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Projects/Programs

Displaying 51 - 75 of 125

Carrier Dynamics Measured by Ultrafast Time-Resolved Terahertz Spectroscopy

Ongoing
We employ ultrafast pulsed optical measurement techniques to directly monitor carrier generation, migration and relaxation dynamics in bulk semiconductors, polymers and mixed organic/organometallic photovoltaic nanofilms. These studies are conducted to measure (without contact) ultrafast carrier...

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...

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...

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: 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...

Comparisons: Radiological Traceability Program (RTP)

Ongoing
The RTP provides an annual exchange of testing samples between NIST and RESL. It is designed to provide a mechanism to evaluate the ability of RESL scientists to prepare testing samples containing known activities of various radionuclides (Table 1), and to analyze samples of unknown activities...

Detector-based color scale

Ongoing
The expanded uncertainty of the NIST primary color-temperature lamp-standards is 8 K ( k=2). However, both the long-term stability and the spectral distribution of the lamps can significantly change with burning time. By performing the tristimulus colorimeter calibrations against detector standards...

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...

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...

Documentary Standards: X-ray Security Screening Applications

Ongoing
This work fills well-documented gaps in transportation security, which have been highlighted in Executive and Legislative requirements for 100 % screening of baggage, cargo, and airline passengers. This is accomplished through a corpus of new standards, test methods, test artifacts, dosimetry...

Electron-Beam Irradiation of Solar Cells

Ongoing
NIST irradiates solar cells that are manufactured by leading developers of high-efficiency solar photovoltaic cells for space applications. As part of the space-qualification process, the performance of these cells in a space environment must be validated. This validation process includes the...

Environmental: NIST Radiochemistry Intercomparison Program (NRIP)

Ongoing
The NRIP includes five matrices (acidified water, air filters, soil, synthetic urine and synthetic feces) of test samples spiked with a well-characterized solution that contains alpha-, beta-, and gamma-emitting radionuclides (see Table 1). The NRIP participants decide which radionuclides they will...

Fundamental Physics: Electric Field Imaging with Neutrons

Completed
An effective magnetic field B eff arises from the relativistic transformation of an electric field E into the frame of reference moving at the neutron velocity v; B eff is proportional to v x E /c 2, hence is small due to the factor of the square of the speed of light in the denominator. This...

Fundamental Physics: Experiments with a Precision Neutron Polarimeter

Ongoing
The NSR neutron polarimeter has limited two separate physical quantities, spin rotation due to parity non-conservation and long-range spin-dependent interactions. Firstly, we completed a successful run of an experiment to study the strong interaction using weak interaction properties of the neutron...

Fundamental Physics: Magnetically Trapped Neutron Lifetime Experiment

Completed
A precise value for the neutron lifetime is required for several internal consistency tests of the SM including searches for right-handed currents and tests of the unitarity of the CKM mixing matrix. Measurements of neutron decay coefficients provide information on the vector and axial-vector...
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