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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Rotary encoding device using polygonal mirror with diffraction gratings on each facet

A device for position encoding of a rotating shaft in which a polygonal mirror having a number of facets is mounted to the shaft and a monochromatic light beam is directed towards the facets. The facets of the polygonal mirror each have a low line density diffraction grating to diffract the monochromatic light beam into a number of diffracted light beams such that a number of light spots are created on a linear array detector. An analog-to-digital converter is connected to the linear array detector for reading the position of the spots on the linear array detector means. A microprocessor with memory is connected to the analog-to-digital converter to hold and manipulate the data provided by the analog-to-digital converter on the position of the spots and to compute the position of the shaft based upon the data from the analog-to-digital converter.

Leviton, Douglas B.↗
NASA NTRS1996

High Angular Sensitivity, Absolute Rotary Encoding Device with Polygonal Mirror and Stand-Alone Diffraction Gratings

A device for position encoding of a rotating shaft in which a polygonal mirror having a number of facets is mounted to the shaft and a monochromatic light beam is directed towards the facets. The facets of the polygonal mirror direct the light beam to a stand-alone low line density diffraction grating to diffract the monochromatic light beam into a number of diffracted light beams such that a number of light spots are created on a linear array detector. An analog-to-digital converter is connected to the linear array detector for reading the position of the spots on the linear array detector means. A microprocessor with memory is connected to the analog-to-digital converter to hold and manipulate the data provided by the analog-to-digital converter on the position of the spots and to compute the position of the shaft based upon the data from the analog-lo-digital converter.

Leviton, Douglas B.↗
NASA NTRS1989

Study of advanced InSb arrays for SIRTF (Space Infrared Telescope Facility)

The Santa Barbara Research Center has completed a study leading to the development of advanced Indium Antimonide detector arrays for the Space Infrared Telescope Facility (SIRTF) Focal Plane Array Detector (FPAD) Subsystem of the Infrared Array Camera (IRAC) Band 1. The overall goal of the study was to perform design tradeoff studies, analysis and research to develop a Direct Readout Integrated Circuit to be hybridized to an advanced, high performance InSb detector array that would satisfy the technical requirements for Band 1 as specified in the IRAC Instrument Requirements Document (IRD), IRAC-202. The overall goal of the study was divided into both a near-term goal and a far-term goal. The near-term goal identifies current technology available that approaches, and in some cases meets the program technological goals as specified in IRAC-202. The far-term goal identifies technology development required to completely achieve SIRTF program goals. Analyses of potential detector materials indicates that InSb presently meets all Band 1 requirements and is considered to be the baseline approach due to technical maturity. The major issue with regard to photovoltaic detectors such as InSb and HgCdTe is to achieve a reduction in detector capacitance.

Hoffman, Alan↗
DOE OSTI2020

CCAT-prime: Designs and status of the first light 280 GHz MKID array and mod-cam receiver

The CCAT-prime project's first light array will be deployed in Mod-Cam, a single-module testbed and first light cryostat, on the Fred Young Submillimeter Telescope (FYST) in Chile's high Atacama desert in late 2022. FYST is a six-meter aperture telescope being built on Cerro Chajnantor at an elevation of 5600 meters to observe at millimeter and submillimeter wavelengths. 1 Mod-Cam will pave the way for Prime-Cam, the primary first generation instrument, which will house up to seven instrument modules to simultaneously observe the sky and study a diverse set of science goals from monitoring protostars to probing distant galaxy clusters and characterizing the cosmic microwave background (CMB). At least one feedhorn-coupled array of microwave kinetic inductance detectors (MKIDs) centered on 280 GHz will be included in Mod-Cam at first light, with additional instrument modules to be deployed along with Prime-Cam in stages. The first 280 GHz detector array was fabricated by the Quantum Sensors Group at NIST in Boulder, CO and includes 3,456 polarization- sensitive MKIDs. Current mechanical designs allow for up to three hexagonal arrays to be placed in each single instrument module. We present details on this first light detector array, including mechanical designs and cold readout plans, as well as introducing Mod-Cam as both a testbed and predecessor to Prime-Cam.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1979

