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Dating can be complicated. Our team uses this instrument — a live-timed anticoincidence counter — to figure the decay rate of an isotope, which we can then use to determine an object’s age in the geological history of our planet (through a process called radiometric dating). Encased in 6,350 kg (14,000 lbs.) of lead blocks to shield from external radiation, its two levels of detection make this one of the most precise instruments for radioactivity measurements at NIST. Right now, our team is preparing to better measure the decay of iodine-129, which could expand dating capabilities beyond carbon’s 50,000 years to 160,000,000 years. That’s a lot of history we’ll be able to account for.

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R. Wilson/NIST

News and Updates

The Shape in Water

Tinkering with a method they helped develop over the last few years, scientists have for the first time used it to measure at the nanometer scale the

Projects and Programs


False Alarm Testing for Radiation Detection Systems

Dennis D. Leber, Leticia S. Pibida
An operator of a radiation detection system that displays a high rate of false alarms may be- come desensitized to these alarms. This action is known as alarm

The Next Generation of Current Measurement for Ionization Chambers

Ryan P. Fitzgerald, Denis E. Bergeron, Dean G. Jarrett, Neil M. Zimmerman, Carine Michotte, Hansjoerg Scherer, Stephen Giblin, Steven Judge
Re-entrant ionization chambers (ICs) are essential to radionuclide metrology and nuclear medicine for maintaining standards and measuring half-lives. Metrology

Tools and Instruments

Medical-Industrial Radiation Facility

The Medical-Industrial Radiation Facility (MIRF) located in the Radiation Physics Division of the NIST Physical Measurement Laboratory is a user facility for