This paper gives the 2010 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. The 2010 adjustment takes into account the data considered in the 2006 adjustment as well as the data that became available from 1 January 2007, after the closing date of that adjustment, until 31 December 2010, the closing date of the new adjustment. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2010 set replaces the previously recommended 2006 CODATA set and may also be found on the World Wide Web at physics.nist.gov/constants.

/pdf/codata-recommended-values-of-the-fundamental-physical-4bsdant71c.pdf

CODATA Recommended Values of the Fundamental Physical Constants: 2006

The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to the duration of the mission. With these data helioseismological methods can be used to probe the solar interior. Certain characteristics of convection and its interaction with magnetic fields, related to, for example, activity, will be studied from the results of the irradiance monitoring and from the comparison of amplitudes and phases of the oscillations as manifest in brightness from VIRGO, in velocity from GOLF, and in both velocity and continuum intensity from SOI/MDI. The VIRGO experiment contains two different active-cavity radiometers for monitoring the solar ‘constant’, two three-channel sunphotometers (SPM) for the measurement of the spectral irradiance at 402, 500 and 862 nm, and a low-resolution imager (LOI) with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 um. In this paper the scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described in detail, and their measured performance is given.

VIRGO: Experiment for helioseismology and solar irradiance monitoring

The paper describes a new solid state detector which fulfils all the requirements of the ideal detector for optical radiation measurements. This trap detector is shown to be spatially uniform, linear, stable and to have a predictable relative spectral response so that it can be used to realize a relative spectral response scale with an uncertainty of less than 0,05%. The detector is also shown to be capable of disseminating an absolute spectral responsivity scale with an uncertainty of less than 0,02% at specific laser wavelengths and, independently, of realizing such a scale with an uncertainty of better than 0,05%.

https://iopscience.iop.org/article/10.1088/0026-1394/28/3/018/pdf

Trap Detectors and their Properties

The stability of the quantum efficiency of inversion layer, phosphorus-diffused (n on p), and boron-diffused (p on n) photodiodes has been investigated. Unsatisfactory silicon-silicon dioxide interfaces, latent recombination centers in the diffused layers, and moisture absorption by the device were identified as possible causes of instability. Diodes were fabricated using processes in which these sources of instability were carefully controlled. The resulting diodes were subjected to various accelerated aging tests, and the external quantum efficiency of the diodes was monitored during the tests. Diodes made by older procedures, in which some important parameters affecting stability were not controlled, were included in the study for comparison. The major result of this work is the demonstration that n on p photodiodes are inherently more stable than p on n types in the ultraviolet and blue spectral regions, but that stable p on n devices can also be produced with sufficient care.

Quantum efficiency stability of silicon photodiodes

A high-accuracy cryogenic radiometer has been developed at the National Institute of Standards and Technology to serve as a primary standard for optical power measurements. This instrument is an electrical-substitution radiometer that can be operated at cryogenic temperatures to achieve a relative standard uncertainty of 0.021% at an optical power level of 0.8 mW. The construction and operation of the high-accuracy cryogenic radiometer and the uncertainties in optical power measurements are detailed.

/pdf/national-institute-of-standards-and-technology-high-accuracy-1kos4me1fq.pdf

National Institute of Standards and Technology high-accuracy cryogenic radiometer

The adoption in 1979 of a new definition of the candela, which permitted a detector-based approach to the realization of the unit, has emphasized the importance of high-accuracy absolute radiation detectors. This paper describes a new electrical-substitution absolute radiometer operating at 5 K, based on a standard commercial helium cryostat, which has been developed at NPL for optical radiant-power measurements. The principal advantages of operating the radiometer at liquid helium temperatures are that the detector can be a large, highly absorbing cavity (absorptivity 99.998%) and that exact equivalence of electrical and radiant heating can be clearly demonstrated. It will be the primary absolute detector for a new realization of the candela at NPL and will provide the basis for the development of a wider range of radiometric and spectroradiometric standards. The use of the radiometer to measure the radiant power of an intensity-stabilized laser source at the milliwatt level with an uncertainty of 4 parts in 105 is also described, together with its application in the determination of the responsivity of transfer-standard detectors, such as silicon photodiodes.

http://iopscience.iop.org/article/10.1088/0026-1394/21/3/007/pdf

A Cryogenic Radiometer for Absolute Radiometric Measurements

Oxide-bias measurement techniques to determine front-surface recombination losses in the silicon photodiode self-calibration technique have been investigated. With the water-drop method it has been shown necessary to restrict the applied bias voltage to the very minimum necessary to produce photocurrent saturation, otherwise non-reversible degradation of quantum efficiency may occur. The corona technique has been found to give satisfactory results only on initial application, as a drastic increase in front-region recombination loss is produced.

https://iopscience.iop.org/article/10.1088/0026-1394/21/2/005/pdf

P J Key

Papers

A Cryogenic Radiometer for Absolute Radiometric Measurements

Oxide-bias Measurements in the Silicon Photodiode Self-calibration Technique