A5089263806- Radiation Detection and Scintillator Technologies
- Nuclear Physics and Applications
- Medical Imaging Techniques and Applications
- Atomic and Subatomic Physics Research
- Nuclear reactor physics and engineering
- Nuclear physics research studies
- Particle Accelerators and Free-Electron Lasers
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Advanced X-ray and CT Imaging
- Nuclear Materials and Properties
- Galaxies: Formation, Evolution, Phenomena
- Seedling growth and survival studies
- Astrophysics and Star Formation Studies
- Particle accelerators and beam dynamics
- Indoor Air Quality and Microbial Exposure
- Astronomy and Astrophysical Research
- Atomic and Molecular Physics
- Advanced X-ray Imaging Techniques
- Radioactive element chemistry and processing
- Cosmology and Gravitation Theories
- Occupational exposure and asthma
- Astrophysical Phenomena and Observations
- Selenium in Biological Systems
- Adaptive optics and wavefront sensing
University of Southern California
2024-2025
Southern California University for Professional Studies
2024
Lawrence Livermore National Laboratory
2008-2019
Lawrence Livermore National Security
2016
University of Oregon
2015
Ohio University
2011
Lawrence Berkeley National Laboratory
2008
Gemini North Observatory
2006-2008
NIU Observatory
2006
Gemini South Observatory
2006
We report the codiscovery of spatially resolved dust disk Vega-like star HR 4796A. Images thermal emission at λ=18 μm show an elongated structure approximately 200 AU in diameter surrounding central A0V star. The position angle (30° ± 10°) is consistent to M companion (225°), suggesting that disk-binary system being seen nearly along its orbital plane. surface brightness distribution with presence inner hole 50 radius, as was originally suggested by Jura et al. on basis infrared spectrum....
Transparent ceramics combine the scintillation performance of single crystals with ruggedness and processability glass. We have developed a versatile, scaleable fabrication method, wherein nanoparticle feedstock is consolidated at temperatures well below melting to form inch-scale phase-pure transparent optical scatter α <0.1 cm<sup>-1</sup>. fabricated Cerium-doped Gadolinium Garnets light yields ~50,000 Ph/MeV energy resolution <5% 662 keV. also methods sheets high-Z ceramic...
Abstract 3D printing of multimaterial parts relies upon efficient mixing the ink components and a rapid response to composition changes. However, at low Reynolds numbers large Peclet numbers, disparate viscosity density inks poses challenge. In this study, performance active micromixers for non‐Newtonian is evaluated using both experiments computational fluid dynamics simulations. The efficiencies are compared with scaling relationships micromixers. Using detailed simulation results,...
The mixing of materials during additive manufacturing is a major benefit which allows one to compositionally and spatially tailor material properties, for example locally control the reactivity in fuel – oxidizer systems known as thermites. This work characterizes an active printhead used conjunction with 3D printing process Direct Ink Writing. Besides compositional control, this approach that it offers safe method working these materials, can otherwise be hazardous once mixed. Custom inks...
In the US, approximately 200,000 nail salon workers face chronic exposure to airborne chemicals. Health effects among this sector have been well documented and public health laws aimed at reduction implemented across US. study, we evaluated accuracy feasibility of using commercially available low-cost sensors as tools for monitor reduce their daily exposures. We compared performance utility six total volatile organic compound (TVOC) (Awair Omni, Kaiterra Sensedge, UHoo Smart Air Monitor,...
Recently discovered scintillators for gamma ray spectroscopy - single-crystal SrI<sub>2</sub>(Eu), GYGAG(Ce) transparent ceramic and Bismuth-loaded plastics offer resolution fabrication advantages compared to commercial scintillators, such as NaI(Tl) standard PVT plastic. Energy at 662 keV of 2.7% is obtained with while 4.5% GYGAG(Ce). A new scintillator radiographic imaging systems, GLO(Eu), offers high light yield 70,000 Photons/MeV, stopping, low radiation damage. Implementation Gd-based...
We report on the development of two new mechanically rugged, high light yield transparent ceramic scintillators: (1) Ce-doped Gd-garnet for gamma spectroscopy, and (2) Eu-doped Gd-Lu-bixbyite radiography. GYGAG(Ce) garnet ceramics offer ρ = 5.8g/cm<sup>3</sup>, Z<sub>eff</sub> 48, principal decay <100 ns, 50,000 Ph/MeV. Gdgarnet scintillators best energy resolution any oxide scintillator, as good R(662 keV) 3% (Si-PD readout) small sizes typically < 5% cubic inch sizes. For...
