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Results for “detector requirements”

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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

The development of an electrochemical technique for in situ calibrating of combustible gas detectors

A program to determine the feasibility of performing in situ calibration of combustible gas detectors was successfully completed. Several possible techniques for performing the in situ calibration were proposed. The approach that showed the most promise involved the use of a miniature water vapor electrolysis cell for the generation of hydrogen within the flame arrestor of a combustible gas detector to be used for the purpose of calibrating the combustible gas detectors. A preliminary breadboard of the in situ calibration hardware was designed, fabricated and assembled. The breadboard equipment consisted of a commercially available combustible gas detector, modified to incorporate a water vapor electrolysis cell, and the instrumentation required for controlling the water vapor electrolysis and controlling and calibrating the combustible gas detector. The results showed that operation of the water vapor electrolysis at a given current density for a specific time period resulted in the attainment of a hydrogen concentration plateau within the flame arrestor of the combustible gas detector.

Shumar, J. W.↗
NASA NTRS2010

Concerning the Development of the Wide-Field Optics for WFXT Including Methods of Optimizing X-Ray Optical Prescriptions for Wide-Field Applications

We present a progress report on the various endeavors we are undertaking at MSFC in support of the Wide Field X-Ray Telescope development. In particular we discuss assembly and alignment techniques, in-situ polishing corrections, and the results of our efforts to optimize mirror prescriptions including polynomial coefficients, relative shell displacements, detector placements and tilts. This optimization does not require a blind search through the multi-dimensional parameter space. Under the assumption that the parameters are small enough so that second order expansions are valid, we show that the performance at the detector can be expressed as a quadratic function with numerical coefficients derived from a ray trace through the underlying Wolter I optic. The optimal values for the parameters are found by solving the linear system of equations creating by setting derivatives of this function with respect to each parameter to zero.

Weisskopf, M. C.↗
NASA NTRS2014

Optimal Energy Measurement in Nonlinear Systems: An Application of Differential Geometry

Design of TES microcalorimeters requires a tradeoff between resolution and dynamic range. Often, experimenters will require linearity for the highest energy signals, which requires additional heat capacity be added to the detector. This results in a reduction of low energy resolution in the detector. We derive and demonstrate an algorithm that allows operation far into the nonlinear regime with little loss in spectral resolution. We use a least squares optimal filter that varies with photon energy to accommodate the nonlinearity of the detector and the non-stationarity of the noise. The fitting process we use can be seen as an application of differential geometry. This recognition provides a set of well-developed tools to extend our work to more complex situations. The proper calibration of a nonlinear microcalorimeter requires a source with densely spaced narrow lines. A pulsed laser multi-photon source is used here, and is seen to be a powerful tool for allowing us to develop practical systems with significant detector nonlinearity. The combination of our analysis techniques and the multi-photon laser source create a powerful tool for increasing the performance of future TES microcalorimeters.

Nonlinear response↗
NASA NTRS1984

Integrating amplifiers using cooled JFETs

It is shown how a simple integrating amplifier based on commercially available JFET and MOSFET switches can be used to measure photocurrents from detectors with noise levels as low as 1.6 x 10 to the -18th A/root Hz (10 electrons/sec). A figure shows the basic circuit, along with the waveform at the output. The readout is completely nondestructive; the reset noise does not contribute since sampling of the accumulated charge occurs between resets which are required only when the stored charge has reached a very high level. The storage capacity ranges from 10 to the 6th to 10 to the 9th electrons, depending on detector parameters and linearity requirements. Data taken with an Si:Sb detector operated at 24 microns are presented. The responsivity agrees well with the value obtained by Young et al. (1981) in the transimpedance amplifier circuit. The data are seen as indicating that extremely low values of NEP can be obtained for integration times of 1 sec and that longer integrations continue to improve the SNR at a rate faster than the square root of time when background noise is not present.

Low, F. J.↗
NASA NTRS2020

Assembly and Integration Process of the High-Density Detector Array Readout Modules for the Simons Observatory

The Simons Observatory will measure the cosmic microwave background tempera-ture and polarization using a suite of new telescopes in the Atacama Desert in Chile. The Simons Observatory will use dichroic transition edge sensor (TES) bolometer arrays spanning six frequency bands from 27 to 280 GHz. The Simons Observa-tory will pioneer the use of a densely packed multiplexing architecture based on the microwave SQUID multiplexer ( 𝜇mux), housing ∼2000 microwave resonators, each coupled to a TES. The Simons Observatory aims to multiplex each array of ∼2000 detectors with a single pair of coaxial cables and requires a multiplexing factor of ∼1000 . The Simons Observatory cryogenic readout system is called the universal microwave multiplexing module (UMM). The UMM couples to both horn and lenslet-coupled detector arrays and is integrated into the universal focal-plane module (UFM) after being independently characterized. We present processes we have developed for highly repeatable and automated integration methods of UMMs, which will be needed for the production of the 49 UFMs required for the first stage of the Simons Observatory.

