The external beamline for detector tests X3ED at the electron accelerator ELSA

Detectors for high energy particle physics research are constantly developed in worldwide collaborations, aiming to improve both spatial and energy resolution. Detector testing is an important process during the development phase. A new beamline for detector tests (X3ED) has been commissioned in Bonn. X3ED supplies a primary particle beam which contrasts to the tertiary test beams provided by most accelerator facilities. At ELSA electrons can be extracted to the test area within an energy range of 0.8 GeV to 3.2 GeV and at particle rates from 300 Hz to 400 MHz. The beam width at the test area in both planes can be altered from 1 mm to 10 mm. A radiation protection concept was designed to meet the requirements of radiation protection ordinance in the new experimental area. The concept has been succesfully validated using the simulation program FLUKA. In operation the beamline's requirements concerning particle rates as well as beam widths met the specifications. In the future the particle accelerator facility ELSA will be increasingly used for detector tests as part of the infrastructure of the Forschungs- und Technologiezentrum Detektorphysik Bonn, providing a worldwide unique test beam on-site.