The INO project BARC-CU-DU-HRI-Hawaii-HPU-IITB-IMSC-IOP-PU-PRL-SINP-SMIT-TIFR-VECC

1. Schematic of the tracking Resistive Plate Chamber (RPC) Some pictures of the test setup Two 2 mm thick float Glass Separated by 2 mm spacer 2 mm thick spacer Pickup strips Because of the small neutrino event rates cosmic ray muons are the most important source of background. This can be reduced to manageable levels by locating the neutrino detector deep underground (depth  1 km) in mines or tunnels Efficiency and timing of glass RPC Glass plates Graphite coating on the outer surfaces of glass Complete RPC How does the RPC work Graphite Glass Plates Spacers 8 KV RPC gas mixture Freon 134a : 62% Argon : 30% Isobutane : 8% Signal pickup (y) Graphite 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 cm2 is consumed. All the above results with RPC in streamer mode. For higher count rate capability and longetivity it could be operated in the avalanche mode (lower HV, amplification needed, better timing Before After ++++++ ++++++ ++++++++++++++++++++ ---------- ------- ------------------------- The discharged area recharges slowly through the high-resistivity glass plates. Cosmic muon flux versus depth The favored explanation of the results of neutrino experiments is that the neutrino flavour and mass eigenstates are not the same, that at least two species have non-zero, but small masses and that matter effects cause resonant transformations of neutrino flavours (MSW effect) Neutrino Oscillations (2 flavors) Neutrino flavor (e, ) & mass eigenstates (1,2) could be different, in general In a weak process flavor eigenstates are produced which propagate in time as The INO project BARC-CU-DU-HRI-Hawaii-HPU-IITB-IMSC-IOP-PU-PRL-SINP-SMIT-TIFR-VECC A brief introduction to neutrinos Neutrinos were proposed by Pauli to save the laws of conservation of energy and angular momentum and statistics in nuclear beta decay. It has zero electric charge, mass  0 and exists, as far as we know, in 3 varieties viz. e   corresponding to the electron and its heavier cousins the muon and tau lepton. Neutrinos interact only weakly with matter making them very hard to detect. For example, a 1 MeV e has a mean free path in matter of about 108 km. Each neutrino has, if it is a Dirac particle, its antiparticle partner. However it could also be its own antiparticle (Majorana particle). If so one should observe neutrinoless double beta decay. • Sources of neutrinos • Atmospheric neutrinos - cosmic ray interaction in upper atmosphere produce  and whose decay generates roughly two  for every e, E  GeV, neutrino flux (e )  105 m2 sec1 • Solar neutrinos - E  0.1-15 MeV, (e )  6  1014 m2 sec1 • Neutrinos from man made sources such as nuclear power reactors - E  0.1-5 MeV, (e )  1013 m2 sec1 GWth1 at 1 km • Geoneutrinos – from beta decays of 40K, U and Th chains (contributing  40% heat production in earth) E  0.1-2 MeV, (e )  5  1010 m2 sec1 • Supernova explosions in the cosmos where 99% energy released as neutrinos (total no. of neutrinos emitted over few secs  1058 Neutrino physics has witnessed an explosive growth following some landmark experiments : 1. SuperKamioka - anomalous ratio of  /e foratmospheric neutrinos and solar e deficit confirming the results of the pioneering 37Cl experiment of Davis (fetching him the 2002 Nobel prize in Physics) 2. Sudbury Neutrino Observatory (deficit of solar e observedas other active species through the neutral current interactions) 3.CHOOZ (no deficit of reactor anti-e over L  1 km) & KamLand (deficit of reactor anti-e over L  200 km) Atmospheric neutrinos were first detected in KGF (1965) by a TIFR group. The Indian Neutrino Observatory (INO) is an initiative to revive underground experiments in this exciting field (see http://www.imsc.res.in/~ino). An MoU signed by participating DAE institutes on 30th August, 2002 to work towards a proposal for INO. • After discussing various possibilities it was decided to work towards a 50-100 kT magnetized iron calorimeter (ICAL) with tracking gas detectors for measuring the momenta of charged products following neutrino interaction with the detector material. The physics goals of such a detector are: • ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Precise determination of neutrino oscillation parameters using atmospheric neutrinos • Matter effect for neutrinos and antineutrinos, observed via R(L/E) = [N()-N()]/[N()+N()] for sin2 213  0.05 • Possible CP and CPT violation in leptonic sector (also if sin2 213  0.05) • Study of Kolar events, ultra high energy neutrinos and multimuon events • In future ICAL could be used as the end detector in a long baseline accelerator neutrino experiment for determining oscillation parameters at a higher precision. The geographical location at a latitude of 11.5N allows the possibility of probing the earth’s core using accelerator neutrinos from Fermilab, USA Schematic of 50 kT magnetized iron calorimeter with tracking detector trays A possible configuration of current coils and magnetic field lines and direction Schematic of underground experimental cavern Of the two possible sites, Rammam near Darjeeling in West Bengal and Pushep near Ooty in Tamilnadu, the latter has been chosen as the preferred site on the basis of seismicity, proximity to industrial towns, equator, connectivity etc. Schematic of atmospheric neutrino transport through earth to detector Disappearance of  through Nup() / Ndown() vs L/E (a simulation for ICAL) 1 - sin2 (2Q) sin2 (1.27 Dm2L/E) - sin2 (2Q) sin2 (1.27 Dm2L/E)  Detector Size of cavern : 150 m  22 m  30 m Earth Site & infrastructure detailed project report by March, 2007 Active collaboration from HEP and NP community is requested !  Panoramic view of Pushep site from TNEB guest house at Masinagudi