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Search Publications by: Zachary H. Levine (Fed)

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Displaying 51 - 75 of 149

Efficient photon pair sources based on Silicon-on-Insulator microresonators

August 30, 2010
Author(s)
Jun Chen, Zachary H. Levine, Jingyun Fan, Alan L. Migdall
We present a general quantum-mechanical formalism to describe photon pair generation via four-wave mixing in a Silicon-on-Insulator (SOI) microresonator. We also provide design principles for efficient photon-pair generation in a SOI microresonator through

RECIST vs. Volume Measurement in Medical CT Using Ellipsoids of Known Size

April 12, 2010
Author(s)
Zachary H. Levine, Bruce R. Borchardt, Nolan J. Brandenburg, Charles W. Clark, Balasubramanian Muralikrishnan, Craig M. Shakarji, Joseph J. Chen, Eliot L. Siegel
(a) Purpose: We wanted to test the extent to which two common methods of determining the sizes of tumors would perform when compared to a statistically significant number of well-characterized reference objects. The size of the objects was chosen to

Heralded, pure-state single-photon source based on a Potassium Titanyl Phosphate waveguide

February 15, 2010
Author(s)
Zachary H. Levine, Jingyun Fan, Jun Chen, Alexander E. Ling, Alan L. Migdall
WWe analyze the generation of single spatial mode, spectrally uncorrelated photon pairs via type II spontaneous parametric downconversion in a Potassium Titanyl Phosphate (KTP) waveguide using real experimental parameters. We show that this source can be

A Low-Cost Density Reference Phantom for Computed Tomography

January 2, 2009
Author(s)
Zachary H. Levine, Ming-Dong Li, Anthony P. Reeves, David F. Yankelevitz, Joseph J. Chen, Eliot L. Siegel, Adele P. Peskin, Diana N. Zeiger
We have characterized a commercially-available polyurethane foam which is marketed for modeling parts in the aircraft, automotive, and related industries. We find that the foam may be suitable for use as a density reference standard in the range below -700

A Low Cost Fiducial Reference for Computed Tomography

November 11, 2008
Author(s)
Zachary H. Levine, Steven Grantham, Daniel S. Sawyer, Anthony P. Reeves, David F. Yankelevitz
Rationale and Objectives. To detect the growth in lesions, it is necessary to ensure that the apparent changes in size are above the noise floor of the system. By introducing a fiducial reference, it may be possible to detect smaller changes in lesion size

Diffraction and Electron Energy Loss to Plasmons in Silicon Slabs

March 10, 2008
Author(s)
Zachary H. Levine
Dynamic diffraction patterns have been calculated for 25-nm thick slabs of silicon with [001], [111], and [110] faces for a 120 keV electron beam. The calculation used the mixed dynamical form factor in the dielectric formulation. Dielectric matrices with

Synthetic Incoherence for Electron Microscopy

July 11, 2007
Author(s)
Zachary H. Levine, Robyn M. Dunstan
Tomographic studies of submicrometer samples in materials science using electron microscopy have been inhibited by diffraction effects. In the present work, we describe two practical methods for ameliorating these effects. In one, the sample is scanned

Synthetic Incoherence Via Scanned Gaussian Beams

December 1, 2006
Author(s)
Zachary H. Levine
Tomography, in most formulations, requires an incoherent signal. For a conventional transmission electron microscope, the coherence of the beam often results in diffraction effects which limit the utility of a tilt series with conventional tomographic

Wake Fields in the Electron Gas Including Transverse Response

January 19, 2006
Author(s)
Eric J. Cockayne, Zachary H. Levine
Relativistic electrons have transverse electric fields comparable in magnitude to the longitudinal fields. We determine the relative effects of transverse and longitudinal fields of a moving point charge on the dielectric response of a uniform electron gas

Ab Initio Calculations of Mean Free Paths and Stopping Powers

January 2, 2006
Author(s)
A P. Sorini, J. Kas, J J. Rehr, M P. Prange, Zachary H. Levine
An approach is presented for theortical calculations of inelastic losses in solids over a broad energy range. The method is based on a many-pole model dielectric function, which is derived from ab initio calculations of optical constants using a real-space

The Boundary of X-Ray and Electron Tomography

January 3, 2005
Author(s)
Zachary H. Levine
Samples a few micrometers in total size offer a challenge to both x-ray and electron tomography. X-ray tomography originated imaging the human body with millimeter resolution, but the resolution has been reduced by over 7 orders of magnitude by the use of