Infrared focal plane arrays for planetary missions

Requirements for infrared detector array focal planes suitable for a set of prospective planetary missions are developed. Using the Galileo mission to Jupiter as a starting point, objectives and constraints applicable to outer planet missions are developed. The concept for an advanced mapping spectrometer utilizing 128 x 128 element infrared detector arrays is described. Specific implementations for the Saturn Orbiter Dual Probe mission, a Mars Orbiter mission, and a Titan Orbiter mission are defined. The analysis indicates that within the 1 to 5 micron range, broad scientific objectives for these missions can be met using focal plane arrays with detectivities on the order of 10 to the 14th cm sq root of Hz per W. The realization of such high detectivities in a low background application will necessitate careful development of the method by which the detector signals are multiplexed and read out.

Wellman, J. B.↗
NASA NTRS1994

Rotary encoding device with polygonal reflector and centroid detection

A device for positioning encoding of a rotating shaft in which a polygonal mirror having a number of facets is mounted to the shaft and a light beam is directed towards the facets. The facets of the polygonal mirror reflect the light beam such that a light spot is created on a linear array detector. An analog-to-digital converter is connected to the linear array detector for reading the position of the spot on the spots on the linear array detector. A microprocessor with memory is connected to the analog-to-digital converter to hold and manipulate the data provided by the analog-to-digital converter on the position of the spot and to compute the position of the shaft based upon the data from the analog-to-digital converter.

Leviton, Douglas B.↗
DOE OSTI2021

A parallel-plate avalanche counter for the prompt fission neutron spectrum measurement

Neutrons, gamma’s, and fission fragments are among the prompt fission observables. Their precision measurements are fundamental to advance our understanding of fission and any application of fission. For our programmatic need, the χ matrix, which defines as the outgoing neutron spectrum as a function of incoming neutron energy, is sparsely populated and poorly measured for 233,235,238 U and 239,240 Pu. To improve the quality of those χ matrices, a joint LANLLLNL project was undertaken to measure their prompt fission neutron spectra at the LANSCE/WNR facility using neutron detector arrays and a charged-particle detector for the fission-fragment detection. A typical setup is shown in Fig. 1, where one of neutron detector array with a charged-particle detector is given.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Wide Dynamic Range, 10 kHz Framing Detector for 4D-STEM

Hybrid pixel array detectors (PADs) have expanded the fidelity, frame rate and dynamic range for diffractive imaging in electron microscopes. With their high detective quantum efficiencies (DQE), the noise performance limited is by counting statistics. Consequently, improving the precision and quality of high-speed images requires increasing the linear dynamic range and the maximum usable beam current. Here we describe a new prototype hybrid PAD, our next-generation electron microscope pixel array detector (NG-EMPAD) that expands both the framing speed and dynamic range of our earlier EMPAD design. Like the EMPAD, electrons are detected directly in a 500 μm thick silicon sensor bonded pixel-by-pixel to a custom signal processing integrated circuit (IC). Each pixel in the IC integrates charge carriers produced by the high-energy incident electrons. Here, in-pixel circuitry uses a combination of techniques to extend the dynamic range, including adaptive gain switching and the quantitative excess charge dumping similar to the EMPAD. In-pixel buffering of signals during readout allows acquiring a new image while reading out the previously collected image, yielding an image collection duty cycle of nearly 100%.

36 MATERIALS SCIENCE↗
NASA NTRS2004

Measurements of K Shell Emission of Highly Charged Ions with the XRS at EBIT

The XRS/EBIT is a 32 channel microcalorimeter spectrometer operating at the electron beam ion trap (EBIT) facility at Lawrence Livermore National Laboratory. The system contains a flight candidate detector array from the XRS instrument for the Astro-E2 mission. The detector array in the XRS/EBIT is functionally identical to the flight array integrated into the XRS instrument and benefits from the enormous amount of calibration data from the XRS program. Since the XRSEBIT was upgraded with the new detector array in October 2003, the system has been used for a number of experiments including a survey of the K shell emission from He-like and H-like O, Ne, Ar, Fe, Ni and Kr as well as for L shell emission to measure the 3C/3D line ratio in Ni. Here we present some basic operational parameters of the instrument as well as direct excitation and simulated maxwellian spectra of He-like and E-like Fe. We show that the XRS instrument can resolve the Lyal and Lya2 lines from each other as well as from the dielectronic recombination satellites in thermal H-like Fe. We also show exactly how well the XRS instrument on Astro-E2 will resolve the thermal He-like triplet in collisionally excited Fe. This work was funded under NASA's Research Opportunities in Space Science program.

