Neutron source BER II

Neutrons for research

Meet the neutrons

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Experimental hall © HZB / Bernhard Ludewig

The neutron source BER II is a research reactor that delivers neutrons. Neutrons are basic building blocks of the matter that makes us up and occur in every atomic nucleus. They are released by splitting uranium nuclei. Much like light, neutrons propagate in a waveform but also have particle properties. When they encounter another material, they become scattered by its atomic lattice or otherwise interact with the atomic nuclei or electrons of that material. Neutrons can therefore be used to see through materials in a similar way to using X-rays.

Researchers in many different fields come to Berlin Wannsee to study their samples at BER II. Materials that contain hydrogen atoms, especially, reveal many secrets when irradiated with neutrons, when X-rays would hardly reveal anything. Neutrons also penetrate deeper into samples than X-rays do. They can even be used to see through metals.

Experimenting at BER II

BER II has over 20 measuring stations, ten of which are currently in user operation. Researchers from all over the world can therefore apply for measurement time to work at these ten experimental stations.

Users of BER II appreciate above all its high reliability and low-noise background. That means the actual measurements stand out clearly from the background noise, even in extreme ranges. This always produces clear results.

Another thing that sets apart working at BER II: neutrons can be fired at samples in extreme environments. We are talking about low temperatures down to near absolute zero, high pressures, and even high magnetic fields that can be applied during the irradiation as standard conditions. One can see effects that would otherwise remain obscure under normal conditions, and materials change their properties. They can become superconducting, for example, to conduct electricity with zero resistance. Series of measurements under defined temperatures, pressures and magnetic fields are therefore particularly meaningful for the development of new materials. For example, those that consume much less power in computer and IT systems.

The end of an era

Neutron research has a long tradition at HZB, but it is now coming to an end. In Europe, there are now several neutron sources that offer a higher neutron flux than BER II. Furthermore, the European neutron spallation source (ESS) is currently being built in Sweden, where researchers will one day be able to use even more intensive neutron radiation for their experiments – and where the neutrons will be produced entirely without nuclear fission.

BER II will still be available to its users until the end of 2019. After that, the HZB Supervisory Board decided in June 2013, the Berlin neutron source will be shut down and dismantled. How interested citizens can become involved in the dismantling process and can contribute to the ongoing dialogue regarding the project, you can find out on our pages concerning the shutdown and dismantling of the Berlin experimental reactor BER II.