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Information PETRA IV

PETRA IV – Beamline Portfolio

Due to the ultra-low emittance of PETRA IV, the current scheme of accommodating a large number of insertion device beamlines in only relatively few straight sections of the storage ring will no longer be possible. In the 3 present experimental halls (Max von Laue, Ada Yonath, and Paul Peter Ewald), 14 sections for photon beamline will be available. In order to preserve the number of beamlines and experiments and to be able to extend the beamline portfolio in the future, a 4th experimental hall in the west of PETRA is planned that can accommodate additional 16 photon beamlines [1].

  • 25 photon beamlines at PETRA IV in total (PETRA III has 23 in operation)
  • 5 “flagship” beamlines (Long straight sections, 10 m Undulator possible, Increased brightness)

The “flagship” beamlines will be designed to make optimal use of the extreme brightness of the source. These beamlines will be selected during the TDR phase of PETRA IV. With the current design of the PETRA IV storage ring, many beamlines will gain both in brightness and in flux, as the electron beam emittance is significantly reduced and the length of most insertion devices can be increased to 5 m or more in the case of the flagship beamlines.

Generally, there is more space at each beamline compared to PETRA III today to add the lab space and infrastructure needed for in-situ/operando and high-throughput experiments. Almost all PETRA IV beamlines will have an undulator source. Depending on the final lattice designs some slots might host a super-bend X-ray source.

During the TDR phase, a detailed design of the beamlines at PETRA IV will be worked out. Dedicated workshops in autumn 2020 will be organized in order to survey the needs of the user community and to identify the experiments to be implemented at PETRA IV.

The new beamline portfolio will be developed with advice from the DESY Photon Science Committee and submitted for approval to the DESY Directorate. The work package WP3.08 will define the full new beamline portfolio, including the new “flagship” beamlines, together with the PETRA III beamline managers, ITT, EMBL, HZG, and an independent expert team. This is done on the basis of the Scientific Instrumentation proposals.

[1] Distribution of possible beamline slots assuming eight beamlines per PETRA octant. Red lines mark the PETRA IV "flagship" beamlines located in long straight sections.


PETRA IV – Beam parameters

PETRA IV will have a significantly reduced horizontal emittance, approaching the ideal overlap of emission cones for all electrons in a bunch for X-ray energies up to 10 keV. The X-ray source will therefore be much better defined in size and divergence. Compared to present-day sources, the X-rays will be confined to a two to three orders of magnitude smaller phase space, resulting in a comparable increase in spectral brightness [3]. In addition, nearly the whole beam will be laterally coherent up to about 10 keV, which means that nearly the full beam can be efficiently focused for microscopy applications. For most experiments, the dramatic gain in spectral brightness translates directly into an improvement of the experimental conditions by many orders of magnitude. These large factors enable many new types of experiments and lead to significant improvements of existing techniques.

[2]  (Top) Design parameters of PETRA III and PETRA IV. (Bottom) Final PETRA IV beam parameters including effects of IBS, higher-harmonic RF system, and impedance.


[3] Brightness of PETRA IV for a storage ring current of 200 mA (blue, green and red curves) in comparison with PETRA III (black curves) for a storage ring current of 100 mA. The red curve shows the brightness of the "flagship" beamlines located in long straight sections. The brightness is calculated using the modelling tools based on the Wigner function formalism of the Synchrotron Radiation Workshop (SRW).


PETRA IV - Materials:

PETRA IV Conceptual Design Report

PETRA IV: the ultralow-emittance source project at DESY 

Status of the PETRA IV project

Light Source Upgrades at DESY: PETRA IV and FLASH2020+