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Detectors with microchannel plates (MCPs) provide unique capabilities to detect single photons with high spatial (<10 µm) and timing (<25 ps) resolution. Although this detection technology was originally developed for applications with low event rates, recent progress in readout electronics has enabled their operation at substantially higher rates by simultaneous detection of multiple particles. In this study, the potential use of MCP detectors with Timepix readout for soft X-ray imaging and spectroscopic applications where the position and time of each photon needs to be recorded is investigated. The proof-of-principle experiments conducted at the Advanced Light Source demonstrate the capabilities of MCP/Timepix detectors to operate at relatively high input counting rates, paving the way for the application of these detectors in resonance inelastic X-ray scattering and X-ray photon correlation spectroscopy (XPCS) applications. Local count rate saturation was investigated for the MCP/Timepix detector, which requires optimization of acquisition parameters for a specific scattering pattern. A single photon cluster analysis algorithm was developed to eliminate the charge spreading effects in the detector and increase the spatial resolution to subpixel values. Results of these experiments will guide the ongoing development of future MCP devices optimized for soft X-ray photon-counting applications, which should enable XPCS dynamics measurements down to sub-microsecond timescales.

Detectors with microchannel plates (MCPs) provide unique capabilities to detect single photons with high spatial (<10 µm) and timing (<25 ps) resolution. Although this detection technology was originally developed for applications with low event rates, recent progress in readout electronics has enabled their operation at substantially higher rates by simultaneous detection of multiple particles. In this study, the potential use of MCP detectors with Timepix readout for soft X-ray imaging and spectroscopic applications where the position and time of each photon needs to be recorded is investigated. The proof-of-principle experiments conducted at the Advanced Light Source demonstrate the capabilities of MCP/Timepix detectors to operate at relatively high input counting rates, paving the way for the application of these detectors in resonance inelastic X-ray scattering and X-ray photon correlation spectroscopy (XPCS) applications. Local count rate saturation was investigated for the MCP/Timepix detector, which requires optimization of acquisition parameters for a specific scattering pattern. A single photon cluster analysis algorithm was developed to eliminate the charge spreading effects in the detector and increase the spatial resolution to subpixel values. Results of these experiments will guide the ongoing development of future MCP devices optimized for soft X-ray photon-counting applications, which should enable XPCS dynamics measurements down to sub-microsecond timescales.

We report on the response of microchannel plates (MCPs) to single relativistic particles and to electromagnetic showers. Particle detection by means of secondary emission of electrons at the MCP surface has long been proposed and is used extensively in ion time-of-flight mass spectrometers. What has not been investigated in depth is their use to detect the ionizing component of showers. The time resolution of MCPs exceeds anything that has been previously used in calorimeters and, if exploited effectively, could aid in the event reconstruction at high luminosity colliders. Several prototypes of photodetectors with the amplification stage based on MCPs were exposed to cosmic rays and to 491 MeV electrons at the INFN-LNF Beam-Test Facility. The time resolution and the efficiency of the MCPs are measured as a function of the particle multiplicity, and the results used to model the response to high-energy showers., SCOPUS: ar.j, info:eu-repo/semantics/published

The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study., QC 20150611

The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study.

The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study.

The NIF is the world's most powerful laser facility and is used for inertial confinement fusion experiments. One hundred and ninety two laser beams are used to compress a small capsule. X-ray framing cameras are an important diagnostic used to help characterize the dynamics of the capsule. The gated x-ray framing cameras consists of several key components including a pin hole array, microstrips, microchannel plate (MCP), pulsed phosphor, and either film pack or CCD for recording images [1]. The pin hole array is a thin piece of tantalum with small holes used to shield most of the incident x-rays, but allows some to be projected onto a microstrip/MCP. When photons strike the microstrip/MCP photoelectrons are created which can be accelerated through pores in the MCP by pulses on the microstrips. The electrons are amplified in the pores by a secondary electron cascade. At the output of the MCP the electrons are accelerated to a phosphor screen where the output is recorded. The x-ray framing cameras have provided excellent information. As the yields at NIF have increased and the data provided by the framing cameras have been further resolved, some streak artifacts were discovered that needed further understanding [2]. A theory was proposed as to the origin of these artifacts [2], as well as a mitigation strategy [2]. In this paper we will discuss the results of electrostatic, full wave electromagnetic, and particle-in-cell simulations used to further understand the streaks in the data as well as simulation results for the mitigation strategy used to help correct the problem. We will also discuss some simulation results that illustrate potential enhancements for future framing cameras., See also ADM002371. 2013 IEEE Pulsed Power Conference, Digest of Technical Papers 1976-2013, and Abstracts of the 2013 IEEE International Conference on Plasma Science. IEEE International Pulsed Power Conference (19th). Held in San Francisco, CA on 16-21 June 2013, The original document contains color images.

