Description of the infrastructure

Transnational Access is offered to Bonn University´s Forschungs- und Technologie-Zentrum Detektorphysik FTD (Research and Technology Centre Detector Physics). It represents a unique combination of infrastructures for hadron physics research and detector development, and includes 

  • The FTD research building with high-grade laboratory space and dedicated instrumentation,
  • The 3.2 GeV electron accelerator ELSA, hosting two hadron physics experiments and a detector test beamline,
  • The Bonn Isochronous Cyclotron, offering 14 MeV/nucleon ion beams mainly for material irradiation. 
Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
© Volker Lannert / Universität Bonn

Research and Technology Centre Detector Physics (FTD)

The FTD research building provides a common infrastructure for detector research and development in high energy physics, hadron physics, and photonics. The centre includes both local accelerators, ELSA and Cyclotron. With this combination a unique research environment is provided in Germany and Europe. It allows development and immediate tests of new detector technologies, including the production of calibration sources and radiation hardness tests at the cyclotron‘s proton/ion beams, and dedicated tests of detector response using the ELSA electron beam.  

Key research areas of the FTD are chip design, Silicon pixel detectors, high-resolution calorimeters, scintillating fibres, micropattern gas detectors, and optical antennas. It includes specialised equipment and large instruments for micro structuring, micro interconnections, micro X-ray inspection, and high resolution 3D coordinate measurements. On 4 floors the FTD building features 2010 m2 of laboratory space, including a shielded underground laboratory and 360 m2 of category ISO 5–6 clean rooms.


The Electron Stretcher Accelerator ELSA of the Physikalisches Institut (PI) is capable of delivering extracted electron beams with energies of up to 3.2 GeV and, energy dependent, longitudinal spin polarisation of up to 80%. The accelerator consists of three stages: Linear accelerator (26 MeV), Booster Synchrotron (0.5 – 1.6 GeV), and the stretcher ring which produces a cw beam up to energies of 3.2 GeV. Due to the spill structure through the filling of the stretcher ring, the macroscopic duty factor depends on the rate of beam extraction and typically is around 80%. The beam is used for hadron physics experiments and for detector tests.

In two different beamlines the electron beam is converted into energy tagged (optionally polarised) photon beams with the highest available energy for such beams in Europe. Two major experiments are set up for hadron physics research: CBELSA/TAPS (CB) and BGO-OpenDipole (BGO-OD). Double polarisation experiments using a spin-polarised target are a domain of the CB setup, which combines central (Crystal Barrel) and forward (TAPS) electromagnetic calorimeters to almost 4π acceptance, optimised to detect multi-photon final states and ideal to study photo-production of  (multiple) neutral mesons. BGO-OD also uses a central calorimeter, the BGO “rugby ball” of INFN (formerly used at the GRAAL experiment at ESRF, Grenoble), combined with a magnetic spectrometer (Open Dipole) in forward directions. This setup covers almost 4π acceptance as well, complementary to CB with full charged particle tracking and thus ideal for final states of both charged and neutral mesons, in particular involving strange particles.

Besides hadron physics research, the second important use of the electron beams is testing of detector components. This is possible either in combination with one of the described hadron physics experiments or in a dedicated external electron beam line and test area. It allows flexible testing of detector components or complicated arrangements, e.g. polarimeters, either prepared in the FTD laboratories or brought in from third places. The usable electron currents range from “single electrons“ (i.e. ≃1 fA) to 100 pA.

© ELSA-Gruppe
Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
© Cyclotron team / University of Bonn


The Bonn Isochronous Cyclotron of the Helmholtz Institut für Strahlen- und Kernphysik (HISKP) accelerates protons and light nuclei to energies up to 14 MeV per nucleon. It offers several irradiation areas. The beam is mainly used for material investigations and detector tests, in particular tests of radiation hardness. A special application is the production of different types of (short-lived) calibration sources. One example is 83Kr for the Katrin neutrino mass experiment at Karlsruhe. In addition, neutron beams are available of kinetic energies up to 11 MeV and intensities of 7.5 ⨯108 s–1.

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