The Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung m. b. H. (English: Berlin Electron Storage Ring Society for Synchrotron Radiation), abbreviated BESSY, is a research establishment in the Adlershof district of Berlin. Founded on 5 March 1979 (in then West-Berlin), it currently operates one of Germany's 3rd generation synchrotron radiation facilities, BESSY II. Originally part of the Leibniz Association, BESSY now belongs to the Helmholtz-Zentrum Berlin (since 1 January 2009).
Owing to the radiometry lab of the PTB http://www.bessy.de/?idart=86&changelang=5, BESSY is the European calibration standard for electromagnetic radiation.[1]
BESSY supplies synchrotron light and provides support for science and industry. There are institutional long-time users, like the Max-Planck-Society, the German Federal Institute for Materials Research and Testing (BAM) and the national metrology institute of Germany (the PTB). Furthermore, research groups from other institutes or universities can apply for utilization (so called beam time) for certain projects.
This original synchrotron facility, costing the equivalent of 66.5 million Euro, became operational on 19 December 1981. It was situated in Wilmersdorf, then a borough of Berlin. The storage ring had a circumference of approx. 60 m. The circulating electrons that provided the radiation were in the energy range of 200 to 800 MeV (Vacuum Ultraviolet through Extreme Ultraviolet).
After its decommissioning in 1999, the component parts of the BESSY I machine were donated to the SESAME project by the German Authorities and have consequently been shipped to Jordan.[2]
Famous achievements of BESSY I were the calibration of the spectrometers for the solar observatory probe SOHO as well as for the detectors for the Chandra X-ray Observatory.[3]
Groundbreaking for the new improved BESSY II synchrotron source in Adlershof took place on 4 July 1994, and the facility was inaugurated on 4 September 1998. The project cost was an equivalent of approximately 100 million Euros. The successor of BESSY I has a circumference of 240 m, providing 46 beam lines, and offers a multi-faceted mixture of experimental opportunities (undulator, wiggler and dipole sources) with excellent energy resolution. The combination of brightness and time resolution enables both femtosecond time and picometer spatial resolutions.
Electrons can be accelerated to an energy of up to 1.7 GeV (X-ray regime), and are subsequently injected into the storage ring. Synchrotron radiation emerges from the dipole magnets that bend the beam on a circular path, as well as from undulators and wigglers. The total power input during regular operation is 2.7 MW.
BESSY II can be run in different modes, according to the time-distance between the electron wave packets that circulate in the storage ring:
Experiments at BESSY II are in the fields of X-ray absorption spectroscopy, Photoemission spectroscopy, Photoemission electron microscopy, X-ray microscopy, Infrared spectroscopy, femtosecond slicing, X-ray lithography, and protein structure analysis.
BESSY maintains a close co-operation with other synchrotron sources in the world, most notably with DESY in Hamburg.
Operation of BESSY II was interrupted on 15 June 2023 because of a cyberattack. The emission of light was restored at the beginning of July, but initially only for Physikalisch Technische Bundesanstalt.[4] [5] [6] [7] [8] [9] [10]