AEGIS (Antimatter Experiment, Gravity, Interferometry and Spectroscopy) isan experiment under development at CERN which will measure earth's gravitationalforce on antimatter. This will be done by creating a horizontal pulsedbeam of low energy antihydrogen, an atom consisting of an antiproton anda positron. The experiment will measure the vertical de ection of the beamthrough which it is possible to calculate the gravitational constant for antimatter.To characterise the production process in the current state of the experimentit is necessary to develop an imaging detector for single excited hydrogenatoms. This thesis covers the design phase of that detector and includes studiesand tests of detector components. Following literature studies, tests and havingdiscarded several potential designs, a baseline design was chosen. The suggesteddetector will contain a set of ionising rings followed by an electron multiplyingmicrochannel plate, a light emitting phosphor screen, a lens system and nallya CCD camera for readout. The detector will be able to detect single hydrogenatoms, measure their time of ight as well as being able to image electronplasmas and measure the time of ight of the initial particles in such a plasma.Tests were made to determine the behaviour of microchannel plates at the lowtemperatures used in the experiment. Especially, the resistance and multiplicationfactor of the microchannel plates have been measured at temperaturesdown to 14 K., AEGIS

AEGIS (Antimatter Experiment, Gravity, Interferometry and Spectroscopy) isan experiment under development at CERN which will measure earth's gravitationalforce on antimatter. This will be done by creating a horizontal pulsedbeam of low energy antihydrogen, an atom consisting of an antiproton anda positron. The experiment will measure the vertical de ection of the beamthrough which it is possible to calculate the gravitational constant for antimatter.To characterise the production process in the current state of the experimentit is necessary to develop an imaging detector for single excited hydrogenatoms. This thesis covers the design phase of that detector and includes studiesand tests of detector components. Following literature studies, tests and havingdiscarded several potential designs, a baseline design was chosen. The suggesteddetector will contain a set of ionising rings followed by an electron multiplyingmicrochannel plate, a light emitting phosphor screen, a lens system and nallya CCD camera for readout. The detector will be able to detect single hydrogenatoms, measure their time of ight as well as being able to image electronplasmas and measure the time of ight of the initial particles in such a plasma.Tests were made to determine the behaviour of microchannel plates at the lowtemperatures used in the experiment. Especially, the resistance and multiplicationfactor of the microchannel plates have been measured at temperaturesdown to 14 K., AEGIS

In this study, experiments have been performed in order to examine two-phase flow boiling in a silicon microgap based heat sink having gap height of 190 microns, 285 microns and 380 microns, using water with inlet temperature of 86 degrees C. The effects of mass flux and heat flux on heat transfer coefficient and pressure drop characteristics were examined by varying mass flux ranging from 420 Kg/square m s to 970 Kg/square m s and effective heat flux up to 100 W/square cm. An array of integrated micro-temperature sensors allows local heat transfer coefficients to be determined. The fluid temperatures and pressure drop across the microgap array were also measured. The size effects on different parameters have been investigated. The extensive microgap boiling experiments and analysis has led to some important findings listed in this final report.

The sensitivity (limit of detection) of high-resolution Rutherford backscattering spectroscopy (HRBS) is mainly determined by the background noise of the spectrometer. There are two major origins of the background noise in HRBS, one is the stray ions scattered from the inner wall of the vacuum chamber of the spectrometer and the other is the dark noise of the microchannel plate (MCP) detector which is commonly used as a focal plane detector of the spectrometer in HRBS. In order to reject the stray ions, several barriers are installed inside the spectrometer and a thin Mylar foil is mounted in front of the detector. The dark noise of the MCP detector is rejected by the coincidence measurement with the secondary electrons emitted from the Mylar foil upon the ion passage. After these improvements, the background noise is reduced by a factor of 200 at a maximum. The detection limit can be improved down to 10 ppm for As in Si at a measurement time of 1 h under ideal conditions.

This report details the design, fabrication and testing of a new class of micro-channel reactors, combining benefits of (i) micromachining for realizing complex, two-dimensional radial distribution patterns for heat transfer and process intensification, and (ii) extrusion for versatile fabrication of scalable micro-channel networks over a range of thermal, mechanical and catalytic properties not currently achievable by current microreactor fabrication methods. This research effort resulted in the successful development of a new class of compact, cost-effective ceramic microreaders for thermal integration. The combination of materials selection and integration architecture enables unparalleled manipulation of three-dimensional thermal profiles for enhancing heat integration in microchemical systems. Experimental efforts demonstrated the ability to realize axial self-insulation with stable thermal gradients in excess of 300 degrees C, with radial thermal profiles in excess of 100 degrees C. In the absence of external insulation of any kind, hydrogen yields of 30% were achieved. Further refinements in system insulation, combustion flame mitigation and distributor designs are expected.

Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to generate a siloxane surface that provided a scaffold for antibody immobilization. AlexaFluor-cadaverine-trinitrobenzene (AlexaFluor- Cad-TNB) was used as the reporter molecule in a displacement immunoassay. The limit of detection was 1-10 ng/mL (ppb) with a linear dynamic range that covered three orders of magnitude. In addition, antibody crossreactivity was investigated using hexahydro-1,3,5- triazine (RDX), HMX, 2,4-dinitrotoluene (DNT), 4-nitrotoluene (4-NT) and 2-amino-4,6- DNT., Published in Sensors, v10 p876-889, Jan 2010. Funded under project title "Bio/Chemical Sensors for Underwater Threat Detection". The original document contains color images. All DTIC reproductions will be in black and white.

This project synthesized active mesoporous silicas with nanospaces to immobilize proteins or fragments of DNA to determine their biosensing utility via electrochemical and spectroscopic methods., Prepared in collaboration with the Department of Chemistry, Washington University, St. Louis, MO.

