scholarly journals Advancements in NRC’s Primary Spectral Irradiance Scale Realization

2022 ◽  
Vol 2149 (1) ◽  
pp. 012005
Author(s):  
A Gamouras ◽  
D J Woods ◽  
É Côté ◽  
A A Gaertner
Keyword(s):  
International System ◽  
National Research Council ◽  
Optical Power ◽  
Thermodynamic Temperature ◽  
Wide Band ◽  
Spectral Irradiance ◽  
Improve Measurement ◽  
Filter Radiometer ◽  
System Of Units ◽  
Power Scale

Abstract The National Research Council (NRC) of Canada has been working to establish new facilities and to improve measurement capabilities traceable to the International System of Units (SI units) in optical radiometry. The NRC primary spectral irradiance scale has transitioned from a detector-based approach in the range of 700 nm to 1600 nm to a detector and source-based realization from 250 nm to 2500 nm. A high temperature blackbody (HTBB) acts as the primary light source for the calibration of 1000 W FEL spectral irradiance standard lamps. The thermodynamic temperature of the HTBB is determined using an NRC-designed wide-band filter radiometer, with spectral responsivity SI-traceable to the NRC optical power scale. This new facility has significantly improved measurement uncertainties compared to the previous NRC spectral irradiance scale.

scholarly journals The kelvin redefinition and its mise en pratique

2016 ◽  
Vol 374 (2064) ◽  
pp. 20150037 ◽  
Author(s):  
B. Fellmuth ◽  
J. Fischer ◽  
G. Machin ◽  
S. Picard ◽  
P. P. M. Steur ◽  
...  
Keyword(s):  
International System ◽  
Thermodynamic Temperature ◽  
Fundamental Constants ◽  
Primary Thermometry ◽  
A Value ◽  
System Of Units ◽  
Mise En Pratique ◽  
Explicit Constant ◽  
Definition Of ◽  
Base Units

In 2018, it is expected that there will be a major revision of the International System of Units (SI) which will result in all of the seven base units being defined by fixing the values of certain atomic or fundamental constants. As part of this revision, the kelvin, unit of thermodynamic temperature, will be redefined by assigning a value to the Boltzmann constant k . This explicit-constant definition will define the kelvin in terms of the SI derived unit of energy, the joule. It is sufficiently wide to encompass any form of thermometry. The planned redefinition has motivated the creation of an extended mise en pratique (‘practical realization’) of the definition of the kelvin ( MeP -K), which describes how the new definition can be put into practice. The MeP -K incorporates both of the defined International Temperature Scales (ITS-90 and PLTS-2000) in current use and approved primary-thermometry methods for determining thermodynamic temperature values. The MeP -K is a guide that provides or makes reference to the information needed to perform measurements of temperature in accord with the SI at the highest level. In this article, the background and the content of the extended second version of the MeP -K are presented.

scholarly journals A SQUID-based primary noise thermometer for low-temperature metrology

2016 ◽  
Vol 374 (2064) ◽  
pp. 20150050 ◽  
Author(s):  
A. Kirste ◽  
J. Engert
Keyword(s):  
Low Temperature ◽  
Quantum Interference ◽  
International System ◽  
Thermodynamic Temperature ◽  
Uncertainty Budget ◽  
Standard Uncertainty ◽  
Primary Thermometry ◽  
Magnetic Field Fluctuation ◽  
Noise Thermometer ◽  
System Of Units

Practical temperature measurements in accordance with the international system of units require traceability to the international temperature scales currently in force. Along with the awaited redefinition of the unit of temperature, the kelvin, on the basis of the Boltzmann constant, in future its mise en pratique will allow the use of approved methods of primary thermometry for the realization and dissemination of the kelvin. To support this process, we have developed a DC superconducting quantum interference device-based noise thermometer especially designed for measurements of thermodynamic temperature in a broad temperature range from 5 K down to below 1 mK. In this paper, we describe in detail the primary magnetic field fluctuation thermometer and the underlying model applied for the temperature determination. Experimental measurement results are presented for a comparison with the Provisional Low Temperature Scale 2000 between 0.7 K and 16 mK including an uncertainty budget for the measured thermodynamic temperatures. In this set-up, the relative combined standard uncertainty is equal to 0.6%.

