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Search Publications by: Joel Ullom (Fed)

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Displaying 301 - 325 of 352

Fabrication of Prototype Imaging Arrays for SCUBA-2

January 4, 2006
Author(s)
Gene C. Hilton, James A. Beall, W.Bertrand (Randy) Doriese, William Duncan, S. L. Ferreira, Kent D. Irwin, Carl D. Reintsema, Joel Ullom, Leila R. Vale, Yizi Xu, Barry L. Zink, William Parkes, Andrew S. Bunting, Camilla Dunare, Alan Gundlach, T. Stevenson, Anthony Walton, Eric Schulte, Elizabeth Corrales, Joseph P. Sienicki, Dan Bintley, Peter Ade, Rashmi Sudiwala, Adam L. Woodcraft, Mark Halpern, Wayne Holland, Damian Audley, Michael MacIntosh
Prototype imaging sub-arrays for SCUBA-2 (the Sub-millimeter Common-User Bolometer Array) have been fabricated and tested. The pixel count (1280) of these wafer-scale imagers are significantly larger than any other low-temperature detectors produced to

Optimized Transition-Edge X-ray Microcalorimeter with 2.4 eV Energy Resolution at 5.9 keV

November 1, 2005
Author(s)
Joel Ullom, James A. Beall, W.Bertrand (Randy) Doriese, William Duncan, S. L. Ferreira, Gene C. Hilton, Kent D. Irwin, Carl D. Reintsema, Leila R. Vale
We present measurements from a series of transition- edge x-ray microcalorimeters designed for optimal energy resolution. We used the geometry of the sensors to control their heat capacity and employed additional normal metal features and a perpendicular

Dilute Al-Mn Alloys for Superconductor Tunneling and Other Devices

June 13, 2005
Author(s)
Steve T. Ruggiero, G. B. Arnold, A Williams, Anna Clark, Nathan A. Tomlin, Joel Ullom
We present tunneling results for junctions comprising Mn doped Al films produced by sputter deposition, with Mn oncentrations in the range of 5000 ppm. Our results for SIS, IS, and NIS junctions demonstrate that Al-Mn alloys can serve as both

Measurements & modeling of phonon cooling by electron-tunneling refrigerators

June 1, 2005
Author(s)
Nathan A. Tomlin, A. M. Clark, Anthony Williams, Steve Ruggiero, Gene C. Hilton, James A. Beall, Kent D. Irwin, Leila R. Vale, Joel Ullom
We demonstrate cooling of the electrons and phonons of a silicon nitride Si-N membrane by solid-state refrigerators based on Normal-metal/Insulator/Superconductor (NIS) tunnel junctions. We report a temperature reduction of the Si-N membrane from 260 mK to

Time-division multiplexing of high-resolution TES X-ray microcalotimeters: Four pixels and beyond

November 15, 2004
Author(s)
W.Bertrand (Randy) Doriese, James A. Beall, Steven Deiker, William Duncan, S. L. Ferreira, Gene C. Hilton, Kent D. Irwin, Carl D. Reintsema, Joel Ullom, Leila R. Vale, Yizi Xu
We present experimental results from a four-pixel array of transition-edge-sensor, x-ray microcalorimeters read out through a single amplifier channel via a time-division superconducting quantum interference device multiplexer. We map the dependence of the

Superconducting transition edge sensor using dilute AlMn alloys

July 6, 2004
Author(s)
Steven Deiker, William B. Doriese, Gene C. Hilton, Kent D. Irwin, William H. Rippard, Joel N. Ullom, Leila R. Vale, Steve T. Ruggiero, Anthony Williams, B. Young
We have fabricated a bolometer using a transition-edge sensor (TES) made of Al doped with Mn to suppress the superconducting critical temperature !Tc" of Al from #1 K to #100 mK. The resulting detector exhibits low-frequency noise consistent with theory

Characterization and Reduction of Unexplained Noise in Superconducting Transition-Edge Sensors

May 7, 2004
Author(s)
Joel N. Ullom, William B. Doriese, Gene C. Hilton, James A. Beall, Steven Deiker, William Duncan, S. L. Ferreira, Kent D. Irwin, Carl D. Reintsema, Leila R. Vale
The noise in superconducting Transition-Edge Sensors (TESs) commonly exceeds simple theoretical predictions. The reason for this discrepancy is presently unexplained. We have measured the amplitude and frequency dependence of the noise in TES sensors with

Cryogenics on a Chip

May 3, 2004
Author(s)
Jukka Pekola, Rob Schoelkopf, Joel Ullom
Low-temperature techniques often bring to mind cryogenic liquids, gas compressors, and massive installations. But researchers are now building refrigerators and sensors that work by controlling electrons on a silicon chip.

Robust infrared filters for x-ray spectroscopy

March 11, 2004
Author(s)
Nathan A. Tomlin, Joel Ullom, James A. Beall, Gene C. Hilton, Steven Deiker, W.Bertrand (Randy) Doriese, Kent D. Irwin, Carl D. Reintsema, Leila R. Vale, Yizi Xu
One challenge to using cryogenic detectors for x-ray spectroscopy on a scanning electron microscope is the implementation of infrared blocking filters. In order to achieve high x-ray transmission, these filters can be as thin as 250 nm and consequently are

X-ray Microcalorimeter Arrays Fabricated by Surface Micromachining

March 1, 2004
Author(s)
Gene C. Hilton, James A. Beall, Steven Deiker, Leila R. Vale, W.Bertrand (Randy) Doriese, Joern Beyer, Joel Ullom, Carl D. Reintsema, Yizi Xu, Kent D. Irwin
We are developing arrays of Mo/Cu TES-based detectors for use as as x-ray microcalorimeters and sub-mm bolometers. We have fabricated 8 x 8 pixel x-ray microcalorimeter arrays pixel using surface micromachining techniques. This surface-micromachining