Density of a Single-Crystal Natural Silicon Sphere

The density of a single-crystal natural silicon sphere identified as ldquoAvo#3rdquo has been redetermined at the National Measurement Institute, Australia (NMIA), as part of an international collaboration to determine the value of the Avogadro constant. A systematic review of the measurement system...

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Bibliographic Details
Published in:IEEE transactions on instrumentation and measurement 2009-04, Vol.58 (4), p.908-914
Main Authors: Giardini, W., Manson, P., Wouters, M., Warrington, B., Ward, B., Bignell, N., Walsh, C., Jaatinen, E., Kenny, M.
Format: Article
Language:English
Subjects:
Atomic measurements
Australia
Bias
Density
Density measurement
Dynamic response
Dynamical systems
Frequency
Instrumentation
interferometry
International collaboration
Laboratories
mass
Mathematical analysis
Optical devices
Phase shifting interferometry
Silicon
silicon spheres
Single crystals
volume
Volume measurement
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Summary:The density of a single-crystal natural silicon sphere identified as ldquoAvo#3rdquo has been redetermined at the National Measurement Institute, Australia (NMIA), as part of an international collaboration to determine the value of the Avogadro constant. A systematic review of the measurement system found that a significant bias was introduced in the measurement of the volume of the sphere, which is calculated from the interferometric measurements of the mean diameter. It was found that the dynamic response of the laser that is used to generate the frequency steps for the phase-shifting interferometry introduced a bias to the returned phase value. We determined the magnitude of the bias and then applied corrections to obtain the final measured value. The density reported here is based on some new and some recalculated measurements taken between April 2000 and May 2006 during the ongoing development of the measurement system.
ISSN:0018-9456
1557-9662
DOI:10.1109/TIM.2008.2007052