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Search Publications by: Joel Ullom (Fed)

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Displaying 101 - 125 of 173

Macroscale refrigeration by nanoscale electron transport

February 26, 2013
Author(s)
Peter J. Lowell, Galen C. O'Neil, Jason M. Underwood, Joel N. Ullom
Nano- and Micro- Electromechanical devices (NEMS & MEMS) have become ubiquitous; examples include automobile accelerometers, inkjet printer heads, infrared viewers, and mirrors for image manipulation and projection. Applications fall broadly in the

Current Distribution and Transition Width in Superconducting Transition-Edge Sensors

December 13, 2012
Author(s)
Daniel S. Swetz, Douglas A. Bennett, Daniel R. Schmidt, Joel N. Ullom
Present models of the superconducting-to-normal transition in transition-edge sensors (TESs)do not describe the current distribution within a biased TES. This distribution is complicated by normal-metal features that are integral to TES design. We present

Observation of bias-specific telegraph noise in large transition-edge sensors

December 11, 2012
Author(s)
Vincent Y. Kotsubo, Douglas A. Bennett, Mark Croce, Michael W. Rabin, Daniel R. Schmidt, Joel N. Ullom
We have observed anomalous random telegraph noise in discrete regions of voltage bias throughout the superconducting transition in larger transition-edge sensors (TESs). The bimodal nature of these noise features is consistent with thermally activated

A high resolution gamma-ray spectrometer based on superconducting microcalorimeters

September 28, 2012
Author(s)
Douglas A. Bennett, Robert D. Horansky, Daniel R. Schmidt, Andrew Hoover, Ryan Winkler, Bradley K. Alpert, James A. Beall, William B. Doriese, Joseph W. Fowler, Gene C. Hilton, Kent D. Irwin, Nathan J. Hoteling, Vincent Y. Kotsubo, John A. Mates, Galen C. O'Neil, Michael W. Rabin, Carl D. Reintsema, Francis J. Schima, Daniel S. Swetz, Leila R. Vale, Joel N. Ullom
Improvements in superconductor device fabrication, detector hybridization techniques, and superconducting quantum interference device readout have made square-centimeter-sized arrays of gammaray microcalorimeters, based on transition-edge sensors (TESs)

A two-fluid model for the transition shape in transition-edge sensors

May 1, 2012
Author(s)
Douglas A. Bennett, Daniel S. Swetz, Robert D. Horansky, Daniel R. Schmidt, Joel N. Ullom
Superconducting microcalorimeters based on transition-edge sensors (TESs) are being successfully used in applications ranging from optical photon counting to gamma-ray and alpha particle spectroscopy. Practical instruments often require a complex

Demonstration of code-division multiplexing for x-ray microcalorimeters

February 13, 2012
Author(s)
Greg Stiehl, W.Bertrand (Randy) Doriese, Gene C. Hilton, Kent D. Irwin, Carl D. Reintsema, Dan Schmidt, Daniel Swetz, Joel Ullom, Leila R. Vale, Joseph Fowler
We demonstrate the code-division multiplexing (CDM) readout of eight transition-edge sensor microcalorimeters. The energy resolution is 3.0 eV (full width at half-maximum) or better at 5.9 keV, with a best resolution of 2.3 eV and a mean of 2.6 eV over the

Advanced Code-Division Multiplexers for Superconducting Detector Arrays

February 11, 2012
Author(s)
Kent D. Irwin, Hsiao-Mei Cho, William B. Doriese, Joseph W. Fowler, Gene C. Hilton, Michael D. Niemack, Carl D. Reintsema, Daniel R. Schmidt, Joel N. Ullom, Leila R. Vale
Multiplexers based on the modulation of superconducting quantum interference devices are now regularly used in multi-kilopixel arrays of superconducting detectors for astrophysics, cosmology, and materials analysis. Over the next decade, much larger arrays

Optimization of the TES-bias circuit for a multiplexed microcalorimeter array

January 27, 2012
Author(s)
William B. Doriese, Bradley K. Alpert, Joseph W. Fowler, Gene C. Hilton, Alex S. Hojem, Kent D. Irwin, Carl D. Reintsema, Daniel R. Schmidt, Greg Stiehl, Daniel S. Swetz, Joel N. Ullom, Leila R. Vale
In the detector-bias circuit of a transition-edge-sensor (TES) microcalorimeter, the TES-shunt resistor (Rsh) and the thermal conductance to the cryogenic bath (G) are often considered to be interchangeable knobs with which to control detector speed

Optimization and analysis of code-division multiplexed TES microcalorimeters

January 20, 2012
Author(s)
Joseph W. Fowler, William B. Doriese, Gene C. Hilton, Kent D. Irwin, Daniel R. Schmidt, Greg Stiehl, Daniel S. Swetz, Joel N. Ullom, Leila R. Vale
We are developing code-division multiplexing (CDM) readout systems for TES arrays for good scalability to large multiplexing factors. We report high energy resolution x-ray measurements made through four-channel CDM that employ a flux-summing architecture

