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Projects/Programs

Topic Area
Displaying 51 - 75 of 468

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

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

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

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

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

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

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

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

BIB-trap detector

Ongoing
Limitations of Standard BIB Detectors Currently available BIB detectors exhibit excellent detectivity, but are limited in their use for spectral calibrations by detection inefficiency and spectral response inhomogeneity. The maximum quantum efficiency of these doped silicon devices is near 60%

Bilateral Comparison of Spectral Responsivity in the Vacuum-Ultraviolet

Completed
The last decade has seen numerous key comparisons in the field of photometry and radiometry between different national metrology institutes (NMIs) in the context of the Mutual Recognition Arrangement. At first, these comparisons were restricted to wavelengths longer than 200 nm, with just the

Bioelectronic Sensors for Tissue/Organ-on-a-Chip Systems

Ongoing
We apply our expertise in micro/nanofabrication, electrokinetics and cell-based assays to develop bioelectronic sensors in microfluidic platforms. We are working on a platform that entraps cells for electrochemical monitoring in an environment that has mechanical properties more similar to those

Biomolecular assembly

Ongoing
The integration of new materials or components into the design and production of diverse nanotechnologies, ranging from electronic devices to therapeutic particles, requires a quantitative understanding of process–structure–property relationships, as well as interactions with other entities in the

Birefringence Properties of Optical Materials (0.12 μm – 2 μm)

Ongoing
For crystals with non-cubic crystal symmetry, we make accurate measurements of the birefringence and its wavelength dispersion (0.12 μm – 15 μm) by separate index measurements of the two polarizations using the NIST's minimum deviation refractometry system. In nominally isotropic materials (cubic

Boulder Microfabrication Facility

Ongoing
The Boulder Microfabrication Facility (BMF) is a 1700 m 2 (18,000 ft 2), ISO class 5 (class 100) clean room dedicated to providing state-of-the-art micro- and nano-fabrication capabilities to meet the microelectronic and microelectromechanical systems needs of NIST-Boulder staff members and their

Bringing the SI to Global Atmospheric Greenhouse Gas Measurement

Ongoing
This multifaceted program leverages expertise in three complementary technical focus areas- all of which involve SI-traceable measurements of relevant atmospheric species such as carbon dioxide, methane, water vapor and oxygen. The efforts include gravimetrically based preparation of primary

Calculation of optical constants and dielectric response

Ongoing
By optical properties, we mean those of the following sort: the index of refraction n and the index of absorption k, from which one can calculate the dielectric function, loss function, absorption coefficient, reflectance, and so forth from standard formulas. All of these quantities, it should be

Calibration of Force Transducers

Ongoing
The calibration report describes the relationship between the applied force and the measured deformation, either in electrical or mechanical units. A transducer can be calibrated using (1) a readout device furnished by the customer, in which case the transducer and the readout device are calibrated