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Pyknometric volume measurement of a quasispherical resonator.

Underwood, R J; Davidson, S; Perkin, M; Morantz, P*; Sutton, G; de Podesta, M (2012) Pyknometric volume measurement of a quasispherical resonator. Metrologia, 49 (3). pp. 245-256.

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We have measured the volume of a diamond-turned copper quasispherical resonator using two independent techniques. The first technique is a pyknometric measurement using water as a liquid of known density. We describe the development of a procedure that results in stable, reproducible volume measurements. We provide a detailed discussion of the factors that affect the water density, such as dissolved gases. The second technique is microwave resonance spectroscopy. Here, we measure the resonant frequencies of the TM1n modes and relate them to the dimensions of the resonator. We evaluate the frequency perturbations that arise from the coupling waveguides and the electrical resistivity of the copper surface. The results of the microwave measurements show evidence of a dielectric coating on the surface. We propose that this is an oxide layer and estimate its thickness from the microwave data. Finally, we compare the volume estimates from the two methods, and find that the difference is well within the combined uncertainty.

Item Type: Article
Keywords: Pyknometry, water density, quasispherical resonator, Boltzmann constant, acoustic thermometry
Subjects: Engineering Measurements
Engineering Measurements > Thermal
Identification number/DOI: 10.1088/0026-1394/49/3/245
Last Modified: 02 Feb 2018 13:14
URI: http://eprintspublications.npl.co.uk/id/eprint/5494

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