Claire'S First Light

The objective of the R&D project CLAIRE is to prove the principle of a gamma-ray lens for nuclear astrophysics. CLAIRE features a Laue diffraction lens, an actively shielded array of germanium detectors, and a balloon gondola stabilizing the gamma-ray lens to a few arcseconds. On June 14 2001, the instrument was flown on a stratospheric balloon by the French Space Agency CNES; the astrophysical target was a "standard candle", the Crab nebula. CLAIRE's first light consists of similar to33 diffracted photons from the Crab, corresponding to a 3sigma detection. The performance of the gamma-ray lens during the balloon flight has been confirmed by ground data obtained at a 200 m long test range. Based on the diffraction efficiencies measured with CLAIRE, the mission concept of a space borne gamma-ray lens is proposed, and its potential for nuclear astrophysics is outlined. (C) 2003 Elsevier B.V. All rights reserved.