85 Matching Results

Search Results

Advanced search parameters have been applied.

Draft photosensor characterization report

Description: The report presents the results of laboratory measurements performed on The Watt Stopper's LS-201 photosensor at the Lawrence Berkeley National Laboratory in January 2003. The purpose of these measurements was to characterize the spatial and spectral response function of the LS-201 photosensor. Sample results of the spectral response and spatial response are shown.
Date: February 23, 2003
Creator: Rubinstein, Francis M.; Yazdanian, Mehry & Galvin, James
Partner: UNT Libraries Government Documents Department

Ultra-high Photoresponsivity in Suspended Metal-Semiconductor-Metal Mesoscopic Multilayer MoS₂ Broadband Detector from UV-to-IR with Low Schottky Barrier Contacts

Description: This article describes the performance of a multifaceted investigation comprising of atomic force microscopy (AFM0, photoluminescence (PL) and Raman spectroscopy to analyze the structural and chemical characteristics to help shed insights on the origins of the superior optoelectronic device performance.
Date: February 23, 2017
Creator: Saenz, Gustavo A.; Karapetrov, Goran; Curtis, James & Kaul, Anupama
Partner: UNT College of Engineering

A New Electrostatically-focused UV HPD for Liquid Xenon

Description: Appropriate photodetectors are a major challenge for liquid xenon technology as proposed by the next generation of double beta decay, solar neutrino, and dark matter searches. The primary photon signal is tiny and in the hard ultraviolet, the installation is cryogenic, and the sensors themselves must not introduce background. Hybrid photodiodes (HPDs) provide an easy substitute for a conventional PMT with the added advantages of low radioactivity, better area coverage, and single photoelectron counting. A computer-controlled test setup capable of characterizing optical properties of ultraviolet photodetectors was installed. It was used to compare photomultiplier tubes, silicon photomultipliers, avalanche photodiodes, and a novel-design custom HPD developed by the DEP company under this proposal.
Date: July 10, 2013
Creator: Cushman, Priscilla Brooks
Partner: UNT Libraries Government Documents Department

Photodetectors for Scintillator Proportionality Measurement

Description: We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.
Date: October 18, 2010
Creator: Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine & Valentine, J.D.
Partner: UNT Libraries Government Documents Department

Fiber positioning and MRS response

Description: This paper provides experimental results on the dependence of the output signal from small-area silicon photodetectors, such as MRS (Metal-Resistive layer-Semiconductor) photodiodes, on the fiber alignment.
Date: May 18, 2004
Creator: al., Pavel Polozov et
Partner: UNT Libraries Government Documents Department

Optimization of Blazed Quantum Grid Infrared Photodetectors

Description: In a quantum grid infrared photodetector (QGIP), the active multiple quantum well material is patterned into a grid structure. The purposes of the grid are on the one hand to create additional lateral electron confinement and on the other to convert part of the incident light into parallel propagation. With these two unique functions, a QGIP allows intersubband transition to occur in all directions. In this work, we focused on improving the effectiveness of a QGIP in redirecting the propagation of light using a blazed structure. The optimization of the grid parameters in terms of the blaze angle and the periodicity was performed by numerical simulation using the modal transmission-line theory and verified by experiment. With a blazed structure, the sensitivity of a QGIP can be improved by a factor of 1.8 compared with a regular QGIP with rectangular profiles.
Date: July 7, 1999
Creator: Chen, C.J.; Choi, K.K.; Jiang, M.; Rokhinson, L.P.; Tamir, T.; Tsui, D.C. et al.
Partner: UNT Libraries Government Documents Department

