First light of BEaTriX, the new testing facility for the modular X-ray optics of the ATHENA mission

S. Basso, B. Salmaso, D. Spiga*, M. Ghigo, G. Vecchi, G. Sironi, V. Cotroneo, P. Conconi, E. Redaelli, A. Bianco, G. Pareschi, G. Tagliaferri, D. Sisana, C. Pelliciari, M. Fiorini, S. Incorvaia, M. Uslenghi, L. Paoletti, C. Ferrari, R. LolliA. Zappettini, M. Sanchez del Rio, G. Parodi, V. Burwitz, S. Rukdee, G. Hartner, T. Mueller, T. Schmidt, A. Langmeier, D. Della Monica Ferreira, S. Massahi, N. C. Gellert, F. Christensen, M. Bavdaz, Fatima Ferreira, M. Collon, G. Vacanti, N. M. Barriere

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Aims. The Beam Expander Testing X-ray facility (BEaTriX) is a unique X-ray apparatus now operated at the Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Brera (OAB), in Merate, Italy. It has been specifically designed to measure the point spread function (PSF) and the effective area (EA) of the X-ray mirror modules (MMs) of the Advanced Telescope for High-ENergy Astrophysics (ATHENA), based on silicon pore optics (SPO) technology, for verification before integration into the mirror assembly. To this end, BEaTriX generates a broad, uniform, monochromatic, and collimated X-ray beam at 4.51 keV. The beam collimation is better than a few arcseconds, ensuring reliable tests of the ATHENA MMs, in their focus at a 12 m distance.

Methods. In BEaTriX, a micro-focus X-ray source with a titanium anode is placed in the focus of a paraboloidal mirror, which generates a parallel beam. A crystal monochromator selects the 4.51 keV line, which is expanded to the final size by a crystal asymmetrically cut with respect to the crystalline planes. An in-house-built Hartmann plate was used to characterize the X-ray beam divergence, observing the deviation of X-ray beams from the nominal positions, on a 12-m-distant CCD camera. After characterization, the BEaTriX beam has the nominal dimensions of 170 mm × 60 mm, with a vertical divergence of 1.65 arcsec and a horizontal divergence varying between 2.7 and 3.45 arcsec, depending on the monochromator setting: either high collimation or high intensity. The flux per area unit varies from 10 to 50 photons s−1 cm−2 from one configuration to the other.

Results. The BEaTriX beam performance was tested using an SPO MM, whose entrance pupil was fully illuminated by the expanded beam, and its focus was directly imaged onto the camera. The first light test returned a PSF and an EA in full agreement with expectations. As of today, the 4.51 keV beamline of BEaTriX is operational and can characterize modular X-ray optics, measuring their PSF and EA with a typical exposure of 30 min. Another beamline at 1.49 keV is under development and will be integrated into the current equipment. We expect BEaTriX to be a crucial facility for the functional test of modular X-ray optics, such as the SPO MMs for ATHENA.

Original languageEnglish
Article number173
JournalAstronomy and Astrophysics
Volume664
Number of pages5
ISSN0004-6361
DOIs
Publication statusPublished - 2022

Keywords

  • Instrumentation: high angular resolution
  • Instrumentation: miscellaneous
  • X-rays: general
  • Space vehicles: instruments

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