Research and Metrology: The fundamental basis of all the measurement services in the Division, from calibrations to standard reference materials (SRMs®) to standard reference data, depends on active research in nuclear physics and radiation metrology as well as well-characterized radiation systems such as accelerators and source-based irradiators. Together with our active participation in international comparisons, such research and infrastructure also support the maintenance and dissemination of the national measurement standards for the Système International (SI) derived units for radiation dosimetry (the gray) and activity (the becquerel), a key responsibility of the Division.