Nanomechanical resonators with their extremely small mass and high surface/volume ratio present a unique opportunity for mass sensing[1-4]. However, functionalization with selective vapor adsorptive functional groups has been an impediment to the realization of nanomechanical systems for mass sensing. Functional groups that adsorb analytes of interest should be patterned only on the nanoresonator itself, and should not be located on structural elements or micro-channel walls, which would greatly limit the minimum detectible limit of the overall device. Also, traditional spin cast polymer films present the problem of being many times thicker than the nanomechanical resonator, essentially burying the resonator in the adsorptive polymer and completely damping the resonator. To address this, we are using a generic monolayer functionalization scheme based on a UV-mediated reaction between terminal alkenes and a hydrogen terminated silicon surface[5]. Specifically, we report the selective surface functionalization with a vapor adsorptive monolayer of hexafluoro-dimethylcarbinol on polycrystalline silicon nanomechanical resonators., See also ADM002137. Presented at the Proceedings of the 2008 IEEE International Conference on Nanotechnology (8th) held in Arlington, TX on 18-21 Aug 2008. Published in the Proceedings of the 2008 IEEE International Conference on Nanotechnology, Aug 2008. U.S. Government or Federal Rights License

Computations of operating temperatures in micro-fabricated upper-millimeter-wave sheet beam traveling wave structures are provided. The studies include the effects of different cooling techniques and construction materials. The scaling of output power capability vs. frequency, as constrained by thermal limits, is also presented., See also ADM002087. Presented at the IEEE International Vacuum Electronic Conference (9th), (IVEC-2008), held in Monterey, CA on 22-24 April 2008. Published in the proceedings of the conference, p50-51, 2008. U.S. Government or Federal Rights License. The original document contains color images.

Microscale combustion is of interest in small-volume energy-demanding systems, such as power supplies, actuation, ignition, and propulsion. Energetic materials can have high burning rates that make these materials advantageous, especially for microscale applications in which the rate of energy release is important or in which air is not available as an oxidizer. In this study we examine the combustion of mixtures of nanoscale aluminum with molybdenum trioxide in microscale channels. Nanoscale composites can have very high burning rates that are much higher than typical materials. Quartz and acrylic tubes are used. Rectangular steel microchannels are also considered. We find that the optimum mixture ratio for the maximum propagation rate is aluminum rich. We use equilibrium calculations to argue that the propagation rate is dominated by a convective process where hot liquids and gases are propelled forward heating the reactants. This is the first study to report the dependence of the propagation rate with a tube diameter for this class of materials.Wefind that the propagation rate decreases linearly with 1=d. The propagation rate remains high in tubes or channels with dimensions down to the scale of 100 m, which makes these materials applicable to microcombustion applications., Published in Journal of Propulsion and Power, v23 n4 p715-721, July-August 2007. Sponsored in part by DOE.

We have newly completed a MicroChannel Plate (MCP) evaluation system, in addition to our existing large-MCP mounting system. We developed an improved computational model and conceptual understanding of MCP performance. We also propose to participate in hydrodynamic experiments at NRL whenever they occur, to prepare for an experiment for NIKE to study the onset of turbulence via the Kelvin Helmholtz instability, and if circumstances permit to conduct such an experiment., The original document contains color images. All DTIC reproductions will be in black and white.

A conical surface roughness model applicable to particle simulations has been developed. The model has been experimentally validated for channel flows using helium and nitrogen gases at Reynolds numbers from 0.01 to 10 based on inlet conditions. To efficiently simulate gas-surface interaction, molecular collisions with the actual rough surface are simulated by collisions with a randomly positioned conical hole having a fixed opening angle. This model requires only one surface parameter, average surface roughness angle. This model has also been linked to the Cercignani-Lampis scattering kernel as a required reference for use in deterministic kinetic solvers. Experiments were conducted on transitional flows through a 150-micron tall, 1cm wide, 1.5cm long microchannel where the mean free path is on the order of the roughness size. The channel walls were made of silicon with: (i) polished smooth surfaces, (ii) regular triangular roughness, and (iii) regular square roughness with characteristic roughness scales. For the triangular roughness, mass flow reductions ranged from 6% at the higher stagnation pressures tested to 25% at the lower stagnation pressures tested when compared to the smooth channel., Submitted for publication in Physics and Fluids. Prepared in collaboration with University of Southern California (USC), Los Angeles, CA, and ERC, Inc., Edwards AFB, CA.

This thesis deals with the development and calibrations of sensors to measure energetic neutral atoms (ENAs) at Mars, Venus, and the Earth. ENAs are formed in charge exchange processes between energetic, singly--charged ions and a cold neutral gas. Since ENAs can travel in long straight trajectories, unaffected by electric or magnetic fields, they can be used to remotely image plasma interactions with neutral atmospheres. ENA instrument techniques have matured over the last decade and ENA images of the Earth's ring current for example, have successfully been analyzed to extract ion distributions and characterize plasma flows and currents in the inner magnetosphere. Three different ENA sensors have been developed to image ENAs at Mars, Venus, and the Earth. Two of them, the nearly identical Neutral Particle imagers (NPIs) are on-board the Mars Express and Venus Express spacecraft as a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3 and 4) instruments. The third is the Neutral Atom Detector Unit, NUADU, aboard the TC-2 spacecraft of the Double Star mission. The NPI design is based on a surface reflection technique to measure low energy (~0.3-60 keV) ENAs, while the NUADU instrument is based on a simple design with large geometrical factor and solid state detectors to measure high energy ENAs (~20-300 keV). The calibration approach of both NPI sensors were to define the detailed response, including properties such as the angular response function and efficiency of one reference sensor direction then find the relative response of the other sensor directions. Because of the simple geometry of the NUADU instrument, the calibration strategy involved simulations to find the cutoff energy, geometrical factor and angular response. The NUADU sensor head was then calibrated to find the response to particles of different mass and energy. The NPI sensor for the Mars Express mission revealed a so-called priority effect in the sensor that lowers the angular reso

