistive Plate Chambers (RPCs) of about 2 m × 2 m in area as active detector elements. An aggressive R&D program to develop and characterise RPCs operating in the avalanche mode was undertaken. We will describe our R&D efforts towards developing these devices and will present the results of their characterisation studies.