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Physical Measurement Laboratory / Radiation Physics Division

Neutron Physics Group

Projects/Programs

Displaying 1 - 25 of 41
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
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
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
electric field signal graph

Fundamental Physics: Electric Field Imaging with Neutrons

Ongoing
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
NG-6 beam line

Fundamental Physics: Experiments with a Precision Neutron Polarimeter

Ongoing
We completed a successful run of an experiment to study the strong interaction using weak interaction properties of the neutron. The neutron spin-rotation experiment is based on the principle that a transversely polarized neutron beam will experience a parity-violating rotation of its polarization
magnetic trap

Fundamental Physics: Magnetically Trapped Neutron Lifetime Experiment

Ongoing
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
NIF

Imaging: Advanced Neutron Imaging Facility

Ongoing
Available as a national user facility since 2006, the NIST Neutron Imaging Facility provides users with a unique “plug and play” approach to imaging operating fuel cells and electrolyzers. In 2016, the NIST-NeXT system was first installed, allowing simultaneous neutron/X-ray tomography of complex
measurement results

Imaging: Characterization of Porous Transport Media for Hydrogen Fuel Cells

Completed
Accurate, in situ characterization of the physical properties of a porous transport layer (PTL) – porosity distribution, liquid saturation as a function of pressure, liquid and gas permeability, thermal conductivity – is critical to improving the understanding, and hence manipulation, of the water
timeline of neutron detector image spatial resolution

Imaging: Evolution of Neutron Image Detector Spatial Resolution

Ongoing
Neutron imaging has yielded valuable insight into the water content of fuel cells because minimal changes to a test section are needed. A limit of neutron imaging is the achievable spatial resolution, which is primarily dominated by the detector. Figure 1 shows the evolution of the spatial