NASA Scientific and Technical Aerospace Reports

detectors or highly cooled (about 4K and lower) quantum and thermal detectors, with the notable exception of high Tc
superconductor detectors. We will describe certain long-wavelength applications in space where only moderate cooling is
feasible, and where better sensitivity is required than possible with uncooled detectors. These requirements could be met with
high Tc bolometers, but it may also be prudent to develop other technologies. Additionally, over the past 16 years a
marketplace has not developed for the commercial production of high Tc bolometers, indicating their production may be a
natural endeavor for government laboratories.
Author
Cooling; High Temperature Superconductors; Infrared Detectors; Bolometers; Space Missions
20040068214 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Fabrication of Monolithic Sapphire Membranes for High T(sub c) Bolometer Array Development
Pugel, D. E.; Lakew, B.; Aslam, S.; Wang, L.; International Thermal Detectors Workshop (TDW 2003); February 2004,
pp. 3-6 - 3-10; In English; See also 20040068186; No Copyright; Avail: CASI; A01, Hardcopy
This paper examines the effectiveness of Pt/Cr thin film masks for the architecture of monolithic membrane structures in
r-plane single crystal sapphire. The development of a pinhole-free Pt/Cr composite mask that is resistant to boiling
H2SO4:H3PO4 etchant will lead to the fabrication of smooth sapphire membranes whose surfaces are well-suited for the
growth of low-noise high Tc films. In particular, the relationship of thermal annealing conditions on the Pt/Cr composite mask
system to: (1) changes in the surface morphology (2) elemental concentration of the Pt/Cr thin film layers and (3) etch pit
formation on the sapphire surface will be presented.
Author
Fabrication; Sapphire; Membrane Structures; High Temperature Superconductors; Bolometers
20040068215 NASA Goddard Space Flight Center, Greenbelt, MD, USA
SQUID Multiplexers for Cryogenic Detector Arrays
Irwin, Kent; Beall, James; Deiker, Steve; Doriese, Randy; Duncan, William; Hilton, Gene; Moseley, S. Harvey; Reintsema,
Carl; Stahle, Caroline; Ullom, Joel; Vale, Leila; International Thermal Detectors Workshop (TDW 2003); February 2004,
pp. 4-5; In English; See also 20040068186; No Copyright; Abstract Only; Available from CASI only as part of the entire
parent document
SQUID multiplexers make it possible to build arrays of thousands of cryogenic detectors with a manageable number of
readout channels. We are developing time-division SQUID multiplexers based on Nb trilayer SQUIDs to read arrays of
superconducting transition-edge sensors. Our first-generation, 8-channel SQUID multiplexer was used in FIBRE, a
one-dimensional TES array for submillimeter astronomy. Our second-generation 32-pixel multiplexer, based on an improved
architecture, has been developed for instruments including Constellation-X, SCUBA-2, and solar x-ray astronomy missions.
SCUBA-2, which is being developed for the James Clerk Maxwell Telescope, will have more than 10,000 pixels. We are now
developing a third-generation architecture based on superconducting hot-electron switches. The use of SQUID multiplexers
in instruments operating at above 2 K will also be discussed.
Author
Cryogenics; Multiplexing; Squid (Detectors); Arrays
20040068217 NASA Goddard Space Flight Center, Greenbelt, MD, USA
High- and Mid-temperature Superconducting Sensors for Far IR/Sub-mm Applications in Space
Lakew, Brook; Brasunas, J. C.; International Thermal Detectors Workshop (TDW 2003); February 2004, pp. 4-1 - 4-4; In
English; See also 20040068186; No Copyright; Avail: CASI; A01, Hardcopy
In this review paper an overview of the potential applications of high Tc (approx. 90 K) superconductors (HTS) and
mid-Tc (approx. 39 K) superconductors (MTS) thin films in far IR/Sub-mm thermal detectors is presented. HTSs (YBCO,
GdBCO etc.) were discovered in the late 80s while superconductivity in MgB2, an MTS, was discovered in 2001. The sharp
transition in transport properties of HTS has allowed the fabrication of composite infrared thermal detectors (bolometers) with
better figures of merit than thermopile detectors - thermopiles are currently on board the CIRS instrument on the Cassini
mission to Saturn. The potential for developing even more sensitive sensors for IR/Sub-mm applications using MgB2 thin
films is assessed. Current MgB2 thin film deposition techniques and film quality are reviewed.
Author
Superconductors (Materials); Thin Films; Far Infrared Radiation; Ybco Superconductors
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