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Search Publications by: Bradley Alpert (Fed)

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Displaying 1 - 25 of 91

Nanoscale Three-Dimensional Imaging of Integrated Circuits Using a Scanning Electron Microscope and Transition-Edge Sensor Spectrometer

April 30, 2024
Author(s)
Nathan Nakamura, Paul Szypryt, Amber Dagel, Bradley Alpert, Douglas Bennett, W.Bertrand (Randy) Doriese, Malcolm Durkin, Joseph Fowler, Dylan Fox, Johnathon Gard, Ryan Goodner, James Zachariah Harris, Gene C. Hilton, Edward Jimenez, Burke Kernen, Kurt Larson, Zachary H. Levine, Daniel McArthur, Kelsey Morgan, Galen O'Neil, Christine Pappas, Carl D. Reintsema, Dan Schmidt, Peter Schulz, Daniel Swetz, Kyle Thompson, Joel Ullom, Leila R. Vale, Courtenay Vaughan, Christopher Walker, Joel Weber, Jason Wheeler
X-ray nanotomography is a powerful tool for the characterization of nanoscale materials and structures, but it is difficult to implement due to the competing requirements of X-ray flux and spot size. Due to this constraint, state-of-the-art nanotomography

Noise-resilient deep tomographic imaging

April 24, 2023
Author(s)
Zhen Guo, Zhiguang Liu, George Barbastathis, Qihang Zhang, Michael Glinsky, Bradley Alpert, Zachary H. Levine
X-ray tomography is a non-destructive imaging technique that reveals the interior of an object from its projections at different angles. Under limited-angle and low-photon sampling, a regularization prior is required to retrieve a high-fidelity

A Tabletop X-Ray Tomography Instrument for Nanometer-Scale Imaging: Reconstructions

April 14, 2023
Author(s)
Zachary H. Levine, Bradley Alpert, Amber Dagel, Joseph Fowler, Edward Jiminez, Nathan J. Nakamura, Daniel Swetz, Paul Szypryt, Kyle Thompson, Joel Ullom
We show three-dimensional reconstructions of a region of an integrated circuit from a 130 nm copper process. The reconstructions employ x-ray computed tomography, measured with a new and innovative high-magnification x-ray microscope. The instrument uses a

Physics-assisted Generative Adversarial Network for X-Ray Tomography

June 10, 2022
Author(s)
Zhen Guo, Jungki Song, George Barbastathis, Michael Glinsky, Courtenay Vaughan, Kurt Larson, Bradley Alpert, Zachary H. Levine
X-ray tomography is capable of imaging the interior of objects in three dimensions non-invasively, with applications in biomedical imaging, materials study, electronic inspection, and other fields. The reconstruction process can be an ill-conditioned

Toward a New Primary Standardization of Radionuclide Massic Activity Using Microcalorimetry and Quantitative Milligram-Scale Samples

February 24, 2022
Author(s)
Ryan P. Fitzgerald, Bradley Alpert, Dan Becker, Denis E. Bergeron, Richard Essex, Kelsey Morgan, Svetlana Nour, Galen O'Neil, Dan Schmidt, Gordon A. Shaw, Daniel Swetz, R. Michael Verkouteren, Daikang Yan
We present a new paradigm for the primary standardization of radionuclide activity per mass of solution (Bq/g). Two key enabling capabilities are 4π decay-energy spectrometry using chip-scale sub-Kelvin microcalorimeters and direct realization of mass by

Advantage of Machine Learning over Maximum Likelihood in Limited-Angle Low-Photon X-Ray Tomography

January 20, 2022
Author(s)
Zhen Guo, Jungki Song, George Barbastathis, Michael Glinsky, Courtenay Vaughan, Kurt Larson, Bradley Alpert, Zachary H. Levine
Limited-angle X-ray tomography reconstruction is an ill-posed inverse problem in general. Especially when the projection angles are limited and the measurements are taken in a photon-limited condition, reconstructions from classical algorithms such as

Near-Field, Spherical-Scanning Antenna Measurements With Nonideal Probe Locations

October 12, 2021
Author(s)
Ronald C. Wittmann, Bradley Alpert, Michael H. Francis
We introduce a near-field, spherical-scanning algorithm for antenna measurements that relaxes the usual condition requiring data points to be on a regular spherical grid. Computational complexity is of the same order as for the standard (ideal-positioning)

Absolute energies and emission line shapes of the x-ray lines of lanthanide metals

February 1, 2021
Author(s)
Joseph Fowler, Galen O'Neil, Bradley K. Alpert, Douglas Bennett, Edward V. Denison, William Doriese, Gene Hilton, Lawrence T. Hudson, Young I. Joe, Kelsey Morgan, Daniel Schmidt, Daniel Swetz, Csilla I. Szabo-Foster, Joel Ullom
We use an array of transition-edge sensors, cryogenic microcalorimeters with 4 eV energy resolution, to measure the x-ray emission-line profiles of four elements of the lanthanide series: praseodymium, neodymium, terbium, and holmium. The spectrometer also

A Robust Principal Component Analysis for Outlier Identification in Messy Microcalorimeter Data

November 12, 2019
Author(s)
Joseph W. Fowler, Bradley K. Alpert, Young I. Joe, Galen C. O'Neil, Daniel S. Swetz, Joel N. Ullom
A principal component analysis (PCA) of clean microcalorimeter pulse records can be a first step beyond statistically optimal linear filtering of pulses toward a fully nonlinear analysis. For PCA to be practical on spectrometers with hundreds of sensors

Approaches to the Optimal Nonlinear Analysis of Microcalorimeter Pulses

March 8, 2018
Author(s)
Joseph W. Fowler, Christine G. Pappas, Bradley K. Alpert, William B. Doriese, Galen C. O'Neil, Joel N. Ullom, Daniel S. Swetz
We consider how to analyze microcalorimeter pulses for quantities that are nonlinear in the data, while preserving the signal-to-noise advantages of linear optimal filtering. We apply the approach to compute the electrothermal feedback energy deficit (the