Metrology Light Source
The Physikalisch-Technische Bundesanstalt operates the Metrology Light Source (MLS), a compact low-energy electron storage ring in close cooperation with the Helmholtz-Zentrum Berlin in Berlin-Adlershof . With a tunable electron energy of 105 MeV to 630 MeV, the MLS is optimized for the radiometric needs of PTB and is used as the primary radiation standard for the realization and transmission of radiometric units in the spectral range of the near IR, the visible, the UV, the extreme UV (EUV) and of the vacuum UV (VUV).
history
In September 2004 construction began on the Willy Wien Laboratory , which houses the MLS, in the immediate vicinity of the BESSY II electron storage ring at the Helmholtz Center Berlin. The first electron beam was stored in the MLS in June 2007, and user operation has been running since April 2008.
functionality
The electron beam is accelerated to 100 MeV in a microtron and injected into the storage ring. Then it is accelerated to a freely selectable electron energy between 105 MeV and 630 MeV. The maximum electron current is 200 mA. The beam life for this current is more than one hour for electron energies of 200 MeV and increases to more than six hours for electron energies of 630 MeV with an average residual gas pressure of 7 · 10 −8 Pa. An active beam position control system, which can be used for electron currents above around 1 mA, stabilizes the beam position to better than 2 μm. The necessary instrumentation is available in the storage ring, which allows an exact determination of all operating parameters. This is a prerequisite for operating the storage ring as the primary source standard. The electron current can be determined absolutely for currents from 1 pA (one electron) to 200 mA. This allows the intensity to be varied in a controlled manner over a dynamic range of more than 11 orders of magnitude.