Groups from all over the world use the DESY test beam. Prototypes of particle detectors of only one square millimetre and others weighing several hundreds of kilograms; components which will become the heart of a detector and others designed for the outer layers of future detectors. All these will be put to the acid test at DESY’s oldest accelerator.

The DESY test beam offers a wide range of possibilities to users. By means of electrons and positrons with energies ranging from one to six gigaelectronvolts, the users can test properties of their detector prototypes, such as response behaviour and accuracy – this is decisive for their future function in the experiment. The beam for the three measuring stations is not decoupled directly from the accelerator. It is generated by introducing a hair-thin wire into the DESY beam. This creates photons that, through another target, are converted into electron–positron pairs. A magnet behind the target gives the test beam users the possibility to select the energy of the electrons individually. This process does not disturb the filling of PETRA III and consequently the photon science user run. The test beam setup offers a pixel telescope and a superconducting magnet, which are both available to the experimenters. The accelerator, which has been in operation since 1964, is a coveted facility for technology development.