A high-speed four-channel infrared pyrometer

Description: A high-speed, four-wavelength pyrometer has been developed for dynamic temperature measurements on samples that are heated by shock compression. The pyrometer uses a pair of off-axis parabolic mirrors to collect radiance emitted from a target of 1 mm in diameter. A single optical fiber delivers the collected radiant flux to the detector housing. Three dichroic beam splitters are used to spectrally split the light into four beams that are then focused onto an equal number of LN2-cooled InSb photodetectors. Broad bandwidth interference filters that are nominally centered at 1.8, 2.4, 3.4, and 5.0 {micro}m define the wavelength ranges of the four channels. The blackbody-temperature threshold of the pyrometer is at about 400 K. The signals are recorded at intervals as short as 20 ns using a four-channel digital oscilloscope. Procedures for calibration and temperature measurements are described.
Date: January 1, 2002
Creator: Boboridis, K. & Obst, A. W. (Andrew W.)
Partner: UNT Libraries Government Documents Department

Development of High Gain Ultraviolet Photo Detectors Based on Zinc Oxide Nanowires

Description: Semiconductor nanowires acts as an emerging class of materials with great potential for applications in future electronic devices. Small size, large surface to volume ratio and high carrier mobility of nanowires make them potentially useful for electronic applications with high integration density. In this thesis, the focus was on the growth of high quality ZnO nanowires, fabrication of field effect transistors and UV- photodetectros based on them. Intrinsic nanowire parameters such as carrier concentration, field effect mobility and resistivity were measured by configuring nanowires as field effect transistors. The main contribution of this thesis is the development of a high gain UV photodetector. A single ZnO nanowire functioning as a UV photodetector showed promising results with an extremely high spectral responsivity of 120 kA/W at wavelength of 370 nm. This corresponds to high photoconductive gain of 2150. To the best of our knowledge, this is the highest responsivity and gain reported so far, the previous values being responsivity=40 kA/W and gain=450. The enhanced photoconductive behavior is attributed to the presence of surface states that acts as hole traps which increase the life time of photogenerated electrons raising the photocurrent. This work provides the evidence of such solid states and preliminary results to modify the surface of ZnO nanowire is also produced.
Date: May 2014
Creator: Mallampati, Bhargav
Partner: UNT Libraries

The oxide defined VCSEL-based smart pixels for the optical database filter

Description: This paper presents the construction of the smart pixel arrays which perform AND and XOR functions with three-input and one-output optical signals for the application of an optical database filter. The device is based on oxide confined VCSELs bump bonded to GaAs MESFET pixels. The MSM photodetectors are monolithically integrated with MESFETs.
Date: April 1, 1997
Creator: Pu, R.; Hayes, E.; Jurrat, R.; Stanko, P.J.; Wilmsen, C.W.; Choquette, K. et al.
Partner: UNT Libraries Government Documents Department

New developments in photdectection in particle physics and nuclear physics

Description: Photodetectors are widely used in particle and nuclear physics research. Since the beginning of the modern era of photoelectric transducers in the late 1930�s, many types of devices have been developed and exploited for physics research. New performance requirements arising in physics experiments have often provided very interesting technological drivers for industry. New ideas for photo-detection are rapidly adapted by the physics community to enable more powerful experimental capabilities. This report gives a sampling of new developments in photodetection for physics research in the period since the first conference in this series, Beaune 96. Representative examples of advances in vacuum devices, solid-state devices and gaseous photodetectors are described including, where appropriate, an indication of areas where technological improvements are needed or expected.
Date: October 8, 1999
Creator: Elias, John E.
Partner: UNT Libraries Government Documents Department

Charge integrator and encoder ASIC for readout of the CMS hadron calorimeter photodetectors

Description: A charge integrator and encoder ASIC is being developed at Fermilab for readout of the CMS hadron calorimeter photodetectors. The chip provides eight nonoverlapping ranges and is pipelined for deadtimeless operation. It is intended to be used with an FADC to digitize hybrid photodiode current pulses at 40 MHz. For each clock period, one range is selected depending on the signal magnitude, and the output of that range is fed to the FADC to form the mantissa. The selected range is encoded and output as a 3-bit digital exponent. Previous versions of this device have been designed for use with photomultipliers which can have high gain. Hybrid photodiodes have gains of only a few thousand so that a new version of the chip is needed which includes a current-mode preamplifier. The principle of the device is described and early results from a demonstrator project are presented.
Date: November 1, 1998
Creator: al., A. Baumbaugh et
Partner: UNT Libraries Government Documents Department

