Synchrotron-radiation-operated cryogenic electrical-substitution radiometer as the high-accuracy primary detector standard in the ultraviolet, vacuum-ultraviolet, and soft-x-ray spectral ranges

Abstract

The accuracy of detector calibration in the UV, vacuum-ultraviolet, and soft-x-ray spectral ranges could be significantly improved by the use of the synchrotron radiation electrical substitution radiometer (SYRES) as the primary detector standard. The SYRES radiometer is optimized for use with spectrally dispersed synchrotron radiation as supplied by two monochromator beam lines in the radiometry laboratory of the Physikalisch-Technische Bundesanstalt at the Berlin electron-storage ring (BESSY). Wavelength ranges from 0.8 to 25 nm and from 35 to 400 nm are covered. The typically available radiant power of approximately 1-10 microW can be measured with the SYRES radiometer with a standard relative uncertainty of less than 0.2%. The spectral responsivity of qualified photodiodes for use as secondary detector standards is determined by direct comparison with the primary detector standard at an arbitrary wavelength. At present, the scale of spectral responsivity is realized with a standard relative uncertainty of well below 1% in the spectral ranges 0.8-3.5 nm, 5-25 nm, and 120-400 nm. We provide a comprehensive description of the SYRES radiometer and of the two facilities for detector calibration in the UV and vacuum-ultraviolet spectral ranges and in the soft-x-ray spectral range, respectively, and we discuss the achievable uncertainties in the calibration of detectors.

A close look at dose: Toward L-edge XAS spectral uniformity, dose quantification and prediction of metal ion photoreduction

“…There is a relatively large uncertainty in the quantification of the incident X-ray flux. While for example AXUV and SXUV diodes can be calibrated against the SYRES spectrometer at the physikalisch-technische bundesanstalt (PTB) in Berlin to allow for an error of <0.3% [108][109][110], there are few beamlines that have such calibrated diodes available. Moreover, diode temperature [111], diode surface coverage [112], the position and size of the beam on the diode [113] and the maximum flux such diodes can handle [112] limit their lifetimes significantly and introduces large errors in absolute flux quantification.…”

A plane-grating monochromator beamline for the PTB undulators at BESSY II

“…For radiometric applications, such as detector calibration with a cryogenic radiometer (Rabus et al, 1997) as primary detector standard, high spectral purity (less than 0.5% of the radiant power due to stray light from all beamline elements and due to higher orders) and high radiant power (P > 10 mW at 100 mA stored electron current at modest resolution) are required (Ulm & Wende, 1995). Hence, the design targets are slightly different from those for other undulator beamlines at BESSY II, where highest energy resolution and¯ux density are the centres of interest.…”

Narrowband and tunable anomalous transmission filters for spectral monitoring in the extreme ultraviolet wavelength region

“…We note that the used photodiode model was confirmed to be operated in a regime where the response across the entire relevant EUV range investigated here is proportional to the incident power, such that T AT is independent of power as required. The measurement of the spectral responsivity of photodiodes in the EUV range is made at PTB by comparison with their primary detector standard, which is an electrical substitution radiometer (ESR) operated at liquid He temperature [46].…”