1. ICRC 2011Ignacio Taboada | Georgia Tech1 Sensitivity of HAWC to Gamma Ray Bursts Ignacio Taboada Georgia Institute of Technology Aug 11, 2011 – ICRC

2. ICRC 2011Ignacio Taboada | Georgia Tech2 HAWC Saddle point between Pico Orizaba (5636 m), and Sierra Negra (4640 m) Site: 4100m, 18 o 58’N 97 o 16’W. Central Mexico 300 Water Tanks. 7.3 m (diam), 4.5 m deep.22,000 m 2, 57% coverage ≈100 % duty cycle 1.5 sr Field of View Ideal for transients 30 GRBs per year in HAWC-Fermi GBM coincidence Ref. “The HAWC observatory” # 1059. Session 2. Aug 17. (OG2.5)

3. ICRC 2011Ignacio Taboada | Georgia Tech3 HAWC HAWC will have three 20 cm PMTs and one high quantum eff. 25 cm PMT (predictions shown are for three 20 cm PMTs/tank) Main DAQ: Use PMT times and a charge proxy to reconstruct shower direction, energy and separate C.R. from  -ray Scaler DAQ: Monitor PMT rates for statistical excess VAMOS: Operational now HAWC 30 tanks: Spring ‘12 (Milagro sensitivity) HAWC 300 tanks: Fall ‘14 (x15 Milagro sensitivity

4. ICRC 2011Ignacio Taboada | Georgia Tech4 Effective Area Main DAQScaler DAQ Signal: individual showers Trigger 70 PMTs hit Cut 1 degree circle around GRB Signal: PMT hits

5. ICRC 2011Ignacio Taboada | Georgia Tech5 Main DAQ sensitivity Trigger 70 PMTs hit in 190 ns Directional cuts gamma/CR separation cut Trigger 30 PMTs hit in 190 ns Directional cuts gamma/CR separation cut Seen by Fermi LAT up to 31-33 GeV Ref. “Low Energy Triggering with HAWC” # 1224. Session 2. Aug 17. (OG2.5)

6. ICRC 2011Ignacio Taboada | Georgia Tech6 Scaler Sensitivity Scaler background: 900 PMTs x 30 kHz Detailed background simulation includes correlations Seen by Fermi LAT up to 31-33 GeV

7. ICRC 2011Ignacio Taboada | Georgia Tech7 GRB 090510 Main DAQ Scalers Model EBL following Gilmore et al (2010)  = 20 o Assume Heaviside cutoff at 125 GeV Main DAQ trigger 30 PMTs hit

8. ICRC 2011Ignacio Taboada | Georgia Tech8 Joint Sensitivity Simulated GRB 090510-like event  = 1.6; E C = 150 GeV flux normalized to LAT No EBL Band: consistent values for main DAQ and scalers

9. ICRC 2011Ignacio Taboada | Georgia Tech9 The HAWC Collaboration George Mason University Georgia Institute of Technology Harvey Mudd College Los Alamos National Laboratory Michigan State University Michigan Technological University NASA/Goddard Space Flight Center Ohio State University at Lima Pennsylvania State University Univ. of California, Irvine University of Maryland University of New Hampshire University of New Mexico University of Utah University of Wisconsin Benemérita Universidad Autónoma de Puebla Centro de Investigación y de Estudios Avanzados Instituto Nacional de Astrofísica Óptica y Electrónica Universidad Autónoma de Chiapas Universidad de Guadalajara Universidad de Guanajuato Universidad Michoacana de San Nicolás de Hidalgo Universidad Nacional Autónoma de México Instituto de Astronomía Instituto de Física Instituto de Ciencias Nucleares Instituto de Geofísica USA Mexico

10. ICRC 2011Ignacio Taboada | Georgia Tech10 Backup

11. ICRC 2011Ignacio Taboada | Georgia Tech11 Flux needed to detect 1 photon above 10 GeV Cutoff only due to EBL Five sigma sensitivity