The Revised SI: Fundamental Constants, Basic Physics and Units

A revised International System of Units (SI) is expected to be established by the 26th General Conference on Weights and Measures when it convenes in November 2018 and to be put into practice starting on 20 May 2019, World Metrology Day. In consequence, the article published in this journal in 2011, “The Current SI Seen from the Perspective of the Proposed New SI,” is updated in this paper, which provides an opportunity to again demonstrate the usefulness of the quantity calculus in dealing with quantities and units. The quantity calculus and the seven defining constants of the current and revised SI are reviewed, and expressions for the seven current and revised SI base units are given. Relationships between the magnitudes of revised and current SI units and expressions for the numerical values of current SI defining constants expressed in revised SI units are also obtained using the quantity calculus.

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High-Precision Atomic Mass Measurements for Fundamental Constants

Atoms ◽

10.3390/atoms7010037 ◽

2019 ◽

Vol 7 (1) ◽

pp. 37 ◽

Cited By ~ 10

Author(s):

Edmund Myers

Keyword(s):

Experimental Methods ◽

Atomic Mass ◽

Current Status ◽

Fundamental Constants ◽

Penning Traps ◽

Mass Measurements ◽

Helium 4 ◽

The Masses ◽

Future Work ◽

Revised Si

Atomic mass measurements are essential for obtaining several of the fundamental constants. The most precise atomic mass measurements, at the 10−10 level of precision or better, employ measurements of cyclotron frequencies of single ions in Penning traps. We discuss the relation of atomic masses to fundamental constants in the context of the revised SI. We then review experimental methods, and the current status of measurements of the masses of the electron, proton, neutron, deuteron, tritium, helium-3, helium-4, oxygen-16, silicon-28, rubidium-87, and cesium-133. We conclude with directions for future work.

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Optical frequency standards: relations to basic physics and fundamental constants

10.1109/cpem.1988.671184 ◽

1988 ◽

Author(s):

Helmcke

Keyword(s):

Optical Frequency ◽

Fundamental Constants ◽

Frequency Standards ◽

Basic Physics

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Luminescence from individual dislocations in II-VI and III-V semiconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088488 ◽

1991 ◽

Vol 49 ◽

pp. 834-835

Author(s):

J W Steeds

Keyword(s):

Group Iv ◽

Luminescence Properties ◽

Carrier Recombination ◽

Transmission Electron ◽

Wide Range ◽

Basic Physics ◽

Semiconducting Compounds ◽

Diamond Group ◽

Non Destructive ◽

Technological Significance

There is a wide range of experimental results related to dislocations in diamond, group IV, II-VI, III-V semiconducting compounds, but few of these come from isolated, well-characterized individual dislocations. We are here concerned with only those results obtained in a transmission electron microscope so that the dislocations responsible were individually imaged. The luminescence properties of the dislocations were studied by cathodoluminescence performed at low temperatures (~30K) achieved by liquid helium cooling. Both spectra and monochromatic cathodoluminescence images have been obtained, in some cases as a function of temperature.There are two aspects of this work. One is mainly of technological significance. By understanding the luminescence properties of dislocations in epitaxial structures, future non-destructive evaluation will be enhanced. The second aim is to arrive at a good detailed understanding of the basic physics associated with carrier recombination near dislocations as revealed by local luminescence properties.

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Creating a standard method of controlling digital microscopes: the microscope access protocol (map)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100136453 ◽

1995 ◽

Vol 53 ◽

pp. 16-17

Author(s):

T. A. Dodson ◽

E. Völkl ◽

L. F. Allard ◽

T. A. Nolan

Keyword(s):

Data Storage ◽

Storage Systems ◽

Digital Systems ◽

Data Networks ◽

Digital Microscopy ◽

Command Language ◽

Access Protocol ◽

Analog To Digital ◽

Basic Physics ◽

Scanning Electron

The process of moving to a fully digital microscopy laboratory requires changes in instrumentation, computing hardware, computing software, data storage systems, and data networks, as well as in the operating procedures of each facility. Moving from analog to digital systems in the microscopy laboratory is similar to the instrumentation projects being undertaken in many scientific labs. A central problem of any of these projects is to create the best combination of hardware and software to effectively control the parameters of data collection and then to actually acquire data from the instrument. This problem is particularly acute for the microscopist who wishes to "digitize" the operation of a transmission or scanning electron microscope. Although the basic physics of each type of instrument and the type of data (images & spectra) generated by each are very similar, each manufacturer approaches automation differently. The communications interfaces vary as well as the command language used to control the instrument.

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