Beamline 3: Irradiance Calibrations

Description:

Beamline 3 is home to the Facility for Irradiance Calibration Using Synchrotrons (FICUS). FICUS takes advantage of the calculability of synchrotron radiation. The beamline is used to calibrate the absolute spectral irradiance of ultraviolet light sources like deuterium lamps.

Calibrated deuterium lamps are available through the NIST Calibration Program.

Beamline 3 was the basis of the NIST contribution to the Consultative Committee for Photometry (CCPR) key comparison K1.b.

Specifications / Capabilities:

Spectral range 200 nm to 400 nm

Table 1: Components of the Relative Uncertainty (k=2) of Spectral Irradiance of Synchrotron Radiation at the FICUS

Source of Uncertainty	Nominal Value	Relative Uncertainty	Sensitivity Coefficient	Uncertainty in Irradiance
Electron energy	380 MeV	0.02 %	0.057	0.0011 %
Beam current	≈15 mA	0.4 %	1	0.4 %
Orbital radius	837.077 mm	10^-10	0.66	6.6 · 10^-11
Window transmittance	≈0.8	0.5 %	1	0.5 %
Distance	6926 mm	0.086 %	0.015	0.17 %
Detector alignment		±0.6 mm	0.0011	0.066 %
Aperture size	9.5 mm	6.5 %	0.015	0.096 %
Air absorption			1	0.24 %
Combined				0.72 %

Table 2: Components of the Relative Uncertainty (k=2) of Spectral Irradiance of Deuterium Lamp Calibration at the FICUS

Source of Uncertainty	Nominal Value	Relative Uncertainty	Sensitivity Coefficient	Uncertainty in Irradiance
SURF radiation			1	0.72 %
Wavelength		±0.1 nm	0.013	0.27 %
Stray light and fluorescence			1	0.5 %
Lamp distance	300 mm	0.066 %	2	0.13 %
Lamp stability			1	0.5 %
Random uncertainty				0.6 %
Combined				1.2 %

Associated Programs/Projects:

Comparison of Synchrotron Radiation-Based Ultraviolet Source Calibrations at PTB and NIST

Selected Publications

Deuterium lamp (left) and undispersed synchrotron radiation (right) at beamline 3.

Contact

Name: Uwe Arp
Phone: 301-975-3233
Email: uwe.arp@nist.gov
Address:
100 Bureau Dr, MS 8410
Gaithersburg, MD 20899-8410

Name: Ping-Shine Shaw
Phone: 301-975-4416
Email: ping-shine.shaw@nist.gov