SEARCH · Engineering Papers

Results for “direct detectors”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53

All sources NASA NTRS DOE OSTI

NASA NTRS1972

On the technology of aerospace communication in multipath.

The mechanism, effects, and modelling of multipath propagation, caused by rough earth reflection, are examined for aerospace communication. Emphasis is on binary digital signalling for aircraft and hybrid vehicles, such as Shuttle. The cases of direct Air-Ground and satellite relay (Aerosat) are treated. The recursive, adaptive, coherent Bayes detector for binary phase-shift-keying in nonselective multipath is presented. The derivation for the frequency-shift-keying detector is indicated.

Painter, J. H.↗

NASA NTRS1974

Doppler shift system

A system is described for measuring velocities of radiating particles based on Doppler shift. Light from the particles is directed through a narrow band optical filter to a Fabry-Perot interferometer initially tuned to a selected center line corresponding to zero particle Doppler shift. The movable mirror of the interferometer is made to sweep about the center line by the output of a modulation oscillator. The fringe pattern output is imaged onto a pin hole through which light is directed to a photomultiplier. The output of the photomultiplier is supplied to a phase sensitive detector with the oscillator output as a reference signal and which operates in the quadrature mode. The detector's output is gain controlled and is combined with the oscillator's output to adjust the interferometer's movable mirror to acquire the line center.

Aisenberg, S.↗

NASA NTRS1976

High resolution Fourier interferometer-spectrophotopolarimeter

A high-resolution Fourier interferometer-spectrophotopolarimeter is provided using a single linear polarizer-analyzer the transmission axis azimuth of which is positioned successively in the three orientations of 0 deg, 45 deg, and 90 deg, in front of a detector; four flat mirrors, three of which are switchable to either of two positions to direct an incoming beam from an interferometer to the polarizer-analyzer around a sample cell transmitted through a medium in a cell and reflected by medium in the cell; and four fixed focussing lenses, all located in a sample chamber attached at the exit side of the interferometer. This arrangement can provide the distribution of energy and complete polarization state across the spectrum of the reference light entering from the interferometer; the same light after a fixed-angle reflection from the sample cell containing a medium to be analyzed; and the same light after direct transmission through the same sample cell, with the spectral resolution provided by the interferometer.

Fymat, A. L.↗

NASA NTRS1983

System description

The VAS, carried onboard the GOES 4 and 5 satellites, is a radiometer with 8 visible channel detectors and 6 thermal detectors that detect infrared radiation in 12 spectral bands. A filter wheel in front of the detector is used to achieve the spectral selection. The spatial resolution is 0.9 kilometer in the visible and 7 or 14 kilometers in the infrared depending on the detector used. Full Earth disk coverage is accomplished by spinning in the west to east direction at 100 rpm and by stepping a scan mirror from north to south. Additional VAS instrument characteristics are summarized. The VAS has three operating modes: the operational VISSR mode, the multispectral imaging (MSI) mode, and the dwell sounding (DS) mode. The operational VISSR mode is used by NOAA/NESS for its operational products, which include a visible picture and an 11 micrometer infrared (channel 8) picture at half hour intervals. The other modes are VAS unique. The MSI mode combines the operational VISSR capability (visible plus infrared window) with two additional spectral channels to provide half hourly full Earth disk imagery of atmospheric water vapor, temperature, and cloud distribution. The DS mode is used primarily for sounding to obtain the temperature and moisture profiles. In this mode, multiple spins on the same scan line in a given band are averaged to obtain the required signal to noise ratio for sounding.

Montgomery, H.↗

NASA NTRS1986

Two complimentary methods for aligning linear arrays

Two approaches are presented for implementing a simple method for aligning the object and image planes of linear arrays of elemental detectors. Both variants begin by firing a laser beam into cubic beamsplitters which change the direction of the resulting parallel beams to one perpendicular to the array. A neutral density filter is located along the beam path and an optical microscope is located beyond the exit plane of the beamsplitters. In the first variant, the beam is tuned to the spectral sensitivity of the elements. In the second version, a lens and a microscope are situated outside the exit plane of the beamsplitters, and spectral tuning is unnecessary. Subsequent rotations of the array are shown to reveal the coincidence or lack of coincidence of the image plane and the linear array.

Finkel, Mitchell W.↗

NASA NTRS1986

The astrometric search for IR dwarfs

The authors are unaware of any current astrometric search for Brown (IR) Dwarfs; the few results available have come from studies directed toward other goals. Nevertheless, the lack of confirmable results is somewhat unexpected. New electronic detectors now in use at two observatories, as well as that of planned systems, have sufficient accuracy to detect IR dwarf companions to any of hundreds, in the latter case millions, of stars. However, because of the limited size of the astrometric program that can be supported by each instrument, the number of existing and planned astrometric facilities are insufficient for extensive surveys.

