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Basic Metrology: Standard Reference Data on Radiation Interactions


NIST is in its eighth decade of providing critically evaluated, comprehensive databases of cross-section information for ionizing photons (x and gamma rays), electrons, and heavy charged particles. These data are often adopted by national and international standards organizations for use in radiation protection, medical therapy, and industrial applications.


photon attenuation cross section measurements

Comparison of photon attenuation cross section measurements for air with NIST databases.

This work continues in the Division's Photon and Charged-Particle Data Center. The compilations of the Data Center rely heavily on evaluating measurements and on their synthesis with available theory to extend the data and provide for comprehensive coverage over broad ranges of energy and materials. The quality of the work of the Data Center is reflected in the large number of requests for our data on our web pages (over a million requests in a recent year), in the use of our data in many computer codes, engineering and scientific compendia, books and review articles, and in the reports and protocols of national and international standards organizations. Each year we respond to inquiries from the medical, industrial, academic, government, and other scientific communities for technical information and data. We also participate as consultants to or as members of committees that evaluate the best available data for particular applications. For example, we served on a committee for the International Commission on Radiation Units (ICRU) that reported on key physical data for use in dosimetry applications. These data are essential in the procedures used to determine the primary standards for the radiation dosimetry quantities absorbed dose to water and air kerma from laboratory measurements.

Created April 13, 2011, Updated April 8, 2021