scholarly journals Low uncertainty Boltzmann constant determinations and the kelvin redefinition

2016 ◽  
Vol 374 (2064) ◽  
pp. 20150038 ◽  
Author(s):  
J. Fischer
Keyword(s):  
International System ◽  
Thermodynamic Temperature ◽  
Boltzmann Constant ◽  
Weights And Measures ◽  
A Value ◽  
System Of Units ◽  
Elementary Charge ◽  
Definition Of The Kelvin ◽  
Definition Of ◽  
Future Revision

At its 25th meeting, the General Conference on Weights and Measures (CGPM) approved Resolution 1 ‘On the future revision of the International System of Units, the SI’, which sets the path towards redefinition of four base units at the next CGPM in 2018. This constitutes a decisive advance towards the formal adoption of the new SI and its implementation. Kilogram, ampere, kelvin and mole will be defined in terms of fixed numerical values of the Planck constant, elementary charge, Boltzmann constant and Avogadro constant, respectively. The effect of the new definition of the kelvin referenced to the value of the Boltzmann constant k is that the kelvin is equal to the change of thermodynamic temperature T that results in a change of thermal energy kT by 1.380 65×10 −23  J. A value of the Boltzmann constant suitable for defining the kelvin is determined by fundamentally different primary thermometers such as acoustic gas thermometers, dielectric constant gas thermometers, noise thermometers and the Doppler broadening technique. Progress to date of the measurements and further perspectives are reported. Necessary conditions to be met before proceeding with changing the definition are given. The consequences of the new definition of the kelvin on temperature measurement are briefly outlined.

scholarly journals A high resolution extra-terrestrial solar spectrum determined from ground-based solar irradiance measurements

2017 ◽  
Author(s):  
Julian Gröbner ◽  
Ingo Kröger ◽  
Luca Egli ◽  
Gregor Hülsen ◽  
Stefan Riechelmann ◽  
...  
Keyword(s):  
High Resolution ◽  
International System ◽  
Metrological Traceability ◽  
Solar Spectrum ◽  
Spectral Irradiance ◽  
Atmospheric Research ◽  
Solar Spectral Irradiance ◽  
Medium Resolution ◽  
System Of Units ◽  
Unbroken Chain

Abstract. A high resolution extraterrestrial solar spectrum has been determined from ground-based measurements of direct solar spectral irradiance over the range 300 nm to 500 nm using the Langley-plot technique. The measurements were obtained at the Iza\\`na Atmospheric Research Center from AEMET, Tenerife, Spain during the period 12 to 24 September 2016. This solar spectrum (QASUMEFTS) was combined from medium resolution (bandpass of 0.86 nm) measurements of the QASUME spectroradiometer in the range 300 nm to 500 nm and high resolution measurements (0.025 nm) from a fourier transform spectroradiometer over the range 305 nm to 380 nm. The KittPeak solar atlas was used to extend this high resolution solar spectrum to 500 nm. The expanded uncertainties of this solar spectrum are 2 % between 310 nm and 500 nm and 4 % at 300 nm. The comparison of this solar spectrum with solar spectra measured in space (top of the atmosphere) gives very good agreements in some cases, while in some other cases discrepancies of up to 5 % could be observed. The QASUMEFTS solar spectrum represents a benchmark dataset with uncertainties lower than anything previously published. The metrological traceability of the measurements to the International System of Units (SI) is assured by an unbroken chain of calibrations leading to the primary spectral irradiance standard of the Physikalisch-Technische Bundesanstalt in Germany.

scholarly journals The high-resolution extraterrestrial solar spectrum (QASUMEFTS) determined from ground-based solar irradiance measurements