Gatewood, George↗

NASA NTRS1988

Rapid code acquisition algorithms employing PN matched filters

The performance of four algorithms using pseudonoise matched filters (PNMFs), for direct-sequence spread-spectrum systems, is analyzed. They are: parallel search with fix dwell detector (PL-FDD), parallel search with sequential detector (PL-SD), parallel-serial search with fix dwell detector (PS-FDD), and parallel-serial search with sequential detector (PS-SD). The operation characteristic for each detector and the mean acquisition time for each algorithm are derived. All the algorithms are studied in conjunction with the noncoherent integration technique, which enables the system to operate in the presence of data modulation. Several previous proposals using PNMF are seen as special cases of the present algorithms.

Su, Yu T.↗

NASA NTRS1992

The EGRET high energy gamma ray telescope

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (GRO) is sensitive in the energy range from about 20 MeV to about 30,000 MeV. Electron-positron pair production by incident gamma photons is utilized as the detection mechanism. The pair production occurs in tantalum foils interleaved with the layers of a digital spark chamber system; the spark chamber records the tracks of the electron and positron, allowing the reconstruction of the arrival direction of the gamma ray. If there is no signal from the charged particle anticoincidence detector which surrounds the upper part of the detector, the spark chamber array is triggered by two hodoscopes of plastic scintillators. A time of flight requirement is included to reject events moving backward through the telescope. The energy of the gamma ray is primarily determined by absorption of the energies of the electron and positron in a 20 cm deep NaI(Tl) scintillator.

Hartman, R. C.↗

NASA NTRS1994

Cosmic microwave background dipole spectrum measured by the COBE FIRAS instrument

The Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the Cosmic Background Explorer (COBE) has determined the dipole spectrum of the cosmic microwave background radiation (CMBR) from 2 to 20/cm. For each frequency the signal is decomposed by fitting to a monopole, a dipole, and a Galactic template for approximately 60% of the sky. The overall dipole spectrum fits the derivative of a Planck function with an amplitude of 3.343 +/- 0.016 mK (95% confidence level), a temperature of 2.714 +/- 0.022 K (95% confidence level), and an rms deviation of 6 x 10(exp -9) ergs/sq cm/s/sr cm limited by a detector and cosmic-ray noise. The monopole temperature is consistent with that determined by direct measurement in the accompanying article by Mather et al.

Fixsen, D. J.↗

NASA NTRS2007

Three-dimension imaging lidar

This invention is directed to a 3-dimensional imaging lidar, which utilizes modest power kHz rate lasers, array detectors, photon-counting multi-channel timing receivers, and dual wedge optical scanners with transmitter point-ahead correction to provide contiguous high spatial resolution mapping of surface features including ground, water, man-made objects, vegetation and submerged surfaces from an aircraft or a spacecraft.

Degnan, John J.↗

NASA NTRS2010

Characterization of LANDSAT Panels Using the NIST BRDF Scale from 1100 nm to 2500 nm

Many earth observing sensors depend on white diffuse reflectance standards to derive scales of radiance traceable to the St Despite the large number of Earth observing sensors that operate in the reflective solar region of the spectrum, there has been no direct method to provide NIST traceable BRDF measurements out to 2500 rim. Recent developments in detector technology have allowed the NIST reflectance measurement facility to expand the operating range to cover the 250 nm to 2500 nm range. The facility has been modified with and additional detector using a cooled extended range indium gallium arsenide (Extended InGaAs) detector. Measurements were made for two PTFE white diffuse reflectance standards over the 1100 nm to 2500 nm region at a 0' incident and 45' observation angle. These two panels will be used to support the OLI calibration activities. An independent means of verification was established using a NIST radiance transfer facility based on spectral irradiance, radiance standards and a diffuse reflectance plaque. An analysis on the results and associated uncertainties will be discussed.

Markham, Brian↗

NASA NTRS2011

Extended HXR Sources - Albedo Patches or Coronal Sources

Extended HXR sources in the presence of compact footpoints have been reported based on visibility amplitudes from different detectors. Attempts have been made to determine the location and extent of these sources through direct imaging. Results of this work will be described for simulated sources and for specific flares at different solar longitudes, with a discussion of the possible nature of the extended sources as either albedo patches or coronal sources or a combination of the two.

