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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14

A Detector for Cosmic Microwave Background Polarimetry

We present preliminary design and development work on polarized detectors intended to enable Cosmic Microwave Background polarization measurements that will probe the first moments of the universe. The ultimate measurement will be challenging, requiring background-limited detectors and good control of systematic errors. Toward this end, we are integrating the beam control of HE-11 feedhorns with the sensitivity of transition-edge sensors. The coupling between these two devices is achieved via waveguide probe antennas and superconducting microstrip lines. This implementation allows band-pass filters to be incorporated on the detector chip. We believe that a large collection of single-mode polarized detectors will eventually be required for the reliable detection of the weak polarized signature that is expected to result from gravitational waves produced by cosmic inflation. This focal plane prototype is an important step along the path to this detection, resulting in a capability that will enable various future high performance instrument concepts.

Wollack, E.↗

Low-Heat-Leak Electrical Leads For Cryogenic Systems

Electrical leads offering high electrical conductivity and low thermal conductivity developed for use in connecting electronic devices inside cryogenic systems to power supplies, signal-processing circuits, and other circuitry located in nearby warmer surroundings. Strip of superconductive leads on ceramic substrate, similar to ribbon cable, connects infrared detectors at temperature of liquid helium with warmer circuitry. Electrical leads bridging thermal gradient at boundary of cryogenic system designed both to minimize conduction of heat from surroundings through leads into system and to minimize resistive heating caused by electrical currents flowing in leads.

Wise, Stephanie A.↗

The X-ray Microcalorimeter Spectrometer (XMS): A Reference Cryogenic Instrument Design for Constellation-X

Constellation-X, a mission now belonging to the Beyond Einstein initiative, is being planned to inherit the x-ray sky from Chandra, XMM-Newton and Astro-E. The first two of four observatories in the constellation will be launched together in 2013 and followed a year later by the launch of the remaining two. The four will independently orbit the Sun-Earth Lagrange point L2. An instrument compliment resides in the Focal Plane Module (FPM) of each observatory 10 m from the Optics Module and consists of three Hard X-ray Telescope (HXT) detectors, a Reflection Grating Spectrometer (RGS) focal plane CCD camera and an X-ray Microcalorimeter Spectrometer (XMS). Instrument awards are scheduled for early 2006. The reference detector for XMS is a 32 x 32 array of microcalorimetric superconducting Transition Edge Sensors (TES). Each pixel casts a variable resistance in a SQUID based multiplexed readout circuit which is coupled to series SQUID arrays for amplification and finally read out by external electronics. A multi-stage continuous ADR will provide the stable 50 mK desired for the TES array and a stable 1 K for the series SQUID arrays while also lifting thermal parasitic and inefficiency loads to a 6 K cryocooler interface. The 6 K cryocooler is expected to emerge from the joint-project Advanced Cryocooler Technology Development Program (ACTDP) in which Constellation-X is an active participant. Project Pre-Formulation activities are marked by extensive technology development necessitating early, but realistic, thermal and cooling load requirements for ADR and ACTDP-cryocooler design points. Such requirements are driven by the encompassing XMS cryostat and ultimately by the thermal environment imposed by the FPM. It is further desired that the XMS instrument be able to operate on its side in the laboratory, with a warm vacuum shell, during an extensive calibration regime. It is that reference system design of the XMS instrument (microcalorimeter, ADR, cryocooler and cryostat) which is the subject of this paper.

Whitehouse, Paul L.↗

Properties of Superconducting Mo, Mo2n and Trilayer Mo2n-Mo-Mo2n Thin Films

We present measurements of the properties of thin film superconducting Mo, Mo2N and Mo2N/Mo/Mo2N trilayers of interest for microwave kinetic inductance detector (MKID) applications. Using microwave resonator devices, we investigate the transition temperature, energy gaps, kinetic inductance, and internal quality factors of these materials. We present an Usadel-based interpretation of the trilayer transition temperature as a function of trilayer thicknesses, and a 2-gap interpretation to understand the change in kinetic inductance and internal resonance quality factor (Q) as a function of temperature.

