A5009880841- Physics of Superconductivity and Magnetism
- Planetary Science and Exploration
- Astro and Planetary Science
- Magnetic properties of thin films
- Calibration and Measurement Techniques
- Superconducting and THz Device Technology
- Gas Sensing Nanomaterials and Sensors
- Transition Metal Oxide Nanomaterials
- Advanced X-ray and CT Imaging
- Microwave Engineering and Waveguides
- Copper Interconnects and Reliability
- Particle Detector Development and Performance
- Electronic and Structural Properties of Oxides
- ZnO doping and properties
- Space Exploration and Technology
- Magnetic and transport properties of perovskites and related materials
- Solid-state spectroscopy and crystallography
- Space Science and Extraterrestrial Life
- Semiconductor Quantum Structures and Devices
- Scientific Research and Discoveries
- Quantum and electron transport phenomena
- Chemical and Physical Properties of Materials
- CCD and CMOS Imaging Sensors
- Superconducting Materials and Applications
- Spacecraft Design and Technology
Jet Propulsion Laboratory
2011-2024
Princess Alexandra Hospital
2020
California Institute of Technology
1991-2015
Honeywell (United States)
2002
Space Micro (United States)
1990-1998
University of Illinois Urbana-Champaign
1985-1991
AT&T (United States)
1989
Diviner Lunar Radiometer Experiment surface-temperature maps reveal the existence of widespread surface and near-surface cryogenic regions that extend beyond boundaries persistent shadow. The Crater Observation Sensing Satellite (LCROSS) struck one coldest these regions, where subsurface temperatures are estimated to be 38 kelvin. Large areas lunar polar currently cold enough cold-trap water ice as well a range both more volatile less species. diverse mixture high-volatility compounds...
The Diviner Lunar Radiometer Experiment on NASA's Reconnaissance Orbiter will be the first instrument to systematically map global thermal state of Moon and its diurnal seasonal variability. measure reflected solar emitted infrared radiation in nine spectral channels with wavelengths ranging from 0.3 400 microns. resulting measurements enable characterization lunar environment, mapping surface properties such as inertia, rock abundance silicate mineralogy, determination locations...
Against a backdrop of intensive exploration the Martian surface environment, intended to lead human exploration, some aspects modern climate and meteorology Mars remain relatively unexplored. In particular, there is need for detailed measurements vertical profiles atmospheric temperature, water vapor, dust, condensates understand intricately related processes upon which conditions, those encountered during descent by landers, depend. The most important these missing data are accurate...
A nonaqueous chemical etch, with Br as the active ingredient, is described which removes insulating hydroxides and carbonates that form on high-temperature superconductor surfaces a result of atmospheric exposure. X-ray photoemission spectra have been recorded before after etching YBa2Cu3O7−x films. It found that, high binding energy O 1s Ba 3d peaks associated surface contaminants are greatly reduced, Y:Ba:Cu ratio close to expected 1:2:3, oxidation state Cu(2+) not affected. The resistance...
X-ray photoelectron spectroscopy (XPS) has been used to investigate the reaction of YBa2Cu3O7−x films with solutions HF, HCl, Br2, HBr, I2, and HI in absolute ethanol (EtOH). The XPS core level x-ray excited Auger spectra from untreated halogen-treated surfaces are identify surface species by comparison data literature more than 20 Y, Ba, Cu halides, oxides, hydroxides, carbonates measured this work. measurements on a number these materials being reported for first time. Treatment HF/EtOH...
The Lunar Reconnaissance Orbiter (LRO) Diviner instrument detected a thermal emission signature 90 seconds after the Crater Observation and Sensing Satellite (LCROSS) Centaur impact on two subsequent orbits. heated region of 30 to 200 square meters at least 950 kelvin, providing sustained heat source for sublimation up ~300 kilograms water ice during 4 minutes LCROSS post-impact observations. visible observations constrain mass sunlit ejecta column be ~10(-6) 10(-5) per meter, which is...
The Thermal and Electrical Conductivity Probe (TECP) is a component of the Microscopy, Electrochemistry Analyzer (MECA) payload on Phoenix Lander. TECP will measure temperature, thermal conductivity, volumetric heat capacity regolith. It also detect quantify population mobile H 2 O molecules in regolith, if any, throughout polar summer, by measuring electrical conductivity regolith as well dielectric permittivity. In vapor phase, capable atmospheric abundance augmenting wind velocity...
