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Physics

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Displaying 1226 - 1250 of 2493

Spectral dependence of carrier lifetimes in silicon for photovoltaic applications

December 21, 2016
Author(s)
John F. Roller, Yu-Tai Li, Mario Dagenais, Behrang H. Hamadani
Charge carrier lifetimes in photovoltaic-grade silicon wafers were measured by a spectral-dependent, quasi-steady-state photoconductance technique. Narrow bandwidth LEDs were used to excite excess charge carriers within the material, and the effective

Entropy Theory of Polymer Glass-Formation in Variable Spatial Dimension

December 20, 2016
Author(s)
Jack F. Douglas, Wensheng Xu, Karl Freed
The importance of packing frustration is broadly appreciated to be an important aspect of glass formation. Recently, great interest has focused on probing the dependence on spatial dimension d as a theoretical tool for exploring essential aspects of glass

A Versatile Technique to Enable Sub-Milli-Kelvin Instrument Stability for Precise Radial Velocity Measurements: Tests with the Habitable-Zone Planet Finder

December 16, 2016
Author(s)
Ryan C. Terrien, Guomundur K. Stefansson, Fred Hearty, Paul Robertson, Suvrath Mahadevan, Tyler Anderson, Chad Bender, Matthew Nelson, Andrew Monson, Basil Blank, Samuel Halverson, Chuck Henderson, Lawrence Ramsey, Arpita Roy, Christian Schwab
Insufficient instrument thermo-mechanical stability is one of the fundamental roadblocks for achieving 10 cm s −1 Doppler radial velocity (RV) precision, the precision needed to detect Earth-twins orbiting Solar-type stars. Exquisite temperature and

Bound Layers Cloak Nanoparticles in Strongly Interacting Polymer Nanocomposites

December 16, 2016
Author(s)
Jack F. Douglas, Francis W. Starr, Sanat K. Kumar
Polymer-nanoparticle (NP) interfacial interactions are expected to strongly influence the properties of nanocomposites, but surprisingly, experiments often report small or no changes in the glass transition temperature, Tg. To understand this paradoxical

60 Year Anniversary of Applied Radiation and Isotopes

December 14, 2016
Author(s)
Bert M. Coursey
Those readers who have a library with the first bound copies of ARI may find it enjoyable to compare Volume 1, No.1 from 1956 with an issue from Volume 118 in 2016. The range of applications has shifted away from agricultural and industrial uses of

An ultra-low noise, high-voltage piezo driver

December 8, 2016
Author(s)
Neal C. Pisenti, Alessandro Restelli, Ben J. Reschovsky, Daniel Barker, Gretchen K. Campbell
We present an ultra-low noise, high-voltage driver suited for use with piezoelectric actuators and other low- current applications. The architecture uses a flyback switching regulator to generate up to 250V in our current design, with an output of 1 kV or

Doppler Sensitivity and Its Effect on Transatlantic TWSTFT Links

December 6, 2016
Author(s)
Shengkang Zhang, Tom Parker, Victor S. Zhang
Two Way Satellite Time and Frequency Transfer (TWSTFT or TW) is a commonly used technique to compare time and frequency precisely among the time and frequency laboratories. The precision of TWSTFT on time comparison is about 0.5 ns or even better, which

Enriching and purifying silicon epilayers for quantum information

December 6, 2016
Author(s)
Joshua M. Pomeroy, Kevin J. Dwyer, Ke Tang, Hyun S. Kim, Aruna N. Ramanayaka, David S. Simons
High quality, enriched silicon contains an exceptionally low density of defects and unpaired electron and nuclear spins that allow candidate qubits (single donors or quantum dots) to exhibit very long dephasing times compared to silicon with a natural

Communication-Comparison of Nanoscale Focused Ion Beam and Electrochemical Lithiation in beta-Sn Microspheres

December 5, 2016
Author(s)
Saya Takeuchi, William R. McGehee, Jennifer L. Schaefer, Truman M. Wilson, Kevin A. Twedt, Christopher L. Soles, Vladimir P. Oleshko, Eddie H. Chang, Jabez J. McClelland
The development of Li focused ion beams (Li-FIB) enables controlled Li ion insertion into materials with nanoscale resolution. We take the first step toward establishing the relevance of the Li-FIB for studies of ion dynamics in electrochemically active