Application of coherent 10 micron imaging lidar

Description: With the continuing progress in mid-IR array detector technology and high bandwidth fan-outs, i.f. electronics, high speed digitizers, and processing capability, true coherent imaging lidar is becoming a reality. In this paper experimental results are described using a 10 micron coherent imaging lidar.
Date: April 1, 1997
Creator: Simpson, M.L.; Hutchinson, D.P.; Richards, R.K. & Bennett, C.A.
Partner: UNT Libraries Government Documents Department

Test of DEP hybrid photodiodes

Description: The goal of the measurement was to study some parameters of DEP HYBRID PHOTODIODES (HPD), and the check its performance for CMS calorimetry at LHC. The principal of the HPD operation is described. The schematic view of the HPD. The HPD is vacuum photo device composed of photocathode (PC) and a silicon PIN diode (Si) as multiplication system in a very close proximity geometry. The distance between PC and Si is of the order of several mm and has an electric field < 10 kV. The photoelectron emited by the photocathode multiply by a factor of several thousand in the silicon and the charge is collected on the HPD`s anode. Several types of HPD`s were tested. There was a single channel HPD, called {open_quotes}E-type{close_quotes} with p-side of the silicon facing the HPD`s photocathode and two multipixel HPD (DEP) namely a 25 pixel HPD and a 7 pixel HPD. Both were of {open_quotes}T-type{close_quotes} structure with n-side of silicon facing the photocathode.
Date: August 1, 1997
Creator: Baumbaugh, A.; Binkley, M. & Elias, J.
Partner: UNT Libraries Government Documents Department

[SSC subsystem proposal for pre-shower and Shower Maximum Detectors]. Final report

Description: The basic purpose of this project was to devise low-cost photodetectors and arrays with large dynamic range capable of high-rate, radiation-resistant operation in multi-TeV hadron colliders. This project`s particular application was changed from the Superconducting Super Collider`s SDC detector to the Large Hadron Collider`s CMS after the Superconducting Super Collider project was cancelled. This report describes development and testing of photodetectors, and contains both a table summarizing the properties of different photodetectors and a paper on the performance of an avalanche photodiode photomultiplier tube tested at the CERN PS.
Date: December 31, 1994
Partner: UNT Libraries Government Documents Department

Low-power, parallel photonic interconnections for Multi-Chip Module applications

Description: New applications of photonic interconnects will involve the insertion of parallel-channel links into Multi-Chip Modules (MCMs). Such applications will drive photonic link components into more compact forms that consume far less power than traditional telecommunication data links. MCM-based applications will also require simplified drive circuitry, lower cost, and higher reliability than has been demonstrated currently in photonic and optoelectronic technologies. The work described is a parallel link array, designed for vertical (Z-Axis) interconnection of the layers in a MCM-based signal processor stack, operating at a data rate of 100 Mb/s. This interconnect is based upon high-efficiency VCSELs, HBT photoreceivers, integrated micro-optics, and MCM-compatible packaging techniques.
Date: December 31, 1994
Creator: Carson, R.F.; Lovejoy, M.L. & Lear, K.L.
Partner: UNT Libraries Government Documents Department

