Expected performance of a Laue lens based on bent crystals

In the context of the LAUE project devoted to build a long focal length focusing optics for soft gamma-ray astronomy (70/100 keV to $>$600 keV), we present results of simulation of a Laue lens, based on bent crystals in different assembling configurations (quasi-mosaic and reflection-like geometries). The main aim is to significantly overcome the sensitivity limits of the current generation of gamma-ray telescopes and improve the imaging capability.Comment: 7 pages, 7 figures, presented at the Space Telescopes and Instrumentation Symposium 2012: Ultraviolet to Gamma Ray Conference. Published in Proceedings of the SPIE, Volume 8443, id. 844331-844331-7 (2012

Bent crystal selection and assembling for the LAUE project

For the first time, with the Laue project, bent crystals are being used for focusing photons in the 80-300 keV energy range. The advantage is their high reflectivity and better Point Spread Function with respect to the mosaic flat crystals. Simulations have already shown their excellent focusing capability which makes them the best candidates for a Laue lens whose sensitivity is also driven by the size of the focused spot. Selected crystals are Germanium (perfect, (111)) and Gallium Arsenide (mosaic, (220)) with 40 m curvature radius to get a spherical lens with 20 m long focal length. A lens petal is being built. We report the measurement technique by which we are able to estimate the exact curvature of each tile within a few percent of uncertainty and their diffraction efficiency. We also discuss some results.Comment: 9 pages, 15 figures, SPIE conference vol. 8861 (2013

Results of the simulations of the petal/lens as part of the LAUE project

In the context of the LAUE project for focusing hard X-/gamma rays, a petal of the complete lens is being assembled at the LARIX facility in the Department of Physics and Earth Science of the University of Ferrara. The lens petal structure is composed of bent Germanium and Gallium Arsenide crystals in transmission geometry. We present the expectations derived from a mathematical model of the lens petal. The extension of the model for the complete LAUE project in the 90 -- 600 keV energy range will be discussed as well. A quantitative analysis of the results of these simulations is also presented.Comment: 12 pages, 26 figures, SPIE optics + Photonics conference 2013, Vol: 886

Characterization of bent crystals for Laue lenses

In the context of the LAUE project devoted to build a long focal-length focusing optics for soft γ–ray astronomy (80 – 600 keV), we present the results of reflectivity measurements of bent crystals in different configurations, obtained by bending perfect or mosaic flat crystals. We also compare these results with those obtained using flat crystals. The measurements were performed using the Kα line of the Tungsten anode of the X–ray tube in the LARIX facility at the University of Ferrara. These results are finalized to select the best materials and to optimize the thickness of the crystal tiles that will be used for building a Laue lens petal which is a part of an entire Laue lens, with 20 m focal length and 100–300 keV passband. The final goal of the LAUE project is to overcome, by at least 2 orders of magnitude, the sensitivity limits of the current generation of γ–ray telescopes, and to improve the current γ–ray imaging capability

Results of the simulations of the petal/lens as part of the LAUE project

In the context of the LAUE project for focusing hard X-/gamma rays, a petal of the complete lens is being assembled at the LARIX facility in the Department of Physics and Earth Science of the University of Ferrara. The lens petal structure is composed of bent Germanium and Gallium Arsenide crystals in transmission geometry. We present the expectations derived from a mathematical model of the lens petal. The extension of the model for the complete LAUE project in the 90 – 600 keV energy range will be discussed as well. A quantitative analysis of the results of these simulations is also presented

Study and characterization of bent crystals for Laue lenses

We report the results obtained from the characterization of bent Silicon, Germanium and Gallium Arsenide crystals, which are being used for focusing photons in the 90-300 keV energy range, in the framework of the LAUE project. Such crystals represent the best choice for building Laue lenses thanks to their high reflectivity and to the narrow Point Spread Function (PSF) they can provide. The test aims to select the best material, to optimize the thickness and to estimate the curvature radius of the crystal tiles that will be used for building a 20 m focal length Laue lens petal

Scientific prospects in soft gamma-ray astronomy enabled by the LAUE project

This paper summarizes the development of a successful project, LAUE, supported by the Italian Space Agency (ASI) and devoted to the development of long foca length (up to 100—m) Laue lenses for hard X–/soft gamma– ray astronomy (80-600 keV). The apparatus is ready and the assembling of a prototype lens petal is ongoing. The great achievement of this project is the use of bent crystals. From measurements obtained on single crystals and from simulations, we have estimated the expected Point Spread Function and thus the sensitivity of a lens made of petals. The expected sensitivity is a few ×10−8 photons cm−2 s−1 keV−1). We discuss a number of open astrophysical questions that can settled with such an instrument aboard a free-flying satellite