Superconducting↗

High-Density Superconducting Cables for Advanced ACTPol

Advanced ACTPol (AdvACT) is an upcoming Atacama Cosmology Telescope (ACT) receiver upgrade, scheduled to deploy in 2016, that will allow measure- ment of the cosmic microwave background polarization and temperature to the highest precision yet with ACT. The AdvACT increase in sensitivity is partly provided by an increase in the number of transition-edge sensors (TESes) per array by up to a factor of two over the current ACTPol receiver detector arrays. The high-density AdvACT TES arrays require 70 μ m pitch superconducting flexible cables (flex) to connect the detec- tor wafer to the first-stage readout electronics. Here, we present the flex fabrication process and test results. For the flex wiring layer, we use a 400-nm-thick sputtered alu- minum film. In the center of the cable, the wiring is supported by a polyimide substrate, which smoothly transitions to a bare (uncoated with polyimide) silicon substrate at the ends of the cable for a robust wedge wire-bonding interface. Tests on the first batch of flex made for the first AdvACT array show that the flex will meet the requirements for AdvACT, with a superconducting critical current above 1 mA at 500 mK, resilience to mechanical and cryogenic stress, and a room temperature yield of 97%.

transition-edge sensors (TESes)↗

Microelectronic fabrication of superconducting devices and circuits

It is expected that thin-film superconductors can be used as detectors or sources of infrared and microwave radiation, as magnetometers, as voltage standards, and for voltage and current measurements, for electronic signal processing, and in digital circuitry.

Kirschman, R. K.↗

Characterizing and testing a thermally isolating superconducting link for SAFIRE-like missions

The discovery of a new class of ceramic superconductors with transition temperatures above the boiling point of liquid nitrogen has opened the doors for several space applications. One important space application is the fabrication of an electrically conducting and thermally isolating link to replace manganin wires used in connecting IR detectors to data acquisition electronics on remote sensing platforms like SAFIRE and SIRTF. These NASA platforms designed to monitor the earth's atmosphere from space use infrared detectors which operate at liquid helium temperature (4.2K) for optimum performance. The SAFIRE mission employs hybrid dewars which combine both mechanical and cryogenic liquid cooling. The lifetime of such a mission is limited by the heat conducted through sensor array leads that connect the electronics (at approximately 80 K) to the sensors (at approximately 4 K). Currently these remoter sensing systems use manganin wires to connect the IR detectors to the data acquisition electronics. This link between a detector operating at 4 K and electronics operating at 80 K must be made of material that has high electrical conductivity and high thermal resistance. The YBCO superconductor with a transition temperature, Tc, of 93 K can achieve these conflicting requirements. A link with these characteristics will improve the thermal isolation of IR detectors and will increase the lifetime of the cryogen. The fabrication of an electrically conducting and thermally isolating link that replaces the manganin wires is an important application that will improve thermal isolation of IR detectors and will increase the lifetime of the cryogen. The link is made by screen printing superconducting lines on a low thermal conductivity ceramic substrate. Developing, modeling, and testing this high temperature superconducting link is a collaborative effort among NASA-Langley Research Center, Christopher Newport University (CNU), Clemson University and the industrial companies that have joined the Commercialization of Space Program for the purpose of developing and testing this link. CNU's effort in the development of this superconducting link included the following major efforts: (1) Development of a thermal conductivity measurement system for high temperature superconductors and ceramic materials which are potential candidates for use as substrates in this link. (2) Development of a mathematical model for the superconducting link that studies the effect of materials and geometry on the heat load and life time of missions. (3) Characterization of high Tc materials and assemblies made for space applications. Properties studied include humidity effects and aging effects on high Tc materials. This report summarizes the results of the research studies that were completed. Copies of publications detailing these findings are attached to this report.

Selim, Raouf R.↗

AC Read-Out Circuits for Single Pixel Characterization of TES Microcalorimeters and Bolometers

SRON is developing Frequency Domain Multiplexing (FDM) for the read-out of transition edge sensor (TES) soft x-ray microcalorimeters for the XMS instrument of the International X-ray Observatory and far-infrared bolometers for the SAFARI instrument on the Japanese mission SPICA. In FDM the TESs are AC voltage biased at frequencies from 0.5 to 6 MHz in a superconducting LC resonant circuit and the signal is read-out by low noise and high dynamic range SQUIDs amplifiers. The TES works as an amplitude modulator. We report on several AC bias experiments performed on different detectors. In particular, we discuss the results on the characterization of Goddard Space Flight Center x-ray pixels and SRON bolometers. The paper focuses on the analysis of different read-out configurations developed to optimize the noise and the impedance matching between the detectors and the SQUID amplifier. A novel feedback network electronics has been developed to keep the SQUID in flux locked loop, when coupled to superconducting high Q circuits, and to optimally tune the resonant bias circuit. The achieved detector performances are discussed in view of the instrument requirement for the two space missions.