This thesis deals with the development and calibrations of sensors to measure energetic neutral atoms (ENAs) at Mars, Venus, and the Earth. ENAs are formed in charge exchange processes between energetic, singly--charged ions and a cold neutral gas. Since ENAs can travel in long straight trajectories, unaffected by electric or magnetic fields, they can be used to remotely image plasma interactions with neutral atmospheres. ENA instrument techniques have matured over the last decade and ENA images of the Earth's ring current for example, have successfully been analyzed to extract ion distributions and characterize plasma flows and currents in the inner magnetosphere. Three different ENA sensors have been developed to image ENAs at Mars, Venus, and the Earth. Two of them, the nearly identical Neutral Particle imagers (NPIs) are on-board the Mars Express and Venus Express spacecraft as a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3 and 4) instruments. The third is the Neutral Atom Detector Unit, NUADU, aboard the TC-2 spacecraft of the Double Star mission. The NPI design is based on a surface reflection technique to measure low energy (~0.3-60 keV) ENAs, while the NUADU instrument is based on a simple design with large geometrical factor and solid state detectors to measure high energy ENAs (~20-300 keV). The calibration approach of both NPI sensors were to define the detailed response, including properties such as the angular response function and efficiency of one reference sensor direction then find the relative response of the other sensor directions. Because of the simple geometry of the NUADU instrument, the calibration strategy involved simulations to find the cutoff energy, geometrical factor and angular response. The NUADU sensor head was then calibrated to find the response to particles of different mass and energy. The NPI sensor for the Mars Express mission revealed a so-called priority effect in the sensor that lowers the angular reso

This thesis deals with the development and calibrations of sensors to measure energetic neutral atoms (ENAs) at Mars, Venus, and the Earth. ENAs are formed in charge exchange processes between energetic, singly--charged ions and a cold neutral gas. Since ENAs can travel in long straight trajectories, unaffected by electric or magnetic fields, they can be used to remotely image plasma interactions with neutral atmospheres. ENA instrument techniques have matured over the last decade and ENA images of the Earth's ring current for example, have successfully been analyzed to extract ion distributions and characterize plasma flows and currents in the inner magnetosphere. Three different ENA sensors have been developed to image ENAs at Mars, Venus, and the Earth. Two of them, the nearly identical Neutral Particle imagers (NPIs) are on-board the Mars Express and Venus Express spacecraft as a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3 and 4) instruments. The third is the Neutral Atom Detector Unit, NUADU, aboard the TC-2 spacecraft of the Double Star mission. The NPI design is based on a surface reflection technique to measure low energy (~0.3-60 keV) ENAs, while the NUADU instrument is based on a simple design with large geometrical factor and solid state detectors to measure high energy ENAs (~20-300 keV). The calibration approach of both NPI sensors were to define the detailed response, including properties such as the angular response function and efficiency of one reference sensor direction then find the relative response of the other sensor directions. Because of the simple geometry of the NUADU instrument, the calibration strategy involved simulations to find the cutoff energy, geometrical factor and angular response. The NUADU sensor head was then calibrated to find the response to particles of different mass and energy. The NPI sensor for the Mars Express mission revealed a so-called priority effect in the sensor that lowers the angular reso

This thesis deals with the development and calibrations of sensors to measure energetic neutral atoms (ENAs) at Mars, Venus, and the Earth. ENAs are formed in charge exchange processes between energetic, singly--charged ions and a cold neutral gas. Since ENAs can travel in long straight trajectories, unaffected by electric or magnetic fields, they can be used to remotely image plasma interactions with neutral atmospheres. ENA instrument techniques have matured over the last decade and ENA images of the Earth's ring current for example, have successfully been analyzed to extract ion distributions and characterize plasma flows and currents in the inner magnetosphere. Three different ENA sensors have been developed to image ENAs at Mars, Venus, and the Earth. Two of them, the nearly identical Neutral Particle imagers (NPIs) are on-board the Mars Express and Venus Express spacecraft as a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3 and 4) instruments. The third is the Neutral Atom Detector Unit, NUADU, aboard the TC-2 spacecraft of the Double Star mission. The NPI design is based on a surface reflection technique to measure low energy (~0.3-60 keV) ENAs, while the NUADU instrument is based on a simple design with large geometrical factor and solid state detectors to measure high energy ENAs (~20-300 keV). The calibration approach of both NPI sensors were to define the detailed response, including properties such as the angular response function and efficiency of one reference sensor direction then find the relative response of the other sensor directions. Because of the simple geometry of the NUADU instrument, the calibration strategy involved simulations to find the cutoff energy, geometrical factor and angular response. The NUADU sensor head was then calibrated to find the response to particles of different mass and energy. The NPI sensor for the Mars Express mission revealed a so-called priority effect in the sensor that lowers the angular reso

