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Cosmic Ray Research in India

4 th Korean Astrophysics Workshop, Daejeon, Korea May 17-19, 2006. Cosmic Ray Research in India. Suresh C. Tonwar Tata Institute of Fundamental Research Mumbai (Bombay), India. Plan of the Talk. Historical remarks Cosmic ray particle physics Cosmic ray astrophysics

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Cosmic Ray Research in India

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  1. 4th Korean Astrophysics Workshop, Daejeon, Korea May 17-19, 2006 Cosmic Ray Research in India Suresh C. Tonwar Tata Institute of Fundamental Research Mumbai (Bombay), India

  2. Plan of the Talk • Historical remarks Cosmic ray particle physics Cosmic ray astrophysics • On-going experiments VHE gamma ray astronomy UHE cosmic ray astrophysics • Plans for the future

  3. Historical Remarks • Ground-based observations in 1920’s and 30’s by D.M. Bose, Vibha Choudhury et al in Kolkata. • Balloon-borne observations by Homi Bhabha in Bangalore in early 1940’s. • Tata Institute of Fundamental Research set up in June 1945 by the Dorabji Tata Trust and the Government of Bombay for research in nuclear sciences, including cosmic rays, and mathematics. • Studies on primary cosmic rays and particle interactions with nuclear emulsion stacks flown on balloon-borne platforms in 1950’s and 60’s.

  4. Historical Remarks • Cosmic ray measurements started in Kolar Gold mines (100 km east of Bangalore) in early 1950’s on particle properties and intensity at various depths underground. Angular distribution measurements showed the suitability of KGF mines for studies on atmospheric neutrinos at a depth of ~ nearly 2 km underground. • An interaction of an atmospheric neutrino in a detector was first observed in KGF in 1964 by a TIFR-Durham U-Osaka CU collaboration, followed very soon by a similar observation by the UCI-led collaboration in a mine in South Africa. Experiments by the TIFR-Osaka CU team continued in KGF during the 1970’s and 80’s. • The first experiment for a search for proton decay was carried out at KGF during the early 1980’s. The mines closed in early 1990’s due to economic reasons.

  5. Historical Remarks • Cosmic Ray Laboratory of TIFR set up at Ooty in December 1954 for direct studies on particle interactions in multi-plate cloud chambers. Ooty (Ootacamund or Udhagamandalam in the State of Tamil Nadu in southern India), 11o 23’ N, 158o 55’ E, 2200 m altitude. • Particle identification (pion or proton) with an air Cherenkov counter above the cloud chamber. Measurement of particle energy with an iron plate–scintillator calorimeter below the chamber. Characteristics of particle interactions, e.g., multiplicity distributions, transverse momentum distributions, neutral/charged ratios, in interactions of pions and protons around 20-40 GeV with carbon and brass nuclei.

  6. Direct Studies on Particle Interactions Ooty (1962-63) Air Cherenkov Counter for particle identification (pion, proton, neutron) Multiplate cloud chamber with carbon and brass plates for interaction display 25-layer iron plate-scintillator calorimeter

  7. Historical Remarks • During 1963-64, a 20-detector air shower array was set-up in Ooty for studies on HE hadrons associated with showers for studies on UHE particle interactions. Measurements were also made on arrival delay spectrum for hadrons, relative to shower front, by timing the signals from the calorimeter. • Detailed comparison of observations on delayed hadrons with Monte Carlo simulations led to the conclusion that the baryon production cross-section was increasing with energy. • Observations also showed the presence of a few ‘energetic’ events which were significantly delayed – massive interacting particles??

  8. Important Cosmic Ray Research Areas • Study of the elemental and isotopic composition of cosmic rays at GeV-TeV energies using balloon or satellite-borne detectors. • Gamma ray astronomy over the GeV-TeV-PeV-EeV energies. • Energy spectrum and composition around the knee (E ~ 3 x 1015 eV). • Energy spectrum and composition around the ankle (E ~ 3 x 1018 eV). • Energy spectrum and composition at energies ~ 1020 eV and observation of the Greisen-Zatsepin-Kuzmin cutoff.

  9. Gamma Ray Astronomy at TeV energies Ooty (India); 1967-83 • A new phase of the search for TeV energy cosmic gamma ray sources started with the discovery of pulsars in 1967. Observations on the Crab pulsar at Ooty during 1968-69 using a 2-reflector (0.9 m dia) system. • The telescope array expanded to 12 in 1977 and 20 in 1979, in order to reduce the energy threshold for detection of gamma rays significantly below 1 TeV. • The 20-reflector array was deployed in the ‘distributed mode’ to measure the arrival angle of each event to an accuracy better than 0.4, to improve the signal to background ratio, during 1981-83 (Crab and Vela pulsars).