2017 ◽  
Vol 10 (9) ◽  
pp. 3375-3383 ◽  
Author(s):  
Julian Gröbner ◽  
Ingo Kröger ◽  
Luca Egli ◽  
Gregor Hülsen ◽  
Stefan Riechelmann ◽  
...  
Keyword(s):  
High Resolution ◽  
Wavelength Range ◽  
International System ◽  
Metrological Traceability ◽  
Solar Spectrum ◽  
Spectral Irradiance ◽  
Research Centre ◽  
Medium Resolution ◽  
System Of Units ◽  
Extraterrestrial Solar Spectrum

Abstract. A high-resolution extraterrestrial solar spectrum has been determined from ground-based measurements of direct solar spectral irradiance (SSI) over the wavelength range from 300 to 500 nm using the Langley-plot technique. The measurements were obtained at the Izaña Atmospheric Research Centre from the Agencia Estatal de Meteorología, Tenerife, Spain, during the period 12 to 24 September 2016. This solar spectrum (QASUMEFTS) was combined from medium-resolution (bandpass of 0.86 nm) measurements of the QASUME (Quality Assurance of Spectral Ultraviolet Measurements in Europe) spectroradiometer in the wavelength range from 300 to 500 nm and high-resolution measurements (0.025 nm) from a Fourier transform spectroradiometer (FTS) over the wavelength range from 305 to 380 nm. The Kitt Peak solar flux atlas was used to extend this high-resolution solar spectrum to 500 nm. The expanded uncertainties of this solar spectrum are 2 % between 310 and 500 nm and 4 % at 300 nm. The comparison of this solar spectrum with solar spectra measured in space (top of the atmosphere) gave very good agreements in some cases, while in some other cases discrepancies of up to 5 % were observed. The QASUMEFTS solar spectrum represents a benchmark dataset with uncertainties lower than anything previously published. The metrological traceability of the measurements to the International System of Units (SI) is assured by an unbroken chain of calibrations leading to the primary spectral irradiance standard of the Physikalisch-Technische Bundesanstalt in Germany.

Dimensions of plane and solid angles and their units in the International System of Units (SI)

2020 ◽  
pp. 26-32
Author(s):  
M. I. Kalinin ◽  
L. K. Isaev ◽  
F. V. Bulygin
Keyword(s):  
Solid Angle ◽  
International System ◽  
International Committee ◽  
Plane Angle ◽  
Arc Length ◽  
Weights And Measures ◽  
International System Of Units ◽  
System Of Units ◽  
In Series ◽  
Solid Angles

The situation that has developed in the International System of Units (SI) as a result of adopting the recommendation of the International Committee of Weights and Measures (CIPM) in 1980, which proposed to consider plane and solid angles as dimensionless derived quantities, is analyzed. It is shown that the basis for such a solution was a misunderstanding of the mathematical formula relating the arc length of a circle with its radius and corresponding central angle, as well as of the expansions of trigonometric functions in series. From the analysis presented in the article, it follows that a plane angle does not depend on any of the SI quantities and should be assigned to the base quantities, and its unit, the radian, should be added to the base SI units. A solid angle, in this case, turns out to be a derived quantity of a plane angle. Its unit, the steradian, is a coherent derived unit equal to the square radian.

scholarly journals A quantum ampere

2020 ◽  
Vol 87 (4) ◽  
pp. 258-265
Author(s):  
Luca Callegaro
Keyword(s):  
Electric Current ◽  
International System ◽  
International System Of Units ◽  
System Of Units ◽  
Elementary Charge ◽  
User Friendly

AbstractThe revision of the International System of Units (SI), implemented since 20 May 2019, has redefined the unit of electric current, the ampere ( A), linking it to a fixed value of the elementary charge. This paper discusses the new definition and the realisation of the electrical units by quantum electrical metrology standards, which every year become more and more accessible, reliable and user friendly.

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