CMB↗
NASA NTRS2016

Fabrication of X-ray Microcalorimeter Focal Planes Composed of Two Distinct Pixel Types

We develop superconducting transition-edge sensor (TES) microcalorimeter focal planes for versatility in meeting the specifications of X-ray imaging spectrometers, including high count rate, high energy resolution, and large field of view. In particular, a focal plane composed of two subarrays: one of fine pitch, high count-rate devices and the other of slower, larger pixels with similar energy resolution, offers promise for the next generation of astrophysics instruments, such as the X-ray Integral Field Unit Instrument on the European Space Agencys ATHENA mission. We have based the subarrays of our current design on successful pixel designs that have been demonstrated separately. Pixels with an all-gold X-ray absorber on 50 and 75 micron pitch, where the Mo/Au TES sits atop a thick metal heatsinking layer, have shown high resolution and can accommodate high count rates. The demonstrated larger pixels use a silicon nitride membrane for thermal isolation, thinner Au, and an added bismuth layer in a 250-sq micron absorber. To tune the parameters of each subarray requires merging the fabrication processes of the two detector types. We present the fabrication process for dual production of different X-ray absorbers on the same substrate, thick Au on the small pixels and thinner Au with a Bi capping layer on the larger pixels to tune their heat capacities. The process requires multiple electroplating and etching steps, but the absorbers are defined in a single-ion milling step. We demonstrate methods for integrating the heatsinking of the two types of pixel into the same focal plane consistent with the requirements for each subarray, including the limiting of thermal crosstalk. We also discuss fabrication process modifications for tuning the intrinsic transition temperature (T(sub c)) of the bilayers for the different device types through variation of the bilayer thicknesses. The latest results on these 'hybrid' arrays will be presented.

Terms—Arrays↗
NASA NTRS2004

Large Format Arrays for Far Infrared and Millimeter Astronomy

Some of the most compelling questions in modem astronomy are best addressed with submillimeter and millimeter observations. The question of the role of inflation in the early evolution of the universe is best addressed with large sensitive arrays of millimeter polarimeters. The study of the first generations of galaxies requires sensitive submillimeter imaging, which can help us to understand the history of energy release and nucleosynthesis in the universe. Our ability to address these questions is dramatically increasing, driven by dramatic steps in the sensitivity and size of available detector arrays. While the MIPS instrument on the SIRTF mission will revolutionize far infrared astronomy with its 1024 element array of photoconductors, thermal detectors remain the dominant technology for submillimeter and millimeter imaging and polarimetry. The last decade has seen the deployment of increasingly large arrays of bolometers, ranging from the 48 element arrays deployed on the KAO in the late 198Os, to the SHARC and SCUBA arrays in the 1990s. The past years have seen the deployment of a new generation of larger detector arrays in SHARC II (384 channels) and Bolocam (144 channels). These detectors are in operation and are beginning to make significant impacts on the field. Arrays of sensitive submillimeter bolometers on the SPIRE instrument on Herschel will allow the first large areas surveys of the sky, providing important insight into the evolution of galaxies. The next generation of detectors, led by SCUBA II, will increase the focal scale of these instruments by an order of magnitude. Two major missions are being planned by NASA for which further development of long wavelength detectors is essential, The SAFlR mission, a 10-m class telescope with large arrays of background limited detectors, will extend our reach into the epoch of initial galaxy formation. A major goal of modem cosmology is to test the inflationary paradigm in the early evolution of the universe. To this end, a mission is planned to detect the imprint of inflation on the CMB by precision measurement of its polarization. This work requires very large arrays of sensitive detectors which can provide unprecedented control of a wide range of systematic errors, given the small amplitude of the signal of interest. We will describe the current state of large format detector arrays, the performance requirements set by the new missions, and the different approaches being developed in the community to meet these requirements. We are confident that within a decade, these developments will lead to dramatic advances in our understanding of the evolution of the universe.

Moseley, Harvey↗
NASA NTRS1973

Compact carbon monoxide sensor utilizing a confocal optical cavity.

