March 14, 2006 Boulder, Colo.—Scientists at the Commerce Department’s National Institute of Standards and Technology (NIST) have designed and demonstrated the world’s most accurate gamma ray detector, which is expected to be useful eventually in verifying inventories of nuclear materials and detecting radioactive contamination in the environment.
The tiny prototype detector, described today at the American Physical Society national meeting in Baltimore, can pinpoint gamma ray emission signatures of specific atoms with 10 times the precision of the best conventional sensors used to examine stockpiles of nuclear materials. The NIST tests, performed with different forms of plutonium at Los Alamos National Laboratory, also show the prototype greatly clarifies the complex X-ray and gamma-ray emissions profile of plutonium.
Emissions from radioactive materials such as uranium or plutonium provide unique signatures that, if accurately measured, can indicate the age and enrichment of the material and sometimes its intended purpose or origin. Contact: Joel Ullom and Jim Beall more ...
September 13, 2005 Gaithersburg, MD—A leading experimental method for defining the kilogram in terms of properties of nature is now more accurate than ever, scientists at the Commerce Department’s National Institute of Standards and Technology (NIST) reported today. The advance may move the scientific community closer to redefining the kilogram, the only one of the seven basic units of the international measurement system still defined by a physical artifact.
The latest NIST work, described in the October 2005 issue of Metrologia and published online today, confirms the institute’s 1998 results using the same method while reducing the measurement uncertainty by about 40 percent, thanks mainly to improvements in the hardware used in the experiments.
“The fact that we got the same values gives us confidence that the uncertainties we’re quoting are probably reasonable,” says NIST physicist Richard Steiner, lead author of the paper.
Scientists at NIST and other institutions around the world have spent years conducting experiments to find a reliable definition based in nature to replace the current international standard for the kilogram, a century-old cylinder of platinum-iridium alloy about the size of a plum. The new results mean that the NIST method, using an apparatus called the watt balance or electronic kilogram, is almost accurate enough now to meet the criteria for redefinition. Contact: Richard Steiner and Edwin Williams. more ...
February 24, 2005—Boulder, Colo. -- Two superconducting devices have been coaxed into a special, interdependent state that mimics the unusual interactions sometimes seen in pairs of atoms, according to a team of physicists at the National Institute of Standards and Technology (NIST) and University of California, Santa Barbara (UCSB). The experiments, performed at the NIST laboratory in Boulder, Colo., are an important step toward the possible use of “artificial atoms” made with superconducting materials for storing and processing data in an ultra-powerful quantum computer of the future.
The work, reported in the Feb. 25 issue of the journal Science*, demonstrates that it is possible to measure the quantum properties of two interconnected artificial atoms at virtually the same time. Until now, superconducting qubits—quantum counterparts of the 1s and 0s used in today’s computers—have been measured one at a time to avoid unwanted effects on neighboring qubits. The advance shows that the properties of artificial atoms can be coordinated in a way that is consistent with a quantum phenomenon called “entanglement” observed in real atoms. Entanglement is the “quantum magic” allowing the construction of logic gates in a quantum computer, a means of ensuring that the value of one qubit can be determined by the value of another in a predictable way. Contact: Ray Simmonds more ...