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Air Shower Gamma Ray Detectors

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  1. Air Shower Gamma Ray Detectors Outline • Air Shower Physics • Extensive Air Showers • Gamma/Hadron sep. • Why use EAS Detectors • Detecting showers on the ground • Water Cherenkov - Milagro • RPCs – ARGO • Recent Milagro Results • Known Sources • New Detections • Future Detectors - HAWC Milagro University of Maryland

  2. Extensive Air Shower Development University of Maryland

  3. From Ralph Engel University of Maryland

  4. Effect of Altitude ARGO Milagro Low Energy Threshold Requires High Altitude University of Maryland

  5. Milagro ARGO 10 TeV 1 TeV Cascade Development University of Maryland

  6. Ngammas Nelectrons Primary Energy (GeV) Shower Content University of Maryland

  7. Photon Shower 2 Gamma (movies by Miguel Morales) Blue – Electrons Muons – Yellow Pions – Green Nucleons – Purple University of Maryland

  8. Proton Shower 2 TeV (movies by Miguel Morales) Blue – Electrons Muons – Yellow Pions – Green Nucleons – Purple University of Maryland

  9. Techniques in TeV Astrophysics Non-pointed instruments Pointed instruments High energy threshold Moderate background rejection Large field of view (~2sr) High duty cycle (>90%) Good for all sky monitor and for investigation of transient and diffuse sources. Low energy threshold Good background rejection Small field of view Low duty cycle Good for sensitive studies of known point sources. University of Maryland

  10. Why Use EAS Detectors • Transient Sources • GRB’s • Don’t know when or where to look • Some indications of 2nd hard comp. • Variable Sources • Diffuse Sources • Galactic Plane • New Sources University of Maryland

  11. Cherenkov Radiation Boat moves through water faster than wave speed. Bow wave (wake) University of Maryland

  12. Cherenkov Radiation Aircraft moves through air faster than speed of sound. Sonic boom Sonic Boom University of Maryland

  13. Cherenkov Radiation When a charged particle moves through transparent media faster than speed of light in that media. Cherenkov radiation Cone of light University of Maryland

  14. Cherenkov Radiation University of Maryland

  15. 8 m 50m 80m Milagro 450 Top Layer 8” PMTs 273 Bottom Layer 8” PMTs University of Maryland

  16. The Milagro Collaboration D. Berley, E. Blaufuss, J.A. Goodman,* A. Smith , G. Sullivan, E. Hayes, D. Noyes University of Maryland At College Park Shoup, and G.B. Yodh University of California, Irvine D.G. Coyne, D.E. Dorfan, L.A. Kelley D.A. Williams S. Westerhoff, W. Benbow, J. McCullough, M. Morales University of California, Santa Cruz A.I. Mincer, and P. Nemethy, L. Fleysher, R. Fleysher New York University R.W. Ellsworth George Mason University G. Gisler, T. J. Haines, C.M. Hoffman*, F. Samuelson, C. Sinnis B. Dingus, Los Alamos National Laboratory J. Ryan, R. Miller, A. Falcone University of New Hampshire J. McEnery, R. Atkins University of Wisconsin *Spokesmen Students University of Maryland

  17. Milagro University of Maryland

  18. Inside Milagro University of Maryland

  19. Milagro Site University of Maryland

  20. Milagro Outriggers University of Maryland

  21. Shower hitting the pond at an angle University of Maryland

  22. 2 Tev Proton Shower hitting the pond University of Maryland

  23. 2 Tev E/M Shower hitting the pond University of Maryland

  24. Angle Reconstruction For large showers, the angle can be reconstructed to better than 0.50o.(However, there are systematics associated with core location) University of Maryland

  25. Events University of Maryland

  26. Shower Curvature University of Maryland

  27. Operations • Milagro has been operating since 2000 at 2650m • 0.22 Trillion Events • Outriggers were finished in 2003 • We run with ~96% on-time • Data rate is ~ 1700 Hz • 8-9% deadtime • We reconstruct in real-time • We look for GRBs and send out alerts • Three months of raw data saved for archival analysis • Data is sent via network to LANL & UMD • Nearly total remote capability University of Maryland

  28. Milagro Energy Response (before/after new trigger) Ratio of response to new trigger 1 TeV 1 TeV New Trigger installed March 2002 – removes muon triggers at large angles to allow triggering on lower energy showers University of Maryland

  29. Milagro Sensitivity Our energy threshold increases with the zenith angle. Milagro Effective Area Energy threshold is not well defined. Even though our peak sensitivity is at a few TeV, we have substantial sensitivity at lower energies. GLAST EGRET University of Maryland

  30. P g Gamma – Hadron Separation University of Maryland

  31. Gammas (MC) Data Proton (MC) Gamma / Hadron Separation in Milagro This cut removes 90% of the protons and keeps 50% of the gammas Q is improvement of signal to root BG which equates to sigma This gives a Q of ~1.5 (same signif in ½ the time) University of Maryland

  32. Tibet – 4300m • ARGO University of Maryland

  33. University of Maryland

  34. ARGO Technique University of Maryland

  35. Limited Streamer Tubes University of Maryland

  36. ARGO Design University of Maryland

  37. ARGO Building University of Maryland

  38. Inside the ARGO Building University of Maryland

  39. ARGO Event ARGO will be a very capable detector when completed in several years! University of Maryland

  40. Recent Milagro Results University of Maryland

  41. Signal map of Mrk 421 during the 2001 flare (1/17/01-4/26/01). The circle shows the position of Mrk 421 with our angular bin. The center corresponds to ~5 s Data taken in the Crab Nebula region with 6.4s at the position of the Crab (2000-2002) Milagro Point Sources University of Maryland

  42. Milagro All Sky Survey Hot Spot Crab Mrk 421 University of Maryland

  43. Effect of the Outriggers With outriggers Core Error Before outriggers With outriggers Before outriggers 0.75o This improved ang. resolution give us an increase in Q factor of ~1.7 This means we see the same signal ~ 3 times faster! More improvement (~1.5 – 2 in Q) is expected with better g/h separation University of Maryland

  44. Effect of the Outriggers 12 months of recent data on the Crab ~3 times faster to get same signal Another factor of ~1.5 - 2 is expected from g/h sep Andy/Tony will provide a new plot University of Maryland

  45. EGRET Observation of the Galactic Plane • Black is EGRET Diffuse Flux > GeV • Red is Milagro Exposure (TeV) Outer Galaxy Inner Galaxy Cygnus region Note that their coordinates run opposite from ours… University of Maryland

  46. Milagro Galactic Plane Preliminary Cygnus region 5 s excess for the “inner galaxy” - Flux fraction ~ 4 x 10-5 of CR This is the first detection of the galactic plane at these energies (~TeV) University of Maryland

  47. Preliminary Cygnus region Milagro Galactic Plane Inner Galaxy Outer Galaxy University of Maryland

  48. Galactic Plane University of Maryland

  49. The Cygnus Region University of Maryland

  50. 3EG_J0520+2556 – Milagro Hot Spot University of Maryland