Glass RPC Detector R&D for a Mega Neutrino Detector

S. Bheesette

Dept. of High Energy Physics, Tata Institute of Fundamental Research, Mumbai, Maharashtra, INDIA

On behalf of the INO Collaboration

India-based Neutrino Observatory (INO) collaboration has proposed a 50 kton 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. The main requirements of the ICAL detector are large target mass, modularity, good tracking and energy resolutions. Good directionality (translating to a time resolution of about 1nS) and charge identification of the detecting particles are the other essential capabilities of this detector, which is proposed to compliment the potentials of other existing and proposed detectors.

ICAL will comprise of about 150 layers of low carbon 56 mm thick iron plates. Lateral dimensions of this cubical geometry detector are 48m x 16m x 14.5m. The iron absorber will be magnetised to a strong field of about 1.5Tesla. Sandwiched between these layers are glass Resistive Plate Chambers (RPCs), which are used as the active detector elements. RPCs are rugged and low-cost gas detectors and provide excellent spatial and temporal resolutions. The ICAL detector will cover an area of about 100,000m2 and will use about 30,000 RPCs of dimensions 2m x 2m.

An aggressive R&D program to develop and characterise RPCs operating in the avalanche mode was undertaken. We have fabricated a large number of glass RPC prototypes of 1m x 1m in size and have studied in detail, their performance and long term stability. A detector stack of 12 RPCs, readout by an indigenously built electronics and data acquisition system is currently tracking about 150,000 cosmic ray muons per day for about two years.

We will review our various activities towards development of glass RPCs. We will present results of their characterisation studies and discuss our plans to develop 2m x 2m sized RPCs. Some interesting results obtained by the detector stack will also be highlighted.