Abstract
The BEaTriX (Beam Expander Testing X-ray facility) project is an X-ray apparatus under construction at INAF/OAB to
generate a broad (200´60 mm2), uniform and low-divergent X-ray beam within a small lab (6´15 m2). BEaTriX will
consist of an X-ray source in the focus a grazing incidence paraboloidal mirror to obtain a parallel beam, followed by a
crystal monochromation system and by an asymmetrically-cut diffracting crystal to perform the beam expansion to the
desired size. Once completed, BEaTriX will be used to directly perform the quality control of focusing modules of large
X-ray optics such as those for the ATHENA X-ray observatory, based on either Silicon Pore Optics (baseline) or Slumped
Glass Optics (alternative), and will thereby enable a direct quality control of angular resolution and effective area on a
number of mirror modules in a short time, in full X-ray illumination and without being affected by the finite distance of
the X-ray source. However, since the individual mirror modules for ATHENA will have an optical quality of 3-4 arcsec
HEW or better, BEaTriX is required to produce a broad beam with divergence below 1-2 arcsec, and sufficient flux to
quickly characterize the PSF of the module without being significantly affected by statistical uncertainties. Therefore, the
optical components of BEaTriX have to be selected and/or manufactured with excellent optical properties in order to
guarantee the final performance of the system. In this paper we report the final design of the facility and a detailed
performance simulation.
