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Search Publications by: Joel Ullom (Fed)

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Displaying 226 - 250 of 350

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