Detecting Air Showers on the Ground Outline Air Shower Physics Extensive Air Showers Gamma/Hadron sep. Why use EAS Detectors Detecting showers on the ground Water Cherenkov - Milagro RPCs – ARGO Milagro Jordan Goodman University of Maryland

University of Maryland Extensive Air Shower Development Jordan Goodman University of Maryland

University of Maryland From Ralph Engel Jordan Goodman University of Maryland

University of Maryland Extensive Air Shower Jordan Goodman University of Maryland

University of Maryland Effect of Altitude ARGO Milagro Low Energy Threshold Requires High Altitude Jordan Goodman University of Maryland

University of Maryland Cascade Development ARGO Milagro 1 TeV 10 TeV Jordan Goodman University of Maryland

Gamma Shower 2 TeV (movies by Miguel Morales) Blue – Electrons Muons – Yellow Pions – Green Nucleons – Purple Jordan Goodman University of Maryland

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

University of Maryland Gamma Shower Content Ngammas Nelectrons Primary Energy (GeV) Jordan Goodman University of Maryland

Lateral distribution of EM energy and muons EM energy from 500 GeV g Muons from 500 GeV Proton Muons from 500 GeV Proton EM energy from 500 GeV g Jordan Goodman University of Maryland

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. Jordan Goodman University of Maryland

University of Maryland Jordan Goodman University of Maryland

University of Maryland Sampling the Shower Water Tanks Scintillators Jordan Goodman University of Maryland

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

University of Maryland Cherenkov Radiation Jordan Goodman University of Maryland

University of Maryland Jordan Goodman University of Maryland

University of Maryland Auger Jordan Goodman University of Maryland

University of Maryland EAS g - Tibet Jordan Goodman University of Maryland

University of Maryland IceTop Jordan Goodman University of Maryland

University of Maryland ARGO Jordan Goodman University of Maryland

Limited Streamer Tubes Jordan Goodman University of Maryland

University of Maryland ARGO Design Jordan Goodman University of Maryland

RPC Satisfied the Requirements on Element of Carpet Resistive Plate Chamber Low cost , high efficiency, high space & time resolution (<1ns), easy access to any part of detector, robust assembling, easy to achieve >90% coverage, mounting without mechanical supports. RPC PAD STRIP Jordan Goodman University of Maryland 2850x1258mm2

University of Maryland ARGO Building Jordan Goodman University of Maryland

University of Maryland DAQ RPC Jordan Goodman University of Maryland

University of Maryland ARGO Events ARGO will be a very capable detector when completed in several years! Jordan Goodman University of Maryland

University of Maryland Milagro 450 Top Layer 8” PMTs 273 Bottom Layer 8” PMTs 8 m 80m 50m Jordan Goodman University of Maryland

University of Maryland Milagro Site Jordan Goodman University of Maryland

University of Maryland Milagro Jordan Goodman University of Maryland

University of Maryland Milagro Outriggers Jordan Goodman University of Maryland

Shower hitting the pond at an angle Jordan Goodman University of Maryland

2 Tev Proton Shower hitting the pond Jordan Goodman University of Maryland

2 Tev E/M Shower hitting the pond Jordan Goodman University of Maryland

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

University of Maryland Events Jordan Goodman University of Maryland

University of Maryland Shower Curvature Jordan Goodman University of Maryland

University of Maryland Conical shape from ARGO Jordan Goodman University of Maryland

Curvature Correction Curved Shower Front 7ns/100m The shower front is not a plane, but is curved about the shower core Times of individual PMTs are adjusted based on the distance to the shower core Core Location Error vs True Core Distance from Center of Pond Without Outriggers Core Error (meters) Core Distance (meters) Curved Shower Front 7ns/100m With Outriggers Core Error (meters) Jordan Goodman University of Maryland Core Distance (meters)

Why Use EAS Detectors to Study Gammas 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 Jordan Goodman University of Maryland

Gamma – Hadron Separation Jordan Goodman University of Maryland

University of Maryland Tibet III + MUON 8,640 m2 Jordan Goodman University of Maryland

University of Maryland miniHAWC g mini- High Altitude Water Cherenkov experiment Jordan Goodman University of Maryland

University of Maryland Detector Layout Milagro: 450 PMT (25x18) shallow (1.4m) layer 273 PMT (19x13) deep (5.5m) layer 175 PMT outriggers Instrumented Area: ~40,000m2 PMT spacing: 2.8m Shallow Area: 3500m2 Deep Area: 2200m2 HAWC: 5625 or 11250 PMTs (75x75x(1 or 2)) Single layer at 4m depth or 2 layers at Milagro depths Instrumented Area: 90,000m2 PMT spacing: 4.0m Shallow Area: 90,000m2 Deep Area: 90,000m2 miniHAWC: 841 PMTs (29x29) 5.0m spacing Single layer with 4m depth Instrumented Area: 22,500m2 PMT spacing: 5.0m Shallow Area: 22,500m2 Deep Area: 22,500m2 Jordan Goodman University of Maryland

Gamma/Hadron Separation Gammas Protons 30 GeV 70 GeV 230 GeV 20 GeV 270 GeV Size of miniHAWC Size of Milagro deep layer Jordan Goodman University of Maryland

University of Maryland Curtains A high altitude version of Milagro would trigger at >10kHz. Need to control spurious triggers due to single muons. Install curtains to optically isolate the PMTs. Intrinsic Gamma hadron separation Jordan Goodman University of Maryland

University of Maryland MiniHAWC  4m 5 m miniHAWC 170m 150m 4.5-5.0 m 6m Jordan Goodman University of Maryland

University of Maryland Tibet – 4300m ARGO Jordan Goodman University of Maryland

Comparison of Effective Areas 50 Tube Trigger Jordan Goodman University of Maryland

University of Maryland The Diffuse Galactic Plane in miniHAWC and HAWC Use Neutral H map to trace out VHE Gamma-Ray flux. Normalize to Milagro observed TeV diffuse emission from the Galactic plane. Jordan Goodman University of Maryland

Conclusions on Air Shower Detectors They are complimentary to ACTs Their features of wide field of view and continuous observation gives them the ability to: Observe transient sources Observe diffuse objects Discover new objects Jordan Goodman University of Maryland