The carbon monoxide sensor discussed in this paper utilizes a unique confocal cavity which allows the complete system to be packaged in a small volume suitable for hand-held use. The optical system is the heart of the instrument with equal emphasis placed on the electronics support circuitry, consisting essentially of a thermal infrared pyroelectric detector and lock-in amplifier. The pyroelectric detector offers a major advantage over other thermal detectors, providing a signal-to-noise ratio and detectivity that remain nearly constant over the frequency range from dc to 2000 Hz. Since bias voltage is not required, low frequency noise is not generated in the detector.

Scott, B.↗
NASA NTRS2008

Optical Communications from Planetary Distances

Future planetary campaigns, including human missions, will require data rates difficult to realize by microwave links. Optical channels not only provide an abundance of bandwidth, they also allow for significant size, weight, and power reduction. Moreover, optical-based tracking may enhance spacecraft navigation with respect to microwave-based tracking. With all its advantages, optical communications from deep space is not without its challenges. Due to the extreme distance between the two ends of the link, specialized technologies are needed to enable communications in the deep space environment. Although some of the relevant technologies have been developed in the last decade, they remain to be validated in an appropriate domain. The required assets include efficient pulsed laser sources, modulators, transmitters, receivers, detectors, channel encoders, precise beam pointing technologies for the flight transceiver and large apertures for the ground receiver. Clearly, space qualification is required for the systems that are installed on a deep space probe. Another challenge is atmospheric effects on the optical beam. Typical candidate locations on the ground have a cloud-free line of sight only on the order of 60-70% of the time. Furthermore, atmospheric losses and background light can be problematic even during cloud-free periods. Lastly, operational methodologies are needed for efficient and cost effective management of optical links. For more than a decade, the National Aeronautics and Space Administration (NASA) has invested in relevant technologies and procedures to enable deep space optical communications capable of providing robust links with rates in the order of 1 Gb/s from Mars distance. A recent publication indicates that potential exists for 30-dB improvement in performance through technology development with respect to the state-of-the-art in the early years of this decade. The goal is to fulfill the deep space community needs from about 2020 to the foreseeable future. It is envisioned that, at least initially, optical links will be complemented by microwave assets for added robustness, especially for human missions. However, it is expected that as optical techniques mature, laser communications may be operated without conventional radio frequency links. The purpose of this paper is to briefly review the state-of-the-art in deep space laser communications and its challenges and discuss NASA-supported technology development efforts and plans for deep space optical communications at JPL.

Laser Communications↗
NASA NTRS1975

Definition of Throw-Away Detectors (TADs) and VLF antenna for the AMPS laboratory

A Throw Away Detector (TAD)/subsatellite to be used as an experiment platform for the test flights to map the EMI from the shuttle and during the AMPS science flights is defined. A range of instrument platforms of varying capabilities is examined with emphasis on the EMI test vehicle. The operational support requirements of TAD/subsatellites are determined. The throw away detector is envisioned as a simple instrument package for supporting specific experiments.

Koons, H. C.↗
NASA NTRS1993

InGaAs Detectors for Miniature Infrared Instruments

In the past year, there has been substantial impetus for NASA to consider missions that are of relatively low cost as a trade off for a higher new mission launch rate. To maintain low mission cost, these missions will be of short duration and will use smaller launch vehicles (e.g. Pegasus). Consequently, very low volume, very low mass instrument (a.k.a. miniature instrument) payloads will be required. Furthermore, it is anticipated that the number of instruments flown on a particular mission will also be highly constrained; consequently increased instrument capability will also be desired. In the case of infrared instruments, focal planes typically require cooling to ensure high performance of the detectors, especially in the case of spectrometers where high D* is necessary. In this paper, we discuss the InGaAs detector technology and its potential.

Krabach, T. N.↗
NASA NTRS1991

Report of the x ray and gamma ray sensors panel

Overall five major areas of technology are recommended for development in order to meet the science requirements of the Astrotech 21 mission set. These are: detectors for high resolution gamma ray spectroscopy, cryogenic detectors for improved x ray spectral and spatial resolution, advanced x ray charge coupled devices (CCDs) for higher energy resolution and larger format, extension to higher energies, liquid and solid position sensitive detectors for improving stopping power in the energy range 5 to 500 keV and 0.2 to 2 MeV. Development plans designed to achieve the desired capabilities on the time scales required by the technology freeze dates have been recommended in each of these areas.