Results of hybrid photodiode irradiation by 200 MeV protons

Description: Hybrid Photodiodes (HPD, [1]) will be used as the photodetector for the Compact Muon Solenoid (CMS) Hadron Calorimeter (HCAL) readout [2]. The HPDs are required to operate in a high radiation environment, where the HCAL detector will receive a total ionizing dose of about 330 rads and a fluence of 4 x 10{sup 11} n/cm{sup 2} over a 10 year running period [3]. Effects of HPD irradiation by low energy neutrons were studied and reported previously [1]. In these studies, high energy protons are used to study possible effects of single event burnout [4], since high energy protons are more likely to induce large energy transfer within the HPD silicon. The HPDs were irradiated by 200 MeV protons at the Indiana University Cyclotron Facility [IUCF, 5]. The results of the study are presented.
Date: December 3, 2001
Creator: Baumbaugh, A.; Freeman, J.; Elias, J.; Los, S.; Mokhov, N.; Rivetta, C. et al.
Partner: UNT Libraries Government Documents Department

Metal Ion Analysis Using Near-Infrared Dyes and the Laboratory-on-a-Chip

Description: The primary research objective of this effort is to develop a portable, capillary electrophoresis (CE) microchip capable of sensitively and rapidly monitoring hazardous waste metal ions critical to the successful deactivation and decommissioning (D&amp;D) of contaminated equipment and structures at various DOE sites. Hazardous waste metal ions to be adapted for sensing on the microchip include UO2 2+, Be2+, Cr6+, Hg2+, Pb2+, Co2+, Ni2+, Cs+, and Sr2+. Particular emphasis will be placed on developing viable, new extraction methods for metal ion sampling from both the air via a microimpinger which is integrated onto the microchip itself, and from contaminated surfaces, both techniques being amenable to on-line introduction onto the microchip. Two different detection methods for monitoring the electrophoretic separations taking place down the microchannel will be exploited in this research, indirect and direct detection. Special emphasis will be placed on maintaining the ultimate portability of the final microchip device through the careful selection of metallochromic dyes and fluorophores which are amenable to use of small, inexpensive light sources (e.g., LED's) and photodetectors.
Date: June 23, 2004
Creator: Collins, Greg E.
Partner: UNT Libraries Government Documents Department

Linearity of photoconductive GaAs detectors to pulsed electrons

Description: The response of neutron damaged GaAs photoconductor detectors to intense, fast (50 psec fwhm) pulses of 16 MeV electrons has been measured. Detectors made from neutron damaged GaAs are known to have reduced gain, but significantly improved bandwidth. An empirical relationship between the observed signal and the incident electron fluence has been determined.
Date: December 31, 1995
Creator: Ziegler, L.H.
Partner: UNT Libraries Government Documents Department

Wire ageing with the TEA photocathode

Description: Recently several RICH protypes successfully tested a gaseous TEA photocathode. However, its wire ageing behavior is unknown. In principle, TEA is a more strongly bonded molecule than TMAE, and, as a result, one would expect better wire ageing behavior. This paper explores this question.
Date: June 1, 1996
Creator: Va`vra, J.
Partner: UNT Libraries Government Documents Department

Fabrication, Packaging, and Performance of VCSELs and Photodetectors for Space Applications

Description: Optocouplers are used for a variety of applications aboard spacecraft including electrical isolation, switching and power transfer. Commercially available light emitting diode (LED)-based optocouplers have experienced severe degradation of light output due to extensive displacement damage occurring in the semiconductor lattice caused by energetic proton bombardment. A new optocoupler has been designed and fabricated which utilizes vertical cavity surface emitting laser (VCSEL) and resonant cavity photodetector (RCPD) technologies for the optocoupler emitter and detector, respectively. Linear arrays of selectively oxidized GaAs/AlGaAs VCSELS and RCPDS, each designed to operate at a wavelength of 850nm, were fabricated using an airbridge contacting scheme. The airbridged contacts were designed to improve packaging yields and device reliability by eliminating the use of a polyimide planarizing layer which provided poor adhesion to the bond pad metallization. Details of the airbridged optocoupler fabrication process are reported. Discrete VCSEL and RCPD devices were characterized at temperatures between {minus}100 to 100 C. Devices were packaged in a face-to-face configuration to form a single channel optocoupler and its performance was evaluated under conditions of high-energy proton bombardment.
Date: March 9, 1999
Creator: Armendariz, M.G.; Briggs, R.D.; Choquette, K.D.; Geib, K.M. & Serkland, D.K.
Partner: UNT Libraries Government Documents Department

