scholarly journals The Measurement of the Silicon Lattice Parameter and the Count of Atoms to Realise the Kilogram

MAPAN ◽  
2020 ◽  
Author(s):  
Enrico Massa ◽  
Carlo Paolo Sasso ◽  
Giovanni Mana
Keyword(s):  
International System ◽  
Lattice Parameter ◽  
Atomic Scale ◽  
X Rays ◽  
Planck Constant ◽  
Contrast Imaging ◽  
Silicon Lattice ◽  
System Of Units ◽  
History Of ◽  
Optical Wavelengths

AbstractX-ray interferometry established a link between atomic and macroscopic realisations of the metre. The possibility of measuring the silicon lattice parameter in terms of optical wavelengths opened the way to count atoms, to determine the Avogadro constant with unprecedented accuracy, and, nowadays, to realise the kilogram from the Planck constant. Also, it is a powerful tool in phase-contrast imaging by X-rays and, combined with optical interferometry, in linear and angular metrology with capabilities at the atomic scale. This review tells the history of the development of this fascinating technology at the Istituto Nazionale di Ricerca Metrologica in the last forty years. Eventually, it highlights its contribution to the redefinition of the International System of Units (SI).

Revision of the SI: The Determination of the Avogadro Constant as the Base for the Kilogram

2014 ◽  
Vol 613 ◽  
pp. 3-10 ◽  
Author(s):  
Arnold Nicolaus ◽  
Horst Bettin ◽  
Michael Borys ◽  
Ulrich Kuetgens ◽  
Axel Pramann
Keyword(s):  
International System ◽  
Fundamental Constant ◽  
Lattice Parameter ◽  
Planck Constant ◽  
Avogadro Constant ◽  
System Of Units ◽  
Working Groups ◽  
Fixed Constant ◽  
Watt Balance

At least four units of the International System of Units (SI) are on the way to a new definition. Especially for the unit of mass, the kilogram, a rigorous change is considered. Instead of the current definition, a 1kg-artifact in form of a Pt-Ir-cylinder, the intended formulation relates the unit of mass to a fundamental constant. In detail this requires in a first step a measurement of the chosen fundamental constant with contemporary lowest uncertainty and best reproducibility. The constant will then be fixed to that value. As an example the metre is related to the fixed constant speed of light.For the kg there are considered two ways: one is a watt balance, which determines the mass in units of the Planck constant, h. While at present the watt balances show a heterogeneous appearance, the second class of experiment the determination of the Avogadro constant, NA, which measures the mass in terms of the number of elementary entities has reached a considerable level of uncertainty and reproducibility. The fundament of the new determination of the Avogadro constant is a highly enriched 28Si crystal. The different working groups of the Avogadro team determine molar mass and lattice parameter of the crystal, and mass and volume of two precision spheres made from different positions, but of the same crystal. All measurements are carried out for both spheres and all measurement quantities are determined at least from two independent working groups, usually of different countries.

scholarly journals A brief history of metrology: past, present, and future

2019 ◽  
Vol 10 ◽  
pp. 5 ◽  
Author(s):  
Jean-Pierre Fanton
Keyword(s):  
French Revolution ◽  
Quantum Physics ◽  
State Of The Art ◽  
International System ◽  
Actual State ◽  
The Past ◽  
System Of Units ◽  
The World ◽  
History Of ◽  
The Impact

In this paper, we take the freedom to paraphrase Stephen Hawking's well-known formula and approach, for a reflection about metrology. In fact, metrology has a past, a present, and a future. The past is marked by a rich series of events, of which we shall highlight only those which resulted in major turns. The impact of the French Revolution is indisputably one of them. The present corresponds to a significant evolution, which is the entry of metrology into the world of quantum physics, with the relevant changes in the International System of units (SI). An apercu of the actual state of the art of metrological technology is given. The future is characterised by a persisting need for a still enhanced metrology, in terms of performance and domain covered. In this respect, soft metrology seems to constitute a promising field for research and development.

Reflective Equilibria in Metrology?