This thesis deals with the development and calibrations of sensors to measure energetic neutral atoms (ENAs) at Mars, Venus, and the Earth. ENAs are formed in charge exchange processes between energetic, singly--charged ions and a cold neutral gas. Since ENAs can travel in long straight trajectories, unaffected by electric or magnetic fields, they can be used to remotely image plasma interactions with neutral atmospheres. ENA instrument techniques have matured over the last decade and ENA images of the Earth's ring current for example, have successfully been analyzed to extract ion distributions and characterize plasma flows and currents in the inner magnetosphere. Three different ENA sensors have been developed to image ENAs at Mars, Venus, and the Earth. Two of them, the nearly identical Neutral Particle imagers (NPIs) are on-board the Mars Express and Venus Express spacecraft as a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3 and 4) instruments. The third is the Neutral Atom Detector Unit, NUADU, aboard the TC-2 spacecraft of the Double Star mission. The NPI design is based on a surface reflection technique to measure low energy (~0.3-60 keV) ENAs, while the NUADU instrument is based on a simple design with large geometrical factor and solid state detectors to measure high energy ENAs (~20-300 keV). The calibration approach of both NPI sensors were to define the detailed response, including properties such as the angular response function and efficiency of one reference sensor direction then find the relative response of the other sensor directions. Because of the simple geometry of the NUADU instrument, the calibration strategy involved simulations to find the cutoff energy, geometrical factor and angular response. The NUADU sensor head was then calibrated to find the response to particles of different mass and energy. The NPI sensor for the Mars Express mission revealed a so-called priority effect in the sensor that lowers the angular reso

Micromachined silica microchannel plates (MCPs) under development have a number of advantages over standard glass MCPs and open completely new possibilities in detector technologies. In this article we present the results of our studies on the thermal properties of silica microchannel plates (sMCPs). Similar to standard glass microchanel plates the resistance of silica MCPs was measured to change exponentially with temperature with a negative thermal coefficient of -0.036 per degreesC, somewhat larger than that of standard glass MCPs. The resistance also decreases linearly with the applied voltage, with the voltage coefficient of -3.1x10(-4) V-1. With the knowledge of these two coefficients, our thermal model allows the calculation of the maximum voltage, which can be applied to a given MCP without inducing a thermal runaway. A typical 25 mm diam, 240 mum thick sMCP with 6 mum pores has to have the resistance larger than similar to30 MOmega to operate safely at voltages up to 800 V. With this model we can also calculate the time required for a given silica MCP to reach the point of thermal equilibrium after a voltage increase. We hope that the ongoing efforts on a proper modification of the sMCP semiconducting layer will lead to the production of new MCPs with a small negative or even a positive thermal coefficient, reducing the possibility of thermal runaways of low-resistance MCPs required for high count rate applications. (C) 2004 American Institute of Physics.

Micromachined silica microchannel plates (MCPs) under development have a number of advantages over standard glass MCPs and open completely new possibilities in detector technologies. In this article we present the results of our studies on the thermal properties of silica microchannel plates (sMCPs). Similar to standard glass microchanel plates the resistance of silica MCPs was measured to change exponentially with temperature with a negative thermal coefficient of -0.036 per degreesC, somewhat larger than that of standard glass MCPs. The resistance also decreases linearly with the applied voltage, with the voltage coefficient of -3.1x10(-4) V-1. With the knowledge of these two coefficients, our thermal model allows the calculation of the maximum voltage, which can be applied to a given MCP without inducing a thermal runaway. A typical 25 mm diam, 240 mum thick sMCP with 6 mum pores has to have the resistance larger than similar to30 MOmega to operate safely at voltages up to 800 V. With this model we can also calculate the time required for a given silica MCP to reach the point of thermal equilibrium after a voltage increase. We hope that the ongoing efforts on a proper modification of the sMCP semiconducting layer will lead to the production of new MCPs with a small negative or even a positive thermal coefficient, reducing the possibility of thermal runaways of low-resistance MCPs required for high count rate applications. (C) 2004 American Institute of Physics.

Increasing attention is being given to partial wetting of micro-channels in MEMS micro-fluidic devices, such as pressure sensors and accelerometers. The behavior of liquids that have contact angles with a solid surface greater than zero but less then 180 degrees is also relevant to many other technologies. Moreover, when the solid surface is not perfectly smooth, liquid contact with that surface is poorly understood and the subject of considerable misconception. When the contact angle is between zero and 90 degrees, the liquid is traditionally said to "wet" the capillary wall and it will enter the capillary on its own accord. Pressure is then needed to expel it from the capillary. If the contact angle is between 90 degrees and 180 degrees, the fluid is termed "non-wetting" and pressure is needed to force it into the capillary. When capillary geometry is allowed to vary, the traditional concepts of wetting and nonwetting must be carefully examined. The authors conducted an experiment to clarify this point. A drop of mercury was placed directly over the juncture of two horizontal glass plates. The plates were mounted in an apparatus designed to keep their upper edges firmly together during rotation, thereby maintaining a sharp interstice. The mercury on the two plates formed a symmetric sessile drop having a contact angle of 140 degrees. When the right plate was rotated so that the angle between the two plates was 135 degrees, the outer surface of the mercury drop assumed a modified sessile-drop curvature, but the juncture between the two plates was still filled. When rotation continued until the included angle was 60 degrees, the outer surface was still asymmetric, but the interstice was no longer filled. The experiment was repeated with a mercury drop on a nonsmooth surface having a 110 degree included angle and with water on a surface having 50 degree and 8 degree included angles. (7 figures, 22 refs.)

We propose to study the appropriate wake environment and support the development of detectors for the Charge Hazards and Wake Studies (CHAWS) Missions. Both computer simulations of the detector and laboratory calibrations will be performed. The proposed detector will consist of a high energy resolution Retarding Potential Energy Analyzer and a high spatial resolution drift chamber with MicroChannel Plates. The electric field inside the detector is designed such that the one-to-one correspondence between the incident ion and the collected signal is guaranteed. A fluid dynamic model will be set up to study the effect of the secondary electron, the backscattering, and the negative ion trapping on the potential profile and ion trajectories in the wake. The results of the fluid dynamic model will be compared to hat from the other models. The CHAWS results will be analyzed based on the simulation, including the secondary effects and the time evolution of the plasma parameters. The position of the probes and the operational time sequence of these probes will be modified for best performance.

