A5084778836- Nuclear Physics and Applications
- Nuclear reactor physics and engineering
- Nuclear Materials and Properties
- Radiation Detection and Scintillator Technologies
- Nuclear physics research studies
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- High-pressure geophysics and materials
- Astro and Planetary Science
- Diamond and Carbon-based Materials Research
- Radioactivity and Radon Measurements
- Galaxies: Formation, Evolution, Phenomena
- Particle physics theoretical and experimental studies
- Superconducting Materials and Applications
- High-Energy Particle Collisions Research
- Radiation Therapy and Dosimetry
- earthquake and tectonic studies
- Semiconductor Lasers and Optical Devices
- Advanced Sensor Technologies Research
- Spacecraft and Cryogenic Technologies
- Nuclear and radioactivity studies
- Scientific Measurement and Uncertainty Evaluation
Lawrence Livermore National Laboratory
2013-2023
Abilene Christian University
2021
Los Alamos National Laboratory
2014
Oregon State University
2014
Colorado School of Mines
2010
Michigan State University
2008
DePauw University
2002
South College
2002
We present a CCD survey of variable stars in the Draco dwarf spheroidal galaxy. This survey, which has largest areal coverage since original star by Baade & Swope, includes photometry for 270 RR Lyrae stars, 9 anomalous Cepheids, 2 eclipsing binaries, and 12 slow, irregular red variables, as well 30 background QSOs. Twenty-six probable double-mode were identified. Observed parameters, including mean V I magnitudes, amplitudes, periods, have been derived. Photometric metallicities ab-type...
The covariance committee of CSEWG (Cross Section Evaluation Working Group) established templates expected measurement uncertainties for neutron-induced total, (n, γ ), charged-particle, and (n,xn) reaction cross sections as well prompt fission neutron spectra, average total multiplicities, yields. Templates provide a list what uncertainty sources are each type observable, suggest typical ranges these correlations based on survey experimental data, associated literature, feedback from...
Fission fragment angular distributions can provide an important constraint on fission theory, improving predictive codes, and are a prerequisite for precise ratio cross section measurement. Available anisotropy data is sparse, especially at neutron energies above 5 MeV. For the first time, three-dimensional tracking detector employed to study emission angles direct measurement of anisotropy. The Neutron Induced Fragment Tracking Experiment (NIFFTE) collaboration has deployed time projection...
The normalized $^{238}$U(n,f)/$^{235}$U(n,f) cross section ratio has been measured using the NIFFTE fission Time Projection Chamber from reaction threshold to $30$~MeV. fissionTPC is a two-volume MICROMEGAS time projection chamber that allows for full three-dimensional reconstruction of fission-fragment ionization profiles neutron-induced fission. measurement was performed at Los Alamos Neutron Science Center, where neutron energy determined time-of-flight. reported here first made with...
The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has performed measurements with a fission time projection chamber (fissionTPC) to study the process by reconstructing full three-dimensional tracks of fragments and other ionizing radiation. amount linear momentum imparted fissioning nucleus incident neutron can be inferred measuring opening angle between fragments. Using this measured momentum, fragment angular distributions converted center-of-mass frame for...
In the last decade, there has been a renaissance of fission research resulting in new high-precision experiments and advanced modeling. For instance, Chi-Nu CEA teams supplied, for first time, 239 Pu prompt neutron spectrum (PFNS) broad ranges incident outgoing energies. The team also measured average multiplicities, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:msub><mml:mrow><mml:mover...
The study of fission fragment yields and how they behave as a function excitation energy provides insight into the process in which are formed. Fission also important for nuclear applications, can be used diagnostic tool. A new instrument, SPIDER (Spectrometer Ion DEtermination Research), is being developed measuring incident neutron at Los Alamos Neutron Science Center. instrument employs time-of-flight mass spectrometry method velocity kinetic fragments measured order to determine their...
The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) is a double-sided Time Projection Chamber (TPC) with micromegas readout designed to measure the energy-dependent neutron-induced fission cross sections of major and minor actinides unprecedented accuracy. NIFFTE project addresses challenge minimizing sources systematic uncertainties from previous chamber measurements such as: target beam non-uniformities, misidentification alpha light charged particles as fragments, inherent...
Abstract We present new results on RR Lyrae stars and anomalous Cepheids in the Draco dwarf spheroidal galaxy. have increased number of double-mode found three Cepheids. With period-magnitude period-amplitude diagrams, we discuss Oosterhoff classification Draco. Contradictory were that appears to contain both I II type populations.
The general properties needed in targets (sources) for high precision, accuracy measurements are reviewed. application of these principles to the problem developing Fission TPC is described. Longer term issues, such as availability actinide materials, improved knowledge energy losses and straggling stability during irradiation also discussed.
The $^{239}$Pu(n,f)/$^{235}$U(n,f) cross-section ratio has been measured with the fission Time Projection Chamber (fissionTPC) from 100 keV to MeV. fissionTPC provides three-dimensional reconstruction of fission-fragment ionization profiles, allowing for a precise quantification measurement uncertainties. was performed at Los Alamos Neutron Science Center which pulsed white source neutrons. data are recommended be used as shape. A discussion status absolute normalization and comparisons ENDF...