Browsing by Subject "Detector"

Now showing 1 - 5 of 5
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    Design and fabrication of state of the art uncooled thermopile infrared detectors with cavity coupled absorption
    (2013-06) Shea, Ryan Patrick
    We present the design, fabrication, and characterization of uncooled thermopile infrared detectors with cavity coupled absorption in the long wave infrared with performance exceeding all published works. These detectors consist of a two die optical cavity which enhances absorption in the desired spectral range while rejecting unwanted noise off resonance. The electrical transduction mechanism is a thermopile consisting of four thermoelectric junctions of co-sputtered Bi2Te3 and Sb2<\sub>Te3<\sub> having a room temperature unitless thermoelectric figure of merit of .43. Processing steps are described in detail for the fabrication of extremely thermally isolated structures necessary for highly sensitive detectors. Optical characterization of the devices reveals a responsivity of 4700 V/W, thermal time constant of 58 ms, and specific detectivity of at least 3.0x109<\super> cmHz1/2/W. Also presented are a theoretical proposal for a midwave infrared detector using semiconductor selective absorption to enhance detectivity beyond the blackbody radiation limit and a new method for the analysis of radiation thermal conduction in highly thermally isolated structures.
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    The development of a simulator system and hardware test bed for deep space X-Ray navigation
    (2013-09) Doyle, Patrick T.
    Currently, there is a considerable interest in developing technologies that will allow using photon measurements from celestial x-ray sources for deep space navigation. The impetus for this is that many envisioned future space missions will require spacecraft to have autonomous navigation capabilities. For missions close to Earth, Global Navigation Satellite Systems (GNSS) such as GPS are readily available for use, but for missions far from Earth, other alternatives must be provided. While existing systems such as the Deep Space Network (DSN) can be used, latencies associated with servicing a fleet of vehicles may not be compatible with some autonomous operations requiring timely updates of their navigation solution. Because of their somewhat predictable emissions, pulsars are the ideal candidates for x-ray sources that can be used to provide key parameters for navigation. Algorithms and simulation tools that will enable designing and analyzing x-ray navigation concepts are presented. The development of a compact x-ray detector system is pivotal to the eventual deployment of such navigation systems. Therefore, results of a high altitude balloon test to evaluate the design of a compact x-ray detector system are described as well.
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    Radiative energy loss of muons in the MINOS Far Detector.
    (2010-07) Bhattarai, Prabhat
    Higher energy (>100GeV)muons lose their energy preferentially through radiativemethods such as Bremsstrahlung, Pair-production and Photo-production. Because the radiative loss of the energy is a stochastic process, it is hard to select muons which lose their energy through the radiative methods. I will present methods of selecting the highest energy muons in MINOS, looking for radiative energy losses. The MINOS far detector is an underground detector. Since August 2003 the MINOS Far Detector has been collecting the underground muons [1]. The detector receives mostly high energy muons because most of the low energy cosmic muons are absorbed by the rocks in the path. They lose energy in the detector in the form of showers of particles and radiation. To study the cosmic muons reaching theMINOS Detector I have used cosmic ray Monte Carlo simulated data. I applied a number of cuts in the simulated data to select high energy muons. Then I compared the Monte Carlo simulated data with theMINOS far Detector data. I found a high correlation in the data with the correlation coefficient of 0.95 or more depending on the variable I chose to compare. The high correlation suffices to tell that the cuts chosen in theMonte Carlo simulated data are applicable in the case of the Detector data also.
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    Studies on the module structure for the NOvA liquid scintillator neutrino detector
    (2014-12) Slotman, Michael James
    This thesis contains studies pertinent to the construction of modules for the detectors of the NOvA experiment.The tensile strength of acrylic and epoxy adhesives used in construction of the detector was studied over time and with various surface preparations. Aging in oil or in air in a hot box as well as sanding and corona discharge surface treatments were examined. All materials used in the detector were studied to determine if interaction would occur with and degrade the pseudocumene liquid scintillator.Following the appearance of cracking manifold covers in installed modules, studies were done to determine the cause and mitigation of these cracks. Manifold covers that had been pressurized during a seal check during module construction were examined for the formation of cracks. Internal cracks were visible on the majority of manifold covers tested at 1.4 bar with the original containment units. It was found that reducing the pressure testing of the modules from 1.4 bar to 0.7 bar and increasing the rigidity of the pressure test containment units eliminated the formation of visible cracks in the manifold covers.
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    SuperCDMS Prototype Detector Design and Testing
    (2017-10) Kennedy, Allison
    A substantial amount of astrophysical evidence indicates that approximately a quarter of all energy in the universe is composed of a nonluminous, and nonbaryonic "dark'' matter. Of the potential dark matter particle candidates, Weakly Interacting Massive Particles, or WIMPs, is particularly well motivated. As a means to directly detect WIMP interactions with baryonic matter, the Cryogenic Dark Matter Search (CDMS) project was established, operating at the Soudan Underground Laboratory from 2003 - 2015, under the CDMS II and SuperCDMS Soudan experiments. CDMS detectors simultaneously measure the ionization and phonon energies of recoil events in Si and Ge crystals kept at cryogenic temperatures in a low-background environment. The ratio of ionization energy to recoil energy serves as a discrimination parameter to separate nuclear recoil events from the electron-recoil background. The next installation, SuperCDMS SNOLAB, is preparing for future operation, with an initial payload of eighteen Ge and six Si, 100 mm diameter, 33 mm thick detectors. Of this initial payload, eight Ge and four Si detectors will operate in a high-voltage (~100 V) mode, which have an increased sensitivity to low-mass WIMPs due to decreased energy thresholds. The SuperCDMS test facility at University of Minnesota aids in the detector R&D and characterization of prototype detectors, as part of the scale-up effort for SuperCDMS SNOLAB. This thesis presents the first full ionization and phonon characterization study of a 100 mm diameter, 33 mm thick prototype Ge detector with interleaved phonon and ionization channels. Measurements include ionization collection efficiency, surface event rejection capabilities, and successful demonstration of nuclear recoil event discrimination. Results indicate that 100 mm diameter, interleaved Ge detectors show potential for use in SuperCDMS SNOLAB. As part of detector R&D, the Minnesota test facility also looks beyond the next stage of SuperCDMS, investigating larger individual detectors as a means to easily scale up the sensitive mass of future searches. This thesis presents the design and initial testing results of a prototype 150 mm diameter, 33 mm thick silicon ionization detector, which is 5.2 times larger than those used in SuperCDMS at Soudan and 2.25 times larger than those planned for use at SuperCDMS SNOLAB. In addition, the detector was operated with contact-free ionization electrodes to minimize bias leakage currents, which can limit operation at high bias voltages. The results show promise for the operation of both large volume silicon detectors and contact-free ionization electrodes for scaling up detector mass and bias.