Neutrinos are tiny, neutral, elementary particles which interact with matter via the “weak force”. The Sun produces over two hundred trillion trillion trillion neutrinos every second, and a supernova can release 1000 times more neutrinos than the Sun will produce in its 10-billion year lifetime. Matter is almost transparent to neutrinos. Billions of neutrinos stream through our body every second, yet perhaps only one or two of the higher energy neutrinos will scatter from you in your lifetime! At least 3 types or “flavours” of neutrinos and anti-particles exist in nature, which have a very tiny mass whose value is still not known. Neutrinos hold the key to several important and fundamental questions on the origin of the universe and energy production in stars. Neutrinos detectors have to be situated deep underground to prevent the comparatively huge background from cosmic rays and natural radioactivity at the earth’s surface. Neutrino detectors have to be enormous in size, as the probability of interaction with matter is so small. First atmospheric neutrinos were detected at Kolar Gold Fields, in 1965 by a TIFR group Detecting Neutrinos Neutrinos More Information  Resistive Plate Chamber Detectors The INO project Goals: Study neutrinos from various natural and lab sources Development of detector technology and its applications Eventually: a centre for other studies in physics, biology, geology, etc., all which benefit from special conditions that exist deep underground India-based Neutrino Observatory (INO) A world-class underground laboratory to study fundamental issues in physics Size of cavern : 150 m  22 m  30 m Schematic of underground experimental cavern Panoramic view of site near Theni, Tamil Nadu In the first phase of its operation a magnetised iron calorimeter detector, weighing about 50 ktons, will be used for studying neutrinos produced from cosmic rays in Earth’s atmosphere. Resistive Plate Chambers are rugged, low- cost gas detectors extensively used in high energy and astroparticle physics experiments for the detection of charged particles. Excellent spatial and temporal resolution leading to applications for time of flight measurements, tracking detectors and digital calorimetry due to large signal amplitudes. RPC is composed of two parallel electrodes usually made of glass or bakelite, separated by suitable spacers. A special gas mixture flows through the chamber, and a high voltage is applied across the electrodes uniformly. A passing charged particle induces an avalanche, whose location can be detected on the x-y pickup strips. A total of RPCs of dimension 2m X 2m will be needed for the INO experiment! Large area RPC prototype How does the RPC work Signal pickup (y) Glass Plates Graphite Spacers 8 KV Before After A passing charged particle induces an avalanche, which develops into a spark. The discharge is quenched when all of the locally available charge in an area  0.1 cm 2 is consumed. The discharged area recharges slowly through the high- resistivity glass plates. Two 2 mm thick float Glass Separated by 2 mm spacer 2 mm thick spacer Glass plates Complete RPC Graphite coating on the outer surfaces of glass Pickup strips RPC gas mixture Freon 134a : 95.5% Isobutane : 4.2% SF 6 : 0.3% A RPC detector and DAQ system tracking cosmic ray muons