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We have developed a new thin-window, n-type, low-resistivity, spiral silicon drift detector (SDD) array - to be used as an extraterrestrial X-ray spectrometer (in varying environments) for NASA. To achieve low-energy response, a thin SDD entrance window was produced using a previously developed method. These thin-window devices were also produced on lower(More)
A time projection chamber for experiments with the laser electron gamma source is being developed. It is composed of a can and a single-ended, dual-stage gas electron multiplier, with associated anode plane pixellated into about 8000 pads. The front-end electronics must provide energy, timing, and address information from those pads involved in measuring(More)
  • G. C. Smith
  • IEEE Transactions on Ultrasonics, Ferroelectrics…
  • 2005
A noncontact method for detecting acoustic emission was developed, using a microwave Doppler radar detector and an active band-pass filter. A theoretical model was developed and a prototype sensor was built and tested. The prototype responds to acoustic emissions (AE), from pencil lead break tests, at ranges up to 1.5 feet.
Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded-aperture thermal-neutron imaging system. Timing signals from the(More)
We describe initial results from a new technical approach aimed at providing advanced, two-dimensional, thermal neutron detectors for high rate applications at new facilities such as the Spallation Neutron Source. The concept is based on neutron conversion in <sup>3</sup>He. The gas mixture is contained in a grid-less ionization chamber, with the conversion(More)
A theoretical and experimental study is report-ed of the gain of microchannel plate (MCP) electron multipliers under conditions of output charge satur-ation. Theoretical calculations, assuming a wall charge saturation mechanism, are used to interpret peak gain and pulse height distribution FWHM data obtained with a number of chevron MCP multipliers. A(More)
Advanced neutron detectors for experiments at new spallation sources will require greater counting rate capabilities than previously attainable. This necessitates careful design of both detector and readout electronics. As part of a new instrument for protein crystallography at LANSCE, we are constructing a detector whose concept was described previously(More)
Measurements have been made of x-ray position resolution in a proportional chamber with both Kr/10% CO<sub>2/sub> and Xe/10% CO<sub>2/sub>, for the x-ray energy region 17-25 keV. Position resolutions in the range of 18-50&#x003BC;m (FWHM) are obtained in krypton, and in the range 50-100 &#x003BC;m (FWHM) for xenon. These results are interpreted in terms of(More)
The commonly used dielectrics, Y<inf>2</inf>O<inf>3</inf>, Al<inf>2</inf>O<inf>3</inf>, Si<inf>3</inf>N<inf>4</inf>, and Ta<inf>2</inf>O<inf>5</inf>, were evaluated for use in ac thin-film electroluminescent displays, along with a composite dielectric SiAlON. Adhesion, stress cracking, charge storage capacity, and display brightness and efficiency were(More)