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Physical Measurement Laboratory / Radiation Physics Division

Radioactivity Group

Projects/Programs

Displaying 1 - 25 of 38
PSD graph

Basic Metrology (Archive): Fit-for-purpose liquid scintillators

Completed
It is now common to use surfactants to entrain aqueous metal salts in organic scintillators. This is crucial for radioactivity measurements because most radionuclides of interest are metals. More, non-metal radionuclides encountered in the environment or in medicine are nearly always in aqueous form

Basic Metrology (Archive): New Standardization of Ra-228

Completed
Radium-228 has a half-life of (5.75 years) and decays by emitting a beta particle. It is a radioactive decay product in the thorium-232 decay series, a very difficult and complex decay chain: 232Th→ 228Ra → 228Ac → 228Th → 224Ra → 220Rn → 216Po → 212Pb → 212Bi → 208Tl → 208Pb(stable); with a sub

Basic Metrology (Archive): New Statistical Analysis Tools

Completed
Several new powerful analysis programs, based on specific requests and evaluations by the RG members, have been developed by the SED collaborators. These tools are now available on the internal NIST web site. It is intended that they will eventually be made available to the general public. The new

Basic Metrology (Archive): Primary Radioactivity Standardization of Ni-63

Completed
Generally, 63Ni has great utility as a low-energy β - calibration standard because of the favorable combination of long half-life (T = 100 a) and β - endpoint energy. Primary standardizations of 63Ni have been actively pursued by national radionuclidic metrology laboratories for over 40 years. As a

Basic Metrology (Archive): Radon Binding to Water-Soluble Cryptophane

Completed
In collaboration with the University of Pennsylvania, a 222Rn emanation sources, similar to the NIST 222Rn emanation standard (SRM 4968, NIST, 1996) was found to have a unique and novel application in a radon-in-water generator for the determination of the binding affinity of radon to a cryptophane

Basic Metrology (Archive): Standardization of Am-243

Completed
The radionuclide 243Am decays by alpha emission and it is the most stable of the americium isotopes however, is not found in nature. It is formed in the nuclear fuel cycle by neutron capture on 242Pu followed by beta decay. It is used as a monitor for radioactive contamination and as a tracer on
photonic emission spectrometry results graph

Basic Metrology: Comparison of NIST-1 and NIST-3 Standard Ampoules

Ongoing
Exhaustive comparisons of the NIST-1 and NIST-3 ampoules are underway. Ion chamber evaluations have been completed for 99Mo, 133Ba, 241Am, 201Tl, and 67Ga. HPGe gamma-ray spectrometry evaluations have been completed for 99Mo, 133Ba, 241Am, 201Tl, and 67Ga. Many more evaluations are in the design /
ampoules

Basic Metrology: NIST-3 Standard Ampoules and Automatic Tip Sealing

Ongoing
Report NISTIR 8254 referenced above was intended to document and archive the historical record for the acquisition and testing of standardized ampoules used by the NIST / NBS Radioactivity Group since the 1950s. These ampoules were intended to contain 5 mL of solutions of radionuclides decaying with
Monte-Carlo simulation

Basic Metrology: Primary Standards for Radionuclides

Ongoing
As the National Metrology Institute (NMI) for the US, NIST is responsible for realizing the SI units. The derived SI unit for activity of a radionuclide is the becquerel, Bq. NIST has a proud history of contributing to the development of new and improved primary standardization methods for the Bq to

Basic Metrology: Recent Primary SRM Standardizations

Ongoing
SRM No. Radionuclide Reference Date Method Used Relative expanded uncertainty ( k = 2) References 4332f Americium-243 8 March 2024 The certified massic activity for 243Am was obtained by 4pab LS spectrometry with two commercial LS counters. The beta detection efficiencies for the 243Am daughter were

Calibrations: Radioactivity Standard Reference Material Program

Ongoing
NIST radioactivity SRMs represent the national basis for accurate radioactivity measurements. SRMs for radioactivity measurements can typically be classified into three general categories: (1) environment and nuclear power, (2) medicine, and (3) basic and applied research using or involving
99Tc graph

Comparisons (Archive): International Comparison of Tc-99 Activity

Completed
Measurements by NIST on the solution were performed by three methods: viz., liquid scintillation (LS) standardizations (with 3H-standard efficiency tracing); with triple-to-double-coincidence ratio (TDCR) method; and with by 4ηβ(LS)-γ(NaI) live-timed anticoincidence (LTAC) measurements. Impurities

Comparisons (Archive): International Comparison of Pu-241 Activity

Completed
Quantitation of 241Pu in low-level waste and environmental samples is of interest because 241Pu is a precursor of other transuranium nuclides that have longer half-lives, greater environmental mobility, and greater toxicity. In addition, 241Pu is the most difficult of the plutonium isotopes to
ionization chambers

Comparisons: NIST Participation in International Intercomparisons

Ongoing
The NIST Radioactivity Group pilots and participates in a variety of different comparison activities. The BIPM’s Consultative Committee on Ionizing Radiation (CCRI) organizes formal comparisons (“key comparisons”) of long-lived radionuclides through its Key Comparison Working Group (KCWG-II). As
illustration

Comparisons: Radiological Traceability Program (RTP)

Ongoing
The RTP provides an annual exchange of PT materials between NIST and RESL. It is designed to provide a mechanism for evaluating the ability of RESL scientists to prepare PT materials containing known activities of various radionuclides (Table 1), and to analyze materials of unknown activities in 6
ANSI/IEEE N42.42 Standard

Documentary Standards: ANSI/IEEE N42.42 Standard

Completed
The ANSI/IEEE N42.42 standard specifies the XML data format that shall be used for both required and optional data to be made available by radiation measurement instruments. The performance requirements for these types of instruments are described in other standards. The output from these

Documentary Standards: IEC 62755 Standard N42 Data Format

Ongoing
The IEC 62755 standard specifies the XML data format that shall be used for both required and optional data to be made available by radiation measurement instruments. The performance requirements for these types of instruments are described in other IEC standards. The output from these instruments
standards for the detection of illicit trafficking of radioactive materials

Documentary Standards: Radiation Detection Documentary Standards Program

Ongoing
NIST leads and participates in the development and revision of documentary ANSI/IEEE (ANSI N42 standards currently transitioning to IEEE IMS TC 45 committee) and IEC (TC 45 WG B15 committee) standards that provide requirements and test methods for instruments used for the detection of illicit