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CLAIRE: First light for a gamma-ray lens

Abstract : The objective of the R&D project CLAIRE was to prove the principle of a gamma-ray lens for nuclear astrophysics. CLAIRE's Laue diffraction lens has a diameter of 45 cm and a focal length of 277 cm; 556 germanium-silicon crystals are tuned to focus 170 keV photons onto a 1.5 cm diameter focal spot. Laboratory measurements of the individual crystals and the entire lens have been used to validate a numerical model that we use to estimate the lens performance for a source at infinity. During a stratospheric balloon flight on 2001 June 14, CLAIRE was directed at the Crab nebula by a pointing system able to stabilize the lens to within a few arcseconds of the target. In 72 min of valid pointing time, 33 photons from the Crab were detected in the 3 keV bandpass of the lens: CLAIRE's first light! The performance of CLAIRE's gamma-ray lens, namely the peak reflectivity for a polychromatic source (9±1%), has been confirmed by ground data obtained on a 205 meter long test range. CLAIRE's measured performance validates the principle of a Laue lens for nuclear astrophysics, opening the way for a space-borne gamma-ray lens telescope that will achieve one to two orders of magnitude improvement in sensitivity over present technologies.
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Submitted on : Monday, November 19, 2007 - 4:50:47 PM
Last modification on : Friday, December 18, 2020 - 12:54:07 PM

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P. von Ballmoos, H. Halloin, J. Evrard, N. Abrosimov, J. Alvarez, et al.. CLAIRE: First light for a gamma-ray lens. Experimental Astronomy, springer Link, 2005, 20, pp.253-267. ⟨10.1007/s10686-006-9071-0⟩. ⟨in2p3-00188976⟩



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