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Search Publications by: Joel Ullom (Fed)

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Displaying 251 - 275 of 352

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

Two-Body Models for Analyzing Complex Impedance

July 24, 2009
Author(s)
Douglas A. Bennett, Robert D. Horansky, Joel N. Ullom
Complex impedance is an important and widely used technique for characterizing microbolometers and microcalorimeters. Often, complex impedance data from actual devices does not fit the simple one-body model of a TES microcalorimeter. In this paper we will

Anomalous thermal behavior in microcalorimeter gamma-ray detectors

July 20, 2009
Author(s)
Robert D. Horansky, James A. Beall, Kent D. Irwin, Joel N. Ullom
Improving the resolution of gamma-ray detectors is important for many fields, including determinations of the Lamb shift in atoms with high atomic numbers , nuclear treaty verification , and environmental monitoring. High-purity germanium detectors are

Improved Isotopic Analysis With a Large Array of Gamma-Ray Microcalorimeters

June 30, 2009
Author(s)
Nikhil Jethava, Joel N. Ullom, Douglas A. Bennett, William B. Doriese, James A. Beall, Gene C. Hilton, Robert D. Horansky, Kent D. Irwin, Eric Sassi, Leila R. Vale, Minesh K. Bacrania, Andrew Hoover, P. J. Karpius, Michael W. Rabin, Clifford R. Rudy, Duc T. Vo
We present results from the largest array of gamma-ray microcalorimeters operated to date. The microcalorimeters consist of Mo/Cu transition-edge sensors with attached Sn absorbers. The detector array contains 66 pixels each with an active area 2.25 mm 2

Improved Isotopic Analysis with a Large Array of Gamma-ray Microcalorimeters

June 30, 2009
Author(s)
Nikhil Jethava, Joel N. Ullom, Douglas A. Bennett, William B. Doriese, James A. Beall, Gene C. Hilton, Robert D. Horansky, Kent D. Irwin, Eric Sassi
We present results from the largest array of gamma-ray microcalorimeters operated to date. The microcalorimeters consist of Mo/Cu transition-edge sensors with attached Sn absorbers. The detector array contains 66 pixels each with an active area 2.25 mm2

Time-of-flight mass spectrometry with latching Nb meander detectors

June 1, 2009
Author(s)
Brian Estey, James A. Beall, Gene C. Hilton, Kent D. Irwin, Daniel R. Schmidt, Joel N. Ullom, Robert E. Schwall
Mass Spectrometry is widely used for protein characterization, structural virology, drug discovery, and clinical chemistry. However the detection efficiency of existing detectors for mass spectrometry degrades rapidly as mass is increased and is only ~10-5

Ultra-high resolution alpha particle spectroscopy using calorimetry

September 23, 2008
Author(s)
Robert D. Horansky, Joel N. Ullom, James A. Beall, Gene C. Hilton, Kent D. Irwin, Don Dry, Beth Hastings, Stephen Lamont, Clifford R. Rudy, Michael W. Rabin
Calorimetry has been used since the late 1700?s to measure the heat output of physical processes ranging from chemical reactions to the respiration of organisms . Calorimetry is performed by measuring the temperature change caused by heat release into a

High resolution X-ray transition-edge sensor cooled by tunnel junction refrigerators and operated above the transition temperature

April 21, 2008
Author(s)
Nathan A. Tomlin, Galen C. O\'Neil, James A. Beall, Gene C. Hilton, Kent D. Irwin, Daniel R. Schmidt, Leila R. Vale, Joel N. Ullom
We demonstrate cooling of an X-ray transition-edge sensor (TES) using solid-state refrigerators based on normal-metal / insulator / superconductor (NIS) tunnel junctions. We are able to operate the TES at a bath temperature of 260 mK, which is 75 mK above

Density of states measurements of Al lightly doped with Mn

January 29, 2008
Author(s)
Galen O'Neil, Dan Schmidt, Nathan A. Tomlin, Joel Ullom, Kent D. Irwin, Anthony S. Williams, Gerry Arnold, Steve T. Ruggiero
Al lightly doped with Mn is a tunable superconductor, potentially useful in normalmetal/insulator/superconductor refrigerators. The superconducting transition temperature varies with Mn concentration and the density of states is like a BCS superconductor

Analysis of Nuclear Material by Alpha Spectroscopy with a Transition-Edge Microcalorimeter

January 26, 2008
Author(s)
Rob Horansky, Joel Ullom, James A. Beall, Gene C. Hilton, Kent D. Irwin, Leila R. Vale, Don Dry, Stephen Lamont, Clifford R. Rudy, Michael W. Rabin
We present measurements from a cryogenic microcalorimeter designed to detect alpha particles. The enhanced resolution of microcalorimeter alpha detectors will provide new capabilities for actinide analysis. We demonstrate a spectral resolution of 2.4 keV

A TDMA Hybrid SQUID Multiplexer

January 25, 2008
Author(s)
Carl D. Reintsema, James A. Beall, W.Bertrand (Randy) Doriese, William Duncan, S. L. Ferreira, Gene C. Hilton, Kent D. Irwin, Dan Schmidt, Joel Ullom, Leila R. Vale, Yizi Xu
We have developed a multiplexed read-out for transition edge sensors based on a hybrid time- and frequency-domain basis set, similar to that used in time-division multiple-access (TDMA) mobile phones. The hybrid basis set uses bandwidth more efficiently