  10. 20-Reflector (12 x 0.9 m dia + 8 x 1.5 m dia) Air Cherenkov Array at Ooty (1977)

  11. Central array of the 20-reflector air Cherenkov telescope array in the ‘Distributed Mode’ at Ooty (1981-83)

  12. Outer array of the 20-reflector air Cherenkov telescope array in the ‘Distributed Mode’ at Ooty (1981-83)

  13. Air Cherenkov Telescope Array at Pachmari (1990)

  14. Air Cherenkov Telescope Array at Pachmari (1990)

  15. Air Cherenkov Telescope Array at Gulmarg, Kashmir (1983)

  16. Air Cherenkov Imaging Telsecope Array at Mount Abu (1998)

  17. Observations on the Crab nebula at Mount Abu

  18. Observations on Mkn 421 at Mount Abu during 2004

  19. Air Cherenkov Telescope – 1st of 6Hanle, Ladakh (2005), 4250 m Altitude

  20. Artist view of the planned air Cherenkov telescope array at Hanle (2007)

  21. GRAPES – 1 Experiment at Ooty (1984)(Gamma Ray Astronomy at PeV EnergieS) • Following the discovery of 4.8 h modulated signal from Cygnus X-3 by the Kiel group, the TIFR group re-configured the 24 detector array at Ooty to improve its angular resolution. • Observations during 1984-87 yielded positive results for Cyg X-3, Her X-1 and Sco X-1. • Observations on the muon content could not be done with GRAPES-1. >> GRAPES-2

  22. 100-detector GRAPES-2 Array Ooty (1990)

  23. 192-module, 200 m2 area, Muon detectorof the GRAPES-2 Array – Ooty (1993)

  24. Water Cherenkov Detector Module of the GRAPES-2 Muon Detector at Ooty

  25. Muon multiplicity distribution expected for various primary nuclei (same Eo) – GRAPES-2 at Ooty

  26. Muon multiplicity distribution expected for various primary nuclei (shower trigger) – GRAPES-2 (Ooty)

  27. A comparison of the observed muon multiplicity distribution with simulations GRAPES-2 at Ooty

  28. Average ‘ln A’ from recent experiments

  29. GRAPES-3 Experiment at Ooty (1995) Energy spectrum and composition, 30 TeV–30 PeV • Muon multiplicity distriubution for small showers – large area muon detector – overlap with direct measurements at ~ 100 TeV. • 721-detector shower array – 1 m2 area plastic scintillators. • 16-module, 560 m2 area muon detector (E > 1 GeV).

  30. GRAPES-3 Air Shower Array at Ooty (2001a)

  31. GRAPES-3 Air Shower Array at Ooty (2001b)

  32. GRAPES-3 Air Shower Array at Ooty (2001c)

  33. GRAPES-3 Air Shower Array at Ooty (2001d)

  34. Distribution of showers of 1-1000 TeVResults from simulations for the GR-3 shower trigger

  35. Distribution of the number of detectors triggeredResults from simulations for the GR-3 shower trigger

  36. Atmospheric effects on the GR-3 shower trigger March, 2002

  37. Lateral distributions for 1000 TeV proton showers Results from simulations for the GR-3 shower trigger

  38. Triggering efficiency for various primary particlesResults from simulations for the GR-3 shower trigger

  39. A 4-layer module of the 16-module, 560 m2 area muon detector of the GR-3 array

  40. A 4-module block of the muon detector of the GR-3 array with common concrete shielding

  41. A view of the 4 muon halls of the GR-3 array, each housing a 4-module block

  42. Forbush Decrease associated with the large Solar flare of 2003 Oct 28, observed with the GR-3 muon detector October-November, 2003

  43. Determination of the directions for muons observed with the GR-3 muon detector at Ooty

  44. Grouping of the trajectories of muons in 9 broad directions, as observed with the GR-3 muon detector

  45. Variation in the muon rate for the 9 direction groups, as observed on 2003, Oct 28

  46. Search for high energy muon flux associated with the large Solar flare on 2003 Oct 28

  47. Forbush decrease observed with the GR-3 muon detector on 2003 Oct 29, in E, V and W directions

  48. Muons in GR-3 Measurements on muon multiplicity distributions as a function of shower size

  49. Muons in GR-3 Measurements on muon multiplicity distributions as a function of shower size

  50. Variation in the muon rate with time over 24 hours, observed with the GR-3 muon detector at Ooty

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