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Your search keyword '"Ian R. Hill"' showing total 2 results
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2 results on '"Ian R. Hill"'

1. Analysis of atomic-clock data to constrain variations of fundamental constants

Author

Nathaniel Sherrill, Adam O Parsons, Charles F A Baynham, William Bowden, E Anne Curtis, Richard Hendricks, Ian R Hill, Richard Hobson, Helen S Margolis, Billy I Robertson, Marco Schioppo, Krzysztof Szymaniec, Alexandra Tofful, Jacob Tunesi, Rachel M Godun, and Xavier Calmet

Subjects
time variation of constants, dark matter, atomic clocks, Science, Physics, QC1-999
Abstract

We present a new framework to study the time variation of fundamental constants in a model-independent way. Model independence implies more free parameters than assumed in previous studies. Using data from atomic clocks based on ^87 Sr, ^171 Yb ^+ and ^133 Cs, we set bounds on parameters controlling the variation of the fine-structure constant, α , and the electron-to-proton mass ratio, µ . We consider variations on timescales ranging from a minute to almost a day. In addition, we use our results to derive some of the tightest limits to date on the parameter space of models of ultralight dark matter and axion-like particles.

Published
2023
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2. A low maintenance Sr optical lattice clock

Author

Ian R. Hill, William B. Bowden, S. Donnellan, Richard Hobson, Elizabeth M. Bridge, E. A. Curtis, and Patrick Gill

Subjects
Physics, History, Optical lattice, Atomic Physics (physics.atom-ph), Emphasis (telecommunications), FOS: Physical sciences, Laser, 01 natural sciences, Physics - Atomic Physics, Computer Science Applications, Education, law.invention, 010309 optics, Reliability (semiconductor), law, Transfer (computing), 0103 physical sciences, Electronic engineering, 010306 general physics
Abstract

We describe the Sr optical lattice clock apparatus at NPL with particular emphasis on techniques used to increase reliability and minimise the human requirement in its operation. Central to this is a clock-referenced transfer cavity scheme for the stabilisation of cooling and trapping lasers. We highlight several measures to increase the reliability of the clock with a view towards the realisation of an optical time-scale. The clock contributed 502 hours of data over a 25 day period (84% uptime) in a recent measurement campaign with several uninterrupted periods of more than 48 hours. An instability of $2\times10^{-17}$ was reached after $10^5$ s of averaging in an interleaved self-comparison of the clock., 8 pages, 4 figures, to be published in the Proceedings of the 8th Symposium on Frequency Standards and Metrology

Published
2016

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