The Provisional Low Temperature Scale of 2000 (PLTS-2000) is an equipment calibration standard for making measurements of very low temperatures, in the range of 0.9 mK (
millikelvin) to 1 K, adopted by the
International Committee for Weights and Measures
The General Conference on Weights and Measures (abbreviated CGPM from the ) is the supreme authority of the International Bureau of Weights and Measures (BIPM), the intergovernmental organization established in 1875 under the terms of the Metre C ...
in October 2000. It is based on the melting pressure of solidified
helium-3
Helium-3 (3He see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and hydrogen-1 are the only stable nuclides with ...
.
[
]
At these low temperatures, the melting pressure of helium-3 varies from about 2.9
MPa
MPA or mPa may refer to:
Academia
Academic degrees
* Master of Performing Arts
* Master of Professional Accountancy
* Master of Public Administration
* Master of Public Affairs
Schools
* Mesa Preparatory Academy
* Morgan Park Academy
* M ...
to nearly 4.0 MPa. At the temperature of approximately 315 mK, a minimum of pressure (2.9
MPa
MPA or mPa may refer to:
Academia
Academic degrees
* Master of Performing Arts
* Master of Professional Accountancy
* Master of Public Administration
* Master of Public Affairs
Schools
* Mesa Preparatory Academy
* Morgan Park Academy
* M ...
) occurs. Although this gives a disadvantage of non-
monotonicity
In mathematics, a monotonic function (or monotone function) is a function between ordered sets that preserves or reverses the given order. This concept first arose in calculus, and was later generalized to the more abstract setting of orde ...
, in that two different temperatures can give the same pressure, the scale is otherwise robust since the melting pressure of helium-3 is insensitive to many experimental factors.
See also
*
International Temperature Scale of 1990
The International Temperature Scale of 1990 (ITS-90) is an equipment calibration standard specified by the CIPM, International Committee of Weights and Measures (CIPM) for making measurements on the Kelvin and Degree Celsius, Celsius temperature s ...
(ITS-90) — the calibration standard used for all temperatures above 0.6 K
*
Leiden scale
The Leiden scale (°L or ÐL) is a temperature scale that was used to calibrate low-temperature indirect measurements in the early 20th century, by providing conventional values (in kelvins, then termed "degrees Kelvin") of helium vapour pressure. ...
References
Temperature
Scales of temperature
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