Szymkowiak, Andrew↗
NASA NTRS2018

Imaging Technique for High Precision Measurement of Detector Stability for the Ocean Color Instrument

One of the new projects by NASA to explore environmental change is the Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) spacecraft. The primary instrument aboard the PACE spacecraft is the Ocean Color Instrument (OCI), an advanced optical spectrometer that will measure the color of the ocean from the ultraviolet to shortwave infrared range for the purpose of observing and monitoring ocean and coastal biology. As part of the optical alignment testing that must be completed before the instrument is built, the measurement stability of the detectors at space flight operating temperatures must be determined to ensure alignment is maintained. Therefore, this project focuses on the development of an imaging technique that adheres to testing requirements and can be used to determine the stability of the OCI detector. The movements of targets affixed to a high-precision stage were analyzed through an image processing program to test the ability of the imaging technique to detect very small (under 10 micrometers) movements. It was found that movements as small as half a pixel (~6 microns) and 1 pixel (~12 microns) were able to be accurately and consistently detected with this imaging technique. This project found that the designed image analysis technique fulfills testing and measurement requirements and will be an effective metrology technique for the OCI detector stability test.

Optics↗
NASA NTRSDate not supplied

Holey Silicon-based Thermopiles for High-Sensitivity Broadband Thermal Detection in Space

Future planetary missions call for thermal detectors with high sensitivity over a wide range of temperature or wavelength. Conventional approaches based upon photon detectors are limited to a narrow and material-selective range of wavelength, and they often require cryogenic cooling for measurements of far-infrared (FIR) radiation or very low-temperature objects, which result in a significant increase in the system’s size, weight, and power (SWaP). While thermal detectors based upon thermopiles are uncooled and sensitive to a wide range of wavelengths including FIR radiation, their sensitivity, limited by the material’s thermoelectric response and heat losses, is an order of magnitude lower than photon detectors. To address the sensitivity requirements for future planetary science missions that target very cold objects such as ice giant planets, icy regoliths, planetary satellites, and primitive bodies, we introduce a high-sensitive broadband thermopile concept using holey silicon – a thin membrane of silicon with a microfabricated arrangement of pores that can be optimized to minimize heat losses and enable breakthrough thermoelectric performance. In this paper, we present our analytical model for the holey silicon-based thermopile, its performance expectations, and its performance comparisons with the state-of-the-art thermopile technology. We will investigate the roles of thermal conductance in holey silicon-based thermopile performance, the impact of thermal conduction and thermal radiation at different temperature limits, and the performance trade-off between the responsivity and noises.

thermopiles↗
NASA NTRS1967

Photovoltaic effect in organic polymer-iodine complex

Certain charge transfer complexes formed from organic polymers and iodine generate appreciable voltages at relatively low impedances upon exposure to light. These films show promise in applications requiring chemically and electrically stable films as detectors of optical radiation and as energy converters in photovoltaic cells.

Hermann, A. M.↗
NASA NTRS1973

Versatile logic system for use in nuclear experiments on scientific satellites.

An improved fast low-power-drain logic system has been developed for use in nuclear experiments on scientific satellites. The basic unit of the system is an AND-NAND gate which has a response in the 10-nsec range, a power drain of 2.0 mw and operates over the temperature range of -40 to +80 C. In addition to providing the AND-NAND logic functions, one or more of the basic units may be connected to yield a monostable pulse generator, a pulse generator proceeding an output pulse at the leading edge of the input pulse, a delay, a threshold detector, and a bistable circuit. The system requires relatively simple circuitry for interfacing at its outputs and inputs.

Cancro, C. A.↗
NASA NTRS1975

Preliminary design report, Large Space Telescope OTA/SI Phase B study: High speed area photometer

A photometer is examined which combines several features from separate instruments into a single package. The design presented has both point and area photometry capability with provision for inserting filters to provide spectral discrimination. The electronics provide for photon counting mode for the point detectors and both photon counting and analog modes for the area detector. The area detector also serves as a target locating device for the point detectors. Topics discussed include: (1) electronic equipment requirements, (2) optical properties, (3) structural housing for the instrument, (4) motors and other mechanical components, (5) ground support equipment, and (6) environment control for the instrument. Engineering drawings and block diagrams are shown.

Source record↗
NASA NTRS1977

Spacecraft Charging Technology Conference, P 78-2, overview

Spacecraft charging technology is presented, including specifications and design. Mission objectives for launching the SAMSO 402 spacecraft are given to determine and analyze payload requirements. Engineering payloads, energy range of particle detectors, and orbital parameters are represented in graphical form.

Shane, D. F.↗