PETRA III Extension


View of the PETRA III storage ring (red line) showing the Max-von-Laue experimental hall together with the additional experimental halls in the North (Paul P. Ewald hall) and East (Ada Yonath hall). The machine lattice in the arc sections has been modified with two DBA cells yielding two 5m long straight sections. Using a canting scheme with 20mrad canting angle, four 2m long straight sections are available for undulators. In addition, the adjacent long straight sections are also being used for beamlines. In the Paul P. Ewald hall the straight section accommodates a 40m long damping wiggler array which provides an intense high energy X-ray beam. The straight section in the Ada Yonath hall provides free space for additional insertion devices.

The focus of the low emittance storage ring PETRA III is on applications making optimum use of the high beam brilliance especially at hard X-ray energies, i.e. experiments aiming at nano-focusing, ultra-high resolution studies and coherence applications. Because a number of very productive techniques formerly available at DORIS III were not initially implemented at PETRA III and the user demand for access to the new beamlines was very high, it was decided to extend the experimental facilities at the new source and to provide additional beamlines.

In the frame of the PETRA III extension project two new experimental halls on either side (North and East) of the Max-von-Laue hall were built making use of the long straight sections and part of the adjacent arcs.

The northern straight section accommodates one of two 40 m long damping wiggler arrays producing an extremely hard and powerful x-ray beam which will also be utilized for materials science experiments. The long straight section in the east is available for additional insertion devices. In order to accommodate insertion device sources in the arc sections, which are filled with long dipole magnets yielding a rather soft X-ray spectrum, the machine lattice was modified. The new lattice included double bent achromat (DBA) cells in the arcs, each allowing for a 5 m long straight section. Similar to the already existing PETRA III beamlines, these straights serve two beamlines independently by use of canting dipoles resulting in two separate 2 m long straights. Different from the present 5 mrad canting scheme, a canting angle of 20 mrad was chosen at the extension beamlines to provide more spatial flexibility for the experiments further downstream. In total, the new lattice provides eight short straight sections in the two arcs with source properties corresponding to a high-beta section at PETRA III making them very suitable for the use of undulators.