Porter, F. Scott↗
NASA NTRS2009

Ultra compact spectrometer apparatus and method using photonic crystals

The present invention is directed to methods of photonic crystal formation, and to methods and apparatus for using such photonic crystals, particularly in conjunction with detector arrays. Photonic crystal parameters and detector array parameters are compared to optimize the selection and orientation of a photonic crystal shape. A photonic crystal is operatively positioned relative to a plurality of light sensors. The light sensors can be separated by a pitch distance and positioned within one half of the pitch distance of an exit surface of the photonic crystals.

Ting, David Z.↗
NASA NTRS2017

Mechanical Design of a 4-Stage ADR for the PIPER mission

The four 1,280 bolometer detector arrays that will fly on the balloon borne PIPER mission will be cooled by a 4-stage adiabatic demagnetization refrigerator (ADR). Two of the three mechanically independent ADR assemblies provide thermal isolation to their salt pills through Kevlar suspensions while the other provides thermal isolation to its salt pill through the use of bellows and Vespel material. The ADR integrates with the detector arrays and it sits in a large bucket Dewar containing superfluid liquid helium. This paper will describe the complex mechanical design of the PIPER ADR, and summarize the mechanical analysis done to validate the design.The four 1,280 bolometer detector arrays that will fly on the balloon borne PIPER mission will be cooled by a 4-stage adiabatic demagnetization refrigerator (ADR). Two of the three mechanically independent ADR assemblies provide thermal isolation to their salt pills through Kevlar suspensions while the other provides thermal isolation to its salt pill through the use of bellows and Vespel material. The ADR integrates with the detector arrays and it sits in a large bucket Dewar containing superfluid liquid helium. This paper will describe the complex mechanical design of the PIPER ADR, and summarize the mechanical analysis done to validate the design.

Cryogenics↗
DOE OSTI2024

Development of an MKID frequency-to-pixel LED mapper for SPT-3G+

SPT-3G+ is the next-generation camera for the South Pole Telescope (SPT). SPT is designed to measure the cosmic microwave background (CMB) and the mm/sub-mm sky. The planned focal plane consists of 34,000 microwave kinetic inductance detectors (MKIDs), divided among three observing bands centered at 220, 285, and 345 GHz. Each readout line is designed to measure 800 MKIDs over a 500 MHz bandwidth, which places stringent constraints on the accuracy of the frequency placement required to limit resonator collisions that reduce the overall detector yield. To meet this constraint, we are developing a two-step process that first optically maps the resonance to a physical pixel location, and then next trims the interdigitated capacitor (IDC) to adjust the resonator frequency. We present a cryogenic LED apparatus operable at 300 mK for the optical illumination of SPT-3G+ detector arrays. We demonstrate integration of the LED controls with the GHz readout electronics (RF-ICE) to take data on an array of prototype SPT-3G+ detectors. We show that this technique is useful for characterizing defects in the resonator frequency across the detector array and will allow for improvements in the detector yield.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

First Time-Resolved Leader Spectra Associated With a Downward Terrestrial Gamma-Ray Flash Detected at the Telescope Array Surface Detector

Optical emissions associated with Terrestrial Gamma ray Flashes (TGFs) have recently become important subjects in space-based and ground-based observations as they can help us understand how TGFs are produced during thunderstorms. In this paper, we present the first time-resolved leader spectra of the optical component associated with a downward TGF. The TGF was observed by the Telescope Array Surface Detector (TASD) simultaneously with other lightning detectors, including a Lightning Mapping Array (LMA), an INTerFerometer (INTF), a Fast Antenna (FA), and a spectroscopic system. The spectroscopic system recorded leader spectra at 29,900 frames per second (33.44 μs time resolution), covering a spectral range from 400 to 900 nm, with 2.1 nm per pixel. The recordings of the leader spectra began 11.7 ms before the -18 kA return stroke and at a height of 2.37 km above the ground. These spectra reveal that optical emissions of singly ionized nitrogen and oxygen occur between 167 μs before and 267 μs after the TGF detection, while optical emissions of neutrals (H I, 656 nm; N I, 744 nm, and O I, 777 nm) occur right at the moment of the detection. The time-dependent spectra reveal differences in the optical emissions of lightning leaders with and without downward TGFs.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS2017

