National Primary Radiometric Standards of the USSR

Abstract

A versatile combined primary standard of the USSR has been established at VNIIOFI for the realization of radiometric units. The standard is based on two black bodies, operable at temperatures from 400 to 3000 K, and an absolute radiometer. Units of both spectral and broadband quantities are reproduced within the 0,2 pm to 25 pm range. A black-body radiator made of niobium carbide and graphite is used over the temperature range of 1500-3000 K, while that for the lower temperatures from 400 to 1200K is a heat-pipe with a sodium heattransfer medium. In order to determine the thermodynamic temperature T of the high-temperature black body, relative values of radiant flux P, ( T ) and spectral radiance Le, (ii, 7;) at several temperatures are found. The method allows realization of radiometric and photometric quantities irrespective of the International Practical Temperature Scale (IPTS-68). The absolute radiometer used is of a special design and has a control system capable of maintaining the conical receiving cavity at constant temperature throughout the measurement process. The absolute radiometer is intended to realize radiometric units as well as to measure the spectral sensitivity of radiation receivers.

A systematic neutron reflectometry study on hydrogen absorption in thin Mg1-xAlx alloy films Special issue on Neutron Scattering in Canada.

“…With detector-based radiometric standards achieving very small uncertainties in the 0.01% range or below (see section IV), several NMIs now measure thermodynamic temperature by radiometric means, traceable to those detector-based standards, rather than using an ITS-90 derived source-based scale [38][39][40][41][42][43][44][45][46]. This practice also anticipates changes in thermometry, where the new mise-en-pratique for the definition of the kelvin (currently being prepared by the Consultative Committee for Thermometry (CCT))…”

Spectral irradiance model for tungsten halogen lamps in 340–850 nm wavelength range

“…High-temperature blackbodies are used as radiation sources in primary spectral irradiance scale realizations in several National Metrology Institutes (NMIs) [1][2][3][4]. The emissivity of a blackbody is predictable and spectrally constant.…”

Alternative Methods of Blackbody Thermodynamic Temperature Measurement Above Silver Point

“…Taking into account these achievements, the method of comparing the ratios of blackbody and synchrotron radiation can be adopted to operations with the FRs having the relative spectral responsivities r 1 (λ) and r 2 (λ). Equation 10 should be re-written in the form,…”

“…However, there are alternative approaches to the determination of blackbody temperatures, which are based on relative radiometry methods, namely, the method of ratios [9][10][11][12][13] and the method of comparing blackbody radiation with that of a synchrotron [14]. Since these methods use only ratios of detector signals, absolute calibration of detectors in terms of radiometric units is not required.…”