Rights statement: Copyright 2016 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Low Temperature Physics, 42 (2), 2016 and may be found at http://http://scitation.aip.org/content/aip/journal/ltp/42/2/10.1063/1.4941005
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Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Influence of the liquid helium meniscus on neutron reflectometry data
AU - Kinane, C. J.
AU - Kirichek, O.
AU - Charlton, T. R.
AU - McClintock, Peter Vaughan Elsmere
N1 - C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)
PY - 2016/2
Y1 - 2016/2
N2 - Neutron reflectometry offers a unique opportunity for the direct observation of nano-stratification in 3He-4He mixtures in the ultra-low temperature limit. Unfortunately the results of recent experiments could not be well-modelled on account of a seemingly anomalous variation of reflectivity with momentum transfer. We now hypothesize that this effect is attributable to an optical distortion caused by the liquid’s meniscus near the container wall. The validity of this idea is tested and confirmed through a subsidiary experiment on a D2O sample, showing that the meniscus can significantly distort results if the beam size in the horizontal plane is comparable with, or bigger than, the diameter of the container. The meniscus problem can be eliminated if the beam size is substantially smaller than the diameter of the container, such that reflection takes place only from the flat region of the liquid surface thus excluding the meniscus tails. Practical measures for minimising the meniscus distortion effect are discussed.
AB - Neutron reflectometry offers a unique opportunity for the direct observation of nano-stratification in 3He-4He mixtures in the ultra-low temperature limit. Unfortunately the results of recent experiments could not be well-modelled on account of a seemingly anomalous variation of reflectivity with momentum transfer. We now hypothesize that this effect is attributable to an optical distortion caused by the liquid’s meniscus near the container wall. The validity of this idea is tested and confirmed through a subsidiary experiment on a D2O sample, showing that the meniscus can significantly distort results if the beam size in the horizontal plane is comparable with, or bigger than, the diameter of the container. The meniscus problem can be eliminated if the beam size is substantially smaller than the diameter of the container, such that reflection takes place only from the flat region of the liquid surface thus excluding the meniscus tails. Practical measures for minimising the meniscus distortion effect are discussed.
U2 - 10.1063/1.4941005
DO - 10.1063/1.4941005
M3 - Journal article
VL - 42
SP - 202
EP - 206
JO - Low Temperature Physics
JF - Low Temperature Physics
SN - 1063-777X
IS - 2
ER -