Coordinated Universal Time and the Leap Second

December 1, 2016
Author(s)
Judah Levine
I will discuss the considerations that were important in the design of the current version of Coordinated Universal Time. The design includes the addition of additional “leap” seconds to keep Coordinated Universal time within 0.9 s of the UT1 time scale

The sixth spectrum of platinum (Pt VI)

November 25, 2016
Author(s)
Vladimir I. Azarov, R R. Gayasov
The spectrum of platinum was observed in the (300 to 2100) A wavelength region. The (5d5 + 5d46s) - 5d46p transition array of five times ionized platinum, Pt VI, has been investigated and 1390 spectral lines have been classified in the region of (399 to

VECSEL systems for generation and manipulation of trapped magnesium ions

November 8, 2016
Author(s)
Shaun C. Burd, David T. Allcock, Tomi Leinonen, Jussi-Pekka Penttinen, Daniel H. Slichter, Raghavendra Srinivas, Andrew C. Wilson, Robert Jordens, Micrea Guina, Dietrich G. Leibfried, David J. Wineland
Experiments in atomic, molecular, and optical (AMO) physics rely on lasers at many different wave- lengths and with varying requirements on spectral linewidth, power and intensity stability. Vertical external-cavity surface-emitting lasers (VECSELs), when

Calibration of Effective Tunneling Bandgap in GaAsSb/InGaAs for improved TFET Performance Prediction

November 3, 2016
Author(s)
Quentin Smets, Anne S. Verhulst, Salim El Kazzi, David J. Gundlach, Curt A. Richter, Anda Mocuta, Nadine Collaert, Aaron Thean, Marc Heyns
The effective bandgap for heterojunction band-to-band tunneling (Eg,eff) is a crucial design parameter for heterojunction TFET. However, there is significant uncertainty on Eg,eff, especially for In0.53Ga0.47As/GaAs0.5Sb0.5. This makes TFET performance

Report for Dedicated JPSS VIIRS Ocean Color Calibration/Validation Cruise December 2015

October 30, 2016
Author(s)
Michael Ondrusek, Veronica P. Lance, Eric Stengel, Menghua Wang, Zhongping Lee, Jianwei Wei, Junfang Lin, Chuanmin Hu, Charles Kovach, David English, Jennifer Cannizzaro, Alex Gilerson, Sam Ahmed, Carlos Carrizo, Ahmed El-Habashi, Robert Foster, Matteo Ottaviani, Robert Arnone, Sherwin Ladner, Wesley Goode, Ryan Vandermeulen, Nicholas Tufillaro, Jasmine Nahorniak, Curtiss Davis, Joaquim I. Goes, Kali McKee, Scott Freeman, Joaquin E. Chaves Cedeno, Kenneth Voss, B. Carol Johnson

Revised and extended analysis of the eighth spectrum of platinum (Pt VIII)

October 27, 2016
Author(s)
Vladimir I. Azarov, R R. Gayasov
The spectrum of platinum was observed in the (300-2100) Å wavelength region. Grazing and normal incidence VUV spectrographs have been used to record the spectrum. The (5d3 + 5d26s) - 5d26p transition array of seven times ionized platinum, Pt VIII, has been

Gas Uptake of 3-D Printed Acrylonitrile Butadiene Styrene (ABS) Using a Vacuum Apparatus Designed for Absorption and Desorption Studies

October 25, 2016
Author(s)
Makfir Sefa, Zeeshan Ahmed, James A. Fedchak, Nikolai Klimov, Julia Scherschligt
We describe a vacuum apparatus for determining the outgassing rate into vacuum, the diffusion coefficient, and the amount of gas absorbed for various materials. The diffusion coefficient is determined from a model applied to time-dependent desorption data

Validating In-Air Remote Sensing Reflectance Measurements During Cruises Using Reflectance Targets

October 25, 2016
Author(s)
Bettye C. Johnson, Catherine C. Cooksey, Ahmed El-Habashi, David English, Georgi T. Georgiev, Sherwin Ladner, Veronica P. Lance, Michael Ondrusek, Ryan Vandermeulen
Annual dedicated ocean color validation cruises off the East Coast of the USA were started in November 2014 with support from the NOAA office of Marine and Air Operations with primary focus on VIIRS/SNPP and upcoming JPSS missions. A portion of the
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