You searched on: Author: kevin coakley
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11. Imaging the p-n junction in a gallium nitride nanowire with a scanning microwave microscope
Atif A. Imtiaz, Thomas M Wallis, Joel C Weber, Kevin J Coakley, Matthew David Brubaker, Paul T Blanchard, Kristine A Bertness, Norman A Sanford
We used a broadband, atomic-force-microscope-based, scanning microwave microscope (AFM-SMM) to probe the axial dependence of the depletion in a GaN nanowire (NW) p-n junction structure. The NWs were c-axis oriented and grown by molecular beam epitax ...
12. Stochastic Modeling and Simulation of Marginally Trapped Neutrons
Kevin J Coakley
For a magnetic trapping experiment, I present an efficient method for simulating experimental beta−decay rates which accounts for loss of marginally trapped neutrons due to wall collisions and other possible loss mechanisms. Monte Carlo estima ...
13. Gallium Nitride Nanowire Probe for Near-Field Scanning Microwave Microscopy
Joel C Weber, Paul T Blanchard, Aric Warner Sanders, Atif A. Imtiaz, Thomas M Wallis, Kevin J Coakley, Kristine A Bertness, Pavel Kabos, Norman A Sanford, Victor M. Bright
We report on the fabrication of a GaN nanowire probe for near-field scanning microwave microscopy.
A single nanowire was Pt-bonded to a commercial Si cantilever prior to evaporation of a Ti/Al
coating to provide a microwave signal pathway. Test ...
14. Neutron Tomography of a Fuel Cell: Statistical Learning Implementation of a Penalized Likelihood
Kevin J Coakley, Dominic F. (Dominic F.) Vecchia, Daniel S Hussey, David L. Jacobson
At the NIST Neutron Imaging Facility, we collect neutron projection data for both the dry and wet
states of a Proton-Exchange-Membrane (PEM) fuel cell. Transmitted neutrons captured in a
scintillator doped with Lithium-6 produce scintillation li ...
15. Improving quantitative neutron radiography through image restoration
Daniel S Hussey, Elias M Baltic, Kevin J Coakley, David L. Jacobson
This in-situ study examines the water content in polymer electrolyte fuel cells (PEFCs) using neutron radiography. Various conditions such as different polytetraflouroethylene (PTFE) loadings in the gas diffusion media including the micro-porous laye ...
16. Scintillation Yield and Time Dependence from Electronic and Nuclear Recoils in Liquid Neon
Kevin J Coakley, W. H. Lippincott, D. Gastler, E. Kearns, D. N. McKinsey, J. A. Nikkel
We have performed measurements of scintillation light in liquid neon, observing a signal yield in
our detector as high as (3.5 +/- 0.04) photoelectrons/keV. We measure pulse shape discrimination
between electronic and nuclear recoils in liquid neon ...
17. A near-field scanning microwave microscope for characterization of inhomogeneous photovoltaics
Joel C Weber, Kristine A Bertness, John B. Schlager, Norman A Sanford, Atif A. Imtiaz, Thomas M Wallis, Pavel Kabos, Kevin J Coakley, Victor Bright, Lorelle M. Mansfield
We present a near field scanning microwave microscope (NSMM) optimized for imaging photovoltaic samples. Our system incorporates a cut Pt-Ir tip inserted into an open ended coaxial cable to form a weak resonator, allowing the microwave reflection S1 ...
18. A gamma and X-ray dector for cryogenic, high magnetic field applications
Thomas R Gentile, R L Cooper, R. Alarcon, M J Bales, E J Beise, H Breuer, J. Byrne, T E Chupp, Kevin J Coakley, Maynard S Dewey, Changbo Fu, Hans P Mumm, Jeffrey S Nico, B. O'Neill, K. Pulliam, Alan K Thompson, F E. Wietfeldt
As part of an experiment to measure the spectrum of photons emitted in beta-decay of the free neu-
tron, we developed and operated a detector consisting of 12 bismuth germanate (BGO) crystals coupled to
avalanche photodiodes (APDs). The detector wa ...
19. Fast Neutron Detection with Li-6-loaded Liquid Scintillator
David McLarty Gilliam, B Fisher, J N Abdurashitov, Kevin J Coakley, V N Gavrin, Jeffrey S Nico, A A Shikhin, Alan K Thompson, Dominic F. (Dominic F.) Vecchia, V E Yants
We report on the development of a fast neutron detector using a liquid scintillator doped with enriched 6Li. The lithium was introduced in the form of an aqueous LiCl micro-emulsion with a di-isopropylnaphthalene based liquid scintillator. A 6Li conc ...
20. Recent Progress in Noise Thermometry at 505 K and 693 K Using Quantized Voltage Noise Ratio Spectra
Weston Leo Tew, Paul David Dresselhaus, Kevin J Coakley, H Rogalla, D. R White, J Labenski
We report on technical advances and new results in noise thermometry at temperatures near the tin freezing point and the zinc freezing point using a Quantized Voltage Noise Source (QVNS). The temperatures are derived in a series of separate measureme ...