Artifacts, Begone! NIST Improves Its Flagship Device for Measuring Mass

Artifacts, Begone! NIST Improves Its Flagship Device for Measuring Mass


The NIST-4 Kibble balance is an electromechanical machine that measures the mass of objects roughly 1 kg. Here, you can see the top of the balance, which includes a wheel that rotates back and forth as the two sides of the balance move. Just visible on the left side of the image are a set of thin electrical wires that connect the electromagnetic coil (not pictured) to other key parts of the balance. Incidentally, the reason the thin wires are coiled like springs instead of being pulled straight is so that as the wheel moves back and forth, the wires stretch without touching each other.



Credit: Jennifer Lauren Lee/NIST



In a brightly lit subterranean lab at the National Institute of Standards and Technology (NIST) sits a room-sized electromechanical machine called the NIST-4 Kibble balance.


The instrument can already measure the mass of objects of roughly 1 kilogram, about as heavy as a quart of milk, as accurately as any device in the world. But now, NIST researchers have further improved their Kibble balance’s performance by adding to it a custom-built device that provides an exact definition of electrical resistance. The device is called the quantum Hall array resistance standard (QHARS), and it consists of a set of several smaller devices that use a quirk of quantum physics to generate extremely precise amounts of electrical resistance. The researchers describe their work in a Nature Communications paper.


The improvement should help scientists use their balances to measure masses smaller than 1 kilogram with high accuracy, something no other Kibble balance has done before.


NIST-4 measurements were used to help scientists redefine the kilogram, th ..

Support the originator by clicking the read the rest link below.