U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Physical Measurement Laboratory

Radiation Physics Division

Projects/Programs

Displaying 1 - 25 of 114

Accelerator Facilities

Ongoing
The Division's accelerator facilities continue to support a broad range of research efforts in the areas of industrial and medical dosimetry, homeland security, radiation-hardness testing and materials-effects studies. Topics of research during this reporting period included: (1) a broad-energy
liquid scintillator detector

Applied: Methods in Neutron Detection and Spectroscopy

Completed
Energetic neutrons (> 1 MeV) play a variety of important roles from dosimetry to the fundamental sciences. Fast neutrons can be an often under-appreciated but significant biological dose from accelerators and nuclear facilities, serve as a way of detecting nuclear materials, and can often yield
incident neutrons

Applied: Photon Assisted Neutron Detector (PhAND)

Ongoing
Due to the simplicity of the PhAND physics package, any number of detector configurations can be deployed. Basic detector operation is illustrated in Fig. 1. Incident neutrons are absorbed in a 10B film and the charged daughter products (𝜶 7Li) enter the surrounding xenon where they produce xenon
lumped element resonant circuit illustration

Applied: Quantum Sensors for Charged Particle Detection

Ongoing
Quantum cryogenic detectors have proven very promising for x-ray and gamma-ray spectroscopy. The suppression of thermal noise due to cryogenic (sub-1K) temperatures leads to excellent energy resolution while still allowing for large collection areas and high absorption efficiency. Specifically, the
top view of the MACS instrument

Applied: Wide-Angle Neutron Polarization Analysis

Ongoing
We have developed a polarizer-analyzer-spin flipper system based solely on 3He spin filters on the Multi-Axis Crystal Spectrometer (MACS) at the NIST Center for Neutron Research. The compact system is housed by a 36 cm diameter, vertical solenoid. Neutrons are polarized by transmission through a
spectrometer images

Basic Metrology: Applications of Diagnostic X-ray Spectrometers

Ongoing
These have been fielded to help characterize the performance and x-ray spectra from advanced medical x-ray sources, laser-produced plasmas, terawatt pulsed accelerators, electron cyclotron resonance ion sources, electron-beam ion traps, intense ultrafast laser sources, and inverse-Compton
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 /

Basic Metrology: Dose/Dose-Rate Effects in Alanine Dosimetry

Ongoing
Check standards are used by the NIST Radiation Physics Division to monitor the performance of the alanine dosimetry system which is central to its high-dose transfer dosimetry service. These measurements are performed to confirm the operational readiness of the calibration curve. Deviations from the

Basic Metrology: High-Dose Dosimetry Uncertainty Tables

Ongoing
Gammacell™ Calibration Geometry Dose Rate Uncertainty Source Type A (%) Type B (%) Water Calorimetry in Vertical Beam 0.16 0.51 Gammacell/Pool Source Ratio Data 0.10 Pool/B036 Source Ratio Data 0.17 Geometry Correction Factor 0.11 Field Uniformity 0.01 Source Timer (irrad time > 8min) 0.20 Co-60
X-ray Spectroscopy

Basic Metrology: High-Resolution X-Ray Spectroscopy

Ongoing
X-ray sources of interest include Electron Beam Ion Trap (EBIT), Electron Cyclotron Resonance Ion Source (ECRIS), and laser-produced plasma ion sources, including the new generation of petawatt lasers. In support of these efforts, we also maintain laboratory x-ray sources from 1 keV to 300 keV
hydrogen angular distribution graph

Basic Metrology: Neutron Cross Section Standards

Ongoing
Data from a number of NIST collaborations have produced measurements for the standards program. Measurements are underway now at NIST of the 6Li(n,t) and 235U(n,f) cross sections at sub-thermal energy. These will be the first absolute measurements of these cross sections in this energy region. These
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