With PETRA III, DESY operates one of the best synchrotron sources of X-rays in the world. Its intense X-ray beams display a particularly high brilliance and are used by research groups from all over the world for a wide range of experiments – from medical research through to nanotechnology. Yet the ring accelerator PETRA, which is 2300 metres long, still has untapped potential. It can be upgraded to become an extremely narrowly focused, high-resolution 3D X-ray microscope, offering outstanding research prospects for cutting-edge nanoscience and materials science.

Plans for an ultimate X-ray microscope of this kind are being drawn up now by DESY. The project is entitled PETRA IV, and when completed it will allow scientists to examine the physical and chemical processes taking place inside materials on all scales – from millimetres through to atomic dimensions. Sequences of events that occur on a molecular level in catalytic converters, batteries or microchips could be analysed under realistic operating conditions, the properties of promising new materials and the processes involved could be understood and controlled, and as a result nanostructured materials could be custom-built.

The findings of X-ray nanoanalytics are essential for future applications in energy, communications and security technologies, as well as in health and transport. The opportunities for industrial users are excellent too.

Focused and extremely brilliant

The PETRA III X-ray source already produces highly focused, brilliant X-ray beams, which are extremely good at penetrating matter. A key parameter for this is the so-called emittance, a measure of the cross-section and concentration of a particle beam inside an accelerator. The smaller the emittance, the better. The planned modifications associated with PETRA IV would drastically reduce the emittance even further, by up to two orders of magnitude. As a result, it will be possible to focus the entire synchrotron radiation onto a tiny point, meaning that all X-ray techniques can be performed with a high spatial resolution – i.e. on a microscopic scale. In doing so, PETRA IV will push its brilliance close to the fundamental physical limits for X-ray energies up to 10 kiloelectronvolts, providing measuring conditions for X-ray analytics that will be unparalleled anywhere in the world for a long time to come.

Implementing this new technology will involve rebuilding the storage ring within the existing PETRA ring tunnel. In addition, existing experiments will be adapted and some will be redesigned. During a preparatory phase, a Conceptual Design Report is to be drawn up by 2019, which will outline PETRA IV’s scientific case and strategic potential and present the concepts for the technical solution of the new PETRA IV storage ring. The upgrade could start in the middle of 2024 and be completed by 2026.