High Energy GeV to TeV, and above

To date the atmospheric Cherenkov technique has been employed with greatest success for photon energies above 300 GeV by several groups. The U.S.-based Whipple collaboration (USA-UK-Ireland) has pioneered many of the techniques now commonly applied to TeV 

FIGURE 17 Schematic of the EGRET instrument on board the Compton Gamma Ray Observatory illustrating the spark-chamber design characteristic of pair-production telescopes. For comparison, schematics of the earlier SAS-2 and COS-B instruments are shown to scale. (Courtesy NASA and the CGRO EGRET Instrument Team.) 

FIGURE 18 Photograph of the Whipple Observatory 10-m imaging atmospheric Cherenkov telescope. (Courtesy of the Whipple Collaboration.) 

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