Helmholtz Zentrum Berlin


hzbEMIL • Watching the Secret Lives of Atoms

The Mirror Zoo

authored 3 years ago:

Mirror, mirror – are you good enough for EMIL?

Last week, we had the possibility to measure our EMIL-M1-hard-X-ray toroidal mirror with the big reflectometer at the Metrological Light Source of the PTB. Thanks to the colleagues there, we will finally be able to analyze whether the new mirror holds all its promises.


The mirror is a narrow strip, one meter long, with two different curvatures, like a segment of a bicycle tube, with a golden coating. It is very important that the coating is even and of the required thickness (some nanometers only), and the geometry of the mirror has to be precise, too. Tolerance limits that are normally something like 0,1mm are a thousand times stricter here.

The reason for our insistence on precision is: This mirror will be placed at the frontend of the hard X-ray beamline at EMIL, and will guide the photons from their source in the undulator some 50 meters before the experiment. So every mistake here will be hugely magnified along the length of the beamline.


Here you see two of us (Frank Siewert and Stefan Hendel) carefully placing the mirror inside the reflectometer. We really handle it with care (and gloves); if damaged, we cannot just buy another one. We would need to wait another year to get a new one.


Fortunately we could insert it without any collisions and now we are waiting for the results.

In the meantime, we got the raw data of the measurements (thanks to our colleagues at PTB). Now these data need to be analyzed and fitted to a model – which will take some time.