Measurement Technology leading to the New Definition of the Kilogram based on the Planck Constant

2019 ◽  
Vol 139 (6) ◽  
pp. 348-351
Author(s):  
Naoki KURAMOTO
Keyword(s):  
Measurement Technology ◽  
Planck Constant ◽  
Definition Of

scholarly journals A critical review of the proposed definitions of fundamental chemical quantities and their impact on chemical communities (IUPAC Technical Report)

2017 ◽  
Vol 89 (7) ◽  
pp. 951-981 ◽  
Author(s):  
Roberto Marquardt ◽  
Juris Meija ◽  
Zoltan Mester ◽  
Marcy Towns ◽  
Ron Weir ◽  
...  
Keyword(s):  
Critical Review ◽  
Planck Constant ◽  
Amount Of Substance ◽  
Work Related ◽  
Avogadro Constant ◽  
Technical Report ◽  
Measurements In Chemistry ◽  
Definition Of ◽  
New Si

AbstractIn the proposed new SI, the kilogram will be redefined in terms of the Planck constant and the mole will be redefined in terms of the Avogadro constant. These redefinitions will have some consequences for measurements in chemistry. The goal of the Mole Project (IUPAC Project Number 2013-048-1-100) was to compile published work related to the definition of the quantity ‘amount of substance’, its unit the ‘mole’, and the consequence of these definitions on the unit of the quantity mass, the kilogram. The published work has been reviewed critically with the aim of assembling all possible aspects in order to enable IUPAC to judge the adequateness of the existing definitions or new proposals. Compilation and critical review relies on the broadest spectrum of interested IUPAC members.

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.

New Definition of the Kilogram by Fixing the Numerical Value of the Planck Constant

2018 ◽  
Vol 35 (4) ◽  
pp. 375-383
Author(s):  
Dongmin Kim ◽  
MyeongHyeon Kim ◽  
Byung-Chill Woo ◽  
Kwang-Cheol Lee
Keyword(s):  
Planck Constant ◽  
Definition Of

scholarly journals The Avogadro constant: determining the number of atoms in a single-crystal 28 Si sphere

2011 ◽  
Vol 369 (1953) ◽  
pp. 3925-3935 ◽  
Author(s):  
Peter Becker ◽  
Horst Bettin
Keyword(s):  
Single Crystal ◽  
Accurate Determination ◽  
Silicon Crystal ◽  
Fundamental Constant ◽  
Planck Constant ◽  
Amount Of Substance ◽  
Avogadro Constant ◽  
Unique Approach ◽  
Definition Of ◽  
Si Isotope

The Avogadro constant, the number of entities in an amount of substance of one mole, links the atomic and the macroscopic properties of matter. Since the molar Planck constant—the product of the Planck constant and the Avogadro constant—is very well known via the measurement of the Rydberg constant, the Avogadro constant is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a new definition of the kilogram in terms of a fundamental constant. Here, we describe a new and unique approach to determine the Avogadro constant from the number of atoms in 1 kg single-crystal spheres that are highly enriched with the 28 Si isotope. This approach has enabled us to apply isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, N A =6.022 140 82(18)×10 23  mol −1 , is now the most accurate input datum for a new definition of the kilogram.

Research of Non-Contact Stiffness Measurement Technology

2014 ◽  
Vol 621 ◽  
pp. 331-336
Author(s):  
Wen Xuan Liu ◽  
Hui Feng Wang ◽  
Guang Lin Wang ◽  
Dong Xiang Shao
Keyword(s):  
Measurement System ◽  
Elastic Element ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Contact Stiffness ◽  
Test System ◽  
Measurement Technology ◽  
Servo Valve ◽  
Stiffness Measurement ◽  
Definition Of

This article describes the elastic element of the servo valve, elaborates the definition of the stiffness of elastic element, analyzes the characteristics of existing rigidity measurement system, points out the limitations of the existing rigidity measurement system when it measures the large-stiffiness elastic element, utilizes a new measuring principle based on the existing stiffness test systems, uses the more accurate laser displacement measurement method to overcome the weaknesses of the existing stiffness test system, improves the measurement accuracy, makes stiffness measurements more accurate and promotes the stiffness measurement technology of the servo valve elastic element.

scholarly journals Realization of the New Kilogram Using 28Si-Enriched Spheres and Dissemination of Mass Standards at NMIJ

MAPAN ◽  
2020 ◽  
Author(s):  
Naoki Kuramoto ◽  
Shigeki Mizushima ◽  
Lulu Zhang ◽  
Kazuaki Fujita ◽  
Yuichi Ota ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Characterization ◽  
Standard Uncertainty ◽  
National Metrology Institute ◽  
Planck Constant ◽  
Sphere Surface ◽  
X Ray ◽  
Crystal Density ◽  
Relative Standard ◽  
Definition Of

