BEaTriX (Beam Expander Testing X-ray Facility) is a facility installed 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.

Origin of name BEaTriX - by Daniele Spiga
As often happens with the names of scientific projects, it is an acronym: initials which in turn form a word. And in this way, the word takes on two meanings: one "serious" and one more "transcendent".
Let’s start with the "serious" one: BEaTriX is the acronym for the Beam Expander testing astronomical X-ray source for the purpose of testing modular optics for telescopes such as Athena. BEaTriX was born as part of our collaboration with ESA and Cosine for the development of silicon pore optics, and it is a facility that the whole world envies us.
But BEaTriX, with this combination of letters, is also dedicated to Beatrice Portinari, the woman who inspired Dante to write the Divine Comedy, the immortal masterpiece that narrates his journey not only through the Cosmos known in his time, but also in the depths of the human soul, made not only of rationality but also of emotions and passions, sometimes destructive but fortunately also high and sublime, the same passions that know how to lift humanity from the Hell of self-destruction to the Paradise of contemplation of the totality of ’Universe.
And just as it is Beatrice ("she who makes us happy") who guides the Supreme Poet towards the sky by the hand, illuminating him with the reflection of divine light, we want to illuminate (even if they are X-rays) the optics that will take the Athena telescope to the sky.
To reveal to Humanity a face of the Universe that we do not yet know, and make it a little happier than it is now.
"Beatrice mi guardò con li occhi pieni
di faville d’amor così divini,
che, vinta, mia virtute diè le reni,
e quasi mi perdei con li occhi chini."
(Paradiso, IV 139-142)

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