SAO HMC photodetector/event timer engineering model test report

Description: The test unit is a custom photodetector/event timer, PET, built for the Smithsonian Astrophysical Observatory, SAO, by Los Alamos which records elapsed time in 10 ps steps. The 1 Kg, 12 cm diameter PET unit uses 10 watts of electrical power and was tested to SAO`s specified flight conditions. The event timer has two inputs -- a reference clock oscillator input and a stop signal. Like a stop watch with split timing capability, the event timer records the instant a stop signal arrives. At that sample instant, the number of elapsed clock cycles are stored and the sample instant position between two reference clock edges is interpolated and stored. Then that stored data can be shifted serially to an external computer. The photodetector part of the PET responds to an optical input and provides the electrical output signal to the event timer specifying the sample instant. This test report discusses the event timer test results. Test equipment is shown for most of the operational tests. The relay rack contains test pursers and clocks. The environmental chamber controls temperature. The computer reads and records the serial data from the PET. Reported testing topics include: Pulse shapes to be used as test inputs, test results obtained using the electrical source`s input, optical test results which are the best simulation of specified operational conditions, heat sink operation in vacuum. Vibration tests performed to SAO`s specification.
Date: October 5, 1994
Partner: UNT Libraries Government Documents Department

Fielding and calibration issues for diamond photoconducting detectors

Description: Diamond photoconducting detectors are routinely fielded as soft x-ray diagnostics on Sandia`s Saturn facility. We have developed an improved detector mount that provides a 200-ps time response, is easily cleanable, and is very rugged. In addition, we have developed a new, fast insertion unit to apply bias voltage to the detectors. Absolute calibration of the PCDs is carried out either at the Brookhaven National Synchrotron Light Source or on Sandia`s laser calibration facility. We are now fielding diamond elements that have the dimensions 1x3x0.5 nun and 1x1xO.5 mm. We are neutron damaging some of the 1x1xO.5-mm detectors to reduce their sensitivity. We can tailor PCD sensitivity by adjusting element size and neutron damage level.
Date: December 1, 1996
Creator: Spielman, R.B.; Ruggles, L.E.; Pepping, R.E.; Breeze, S.F.; McGurn, J.S. & Struve, K.W.
Partner: UNT Libraries Government Documents Department

Multispectral Focal Plane Assembly for Satellite Remote Sensing

Description: Sandia National Laboratories and several subsystem contractors are developing technologies applicable to multispectral remote sensing from space. A proof of concept multispectral sensor system is under development. The objective of building this sensor is to demonstrate and evaluate multispectral imaging technologies for various applications. The three major subsystems making up the sensor are the focal plane assembly (FPA), the cryocooler, and the telescope. This paper covers the focal plane assembly, which is the basis of the sensor system. The focal plane assembly includes sensor chip assemblies, optical filters, and a vacuum enclosure with cold shielding. Linear detector arrays provide spatial resolution in the cross-track direction for a pushbroom imager configuration. The optical filters define 15 spectral bands in a range from 0.45 microns to 10.7 microns. All the detector arrays are mounted on a single focal plane and are designed to operate at 75 K. No beam splitters are used. The four spectral bands covering the visible to near infrared have roughly 2400 pixels each, and the remaining 11 spectral bands have roughly 600 pixels each. The average total rate of multispectral data from the FPA is approximately 15.4 megapixels per second. At the time this paper is being written, the multispectral focal plane assembly is in the fabrication phase. A thermal/mechanical mockup has been built and tested for the vibration environment and to determine the thermal load. Some of the sensor chip assemblies and filters have been built and tested. Several notable features of the design are covered in the paper as well as preliminary test data.
Date: December 31, 1997
Creator: Rienstra, J. & Ballard, M.
Partner: UNT Libraries Government Documents Department