Cascade summing, gamma spec, Marinelle-Beaker Radionuclides emitting multiple gamma-rays in cascade give rise to summing effects that may be a source of error in the efficiency-curve based interpretation of gamma-ray spectra obtained in highly efficient counting geometries. Correction methods for sources that are small enough for the detector efficiency to be constant over the source volume are well-known. However, in geometries where the detector efficiency is not constant throughout the sample volume, such as Marinelli-beaker geometries, appreciable underestimation of the source activity may still occur if the variation of the efficiencies over the source volume is not accounted for. By introducing a third efficiency curve that accounts for the variation of the detector efficiency over the source volume, we have developed a practical, easy-to-use method that allows for determination of all three efficiency curves from a single, high-resolution gamma-ray spectrum, as well as for accurate correction for cascade summing effects.

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The first is the link for the SRM program within the Radiation Physics Division. (This link also provides links to the different type of SRMs sold).

Calibrations: Radioactivity Standard Reference Material Program | NIST – The Standard Reference Materials Program of the National Institute of Standards and Technology (NIST) provides science, industry, and government with a central source of well-characterized materials certified for chemical composition or for some chemical or physical property. These materials are designated Standard Reference Materials (SRMs) and Reference Materials (RMs), and are used to calibrate measuring instruments, to evaluate methods and systems, and to produce scientific data that can be referred readily to a common base. The NIST Radioactivity Group of the Radiation Physics Division conducts a variety of programs in standards development, calibration services, traceability testing, and basic research to meet the requirements for new standards in radionuclide metrology, environmental monitoring, and nuclear medicine. Many research efforts lead to the development of unique radioactivity standards and measurements, which are transferred to industry via SRMs, calibration services, comparative measurements, and traceability testing programs.  

The procedures listed below are used at NIST within the Radiation Physics Division. This includes procedures from the Dosimetry and Neutron groups in addition to the Radioactivity Group. 

Gamma-Ray-Emitting Radionuclides in Solution

Alpha- and Beta-Particle-Emitting Solid Source Calibrations

Calibration of X-Ray Radiation Detectors

Calibration of Radiation Detectors in Terms of Air-Kerma Using Gamma-Ray Beams

Irradiation of Passive Dosimeters

Absorbed-Dose-To-Water Calibrations for Ionization Chambers

Calibration of Gamma-Ray Source Containing 137Cs or 192Ir

Calibration of 125I, 103Pd, or 131Cs Brachytherapy Seeds

Protection-Level Beta Particle Source & Instrument Calibrations

Calibration Irradiations of Customer Supplied Dosimeters with 60Co Gamma Rays

Dose Interpretation of Customer-Irradiated NIST Transfer Dosimeters

Radioactive Neutron Sources Emission Rates (105/s to 108/s) and (108/s to 1010/s)

Neutron Personnel Dosimetry

Radioactivity Standard Reference Materials

Natural-Matrix Radionuclide Standard Reference Materials

Well Ionization Chamber Calibration with Electronic Brachytherapy Sources

Beta-Particle Emitting Radionuclides

The Radiological Environmental Sciences Laboratory (RESL) is located at the Idaho DOE site.  It has conducted the MAPEP program since 1994, through a performance-based PE program that tests the ability of the laboratories to correctly analyze for radiological, stable organic and inorganic constituents’ representative of those at DOE sites.  Extensive information regarding publications and results of the MAPEP program can be found at link.

NIST Radiochemistry Intercomparison Program (NRIP) is a proficiency testing program that evaluates the capabilities of laboratories to measure low-levels of radionuclides in environmental and simulated bioassay samples. The program is open to any organization/lab worldwide.

The CRMs are used by the radioanalytical measurements community for the assessment of radioanalytical methods and for equipment calibrations contributing to the accuracy and precision of analyses and providing traceability to SI standards.

Radiological Traceability Program (RTP) is a proficiency testing (PT) program that established traceability for the Radiological and Environmental Sciences Laboratory (RESL), the Department of Energy’s (DOE) reference laboratory; to the NIST.