Electron Storage Rings as Primary Source Standards
The spectral output characteristics of electron storage rings can be calculated from fundamental principles, given that
the physical parameters that describe them are known. This quality allows the usage of electron storage rings as primary
sources for radiometry over a wide spectral range from the visible to the X-ray region.
, B = 1.3 T (0.22 T), I = 200 mA, d = 5 m; <br>Black Body: T = 3000 K, A<sub>em</sub> = 78.5 mm<sup>2</sup>, d = 1 m; <br>all for a flux defining circular aperture of radius 10 mm and a relative spectral bandwidth of ΔE/E = 0.1 %.)','700','500');)
Typical calculated spectral power for the MLS and
BESSY II compared to a black body radiator
(Click to enlarge)
Before the utilization of electron storage rings, the black body radiator, the spectral output of which is
determined by Planck's law from its temperature and emissivity, was the only primary source available for radiometry.
The radiometric application of a black body radiator, however, is limited to the spectral range form the IR
to the UV. The spectral output characteristics of electron storage rings are determined by Schwingers theory from the
storage ring parameters and have their maximum of emission in the vacuum-UV (VUV) and X-ray spectral range.
Electron storage rings with calculable bending magnet radiation are used as primary source standards for radiometry
in the spectral range from the visible to the X-ray region at several national metrology institutes, such as the National
Institute of Standards and Technology (at SURF III, Gaithersburg, USA), the National Metrology
Institute of Japan (at TERAS, Tsukuba, Japan), the Budker Institute of Nuclear Physics
(at VEPP-3, Novosibirsk, Russia) or PTB (at BESSY II and MLS).
Major applications are the calibration of radiation sources and energy dispersive detectors.
- Measurement of the parameters
- Typical uncertainties MLS
- Typical uncertainties BESSY II
References
R. Klein et al.
Operation of the Metrology Light Source as a primary radiation source standard.
Phys. Rev. STAB 11, 110701 (2008)
R. Klein et al.
Absolut Measurement of the MLS Storage ring parameters.
Proceedings of EPAC 2008, Genoa, Italy, 2055-2057 (2008)
R. Klein et al.
The Metrology Light Source operated as a Primary Source Standard
accepted for publication in Metrologia
last update: 2011-09-30
