BEaTriX (Beam Expander Testing X-ray Facility) is a facility at INAF-Osservatorio Astronomico Brera in its Merate seat (Lecco). It represents the first realization of an instrument with an parallel and wide X-ray beam.
The prime goal of BEaTriX is to prove that it is possible to perform the acceptance tests of the optical components of the ATHENA telescope at its production rate.

Design of the BEaTriX laboratory

ATHENA is an observatory for X-rays of the European Space Agency, with launch foreseen for early 2030’s.
The telescope is made by several hundreds of optical modules (Mirror Module, MM) in silicon (Silicon Pore Optics, SPO) that have to be assembled. The MM, produced with the consolidated silicon technology developed by the semiconductor industry, will be produced at the rate of 2 MM/day and they have to be tested for acceptance prior to integration.

At present, the MM are tested at the BESSY II synchrotron facility in Berlin, but the synchrotron X-ray beam is parallel but small and does not cover the full aperture of the modules. The MM are also tested at PANTER, a facility of the Max-Planck-Institut für Extra-terrestrische Physik, close to Munich in Germany, but the vacuum chamber is very large and several days are necessary to reach the vacuum needed for the measurements.

Artistic view of Athena Telescope (Credit ESA).

Conceptual design of the mirror structure - left, mirror assembly and accommodation - right, mirror modules and stacks (Credit ESA, Cosine and ACO Team).

INAF-OABrera has started in 2012 to design a unique facility with the aim to overcome the limitations of the existing facilities. It was at first financed by the AHEAD consortium (Activities for the High-Energy Astrophysics Domain), with grant from the Horizon-2020 European program.
Owing the reached results, INAF-OABrera has received other funds to realize the laboratory: an ESA contract, a second AHEAD grant, ASI and INAF funds.

BEaTriX has been designed with flexibility, to enable in the future its use for the testing of other X-ray optics, with different size and focal length from the ATHENA MMs.

The current status of the facility in Merate, Lecco - Autumn 2021.