The goal of this research is to fabricate X-ray mammography screens with dramatically increased contrast/resolution capabilities. A conventional X-ray phosphor screen has a thickness of about 50 to 200 microns and consists of phosphor particles with a mean size between 3 to 10 microns. The light generated in the phosphor screen by the incident X-rays scatters over the thickness of the screen material. As the light scatters, it spreads out which results in loss of spatial resolution and contrast. To overcome the severe light scattering that stems from the phosphor screen thickness, without compromise in X-ray absorption, two approaches have been rigorously investigated. The first approach is to manufacture screens based on a novel type of efficient phosphors: nanocrystalline phosphors. The second approach is to fill microchannel plates with nanocrystalline or micron-sized phosphors. The X-ray-induced light is now transmitted and confined within the microchannel, which operates like an optical-fiber waveguide. Under X-ray excitation, the nanocrystalline phosphors exhibited luminescence efficiency that is 25% of the standard phosphors. Line-pair-phantom images, obtained from standard-phosphor-filled microchannel-plates of 10 microns diameter size, exhibited a resolution of 40-lp/mm. This resolution is twice that of analog screen/film systems currently used in mammography.

A device for scanning in a scanning axis includes a periodic array of conductive plates disposed along the scanning axis. The device has a periodic array of ferroelectric material slabs disposed along the scanning axis, each slab being disposed between a pair of adjacent conductive plates,adjacent slabs being separated by one of conductive plates. Each of the slabs has a receiving face and a radiating face substantially parallel to each other. Input transmission means feed an input electromagnetic signal to the periodic array of slabs in a propagation direction so that the input electromagnetic signal is incident on the receiving faces of the slabs and so that the electrical component of the input electromagnetic signal received at each receiving face has a component parallel to the scanning axis. Output transmission means for transmitting an output signal from the slabs responsive to the electromagnetic signal transmitted from each receiving face in the corresponding slab and received at the corresponding radiating face. The device includes a plurality of means for selectively applying a voltage across each of pairs of conductive plates disposed about a slab so as to selectively control the phase of the electromagnetic signal received at each of the radiating faces having been transmitted from the receiving face in the corresponding slab., Supersedes PAT-APPL-521 847-95, AD-D017 798.

An experimental apparatus was designed to test friction and heat transfer characteristics of microchannels (diameters of 500 micrometers or less). Two sets of microchannels were tested: a set of nine 508 micrometers square channels and a single 254 micrometers square channel. The laminar friction factor for the 508 mm channels was lower than expected and was Reynolds number dependent. This result was attributed to experimental uncertainty. The turbulent data followed theoretical predictions. The heat transfer data were also lower than expected. Again, this rsult was attributed to experimental uncertainties. The 254 micrometers channel resulted in lower friction factor, but showed the same trends shown in the Moody diagram: laminar, transition, then turbulence. The Nusselt number data were shown to be within 10% of the theoretical predictions. In addition, an analytical model which accurately predicts the heat transfer and friction characteristics for the 508 micrometers rectangular channels tested in this work was developed. The model may be used to predict optimal configurations for future tests. However, the model requires further experimental validation for smaller channel sizes.

During the period of this grant, 2/1/91-1/31/92, we completed the new version of our cold hydrogen trap and brought into operation our highly stabilized 243 nm laser system. The new trap has provisions for passing laser light through it, and reflecting it back by a steerable mirror. The light is brought to a focus on the axis of the trap where the hydrogen density is highest. Servo systems control the frequency of the laser light to within a few kilocycles of the frequency of a reference cavity, and also the position of the light beam in the cell. The excited atoms are detected by quenching them with a small electric field and observing the radiated Lyman-alpha photons with a microchannel plate detector mounted on the bottom of the trap. We had one test run in which we searched for an optical signal from the cold trapped hydrogen, without success. Considering that this represented the first attempt to integrate laser spectroscopy with trapped hydrogen, it is not remarkable that we ran into a problem on our first attempt.

We have developed a system capable of rapid characterization of optics in the soft x-ray region. X-rays from a laser produced plasma source are dispersed by a grating spectrograph onto a microchannel plate detector which is coupled to a CCD detector. The CCD image is then read by a Macintosh computer. Part of the x-ray flux from the plasma is passed through the optic under test before being analyzed by the grating. In this way, spectral images with and without the test component in the optical path can be recorded simultaneously and compared to give throughput. A .7 Joule Nd:Yag laser with 8ns pulse width, frequency doubled and capable of 10Hz operation, is focussed onto various targets to produce the x-ray pulses. A thin film filter is used to stop visible laser light from reaching the detector. Multiple diffraction orders from the grating are recorded so that the wavelength scale on the detector can be determined with high precision., This article is from 'Physics of X-Ray Multilayer Structures' AD-A255 383, p35-39.

A microchannel plate device utilizing a semiconducting bulk material is characterized by electron emissions of high output current density and efficiency. The channel passages in the plate device which are square in cross-section accommodates a larger open area ratio at the input and output plate surfaces. An extended range of high electron emission applications for the plate device is provided. Such applications may include a photocathode installation to which a modulation pulse input is applied under low voltages isolated from high post-accelerating voltages., Supersedes PAT-APPL-680 864-91.