Abstract The new definition of the kilogram was implemented on May 20, 2019. The kilogram is presently defined by a fixed value of the Planck constant. On the basis of the new definition, the kilogram will be realized at the National Metrology Institute of Japan by the X-ray crystal density method using 28Si-enriched spheres. For the realization, the volume of 28Si-enriched spheres is measured by optical interferometry. The sphere surface characterization by X-ray photoelectron spectroscopy and ellipsometry is also performed. The relative standard uncertainty of the realization is estimated to be 2.4 × 10−8. Details of the realization and future dissemination of mass standards in Japan based on the 28Si-enriched spheres are described.

scholarly journals Editorial

2020 ◽  
Vol 48 (3) ◽  
pp. 191-191
Author(s):  
   
Keyword(s):  
Periodic Table ◽  
Chemical Elements ◽  
50Th Anniversary ◽  
Planck Constant ◽  
System Of Units ◽  
Dear Reader ◽  
Definition Of ◽  
Lothar Meyer ◽  
New Si ◽  
New System

Dear reader, This year is full of events, anniversaries and milestones. Not only does HTHP celebrate its 50th anniversary, but also the Periodic Table of Elements has its 150th birthday. In 1869 Dimitri Mendeleyev and Lothar Meyer discovered and presented this table. In order to commemorate this breakthrough, UNESCO has declared 2019 as the “International Year of the Periodic Table of Chemical Elements”. In addition, another important event takes place in May 2019. The Conférence Générale des Poids et Mesures will put into effect the new SI system of units on May 20, 2019, the “World Metrology Day”. The introduction of this new system marks a change in paradigm: the new system relates all units to fundamental constants, rather than artefacts. The most prominent example is the definition of the new kilogram, which is now linked to the Planck constant, h. Of course, all of this has an impact on thermophysical property measurements. Therefore, we have asked Dr. Matthieu Thomas from the Laboratoire National de Métrologie et d’Essais (LNE), France, to explain shortly how this new definition works and how it was implemented. Dr. Thomas is involved in the Kibble balance project of LNE, a key element in the realisation of the new kilogram. You find his article in this issue of HTHP. The editors thank Dr. Thomas for his cooperation; we hope you will enjoy reading his article as well as the rest of this issue.

scholarly journals Explaining to different audiences the new definition and experimental realizations of the kilogram

2021 ◽  
Vol 10 (1) ◽  
pp. 1-4
Author(s):  
Joaquín Valdés
Keyword(s):  
International System ◽  
Atomic Mass ◽  
Planck Constant ◽  
International System Of Units ◽  
Si Units ◽  
System Of Units ◽  
Final Agreement ◽  
Definition Of

Abstract. Different options were discussed before reaching the final agreement on the new definitions of the SI units, effective from 20 May 2019, especially with regard to the kilogram, now defined in terms of the numerical value of the Planck constant (h). Replacing the artefact definition of the kilogram with a new one based on the mass of a particle, or the atomic mass constant (mu), would have been preferable for ease of understanding, among other reasons. In this paper we discuss some limitations of teaching to different audiences what a kilogram is in the redefined International System of Units (SI), including realizations of the new definition.

Base units of the SI, fundamental constants and modern quantum physics

2005 ◽  
Vol 363 (1834) ◽  
pp. 2177-2201 ◽  
Author(s):  
Christian J Bordé
Keyword(s):  
Quantum Physics ◽  
Rest Mass ◽  
Structure Constant ◽  
Coupling Constants ◽  
Electron Mass ◽  
Boltzmann Constant ◽  
Fundamental Constants ◽  
Planck Constant ◽  
Definition Of ◽  
Base Units

Over the past 40 years, a number of discoveries in quantum physics have completely transformed our vision of fundamental metrology. This revolution starts with the frequency stabilization of lasers using saturation spectroscopy and the redefinition of the metre by fixing the velocity of light c . Today, the trend is to redefine all SI base units from fundamental constants and we discuss strategies to achieve this goal. We first consider a kinematical frame, in which fundamental constants with a dimension, such as the speed of light c , the Planck constant h , the Boltzmann constant k B or the electron mass m e can be used to connect and redefine base units. The various interaction forces of nature are then introduced in a dynamical frame, where they are completely characterized by dimensionless coupling constants such as the fine structure constant α or its gravitational analogue α G . This point is discussed by rewriting the Maxwell and Dirac equations with new force fields and these coupling constants. We describe and stress the importance of various quantum effects leading to the advent of this new quantum metrology. In the second part of the paper, we present the status of the seven base units and the prospects of their possible redefinitions from fundamental constants in an experimental perspective. The two parts can be read independently and they point to these same conclusions concerning the redefinitions of base units. The concept of rest mass is directly related to the Compton frequency of a body, which is precisely what is measured by the watt balance. The conversion factor between mass and frequency is the Planck constant, which could therefore be fixed in a realistic and consistent new definition of the kilogram based on its Compton frequency. We discuss also how the Boltzmann constant could be better determined and fixed to replace the present definition of the kelvin.

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