Here - PMOD/WRC

Absolute cryogenic radiometry in the extreme ultraviolet at NIST
R. E. Vest, S. Grantham, and C. Tarrio
National Institute of Standards and Technology, Gaithersburg, MD, USA
Abstract. The absolute cryogenic radiometer (ACR) is an
optical power detector with inherently lower uncertainty.
At the National Institute of Standards and Technology
(NIST) in Gaithersburg, MD, USA, we have recently
implemented an ACR on a synchrotron beamline to
establish a new radiometric scale in the wavelength range
from 11 nm to 35 nm. The new scale is in good agreement,
within the combined uncertainty of the measurements,
with the extant scale based on an ionization chamber. Here
we describe the high-throughput beamline at NIST’s
Synchrotron Ultraviolet Radiation Facility (SURF III) and
the measurement system for calibration of Si photodiodes
against the ACR, we present the calibration results for an
uncoated Si photodiode and a photodiode with a Si/Zr
coating deposited directly onto the active area, and we
compare the ACR-based calibrations with calibrations
traceable to an ionization chamber on a different
synchrotron beamline.
Proceedings NEWRAD, 17-19 October 2005, Davos, Switzerland 323