A new method for time - resolved mass and kinetic energy analysis of ionic or neutral species in the range of 1 to 150 amu and 0.5 to 500 eV is described. Time - of - flight mass spectrometry is combined with position - sensitive detection to measure energy spectra for multiple masses at burst - mode sampling rates as high as 50 kHz. The detector is a rectangular microchannel plate with a 96 - element metal anode array that is read out either by fast analog - to - digital converters or by discriminators and scalers. The apparatus is configured so that the measured ion drift time varies as the square root of the mass - to - charge ratio and the displacement along the detector varies as the square root of the energy - to - charge ratio. Applications are envisioned in plasma analysis, in beam - scattering experiments, and in diagnostic measurements for spacecraft propulsion.

Coaxial plasma gun plasma parameters were determined using a diagnostic array to observe electron density, temperature, luminosity, beam target interactions, target luminosity, magnetic fields and ion species. Diagnostics included He-Ne and CO2 laser and 94 GHz microwave interferometry, visible spectrometry using an optical multichannel analyzer, rotating mirror fast framing camera, gated microchannel plate framing cameras, optical vacuum photodiodes, X-ray diodes aad inductive magnetic probes. The plasma gun was operated with 126 or 252 microfarads, 18 kV discharges with Ar or H gas. For these conditions, 70-80 km/s average plasma velocity and 0.5-2 eV plasma electron temperature was observed. The dominant plasma ionic species was Si+1 with a quartz insulator; with an alumina insulator, Al+1 and Al+2 were the dominant species. The plasma was self-luminous for 1.5-3 m. Interferometry showed averaged electron densities of 10 to the 15th power/cc. The plasma showed MHD instabilities. Plasma currents were 0.5-1.5 kA. Fast plasma velocities contributed less than 1 percent of the total beam energy., Prepared collaboration with Mission Research Corp., Albuquerque, NM and North Star, Albuquerque, NM.

A microchannel plate device utilizing a semiconducting bulk material is characterized by electron emissions of high output current density and efficiency. The channel passages in the plate device which are square in cross-section accommodates a larger open area ratio at the input and output plate surfaces. An extended range of high electron emission applications for the plate device is provided. Such applications may include a photocathode installation to which a modulation pulse input is applied under low voltages isolated from high post-accelerating voltages.

A technique for measuring near instantaneous concentration profiles of a fluid injected through a narrow inclined slot at the wall into a high unit Reynolds turbulent boundary layer is discussed. The concentration profiles are determined by measuring the light intensity emitted from a fluorescent dye premixed into the injectant flow as the injectant convects through an excitation laser beam. The fluorescence intensity is quantified by an electronically shuttered single stage microchannel plate image intensifier coupled to a linear photodiode array. This high resolution technique is being used to study the diffusion of injected polymer solutions away from the near wall region in a flat plate turbulent boundary layer where these solutions are effective in reducing drag. Keywords: Reynolds turbulent boundary layer.

A technique for measuring near instantaneous concentration profiles of a fluid injected through a narrow inclined slot at the wall into a high unit Reynolds number flat plate turbulent boundary layer is discussed. The concentration profiles are determined by measuring the light intensity emitted from a fluorescent dye, premixed into the injectant flow, as the injectant convects through an excitation laser beam. The fluorescence intensity is quantified by an electronically shuttered single stage microchannel plate image intensifier coupled to a linear photoidode array. This instrumentation provided the high spatial and temporal resolution required for these boundary layer concentration profile measurements. The laser induced fluorescence technique is being used to study the diffusion of injected polymer solutions away from the near wall region of the boundary layer where these solutions are effective in reducing drag. The diffusion of slot injected water has also been examined and the present results are in excellent agreement with previous studies.

A study of the extreme ultraviolet radiation emitted by ion beams of highly ionized neon and argon after passage through thin foils was conducted. A grazing incidence spectrometer was equipped with a position sensitive microchannel plate (MCP) detector which improved the detection efficiency by two orders of magnitude. The position information of the MCP was determined to be linear over 90% of the 50 mm wide detector. Spectra spanning regions of over 100 A were accumulated at a resolution of less than 1 A. A wavelength calibration based on a second order equation of spectrometer position was found to result in an accuracy of for - 0.1 A. Ovet 40 transitions of Ne VIII, Ne IX, and Ne X were observed in the wavelength region from 350 to 30 A from n=2-3,4,5; n=3-4,5,6,7,8; n=4-6,7; and n=5-9. An intensity calibration of the detection system allowed the determination of the relative populations of n=3 states of Ne VIII and Ne IX. An overpopulation of states with low orbital angular momenta support electron capture predictions by the first order Born approximation. The argon beam foil data confirmed the wavelength predictions of 30 previously unobserved transitions in the wavength region from 355 to 25 A from n=2-2; n=3-4; n=4-5,6,7; and n=6-8. Lifetime determinations were made by the simultaneous measurement of 26 argon lines in the spectral region from 295-180 A. Many of the n=2-2 transitions agreed well with theory.

Nonlinear real-time optical processing on spatial pulse frequency modulation has been pursued through the analysis, design, and fabrication of pulse frequency modulated halftone screens and the modification of micro-channel spatial light modulators (MSLMs). Micro-channel spatial light modulators are modified via the Fabry-Perot method to achieve the high gamma operation required for non-linear operation. Real-time nonlinear processing was performed using the halftone screen and MSLM. The experiments showed the effectiveness of the thresholding and also showed the needs of higher SBP for image processing. The Hughes LCLV has been characterized and found to yield high gamma (about 1.7) when operated in low frequency and low bias mode. Cascading of two LCLVs should also provide enough gamma for nonlinear processing. In this case, the SBP of the LCLV is sufficient but the uniformity of the LCLV needs improvement. These include image correlation, computer generation of holograms, pseudo-color image encoding for image enhancement, and associative-retrieval in neural processing. The discovery of the only known optical method for dynamic range compression of an input image in real-time by using GaAs photorefractive crystals is reported. Finally, a new architecture for non-linear multiple sensory, neural processing has been suggested.

