G. Charpak et al., RESULTS OF A HIGH-ENERGY GAMMA TELESCOPE, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 343(1), 1994, pp. 300-305
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.