The Astro2010 Decadal Survey recommended a Wide Field Infrared Telescope (WFIRST) as its top priority for new large space mission. report of the WFIRST-AFTA Science Definition Team (SDT) presents Design Reference Mission WFIRST that employs one 2.4-m, Hubble-quality mirror assemblies recently made available to NASA. 2.4-m primary enables mission with greater sensitivity and higher angular resolution than smaller aperture designs previously considered WFIRST, increasing both science return...
High quality YBa2Cu3O7−x/normal-metal/YBa2Cu3O7−x edge-geometry weak links have been fabricated using nonsuperconducting Y-Ba-Cu-O barrier layers deposited by laser ablation at reduced growth temperatures. Devices incorporating 25–100 Å thick exhibit current-voltage characteristics consistent with the resistively shunted junction model, strong microwave and magnetic field response temperatures up to 85 K. The critical currents vary exponentially thickness, resistances scale linearly...
PIXL (Planetary Instrument for X-ray Lithochemistry) is a micro-focus fluorescence instrument examining fine scale chemical variations in rocks and soils on planetary surfaces. Selected flight the science payload proposed Mars 2020 rover, can measure elemental chemistry of tiny features observed rocks, such as individual sand grains, veinlets, cements, concretions crystals, using 100 µm-diameter, high-flux beam that be scanned across target
We have fabricated 63-element linear arrays of micromachined thermopile infrared detectors on silicon substrates. Each detector consists a suspended nitride membrane with 11 thermocouples sputtered Bi-Te and Bi-Sb-Te films. At room temperature under vacuum these exhibit response times 99 ms, zero frequency D* values 1.4/spl times/ 10/sup 9/ cmHz/sup 1/2//W responsivity 1100 V/W when viewing 1000 K blackbody source. The only measured source noise above 20 mHz is Johnson from the resistance....
Using both dc and low-frequency-ac (10--${10}^{5}$ Hz) transport measurements in low magnetic fields (0--6.3 kOe), we find that the vortex properties of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{2.98}$${\mathrm{Au}}_{0.02}$${\mathrm{O}}_{\mathit{x}}$ (x=6.97\ifmmode\pm\else\textpm\fi{}0.02) single crystals are consistent with a three-dimensional second-order solid melting transition, static exponent \ensuremath{\nu}=0.9\ifmmode\pm\else\textpm\fi{}0.2, dynamic z=2.0\ifmmode\pm\else\textpm\fi{}0.2,...
The Planetary Instrument for X-ray Lithochemistry (PIXL) is a rasterable focused-beam fluorescence (XRF) spectrometer mounted on the arm of National Aeronautics and Space Administration's (NASA) Mars 2020 Perseverance rover. To ensure that PIXL would be capable performing accurate in-flight compositional analysis martian targets, in situ, an elemental calibration was performed pre-flight flight instrument simulated environment. details this calibration, implications measuring unknown...
A stable capacitance bridge has been designed to measure changes both in and loss of three-terminal capacitors at temperatures ranging from 0.01 100 K. The circuit uses commercially available components, a resolution better than 10−6. Also described is an anomalous voltage dependence present low which have electrodes applied using evaporative or similar technique.
A nonaqueous solution of Br in absolute ethanol (EtOH) has recently been reported [R. P. Vasquez, B. D. Hunt, and M. C. Foote, Appl. Phys. Lett. 53, 2692 (1988)] to be effective at removing nonsuperconducting surface species from YBa2 Cu3 O7−x films, leaving the close ideal stoichiometry. This same etchant is shown here an bulk chemical depth profiling through 1-μm-thick films. The Cu remains 2+oxidation state stoichiometry, as determined by x-ray photoelectron spectroscopy, nearly constant...
Thermal expansion coefficients and specific heats are reported for orientationally disordered KBr samples containing CN concentrations ranging from 0.03 to 50 mol %, within a temperature range of 0.08--10 K. With increasing concentration, broad spectrum develops in the coupling parameter between tunneling excitations lattice strains. As with other properties previously, thermal % is similar that an amorphous solid.