2016 ◽  
Vol 38 (2) ◽  
Author(s):  
Oliver Schlaudt
Keyword(s):  
International System ◽  
International System Of Units ◽  
System Of Units ◽  
History Of ◽  
Current Reform ◽  
Shed Light

AbstractIn this paper I propose to read the history of systems of units, and in particular the current reform of the International System of Units (SI), understood as a set of measuring norms, in the light of reflective equilibria. The idea is that the model of reflective equilibria actually applies to processes which can be empirically observed or studied. This can help us to understand the nature of normativity and to shed light on its relativity to, and dependence on, practice.

scholarly journals Progress on vacuum-to-air mass calibration system using magnetic suspension to disseminate the Planck-constant realized kilogram

ACTA IMEKO ◽  
2017 ◽  
Vol 6 (2) ◽  
pp. 70 ◽  
Author(s):  
Eric Carl Benck ◽  
Corey Stambaugh ◽  
Edward Mulhern ◽  
Patrick Abbott ◽  
Zeina Kubarych
Keyword(s):  
International System ◽  
High Accuracy ◽  
Magnetic Suspension ◽  
Calibration System ◽  
Font Size ◽  
Planck Constant ◽  
Air Mass ◽  
System Of Units ◽  
Mass Calibration ◽  
Definition Of

<p><span style="font-size: small;">The kilogram is the unit of mass in the International System of units (SI) and has been defined as the mass of the International Prototype Kilogram (IPK) since 1889.  </span><span style="font-size: small;">In the future, a new definition of the kilogram will be realized by fixing the value of the Planck constant.</span><span style="font-size: small;">  </span><span style="font-size: small;">The new definition of the unit of mass will occur in a vacuum environment by necessity, so the National Institute of Standards and Technology (NIST) is developing a mass calibration system in which a kilogram artefact in air can be directly compared with a kilogram realized in a vacuum environment.</span><span style="font-size: small;">  </span><span style="font-size: small;">This apparatus uses magnetic suspension to couple the kilogram in air to a high accuracy mass balance in vacuum.</span><span style="font-size: small;"> </span></p><p> </p>

scholarly journals The watt balance: determination of the Planck constant and redefinition of the kilogram

2011 ◽  
Vol 369 (1953) ◽  
pp. 3936-3953 ◽  
Author(s):  
M. Stock
Keyword(s):  
International System ◽  
Accurate Determination ◽  
Electrical Power ◽  
Planck Constant ◽  
System Of Units ◽  
Macroscopic Quantum Effects ◽  
Watt Balance ◽  
Definition Of ◽  
Base Units

Since 1889, the international prototype of the kilogram has served as the definition of the unit of mass in the International System of Units (SI). It is the last material artefact to define a base unit of the SI, and it influences several other base units. This situation is no longer acceptable in a time of ever-increasing measurement precision. It is therefore planned to redefine the unit of mass by fixing the numerical value of the Planck constant. At the same time three other base units, the ampere, the kelvin and the mole, will be redefined. As a first step, the kilogram redefinition requires a highly accurate determination of the Planck constant in the present SI system, with a relative uncertainty of the order of 1 part in 10 8 . The most promising experiment for this purpose, and for the future realization of the kilogram, is the watt balance. It compares mechanical and electrical power and makes use of two macroscopic quantum effects, thus creating a relationship between a macroscopic mass and the Planck constant. In this paper, the operating principle of watt balance experiments is explained and the existing experiments are reviewed. An overview is given of all available experimental determinations of the Planck constant, and it is shown that further investigation is needed before the redefinition of the kilogram can take place. Independent of this requirement, a consensus has been reached on the form that future definitions of the SI base units will take.

scholarly journals The role of the international prototype of the kilogram after redefinition of the International System of Units

2011 ◽  
Vol 369 (1953) ◽  
pp. 3975-3992 ◽  
Author(s):  
R. S. Davis
Keyword(s):  
International System ◽  
Physical Constant ◽  
Reference Standards ◽  
First Century ◽  
Planck Constant ◽  
Practical Matter ◽  
International System Of Units ◽  
System Of Units ◽  
Great Progress

Since 1889, the international prototype of the kilogram has served to define the unit of mass in what is now known as the International System of Units (SI). This definition, which continues to serve mass metrology well, is an anachronism for twenty-first century physics. Indeed, the kilogram will no doubt be redefined in terms of a physical constant, such as the Planck constant. As a practical matter, linking the quantum world to the macroscopic world of mass metrology has, and remains, challenging although great progress has been made. The international prototype or, more likely, a modern ensemble of reference standards, may yet have a role to play for some time after redefinition, as described in this paper.

scholarly journals Evaluation of the accuracy, consistency, and stability of measurements of the Planck constant used in the redefinition of the international system of units