We present subarcsecond resolution infrared (IR) imaging and mid-IR (MIR) spectroscopic observations of the Seyfert 1.9 galaxy NGC 2992, obtained with Gemini North Telescope Gran Telescopio CANARIAS (GTC). The N-band image reveals faint extended emission out to ∼3 kpc, polycyclic aromatic hydrocarbon features detected in GTC/CanariCam 7.5–13 μm spectrum indicate that bulk this is dust heated by star formation. also report arcsecond MIR far-IR interacting system Arp 245, taken Spitzer Space...
We present diffraction-limited, 10 μm imaging polarimetry data for the central regions of archetypal Seyfert active galactic nucleus NGC 1068. The position angle polarization is consistent with three dominant polarizing mechanisms. identify distinct polarization: (1) north nucleus, arising from aligned dust in narrow emission line region, (2) south, east, and west being channeled toward engine, (3) a minimum compact (≤22 pc) torus. These observations provide continuity between geometrically...
Breakthrough energy resolution, R(662keV) < 4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce). Transparent ceramic GYGAG(Ce), a peak emission wavelength of 550 nm that is better matched to Silicon photodetectors than standard PMTs. We are therefore developing spectrometer based on pixelated GYGAG(Ce) photodiode array can provide R(662 keV) = 3.6%. In comparison, large 1-2 in<sup>3</sup> size ceramics we obtain 4.6% PMT...
There is an ever increasing demand for gamma-ray detectors which can achieve good energy resolution, high detection efficiency, and room-temperature operation. We are working to address each of these requirements through the development large volume SrI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (Eu) scintillator detectors. In this work, we have evaluated a variety crystals with volumes >;10 cm <sup...
The behavior of vaporous hydrogen peroxide (VHP) was examined in clean, room-scale galvanized steel (GS) and polyvinylchloride-coated air ducts, to understand how it might be used decontaminate larger ventilation systems. VHP injected into the GS duct decreased concentration along length duct, whereas concentrations polyvinylchloride coated remained essentially constant, suggesting that decomposed at surface. However, decomposition reduced lower temperatures (∼22 °C) higher flow rates (∼80...
Development of the Europium-doped Strontium Iodide scintillator, SrI2(Eu2+), has progressed significantly in recent years. SrI2(Eu2+) excellent material properties for gamma ray spectroscopy: high light yield (<80,000 ph/MeV), proportionality, and effective atomic number (Z = 49) photoelectric cross-section. High quality 1.5" 2" diameter boules are now available due to rapid advances SrI2(Eu) crystal growth. In these large crystals, optical self-absorption by Eu<sup>2+</sup> degrades...
We are developing new scintillator materials that offer potential for high resolution gamma ray spectroscopy at low cost. Single crystal SrI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (Eu) offers ~3% 662 keV, in sizes of ~1 <sup xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . have developed ceramics processing technology allowing us to achieve cubic inch scale transparent ceramic scintillators offering performance superior...
The fifth edition of the
Ceramic and single crystal Lutetium Aluminum Garnet scintillators exhibit energy resolution with bialkali photomultiplier tube detection as good 8.6% at 662 keV. fabrication allows production of garnets that cannot easily be grown crystals, such Gadolinium Terbium Garnet. Measured scintillation light yields Cerium-doped ceramic indicate prospects for high resolution.
High energy resolution gamma-ray detectors that can be formed into relatively large sizes while operating at room temperature offer many advantages for national security applications. We are working toward goal through the development of SrI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (Eu) scintillator detectors, which routinely provide <;3.0% 662 keV with volumes >;10 cm <sup xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . In...
We report on an unprecedented infrared time series of spectra V1187 Sco, a very fast ONeMg nova. The observations covered 56 day period (2004 August 6-September 30) starting 2 days after the nova's peak brightness. Time evolution revealed changing line strengths and profiles timescales less than to weeks as nova evolved from early postmaximum coronal phases. When our ground-based optical Spitzer Space Telescope data were combined, wavelength coverage 0.38-36 μm allowed accurate spectral...
Eu-doped strontium iodide single crystal growth has reached maturity and prototype SrI<sub>2</sub>(Eu)-based gamma ray spectrometers provide detection performance advantages over standard detectors. SrI<sub>2</sub>(Eu) offers a high, proportional light yield of >80,000 photons/MeV. Energy resolution <3% at 662 keV with 1.5" x crystals is routinely achieved, by employing either small taper the top or digital readout technique. These methods overcome light-trapping, in which...