Characterization of Si-Membrane TES Bolometer Arrays for the HIRMES Instrument

The High Resolution Mid-Infrared Spectrometer (HIRMES) instrument will fly onboard NASA's airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) in 2019. HIRMES will provide astronomers with a unique observing window (25 122 µm) for exploring the evolution of protoplanetary disks into young solar systems, and the composition of our Solar System. There are two focal plane detector arrays for the instrument: a high-resolution (/ = 100,000) 8x16 detector array with a target noise-equivalent power, NEP 3x10-18 W/Hz; and a low-resolution (/ = 2,000 19,000) 16x64 detector array with a target NEP 2x10-17 W/Hz. The detectors for both of these arrays are superconducting Mo/Au bilayer transition edge sensor (TES) bolometers on thin suspended single-crystal silicon membranes. Here we present our characterization results for the detectors in both arrays, including measurements of thermal conductance with comparison to phonon transport models, saturation power, noise, and array uniformity.

Instrumentation and Photography↗
DOE OSTI2026

Design and commissioning of the Correlated Gamma-Neutron Array for sCattering (CoGNAC)

The Correlated Gamma-Neutron Array for sCattering (CoGNAC) is a dual $n$-$γ$ detector array fielded at the Weapons Neutron Research facility at the Los Alamos Neutron Science Center. Here, the detector array utilizes elpasolite detectors and liquid scintillators to perform measurements of neutron elastic and inelastic scattering cross sections and emitted particle angular distributions. This manuscript details the design and experimental setup of CoGNAC as well as some of the preliminary studies performed to select the elpasolite detectors deployed in the array. Examples of the analysis methods available to CoGNAC are given in the context of past CoGNAC measurements of neutron scattering reactions on 28 Si and 56 Fe.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

High Elevation Radiation Array (HERA) detectors for airborne thunderstorm investigations

A high-energy atmospheric physics phenomenon, referred to as a terrestrial gamma ray flash (TGF), is associated with lightning and produces large bursts of energetic photon radiation. TGFs will be investigated using a suite of gamma-ray instruments designed and constructed to fly on ten United States Air Force (USAF) WC-130J Hurricane Hunter aircraft as part of an aircrew ionization study led by the Air Force Institute of Technology (AFIT) and the United States Air Force School of Aerospace Medicine (USAFSAM), in cooperation with the 53rd Weather Reconnaissance Squadron (WRS). Each instrument consists of one NaI and one plastic detector, a GPS timing device, and an instrument computer that performs data acquisition. High Elevation Radiation Array (HERA) detectors will be employed to maximize the chances of observing TGFs near their source and to gain a better understanding of their origin, mechanism, ubiquity, and to assess potential hazards posed to military and commercial aircrew and passengers. The HERA program, deployed on 10 separate Air Force aircraft over a multi-year campaign, will result in thousands of observational flight hours and be the largest concerted effort to date to observe TGFs in situ through aircraft observations. In this paper, we give an overview of the scientific goals of this campaign and how the HERA instruments have been designed to meet those goals. Here, we include a detailed description of the HERA instrument, along with mass model and signal processing simulations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2006

Towards Dualband Megapixel QWIP Focal Plane Arrays

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 x 1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NEDT) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEDT of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In addition, we have demonstrated MWIR and LWIR pixel co-registered simultaneously readable dualband QWIP focal plane arrays. In this paper, we will discuss the performance in terms of quantum efficiency, NEDT, uniformity, operability, and modulation transfer functions of the 1024 x 1024 pixel arrays and the progress of dualband QWIP focal plane array development work.

Infrared detectors↗