QUANTITATIVE SPECTRAL RADIATION MEASUREMENTS IN THE VUV AND SOFT-X-RAY REGION

The Physikalisch-Technische Bundesanstalt (PTB), the German national i nstitute of metrology, operates a radiometry laboratory at the electro n storage ring BESSY. Now, after more than ten years of BESSY operatio n, six experimental stations on four beamlines optimized for radiometr ic calibrations and characterization of optical components are in use. The calculable undispersed spectral photon flux of the primary radiat ion standard BESSY with relative uncertainties of below 0.4% is used i n a broad spectral range from about 1 eV to 15 keV for the calibration of energy-dispersive detectors and of monochromator-detector systems at one beamline and for the calibration of radiation sources in the sp ectral range from 3 eV to 1.8 keV at three experimental stations equip ped with monochromators. Monochromatized synchrotron radiation, with e mphasis placed on high spectral purity, is provided at three stations covering the spectral range from 3 eV to about 1.5 keV for detector ca librations and for reflectometry. Brief descriptions of the beamlines, experimental stations and associated instruments are given, In additi on, examples of recent radiometric calibrations and investigations and an outlook on radiometry at the future storage ring BESSY II are pres ented.