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Physical Measurement Laboratory

Radiation Physics Division

Projects/Programs

Displaying 26 - 50 of 121
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
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
Remote Sensing

Basic Metrology: Remote Sensing Methods for Imaging Dose to Water

Ongoing
Ultrasound and laser interferometry, widely used for nondestructive testing and remote sensing applications, are being used here to measure dose distributions in irradiated water phantoms by taking advantage of temperature dependence in the speed of sound and optical index of refraction of water
photon attenuation cross section measurements

Basic Metrology: Standard Reference Data on Radiation Interactions

Ongoing
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

Calibration Services: High-Dose Dosimetry

Ongoing
NIST developed the alanine dosimetry system in the early 1990's to replace radiochromic dye film dosimeters. Later in the decade the alanine system was firmly established as a transfer service for high-dose radiation dosimetry and an integral part of the internal calibration scheme supporting these
WAFAC system

Calibration Services: Low-Energy Photon Brachytherapy Sources

Ongoing
Since 1999, over 1,500 seeds of more than 40 different designs from 18 manufacturers have been calibrated using the WAFAC. On-site characterization at seed manufacturing plants for quality control, as well as at therapy clinics for treatment planning, relies on well-ionization chamber measurements

Calibration Services: New Calibration Facility for X-Ray Air Kerma

Ongoing
The NIST x-ray calibration facility is composed of a suite of rooms that includes the 11 m by 7 m calibration range, a dedicated equipment room, connected by custom shielding ports for communication with the x-ray tubes in the radiation area, an operator control center with a viewing window and
Californium Neutron Irradiation Facility

Calibrations: Californium Neutron Irradiation Facility

Ongoing
A high-activity Cf-252 source (~10 10 neutrons/s as of May 2024) is housed in a large (approximately 15 m x 10 m x 10 m high) room with concrete walls, floor, and ceiling (see photograph) at a depth of 10 meters-water-equivalent. In addition, there are two monoenergetic neutron generators for 2.5
Low Scatter Neutron Calibration Facility

Calibrations: Neutron Device Calibrations

Ongoing
The Neutron Physics Group calibrates neutron radiation detectors used for personnel protection and irradiates personnel dosimeters in standard neutron fields. The fields are produced by unmoderated 252Cf and 252Cf moderated with a D 2O sphere (represented by the gray sphere near the center of the
Mn Bath

Calibrations: Neutron Source Strength

Ongoing
Calibrations are performed using the manganous sulfate bath technique in which the emission rate of the source to be calibrated is compared to the emission rate of NBS–1, the national standard Ra–Be photo-neutron source. Neutron source calibrations typically have a relative expanded uncertainty ( k
manganese bath

Calibrations: Portable Manganese Sulfate Bath

Ongoing
The Manganese Sulfate Bath uses a sphere of neutron-absorbing material that surrounds a neutron source. The induced radioactivity is a measure of the neutron source strength. Lower intensity sources provide less manganese activation, resulting in a reduced signal over background, and this signal-to
Taxonomy of Radioactivity Group Programs showing the central role of SRMs

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

Comparison: Co-60 Absorbed Dose for High-Dose Dosimetry

Completed
The NIST comparison demonstrated the need to know the participant's calibration scheme and dose rates, as well as the inclusion of an additional dose level (1 kGy, in addition to 5 kGy, 15 kGy, and 30 kGy). The rationale for modifying the protocol was based on the recent NIST characterization of a
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