Gottardi, L.↗

In situ Pulsed Laser Deposition of C-Axis Oriented MgB2 Films and Their Characterization

The recent discovery of an intermetallic superconductor MgB2 has renewed interest in the area of superconductivity not only because of fundamental understanding of superconductivity but also due to its potential applicability in devices such as thermal detectors. Considerable amount of research has been devoted to obtain MgB2 films by an all in situ growth technique. We have grown MgB2 thin films by an all in situ pulsed laser deposition process from pure B and Mg targets. Ultrathin layers of B and Mg were deposited in a multilayer configuration. Hundreds of such Mg-B bilayers with a capping Mg layer on the top were deposited on sapphire substrate. These depositions were done in high vacuum (approx. 10(exp -7) Torr) and at room temperature. After deposition, such a configuration was annealed at high temperature for a short time in a forming gas (4% H2 in Ar). The best films, obtained by this procedure, showed superconducting transition temperature approx. 30 K. These films have been characterized by x-ray diffraction, Rutherford Backscattering Spectrometry, AC susceptibility-, resistivity- (with and without magnetic field) and 1/f noise-measurements. The physical properties of these films will be presented and discussed.

Shinde, Sanjay↗

Ultra-Compact, Superconducting Spectrometer-on-a-Chip at Submillimeter Wavelengths

Small size, wide spectral bandwidth, and highly multiplexed detector readout are required to develop powerful multi-beam spectrometers for high-redshift observations. Currently available spectrometers at these frequencies are large and bulky. The grating sizes for these spectrometers are prohibitive. This fundamental size issue is a key limitation for space-based spectrometers for astrophysics applications. A novel, moderate-resolving-power (R-700), ultra-compact spectrograph-on-a-chip for millimeter and submillimeter wavelengths is the solution.

Chattopadhyay, Goutam↗

SAFIRE: A Far-Infrared Imaging Spectrometer for SOFIA

The SOFIA airborne observatory will provide a high spatial resolution, low background telescope for far-infrared astrophysical investigations. Selected as a PI instrument for SOFIA, SAFIRE is an imaging Fabry-Perot spectrograph covering 145 micrometers-655 micrometers with spectral resolving power of approx. 1500 (200km/s). This resolution is well matched to extragalactic emission lines and yields the greatest sensitivity for line detection. SAFIRE will make important scientific contributions to the study of the powering of ULIRGs and AGN, the role of CII cooling in extragalactic star formation, the evolution of matter in the early Universe, and the energetics of the Galactic center. SAFIRE will employ a two-dimensional pop-up bolometer array to provide background-limited imaging spectrometry. Superconducting transition edge bolometers and SQUID amplifiers have been developed for these detectors. An engineering prototype of SAFIRE with a small but cutting edge detector array will be available for use during the initial SOFIA operations; further expansion to larger format arrays will be incorporated during SAFIRE's lifetime.

Shafer, Richard A.↗

Far-Infrared Imaging Spectroscopy with SAFIRE on SOFIA

The SOFIA airborne observatory will provide a high spatial resolution, low background telescope for far-infrared astrophysical investigations. Selected as a PI instrument for SOFIA, SAFIRE is an imaging Fabry-Perot spectrograph covering 100 micrometers - 655 micrometers, with spectral resolving power of approx. 1500 (200 kilometers per second). This resolution is well matched to extragalactic emission lines and yields the greatest sensitivity for line detection. SAFIRE will make important scientific contributions to the study of the powering of ULIRGs and AGN, the role of CII cooling in extragalactic star formation, the evolution of matter in the early Universe, and the energetics of the Galactic center. SAFIRE will employ a two-dimensional pop-up barometer array in a 16 x 32 format to provide background-limited imaging spectrometry. Superconducting transition edge barometers and SQUID amplifiers have been developed for these detectors.