In the next few years the Remote Atmospheric and Ionospheric Detector System (RAIDS) package will be flown on a TRIOS spacecraft. The Extreme Ultraviolet Spectrometer (EUVS) experiment contains a position-sensitive detector based on wedge and strip anode technology. A detector design has been implemented in brazed alumina and Kovar to provide a rugged bakeable housing and anode. A stack of three 80:1 microchannel plates is operated at 3500-4100 V to achieve a gain of about 10 to the 7th power. The top MCP is to be coated with MgF for increased quantum efficiency in the range of 500-1150 A. Fabrication of the wedge and strip anode on brazed alumina has presented some challenging problems. In this report, a summary of fabrication techniques and detector performance characteristics is presented. Keywords: Alumina; Kovar. (JHD), Prepared in cooperation with California Univ., Berkeley. Space Sciences Lab.

This technical report contains an overview of the development and production of a critical night vision electronic device, the microchannel multiplier or microchannel plate (MCP). Technological challenges and manufacturing processes for the second and third generation image intensifier tube systems are outlined including materials selection, thermo-mechanical processing, chemical processing, mechanical processing, and assembly, and cleaning, chemical activation, and electron scrub. also contained in this report are three figures which chart MCP research and development investment/payoff, unit cost reduction curve for second generation, and estimated production cost comparisons of years 1977 and 1987. The Appendix contains Varian Associates' pamphlet MCP-2819B, Applications for Microchannel Plates.

We describe a fast (exposure down to approx. 10 ns) electrically triggered camera back/shutter designed for use with the Haselblad 500C still camera. This camera back contains a microchannel plate image intensifier which can be gated and provides a gain of approximately X1000. It reads out on to Polaroid film through a fiber optic face plate. The gated camera back is interchangeable with the regular Polaroid back (or any other) for the Hasselblad 500C and maintains the through the lens focussing. Keywords include: Framing camera; and Image intensifier.

The ability to significantly reduce the vulnerability of spread spectrum radar communication or intercept systems to narrowband jammer interference has been successfully demonstrated in the laboratory. The interference signal levels were attenuated by the self-adaptive frequency selective limiting properties of an optical processor invented by PROBE SYSTEMS, INC. The key component in these tests was a standard microchannel plate photomultiplier detector that, when exposed to narrowband signals, would saturate and at the same time amplify low-level broadband signals. This electronic clipping of high power spectral density signals was responsible for the successful demonstration of the feasibility of using a microchannel plate photomultiplier for optical excision of interference.

Description is made of two-dimensional photon counters that preserve the temporal ordering of the photons in a form suitable for a new algorithm for speckle imaging. Specifications are given for such a device that is under development by Lockheed and attention is given to a commercially available device that is being procured under this contract. Certain developments concerning the calibration and sensitivity of the speckle imaging algorithm are also described. (Author)

Pulse-height analysis (PHA) of image intensifier tubes (I2 tube) is described using a multiple-channel analyzer (MCA). The experimental setup, schematics of I2 tubes, statistics and mathematics for the analysis, and methods for data acquisition and reduction are included in the report. PHA complements another experimental technique which measures the noise figure (N(f)) of an I2 tube by explaining causes for good or bad performance of the tube. Technical developments of I2 tubes over the years were retraced to point out the improvements or the distinctions of a later generation I2 tube over an earlier one. Some of the tube characteristics are described in detail when they affect the N(f) or the gain noise figure. Background mathematics and statistics are illustrated, and some useful oscilloscope traces are given.

Wide rim 18 mm microchannel plates were successfully manufactured during this contract. The necessary modifications to fixturing and equipment to accomplish the program objectives are detailed in this report. Adjustments to hydrogen firing and vacuum baking schedules were made to achieve optimized MCP characteristics. Detailed test results of all wide rim MCPs processed are included in Tables I, II and III. (Author)

Effort during the third quarter of the contract was concentrated on fabrication and testing of the second submission of 10 engineering samples. In addition, tasks continued during the report period include: (1) achievement of uniform firepolishing of entire MCP input surface by using a mesh heater structure, (2) improved MCP surface quality by optimizing prepolish condition of MCP's and (3) employment of thicker laquer films to improve Al2O3 quality. The new Varian evaporator was completed and used to perform all Al2O3 evaporations. To achieve better thickness control, a dual shutter system was employed. Several flood gun designs were tested in the present engineering demountable testhead to achieve higher electron density for improved viewing of Al2O3 film defects. Several MCP's were coated with very thick Al2O3 films to study Al2O3 film defects. The bakeable demountable test system was completely assembled and is now undergoing heat and pressure tests. (Author)

A prototype sealed multi-anode detector employing a microchannel array plate (MCP) and a CsI photocathode for use at ultraviolet wavelengths has been designed, tested and delivered to the Air Force Geophysical Laboratory (AFGL). Prototype electronics and the associated mechanical assembly have also been delivered to AFGL. This final report for the contract describes the construction and mode of operation of the detector and presents the results of the preliminary laboratory evaluation of the prototype unit. (Author)