1. Moriond 2001Jordan GoodmanMilagro Collaboration The Milagro Gamma Ray Observatory The Physics of Milagro Milagrito –Mrk 501 –GRB 970417a Milagro –Description –Recent Results - Crab –Future Directions Jordan Goodman University of Maryland

2. Moriond 2001Jordan GoodmanMilagro Collaboration The Physics of Milagro The Sources of VHE/UHE Cosmic Rays –Crab –Super Nova Remnants Active Galactic Nuclei –High variability Gamma Ray Bursts –High energies Absorption of TeV Photons Primordial Black Holes Solar Physics

3. Moriond 2001Jordan GoodmanMilagro Collaboration Observing the High Energy Sky 10 9 10 11 101010 10 131517 19 1 GeV1 TeV1 PeV1 EeV Satellites Fly’s Eye / HiRes Air Cherenkov Milagro EAS Arrays Solar Arrays Akeno /Auger Milagro Water-Cherenkov Detector Threshold ~300 GeV Wide-angle  /hadron Separation 24 Hour – all year operation

4. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro Site Located near Los Alamos, NM, USA 8650’ Elevation 60m X 80m X 8m covered pond

5. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro Site Counting House Pond Utility Building (PUB) Office Trailer Testing Trailer

6. Moriond 2001Jordan GoodmanMilagro Collaboration Milagrito A prototype for the full Milagro detector Single layer of 230 PMTs with no muon detection Milagrito operated at >250Hz from Feb 97 to April 98 (>85% livetime) More than 9 billion events - 9 Terabytes

7. Moriond 2001Jordan GoodmanMilagro Collaboration Mrk 501 Flare

8. Moriond 2001Jordan GoodmanMilagro Collaboration Milagrito Results – MRK 501

9. Moriond 2001Jordan GoodmanMilagro Collaboration MRK 501

10. Moriond 2001Jordan GoodmanMilagro Collaboration Milagrito - GRB 970417a Searching 54 Batse bursts (T90) One burst 970417a showed 18 events w/background of 3.46 This has a prob< 2.9x10 -8 Accounting for all search trials – combined accidental chance 1/150 This could mean TeV emission from GRBs Batse 1  error circle

11. Moriond 2001Jordan GoodmanMilagro Collaboration Milagrito - GRB 970417a

12. Moriond 2001Jordan GoodmanMilagro Collaboration Milagrito Moon Shadow

13. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro 8 m 80m 50m 450 Top Layer 8” PMTs 273 Bottom Layer 8” PMTs

14. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro Construction

15. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro

16. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro

17. Moriond 2001Jordan GoodmanMilagro Collaboration Angle Reconstruction For large showers, the angle can be reconstructed to better than 0.50 o. (However, there are systematics associated with core location)

18. Moriond 2001Jordan GoodmanMilagro Collaboration Events

19. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro Energy Response

20. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro Moon Shadow: Aug 2000 – Jan 2001 Nhit >  150, Nfit > 20

21. Moriond 2001Jordan GoodmanMilagro Collaboration Gamma / Hadron Separation in Milagro Gammas (MC) Data Gammas (MC)

22. Moriond 2001Jordan GoodmanMilagro Collaboration P 

23. Moriond 2001Jordan GoodmanMilagro Collaboration Crab Nebula

24. Moriond 2001Jordan GoodmanMilagro Collaboration

25. Moriond 2001Jordan GoodmanMilagro Collaboration Crab Data

26. Moriond 2001Jordan GoodmanMilagro Collaboration Crab Signal - Time Evolution

27. Moriond 2001Jordan GoodmanMilagro Collaboration Predicted Crab Signal in Milagro from ACTs Events per Day in Milagro Flux F(E) x (10 -7 /s/m 2 /TeV) Whipple 1 22.53.2 ± 0.70 x E(TeV) -(2.49 ± 0.08) HEGRA 1 16.82.7 ± 0.82 x E(TeV) -(2.61 ± 0.12) CAT 1 17.32.7 ± 0.43 x E(TeV) -(2.57 ± 0.16) Tibet 2 49.88.2 ± 1.6 x E(TeV) -(2.62 ± 0.17) 1 Cantenese and Weeks (1998) 2 Amenomori et al (1999)

28. Moriond 2001Jordan GoodmanMilagro Collaboration Milagro Sensitivity to the Crab Events per Day No  /had Separation With  /had Separation Complete Milagro Whipple 22.5 2.8  9.5  HEGRA16.8 2.1  3.8  6.9  CAT17.3 2.2  3.9  7.0  Tibet49.8 6.2  11.1  21.0  Milagro Prelim. ~20 1.6  5.0 

29. Moriond 2001Jordan GoodmanMilagro Collaboration Outrigger array Adding ~150 tanks Used for Core location –Improved angle –Improved Energy

30. Moriond 2001Jordan GoodmanMilagro Collaboration Future Plans Complete Outriggers –34 are now online Put burst/GRB analysis online –GRB alerts to network New trigger processor to lower threshold –Discriminate against muon triggers –Lower energy threshold –Increase reach for GRB and other studies Improve Gamma / Hadron Separation Improve Angle Reconstruction

31. Moriond 2001Jordan GoodmanMilagro Collaboration Lowering the trigger threshold

32. Moriond 2001Jordan GoodmanMilagro Collaboration Risetime Trigger Processor Data Gives: At 27PMT threshold: Raw Trigger Rate = 14.5 kHz Not Fit (Muon Rate) = 9 kHz Simulation Predicts (Preliminary) Making a 100ns risetime cut: Total Trigger rate = 2.6kHz Not Fit(Muon Rate) = 0.5kHz Gamma Efficiency = 66% Proton Efficiency = 40%

33. Moriond 2001Jordan GoodmanMilagro Collaboration Conclusions Milagro is now online We are seeing sources We are improving the detector We hope for many important Physics results soon!