Comite International de Poids

PLTS-2000 was formally adopted by the Comite International des Poids et Mesures in October The PLTS-2000 covers die range of temperature from 1K down to 0.9 mK and is defined by an equation for the melting pressure of 3He... 

The ITS 90 was adopted by the Comite International des Poids et Mesures in September 1989 [14-16], The ITS 90 extends from 0.65 K to the highest temperatures, practicably measurable in terms of the Planck radiation law using monochromatic radiation. The defining fixed points of the ITS 90 are mostly phase transition temperatures of pure substances given in Table 8.2. 

Taking up a 2005 recommendation of the Consultative Committee for Thermometry (CCT) [25], the Comite International des Poids et Mesures (CIPM) created a mise en practique of the definition of the kelvin containing clarifications and recommendations of the CCT concerning the realization of the definition of the kelvin and the implementation of practical temperature scales. 

Cominco, Ltd., 26 562 Comite International des Poids et Mesures (CIPM), 24 434, 435, 436 Comite International Special de Perturbations Radioelectriques (CISPR), 76 512... 

BIPM (1993) BIPM Proc.-Verb. Comite International des Poids et Mesures 82 122... 

Abstract. We present a frequency comparison and an absolute frequency measurement of two independent -stabilized frequency-doubled Nd YAG lasers at 532 nm, one set up at the Institute of Laser Physics, Novosibirsk, Russia, the other at the Physikalisch-Technische Bundesanstalt, Braunschweig, Germany. The absolute frequency of the l2-stabilized lasers was determined using a CH4-stabilized He-Ne laser as a reference. This laser had been calibrated prior to the measurement by an atomic cesium fountain clock. The frequency chain linking phase-coherently the two frequencies made use of the frequency comb of a Kerr-lens mode-locked Ti sapphire femtosecond laser where the comb mode separation was controlled by a local cesium atomic clock. A new value for the R.(56)32-0 aio component, recommended by the Comite International des Poids et Mesures (CIPM) for the realization of the metre [1], was obtained with reduced uncertainty. Absolute frequencies of the R(56)32-0 and P(54)32-0 iodine absorp tion lines together with the hyperfine line separations were measured. 

Presently, twelve reference frequencies covering the visible and infrared regions of the electromagnetic spectrum are recommended by the Comite International des Poids et Mesures (CIPM) for the realization of the metre [1]. Up to now, practical length metrology is performed mainly using the red line of the iodine stabilized He-Ne laser at A = 633 nm with a relative standard uncertainty of 2.5 x Hr11 [2],... 

Recommendation adopted by the Comite International des Poids et Messures at its 86th meeting T. J. Quinn Metrologia 30, 523 (1993/1994) T. Quinn Metrologia 36 211 (1999)... 

The -> Faraday constant is not recognized as a unit by the Comite International des Poids et Mesures, however, one may find it occasionally wrongly used as such in electrochemical literature.)... 

In a first experiment, the freqnency of the aio HFS component of the R(56)32-0 iodine absorption line was measnred. This line is recommended by the Comite International des Poids et Mesnres (CIPM) for the realization of the metre [Ij. Since the PTB laser is not tnnable to this frequency, the experiment has been carried ont with the ILP laser only. Using cell 13/97PTB with the parameters T = -5 °C (p = 2,42 Pa), P = 1,7 mW, I = 80 mWjcmf the result is ... 

The SI takes its origin from the Conference Generales des Poids et Mesures (CGPM), which since 1889 has functioned as the international authority for measurement. Operating under CGPM is the Comite International des Poids et Mesures (CIPM), whose prime responsibilities are to define units and to direct the Bureau International des Poids et Mesures (BIPM). The BIPM, estabhshed m 1875, serves as the international reference laboratory and has the responsibility for ensuring uniformity of physical measurements. 

Comite International des Poids et des Mesures, The International Practical Temperature Scale of 1968, Metrologia, 5, (1969), 35-47. Cited on page 33. 

Comite International des Poids et Mesures (1955), Proces-verbaux des Stances de I annee 1954, 24, 81-82, T20-T23, T44-T47 see also Comptes Rendus des Stances de la Dixieme Conference Generate des Poids et Mesures, 1954, Gauthier-Villars et Fils, Paris. 

Well-designed low-pressure gas thermometers can be used to determine (really approximate) the thermodynamic temperature. However, from a practical standpoint, where precision and simplicity in the implementation and transfer are the major considerations, secondary thermometers were chosen as the defining standard thermometers for a practical temperature scale. This scale was defined by the use of fixed reference points whose thermodynamic temperatures were determined from gas thermometer measurements. The International Committee of Weights and Measures (Comite International des Poids et Mesures, CIPM) is responsible for developing and maintaining the scale. 

A new temperature scale, the International Temperature Scale of 1990 (ITS-90), was officially adopted by the Comite International des Poids et Mesures (CIPM), meeting 26—28 September 1989 at the Bureau International des Poids et Mesures (BIPM). The ITS-90 was recommended to the CIPM for its adoption following the completion of the final details of the new scale by the Comite Consultatif de Thermometrie (CCT), meeting 12—14 September 1989 at the BIPM in its 17th Session. The ITS-90 became the official international temperature scale on 1 January 1990. The ITS-90 supersedes the present scales, the International Practical Temperature Scale of 1968 (IPTS-68) and the 1976 Provisional 0.5 to 30 K Temperature Scale (EPT-76). 

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