Dennis, Brian R.↗

NASA NTRS1972

The response of a 0.03-cm silicon detector to a mixed neutron and gamma field as a function of shield material and thickness

The neutron and gamma radiation from a MHW-RTG was used to evaluate the total response of a shielded 0.3-mm silicon detector. The generator employs a 2200 W(th) PuO2 heat source concept known as the HELIPAK. The total integrated neutron and gamma ray fluxes at 100 cm away from the source along the radial direction were 1.67 x 1,000 n/sq cm/s and 1.49 x 10,000 gamma sq cm/s, respectively. Experimental values of the response function of the shielded silicon detector were used to determine the total counting rates due to photons at bias energies ranging from 50 to 200 keV. For neutrons, analytically computed response functions were used to determine the total counting rates at the same bias energies. It was found that for an aluminum shield the neutrons are not significant, regardless of the thickness of the shield. However, the magnitude of the total counting rate due to neutrons increases with increased atomic number of the shield and becomes comparable to the counting rate due to photons for a platinum shield thickness of 5 cm.

Taherzadeh, M.↗

NASA NTRS2004

Accurate electromagnetic modeling of terahertz detectors

Twin slot antennas coupled to superconducting devices have been developed over the years as single pixel detectors in the terahertz (THz) frequency range for space-based and astronomy applications. Used either for mixing or direct detection, they have been object of several investigations, and are currently being developed for several missions funded or co-funded by NASA. Although they have shown promising performance in terms of noise and sensitivity, so far they have usually also shown a considerable disagreement in terms of performance between calculations and measurements, especially when considering center frequency and bandwidth. In this paper we present a thorough and accurate electromagnetic model of complete detector and we compare the results of calculations with measurements. Starting from a model of the embedding circuit, the effect of all the other elements in the detector in the coupled power have been analyzed. An extensive variety of measured and calculated data, as presented in this paper, demonstrates the effectiveness and reliability of the electromagnetic model at frequencies between 600 GHz and 2.5THz.

Hot Electron Bolometer (HEB)↗

DOE OSTI2023

Detectors in weakly-coupled field theories

We initiate a study of asymptotic detector operators in weakly-coupled field theories. These operators describe measurements that can be performed at future null infinity in a collider experiment. In a conformal theory they can be identified with light-ray operators, and thus have a direct relation to the spectrum of the theory. After a general discussion of the underlying physical picture, we show how infrared divergences of general detector operators can be renormalized in perturbation theory, and how they give rise to detector anomalous dimensions. We discuss in detail how this renormalization can be performed at the intersections of the Regge trajectories where non-trivial mixing occurs, which is related to the poles in anomalous dimensions at special values of spin. Finally, we discuss novel horizontal trajectories in scalar theories and show how they contribute to correlation functions. Our calculations are done in the example of Φ 4 theory in d = 4 - ϵ dimensions, but the methods are applicable more broadly. At the Wilson-Fisher fixed point our results include an explicit expression for the Pomeron light-ray operator at two loops, as well as a prediction for the value of the Regge intercept at five loops.

47 OTHER INSTRUMENTATION↗

NASA NTRS1982

A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

Hartig, G. F.↗

NASA NTRS1982

Photon counting photodiode array detector for far ultraviolet (FUV) astronomy

Hartig, G. F.↗

DOE OSTI2026

iDDS: intelligent distributed dispatch and scheduling for workflow orchestration

The intelligent distributed dispatch and scheduling (iDDS) service is a versatile workflow orchestration system designed for large-scale, distributed scientific computing. iDDS extends traditional workload and data management by integrating data-aware execution, conditional logic, and programmable workflows, enabling automation of complex and dynamic processing pipelines. Originally developed for the ATLAS experiment at the large hadron collider, iDDS has evolved into an experiment-agnostic platform that supports both template-driven workflows and a Function-as-a-Task model for Python-based orchestration. This paper presents the architecture and core components of iDDS, highlighting its scalability, modular message-driven design, and integration with systems such as PanDA and Rucio. We demonstrate its versatility through real-world use cases: fine-grained tape resource optimization for ATLAS, orchestration of large Directed Acyclic Graph (DAG) workflows for the Rubin Observatory, distributed hyperparameter optimization for machine learning applications, active learning for physics analyses, and AI-assisted detector design at the electron–ion collider. By unifying workload scheduling, data movement, and adaptive decision-making, iDDS reduces operational overhead and enables reproducible, high-throughput workflows across heterogeneous infrastructures. We conclude with current challenges and future directions, including interactive, cloud-native, and serverless workflow support.

97 MATHEMATICS AND COMPUTING↗