119 research outputs found
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Kinetic inductance detectors for measuring the polarization of the cosmic microwave background
Kinetic inductance detectors (KIDs) are superconducting thin-film microresonators that are sensitive photon detectors.
These detectors are a candidate for the next generation of experiments designed to measure the polarization of the cosmic microwave background (CMB).
I discuss the basic theory needed to understand the response of a KID to light, focusing on the dynamics of the quasiparticle system.
I derive an equation that describes the dynamics of the quasiparticle number, solve it in a simplified form not previously published, and show that it can describe the dynamic response of a detector.
Magnetic flux vortices in a superconducting thin film can be a significant source of dissipation, and I demonstrate some techniques to prevent their formation.
Based on the presented theory, I derive a corrected version of a widely-used equation for the quasiparticle recombination noise in a KID.
I show that a KID consisting of a lumped-element resonator can be sensitive enough to be limited by photon noise, which is the fundamental limit for photometry, at a level of optical loading below levels in ground-based CMB experiments.
Finally, I describe an ongoing project to develop multichroic KID pixels that are each sensitive to two linear polarization states in two spectral bands, intended for the next generation of CMB experiments.
I show that a prototype 23-pixel array can detect millimeter-wave light, and present characterization measurements of the detectors
DoD Program Management Competency Model
Symposium Student Poster ShowAs of today DOD project management is structured differently from industry. Industry has made advancements in PM that the DOD should consider for adoption. By better aligning the DOD and industry recognized competency standards, the DOD may be able to better address long observed cost, schedule, and performance issues.Approved for public release; distribution is unlimited
DEVELOPING A PROJECT MANAGER COMPETENCY MODEL TO BETTER SERVE THE WARFIGHTER AND THE DOD
As of today, the Department of Defense (DOD) project management competencies are structured differently from industry. Industry has made advancements in project management that the DOD does not currently take advantage of. By better aligning the DOD and PMI competency standards we can decrease cost, schedule, and performance issues. Based on previous research on the topic, the current DOD competency model is not sufficient for assessing today’s program managers. The purpose of this research is to use the three PMI industry standards to develop a survey tool to better serve the DOD acquisition workforce. We were able to create this survey tool and hope that, by using this survey tool, future research teams will be able to effectively gauge the acquisition community’s correlation between the three PMI standards and the current DOD workload. The information gathered from this research can be useful not only to DOD acquisition communities, but also can set future guidelines to program managers in order to save the DOD on schedule, cost, and performance.Civilian, Department of the NavyCivilian, Department of the NavyApproved for public release. Distribution is unlimited
Multisensory integration supports configural learning of a home refuge in the whip spider \u3ci\u3ePhrynus marginemaculatus\u3c/i\u3e
Predator diets represent a potential interaction between local prey availability, prey antipredator defenses, and predator foraging behavior. Female spider-specialist muddauber wasps (Hymenoptera: Sphecidae) collect spiders and provision them intact, but paralyzed, to their developing larvae, providing a unique means of quantifying the diversity and abundance of prey that they capture. Mud-dauber wasps are hypothesized to be a major source of selection on antipredator defenses in web-building spiders, and the spiny and thickened abdomens of female spiny orb-weaving spiders (Araneae: Araneidae) are hypothesized to function as antiwasp defenses. We inventoried spider prey from nests of the mud-dauber wasps Sceliphron caementarium (Drury) and Chalybion californicum (Saussure), and surveyed for spider fauna in areas surrounding nest collection sites, to specifically investigate if the spiny orb-weaver Micrathena gracilis (Walckenaer) was collected as prey by these wasps. We collected nests from six sites in southeastern Nebraska from two regions that we classify based on habitat—a forest corridor and agricultural land. We collected 761 intact spider prey from 87 nests and identified them to the family level. None of these spiders were M. gracilis. Micrathena gracilis were rare in faunal surveys on agricultural land and, surprisingly, absent in forest corridor surveys. Mud-dauber wasps were more common; we collected more spiders on agricultural land than in the forest corridor. We propose that in agricultural landscapes, the lack of certain spiders in mud-dauber wasp nests is driven by habitat use differences between predators and prey rather than physical antipredator defenses
WSPEC: A waveguide filter-bank focal plane array spectrometer for millimeter wave astronomy and cosmology
Imaging and spectroscopy at (sub-)millimeter wavelengths are key frontiers in
astronomy and cosmology. Large area spectral surveys with moderate spectral
resolution (R=50-200) will be used to characterize large scale structure and
star formation through intensity mapping surveys in emission lines such as the
CO rotational transitions. Such surveys will also be used to study the SZ
effect, and will detect the emission lines and continuum spectrum of individual
objects. WSPEC is an instrument proposed to target these science goals. It is a
channelizing spectrometer realized in rectangular waveguide, fabricated using
conventional high-precision metal machining. Each spectrometer is coupled to
free space with a machined feed horn, and the devices are tiled into a 2D array
to fill the focal plane of the telescope. The detectors will be aluminum
Lumped-Element Kinetic Inductance Detectors (LEKIDs). To target the CO lines
and SZ effect, we will have bands at 135-175 GHz and 190-250 GHz, each
Nyquist-sampled at R~200 resolution. Here we discuss the instrument concept and
design, and successful initial testing of a WR10 (i.e. 90 GHz) prototype
spectrometer. We recently tested a WR5 (180 GHz) prototype to verify that the
concept works at higher frequencies, and also designed a resonant backshort
structure that may further increase the optical efficiency. We are making
progress towards integrating a spectrometer with a LEKID array and deploying a
prototype device to a telescope for first light.Comment: 7 pages, 4 figures, submitted to Journal of Low Temperature Physic
Magnetic field dependence of the internal quality factor and noise performance of lumped-element kinetic inductance detectors
We present a technique for increasing the internal quality factor of kinetic
inductance detectors (KIDs) by nulling ambient magnetic fields with a properly
applied magnetic field. The KIDs used in this study are made from thin-film
aluminum, they are mounted inside a light-tight package made from bulk
aluminum, and they are operated near . Since the thin-film
aluminum has a slightly elevated critical temperature (), it therefore transitions before the package (), which also serves as a magnetic shield. On cooldown, ambient
magnetic fields as small as approximately can produce
vortices in the thin-film aluminum as it transitions because the bulk aluminum
package has not yet transitioned and therefore is not yet shielding. These
vortices become trapped inside the aluminum package below
and ultimately produce low internal quality factors in the thin-film
superconducting resonators. We show that by controlling the strength of the
magnetic field present when the thin film transitions, we can control the
internal quality factor of the resonators. We also compare the noise
performance with and without vortices present, and find no evidence for excess
noise beyond the increase in amplifier noise, which is expected with increasing
loss.Comment: 5 pages, 4 figure
Activated Carbon Produced from Agricultural Residues
A process for producing activated carbon from agricultural residues by heating the residues to a temperature in the range of about 250° C. to about 550° C. to volatilize organic compounds in the residues and to carbonize the residues and further heating to activate the carbonized residues. Activated carbon produced from agricultural residues
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