Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray referenc...

An increasing number of calibration and metrology laboratories now employ a Global Positioning System disciplined oscillator (GPSDO) as their primary standard for frequency. GPSDOs have the advantage of costing much less than cesium standards, and they serve as “self-calibrating” standards that should not require adjustment or calibration. These attributes make them an attractive choice for man...

National and international comparisons in Rockwell hardness tests show significant differences. Uncertainties in the geometry of the Rockwell diamond indenters are largely responsible for these differences. By using a stylus instrument, with a series of calibration and check standards, and calibration and uncertainty calculation procedures, we have calibrated the microform geometric parameters ...

The Landsat-8 Operational Land Imager (OLI) was radiometrically calibrated prior to launch in terms of spectral radiance, using an integrating sphere source traceable to National Institute of Standards and Technology (NIST) standards of spectral irradiance. It was calibrated on-orbit in terms of reflectance using diffusers characterized prior to launch using NIST traceable standards. The radian...

Influencing the "injection barriers" into prototype molecular wires through metal-molecule Context: Many NIST customers using our vacuum calibration services spanning the pressure range from 0.65 Pa to 133 kPa (5 millitorr to 1000 torr) desire direct traceability to NIST but cannot justify the cost of calibration against relative to the NIST NIST Ultrasonic Interferometer Manometers (UIMs). The...

A new procedure is provided for transferring analyte concentration values from a reference material to production calibrators. This method is robust to calibration curve-fitting errors and can be accomplished using only one instrument and one set of reagents. An easily implemented stochastic approximation algorithm iteratively finds the appropriate analyte level of a standard prepared from a re...

The nondestructive assay (NDA) of nuclear material must deal with large sample sizes and high self-absorption. Typical containers range from 2-L bottles to 220-L drums, and even a small sample with a high concentration of nuclear material has significant self-attenuation. Although gamma-ray self-attenuation may frequently be ignored in the filter papers or small vials encountered in radiochemic...