Shafer, Richard A.↗

SAFIRE: Far-Infrared Imaging Spectroscopy with SOFIA

The SOFIA airborne observatory will provide a high spatial resolution, low background telescope for far-infrared astrophysical investigations. Selected as a PI instrument for SOFIA, SAFIRE is an imaging Fabry-Perot spectrograph covering 145 microns-655microns, with spectral resolving power of approx. 1500 (200 kilometers per second). This resolution is well matched to extragalactic emission lines and yields the greatest sensitivity for line detection. SAFIRE will make important scientific contributions to the study of the powering of ULIRGs and AGN, the role of CII cooling in extragalactic star formation, the evolution of matter in the early Universe, and the energetics of the Galactic center. SAFIRE will employ a two-dimensional pop-up bolometer array to provide background limited imaging spectrometry. Superconducting transition edge bolometers and SQUID amplifiers have been developed for these detectors.

Benford, Dominic↗

Close-packed Arrays of Transition-edge X-ray Microcalorimeters with High Spectral Resolution at 5.9 keV

We present measurements of high fill-factor arrays of superconducting transition-edge x-ray microcalorimeters designed to provide rapid thermalization of the x-ray energy. We designed an x-ray absorber that is cantilevered over the sensitive part of the thermometer itself, making contact only at normal metal-features. With absorbers made of electroplated gold, we have demonstrated an energy resolution between 2.4 and 3.1 eV at 5.9 keV on 13 separate pixels. We have determined the thermal and electrical parameters of the devices throughout the superconducting transition, and, using these parameters, have modeled all aspects of the detector performance.

Iyomoto, N.↗

Fabrication of an Antenna-Coupled Bolometer for Cosmic Microwave Background Polarimetry

We describe the development of a detector for precise measurements of the cosmic microwave background polarization. The detector employs a waveguide to couple light between a pair of Mo/Au superconducting transition edge sensors (TES) and a feedhorn. Incorporation of an on-chip ortho-mode transducer (OMT) results in high isolation. The OMT is micromachined and bonded to the microstrip and TES circuits in a low temperature wafer bonding process. The wafer bonding process incorporates a buried superconducting niobium layer with a single crystal silicon layer which serves as the leg isolated TES membrane and as the microstrip dielectric. We describe the micromachining and wafer bonding process and report measurement results of the microwave circuitry operating in the 29-43GHz band along with Johnson noise measurements of the TES membrane structures and development of Mo/Au TES operating under '00mK.

Denis, K.L.↗

Development of a TES-Based Anti-Coincidence Detector for Future X-ray Observatories

Microcalorimeters onboard future x-ray observatories require an anti-coincidence detector to remove environmental backgrounds. In order to most effectively integrate this anticoincidence detector with the main microcalorimeter array, both instruments should use similar read-out technology. The detectors used in the Cryogenic Dark Matter Search (CDMS) use a phonon measurement technique that is well suited for an anti-coincidence detector with a microcalorimeter array using SQUID readout. This technique works by using a transition-edge sensor (TES) connected to superconducting collection fins to measure the athermal phonon signal produced when an event occurs in the substrate crystal. Energy from the event propagates through the crystal to the superconducting collection fins, creating quasiparticles, which are then trapped as they enter the TES where they produce a signal. We are currently developing a prototype anti-coincidence detector for future x-ray missions and have recently fabricated test devices with Mo/Au TESs and Al collection fins. We will present results from the first tests of these devices which indicate a proof of concept that quasiparticle trapping is occurring in these materials.

Bailey, Catherine↗

Development of a TES-Based Anti-Coincidence Detector for Future X-Ray Observations

Microcalorimeters onboard future x-ray observatories require an anticoincidence detector to remove environmental backgrounds. In order to most effectively integrate this anti-coincidence detector with the main microcalorimeter array, both instruments should use similar read-out technology. The detectors used in the Cryogenic Dark Matter Search (CDMS) use a phonon measurement technique that is well suited for an anti-coincidence detector with a microcalorimeter array using SQUID readout. This technique works by using a transition-edge sensor (TES) connected to superconducting collection fins to measure the athermal phonon signal produced when an event occurs in the substrate crystal. Energy from the event propagates through the crystal to the superconducting collection fins, creating quasiparticles, which are then trapped as they enter the TES where they produce a signal. We are currently developing a prototype anti-coincidence detector for future x-ray missions and have recently fabricated test devices with Mo/Au TESs and Al collection fins. We present results from the first tests of these devices which indicate a proof of concept that quasiparticle trapping is occurring in these materials.

Bailey, Catherine N.↗