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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1961

Quantum Yield of Gold-Cathode Photomultipliers

Two gold-cathode EMI 6255G tubes have been investigated for their quantum yield between 3100 and 1900 A. The tubes had cathodes of different appearances. One of these, numbered 3012, had a slight bluish tinge and was very transparent to visible light; the other, numbered 3021, had a definite gold coloration. The relative quantum yield of each tube was determined with the aid of a Cary model 14 recording spectrophotometer used as a monochromator. The monochromator relative-energy output was determined from the current output of a sodium-salicylate-coated RCA 1P21 photomultiplier. Each gold-cathode tube was then operated at 3000 v, and the central 1.8 cm cube of the cathode was exposed to the monochromator output.

Childs, Charles B.↗
NASA NTRS2019

Gated-Dynode Photomultiplier Tube Assembly for the Boronated Scintillator Detector of the ISS-CREAM Experiment

We present the design of a four-photomultiplier tube (PMT) assembly for measuring light generation in theBoronated Scintillator Detector (BSD) of the Cosmic Ray Energetics And Mass experiment for the InternationalSpace Station (ISS-CREAM). The light produced in the scintillator includes a contribution from the captureof thermalized neutrons produced in cosmic ray interactions, as well as delayed fluorescence, in the range ofseveral microseconds following the incident cosmic ray impact. The BSD is held in an insensitive state until acosmic-ray trigger causes a rapid turn on of the PMTs to detect late light signals, several microseconds afterthe trigger. The design includes two pulsed high-voltage supplies, which serve to gate the first two dynodesof the Hamamatsu R1924A PMTs used in the assembly. When the dynode gates are held in the "off" state,this scheme is shown to suppress >105 photons from injection into the tube's multiplier stage, while beingcapable of rapid switching into a stable operating mode in less than 1 s. This mitigates any backgroundsfrom afterpulsing that might otherwise be present in the PMT response following the cosmic ray incidence.

Anderson, T.↗
NASA NTRS1966

Improved design provides faster response time in photomultiplier

Dynamic Crossed-Field Electron Multiplying /DCFEM/ light demodulator avoids the normal response time limitations inherent in static field devices by using time varying crossed electric and static magnetic fields. This eliminates the transit time spread that affects electrons as they proceed along the secondary emission stages of the tube.

Source record↗
NASA NTRS1968

System measures response time of photomultiplier tubes

Calibration system enables precise determination of rise time of photosensitive detectors. To perform a calibration, the time-voltage curve of the excitation voltage for a light source is compared with the time-voltage curve of the voltage output from a photosensitive detector which is responding to the light.

Lauver, M. R.↗
NASA NTRS1970

Signal conditioner circuit for photomultiplier tube

Miniaturized circuit improves measurement of radiation dose absorbed in a scintillation crystal. The temperature coefficient of the field-effect transistor gate-source voltage in the isolation amplifier can be readily controlled.

Cellier, A.↗
NASA NTRS1971

Optical enhancement of photomultiplier sensitivity

Transmission and reflection light losses are reduced by introducing light into end-window of device at an angle large enough to normal so total internal reflection occurs at both photocathode-vacuum and window-air interfaces.

Grant, G. R.↗
NASA NTRS1972

Advanced infrared photomultiplier

Photocathode for the 8500 angstrom through 9000 angstrom range, improving efficiency by an order of magnitude, is achieved with a gallium arsenide cesium oxide photocathode. Protection of the GaAs surface from contamination during bake-out is another important function.

Sonnenberg, H.↗
NASA NTRS1982

Development of photomultiplier electronics and computer interfacing software for a high speed photoelectric photometer-Stoke's meter

Preliminary stages in the design, construction, and development of a photoelectric photometer system interfaced with an IMSAI 8080 microcomputer. The instrument will also include magnetic tape and magnetic disk storage capabilities to enable rapid data storage. The capability of the instrument to make observations with very high time resolution, as high as 10 msec, and measure the intensity and polarization of radiation emitted by objects which show very rapid light variations, pulsars and optical counterparts of X-ray sources was of concern. A better understanding of the magnetic fields and interstellar material which characterize the immediate environment of these stellar systems and an expansion of the observational capabilities of even modest-sized telescopes are expected.

Flesch, T. R.↗
NASA NTRS1982

A statistical model of the photomultiplier gain process with applications to optical pulse detection

A Markov diffusion model was used to determine an approximate probability density for the random gain. This approximate density preserves the correct second-order statistics and appears to be in reasonably good agreement with experimental data. The receiver operating curve for a pulse counter detector of PMT cathode emission events was analyzed using this density. The error performance of a simple binary direct detection optical communication system was also derived.

Tan, H. H.↗
NASA NTRS1982

A statistical model of the photomultiplier gain process with applications to optical pulse detection

A Markov diffusion model was used to determine an approximate probability density for the random gain. This approximate density preserves the correct second-order statistics and appears to be in reasonably good agreement with experimental data. The receiver operating curve for a pulse counter detector of PMT cathode emission events was analyzed using this density. The error performance of a simple binary direct detection optical communication system was also derived. Previously announced in STAR as N82-25100

Tan, H. H.↗
DOE OSTI2024

Phase II Final Technical Report | Neutron Dose Tolerant Solid-State Photomultiplier for Nuclear Imaging | Award Number DE-SC0021560 | Prepared for U.S. Department of Energy, Office of Science, SC-1 | For the Period April 4, 2022 – April 3, 2024 | Report Date July 31, 2024 | Submitted by Erik Johnson, Ph.D., Principal Investigator | Report Contributors Erik Johnson, Radiation Monitoring Devices, Inc., 44 Hunt Street, Watertown, MA 02472

Explore the source record for details and available documents.

Johnson, Erik↗
NASA NTRS1998

Signal-Induced Noise Effects in a Photon Counting System for Stratospheric Ozone Measurement

A significant source of error in making atmospheric differential absorption lidar ozone measurements is the saturation of the photomultiplier tube by the strong, near field light return. Some time after the near field light signal is gone, the photomultiplier tube gate is opened and a noise signal, called signal-induced noise, is observed. Research reported here gives experimental results from measurement of photomultiplier signal-induced noise. Results show that signal-induced noise has several decaying exponential signals, suggesting that electrons are slowly emitted from different surfaces internal to the photomultiplier tube.

Harper, David B.↗
NASA NTRS1973

Apparatus for photographing meteors

Apparatus for photographing meteors in a selected area of the sky is described. A photomultiplier is pointed in the direction of the area. When a meteor passes through the area the signal output of the photomultiplier increases. Means are provided that activate a camera, pointed at the area, in response to an increased signal from the photomultiplier. Hence, the camera photographs the selected are only while meteors are likely to be passing through the area.

Harvey, G. A.↗