TA4-Transnational Access to FTD/ELSA

The FTD research building is a completely new infrastructure, at present (January 2018) in the final phase of civil construction. It is expected to begin its research operation by the end of 2018. A common FTD Steering Board combines the management and will guide the operation of the three facilities involved, based on a common budget. In the following, the three parts of the FTD-Hadron infrastructure are briefly described.

Research and Technology Centre Detector Physics (FTD): The FTD research building is a new 33 M€ research infrastructure which will go into operation by the end of 2018 and transnational access will be provided from the beginning of operation. It 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, which are described below. 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 and 880 m2 of office space.

ELSA: 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.

Cyclotron: 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.

Services currently offered by the infrastructure: All services described in the previous section are intended to be offered for transnational access. The ongoing activities, mainly at the ELSA experiments and test beam, are pursued by approximately 200 physicists. There is significant international co-operation with groups from France, Italy, Poland, Russia, Switzerland, UK, and US. The test beam is also exploited by international collaborations preparing detectors for future experiments at CERN and elsewhere.