CLAIRE - towards the first light for a gamma-ray lens

The CLAIRE collaboration is presently preparing the first astronomical obse rvation of a gamma-ray lens. In June 2000, the instrument is to be flown on a stratospheric balloon by the French Space Agency CNES. CLAIRE features a Laue diffraction lens, a detector module with a 3 x 3 germanium array, and a balloon gondola stabilized to 15 " pointing accuracy. The instruments le ns focuses gamma-ray photons from its 526 cm(2) area onto a small solid-sta te detector, with only 18 cm(3) equivalent volume for background noise. Hen ce, for the first time in gamma-ray astronomy, the statistics will be domin ated by the signal. Besides its excellent sensitivity, the telescope has ou tstanding angular and spectral resolution. The primary objective for the fi rst balloon flight of CLAIRE is to detect the Crab nebula and measure its e xtend at 170 keV with an angular resolution of about I arcmin. Scientific o bjectives for further flights include collapsed objects, SNRs, and broad cl ass annihilators. (C) 2000 Elsevier Science B.V. All rights reserved.