Metrologia ◽  
2017 ◽  
Vol 55 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Antonio Possolo ◽  
Stephan Schlamminger ◽  
Sara Stoudt ◽  
Jon R Pratt ◽  
Carl J Williams
Keyword(s):  
International System ◽  
Planck Constant ◽  
International System Of Units ◽  
System Of Units

scholarly journals New SI and precision measurements: an interview with Tianchu Li

2020 ◽  
Vol 7 (12) ◽  
pp. 1837-1840
Author(s):  
Jin Wang
Keyword(s):  
International System ◽  
Precision Measurements ◽  
Weights And Measures ◽  
Frequency Standards ◽  
System Of Units ◽  
Constant E ◽  
Most Significant Change ◽  
History Of ◽  
Metre Convention ◽  
New Si

Abstract On 13–16 November 2018, the 26th General Conference of Weights and Measures (CGPM) was held in Paris. The conference adopted Resolution A on ‘Revision of the International System of Units (SI).’ According to Resolution A: four of the SI basic units, namely kilograms, amps, kelvin and mole, are defined by the Planck constant h, the basic charge constant e, the Boltzmann constant k and the Avogadro constant NA, respectively. This establishes the basic quantities and units in SI on a series of constants. The new SI was officially launched on 20 May 2019. This is the most significant change and a milestone in the history of metrology since the Metre Convention was signed in 20 May 1875. Professor Tianchu Li, an academician of the Chinese Academy of Engineering, has been working on time and frequency standards for 37 years. In this interview, Prof. Li reviews the quantization and constant evolutions of the second and meter, and introduces the redefinitions of ampere, kelvin, kilogram and mole, and their significance for precision measurements.

scholarly journals On the five base quantities of nature and SI (The International System of Units)

2011 ◽  
Vol 47 (2) ◽  
pp. 241-246
Author(s):  
G. Kaptay
Keyword(s):  
International System ◽  
Fundamental Constant ◽  
Fundamental Constants ◽  
Planck Constant ◽  
Amount Of Substance ◽  
Substance Mole ◽  
System Of Units ◽  
Elementary Charge ◽  
Base Units ◽  
Constants Of Nature

It is shown here that five base quantities (and the corresponding five base units) of nature are sufficient to define all derived quantities (and their units) and to describe all natural phenomena. The base quantities (and their base units) are: length (m), mass (kg), time (s), temperature (K) and electric charge (C). The amount of substance (mole) is not taken as a base quantity of nature and the Avogadro constant is not considered as a fundamental constant of nature, as they are both based on an arbitrary definition (due to the arbitrary value of 0.012 kg for the mass of 1 mole of C-12 isotope). Therefore, the amount of substance (mole) is moved from the list of base quantities to the category of the supplementary units (to be re-created after its abrogation in 1995). Based on its definition, the luminous intensity (cd) is not a base quantity (unit), therefore it is moved to the list of derived quantities (units). The ampere and coulomb are exchanged by places in the list of base and derived units, as ampere is a speed of coulombs (but SI defines meter, not its speed as a base unit). The five base quantities are re-defined in this paper by connecting them to five fundamental constants of nature (the most accurately known frequency of the hydrogen atom, the speed of light, the Planck constant, the Boltzmann constant and the elementary charge) with their numerical values fixed in accordance with their CODATA 2006 values (to be improved by further experiments).

Quantum Metrology of Electrical Quantities and Mass

2021 ◽  
Vol 30 (3) ◽  
pp. 17-25
Author(s):  
Mun-Seog KIM ◽  
Dong-Hun CHAE ◽  
Kwang-Cheol LEE
Keyword(s):  
Quantum Physics ◽  
Josephson Effect ◽  
International System ◽  
Quantum Hall ◽  
Fundamental Constants ◽  
Planck Constant ◽  
System Of Units ◽  
Elementary Charge ◽  
Base Units ◽  
New Si

The new International System of Units (SI) became effective on 20 May 2019. In the new SI, the complete system of units can be traced to seven fixed values of the fundamental constants, not to seven base units as in the old system. Electrical metrology has two important quantum mechanical foundations. Here, we introduce the basics and the metrological applications of the Josephson effect and the quantum Hall effect, which play key roles in linking electrical quantities to the fundamental constants, including the Planck constant h, the elementary charge e, and the transition frequency of cesium 133 ΔνCs. Finally, we discuss the redefinition of the kilogram as one of the important examples of electrical metrology based on quantum physics.

Sign in / Sign up

Export Citation Format

Share Document