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Posted on: 1/6/2013 12:00:00 AM... The years have not been kind to the international prototype kilogram (IPK).

Like many who face advancing years, the platinum-iridium alloy cylinder has put on a little weight. This, however, represents much more than an embarrassing moment on the scale, since the IPK essentially defines the scale, as the fundamental unit of mass against which extremely precise science experiments are measured.

The problem is that since the 1880s, when 40 of these units were distributed throughout the world, air contamination has slowly built up micrograms of debris, despite extreme efforts to protect the cylinders. Inconsistent cleaning practices from cylinder to cylinder have also created some concerns about the precision of the IPK system.

A study published in the January issue of Metrologia presents research conducted into the IPK’s stability as a reference mass, as well as investigation into a cleaning technique using ozone and ultraviolet light.

For More Information:

• Read "Stability of Reference Masses V: UV/Ozone Treatment of Gold and Platinum Surfaces"

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