RESULTS OF A HIGH-ENERGY GAMMA TELESCOPE

We report on experimental results obtained using a new type of detecto r for high energy gamma astrophysics. The apparatus can detect gamma-r ays in the GeV range, with an angular resolution of a few mrad and an acceptance of 50-degrees. The telescope is based on the.imaging of the Cherenkov light produced in a dense medium (liquid or solid) backed b y a parabolic or spherical reflecting surface. The high energy electro ns, produced at the start of the electromagnetic shower, generate a ri ng-shaped photon image which may produce tens or hundreds of photoelec trons on an appropriate photon imaging detector placed at the focal pl ane of the system on the entrance surface of the converter. A prototyp e consisting of a liquid radiator (C6F14), a multistep parallel-plate avalanche chamber and an optical readout system has been tested in a 1 -10 GeV/c charged particle beam. The analysed data indicate that the i nitial direction of particles can be reconstructed with an angular res olution of approximatelly 3.5 mrad. Furthermore, the capability of suc h a detector to separate e/pi in the GeV range seems promising. Possib le use of the apparatus in a space-borne experiment for distinct gamma -ray sources is also discussed.