Insensitivity of Sub-Kelvin Electron-Phonon Coupling to Substrate Properties

December 16, 2011
Author(s)
Jason M. Underwood, Peter J. Lowell, Galen C. O'Neil, Joel N. Ullom
We have examined the role of the substrate on electron-phonon coupling in normal metal films of Mn-doped Al at temperatures below 1 K. Normal metal-insulator-superconductor junctions were used to measure the electron temperature in thin metal films as a

Predicted Energy Resolution of a Running-Sum Algorithm for Microcalorimeters

December 1, 2011
Author(s)
Bradley K. Alpert, William B. Doriese, Joseph W. Fowler, Joel N. Ullom
The energy resolution of a high-pulse-rate filtering algorithm recently introduced by Hui Tan et al., based on running sums of TES microcalorimeter output streams, is predicted from average pulse shape and noise autocovariance. We compare with empirical

Al-Mn transition edge sensors for cosmic microwave background polarimeters

November 22, 2010
Author(s)
Daniel R. Schmidt, Hsiao-Mei Cho, Johannes Hubmayr, Peter J. Lowell, Michael D. Niemack, Galen C. O'Neil, Joel N. Ullom, Ki W. Yoon, Kent D. Irwin
Superconducting transition edge sensors (TES) require superconducting films with transition temperatures (Tc)and properties that can be tailored to the particular requirements of individual applications. We have been developing Al-Mn films with a tunable

Al-Mn Transition Edge Sensors for Cosmic Microwave Background Polarimeters

November 22, 2010
Author(s)
Daniel R. Schmidt, Hsiao-Mei Cho, Johannes Hubmayr, Peter J. Lowell, Michael D. Niemack, Galen C. O'Neil, Joel N. Ullom, Ki W. Yoon, Kent D. Irwin, W L. Holzapfel, M Lueker, E M. George, E Shirokoff
Superconducting transition edge sensors (TES) require superconducting films with transition temperatures (Tc)and properties that can be tailored to the particular requirements of individual applications. We have been developing Al-Mn films with a tunable

An Analytical Model for Pulse Shape and Electrothermal Stability in Two-Body Microcalorimeters

September 9, 2010
Author(s)
Douglas A. Bennett, Robert D. Horansky, Daniel R. Schmidt, Daniel S. Swetz, Leila R. Vale, Joel N. Ullom, Andrew Hoover, Michael W. Rabin, Nathan J. Hoteling
High resolution superconducting gamma-ray sensors show potential for the more accurate analysis of nuclear material. These devices are part of a larger class of microcalorimeters and bolometers based on transition edge sensors (TESs) that have two distinct

Quasiparticle Density of States Measurements in Clean Superconducting AlMn Alloys

May 6, 2010
Author(s)
Galen C. O'Neil, Daniel R. Schmidt, Nathan A. Tomlin, Joel N. Ullom
Aluminum doped with Manganese (AlMn) forms a superconducting alloy with the transition temperature suppressed by the added Manganese. We present quasiparticle density of states measurements on superconducting AlMn alloys made by current-voltage

Code-division SQUID multiplexing

April 23, 2010
Author(s)
Michael D. Niemack, Kent D. Irwin, Joern Beyer, Hsiao-Mei Cho, William B. Doriese, Gene C. Hilton, Carl D. Reintsema, Daniel R. Schmidt, Joel N. Ullom, Leila R. Vale
Multiplexed superconducting quantum interference device (SQUID) readout systems are a critical technology for measuring large arrays of superconducting transition-edge sensor (TES) detectors. Current successful SQUID multiplexing architectures are

Superconductor Science and Technology

February 22, 2010
Author(s)
Kent D. Irwin, Michael D. Niemack, Joern Beyer, Hsiao-Mei Cho, William B. Doriese, Gene C. Hilton, Carl D. Reintsema, Daniel R. Schmidt, Joel N. Ullom, Leila R. Vale
Multiplexed superconducting quantum interference device (SQUID) amplifiers have recently enabled the deployment of kilopixel arrays of superconducting transition-edge sensor (TES) detectors on a variety of receivers for astrophysics. Existing multiplexing

Optimal filtering, record length, and count rate in transition-edge-sensor microcalorimeters

December 16, 2009
Author(s)
William B. Doriese, Gene C. Hilton, Kent D. Irwin, Francis J. Schima, Joel N. Ullom, Joseph S. Adams, Caroline A. Kilbourne
In typical algorithms for optimally filtering transition-edge-sensor-microcalorimeter pulses, the average value of a filtered pulse is set to zero. The achieved energy resolution of the detector then depends strongly on the chosen length of the pulse