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AO Group Annual Report
The Adaptive Optics (AO) Group in I Division develops and tests a broad range of advanced wavefront control technologies. Current applications focus on: Remote sensing, High power lasers, Astronomy, and Human vision. In the area of remote sensing, the AO Group leads a collaborative effort with LLNL's Nonproliferation, Arms Control & International Security (NAI) Directorate on Enhanced Surveillance Imaging. The ability to detect and identify individual people or vehicles from long-range is an important requirement for proliferation detection and homeland security. High-resolution imaging along horizontal paths through the atmosphere is limited by turbulence, which blurs and distorts the image. For ranges over {approx}one km, visible image resolution can be reduced by over an order of magnitude. We have developed an approach based on speckle imaging that can correct the turbulence-induced blurring and provide high resolution imagery. The system records a series of short exposure images which freeze the atmospheric effects. We can then estimate the image magnitude and phase using a bispectral estimation algorithm which cancels the atmospheric effects while maintaining object information at the diffraction limit of the imaging system.
Date:
October 4, 2005
Creator:
Olivier, S.
Object Type:
Report
System:
The UNT Digital Library
A QUICK KEY TO THE SUBFAMILIES AND GENERA OF ANTS OF THE SAVANNAH RIVER SITE, AIKEN, SC
This taxonomic key was devised to support development of a Rapid Bioassessment Protocol using ants at the Savannah River Site. The emphasis is on ''rapid'' and, because the available keys contained a large number of genera not known to occur at the Savannah River Site, we found that the available keys were unwieldy. Because these keys contained more genera than we would likely encounter and because this larger number of genera required both more couplets in the key and often required examination of characters that are difficult to assess without higher magnifications (60X or higher) more time was required to process samples. In developing this set of keys I recognize that the character sets used may lead to some errors but I believe that the error rate will be small and, for the purpose of rapid bioassessment, this error rate will be acceptable provided that overall sample sizes are adequate. Oliver and Beattie (1996a, 1996b) found that for rapid assessment of biodiversity the same results were found when identifications were done to morphospecies by people with minimal expertise as when the same data sets were identified by subject matter experts. Basset et al. (2004) concluded that it was not as …
Date:
October 4, 2006
Creator:
Martin, D
Object Type:
Report
System:
The UNT Digital Library
Plasma conditions for improved energy coupling into the gain region of the Ni-like Pd transient collisional x-ray laser
We have directly probed the plasma conditions in which the Ni-like Pd transient collisional x-ray laser is generated and propagates by measuring the near-field image and by utilizing picosecond resolution soft x-ray laser interferometry of the preformed Pd plasma gain medium. The electron density and gain region of the plasma have been determined experimentally and are found to be in good agreement with simulations. We observe a strong dependence of the laser pump-gain medium coupling on the laser pump parameters. The most efficient coupling of laser pump energy into the gain region occurs with the formation of lower density gradients in the pre-formed plasma and when the duration of the main heating pulse is comparable to the gain lifetime ({approx}10ps for mid-Z Ni-like schemes). This increases the output intensity by more than an order of magnitude relative to the commonly utilized case where the same pumping energy is delivered within a shorter heating pulse duration (< 3ps). In contrast, the higher intensity heating pulses are observed to be absorbed at higher electron densities and in regions where steep density gradients limit the effective length of the gain medium.
Date:
October 4, 2004
Creator:
Smith, R. F.; Dunn, J.; Filevich, J.; Moon, S.; Nilsen, J.; Keenan, R. et al.
Object Type:
Article
System:
The UNT Digital Library
Spacetime thermodynamics and subsystem observables in akinetically constrained model of glassy systems
In a recent article it was argued that dynamic heterogeneity in d-dimensional glass formers is a manifestation of an order-disorder phenomenon in the d+1 dimensions of spacetime. By considering a dynamical analogue of the free energy, evidence was found for phase coexistence between active and inactive regions of spacetime, and it was suggested that this phenomenon underlies the glass transition. Here we develop these ideas further by investigating in detail the one-dimensional Fredrickson-Andersen (FA) model in which the active and inactive phases originate in the reducibility of the dynamics. We illustrate the phase coexistence by considering the distributions of mesoscopic spacetime observables. We show how the analogy with phase coexistence can be strengthened by breaking microscopic reversibility in the FA model, leading to a non-equilibrium theory in the directed percolation universality class.
Date:
October 4, 2006
Creator:
Jack, Robert L.; Garrahan, Juan P. & Chandler, David
Object Type:
Article
System:
The UNT Digital Library
RF Sources for the ITER Ion Cyclotron Heating and Current Drive System
The RF source requirements for the ITER ion cyclotron (IC) heating and current drive system are very challenging ? 20 MW CW power into an antenna load with a VSWR of up to 2 over the frequency range of 35-65 MHz. For the two present antenna designs under consideration, 8 sources providing 2.5 MW each are to be employed. For these sources, the outputs of two final power amplifiers (FPAs), using the high power CPI 4CM2500KG tube, are combined with a 180? hybrid combiner to easily meet the ITER IC source requirements ? 2.5 MW is supplied at a VSWR of 2 at ? 70% of the maximum tube power available in class B operation. The cylindrical cavity configuration for the FPAs is quite compact so that the 8 combined sources fit into the space allocated at the ITER site with room to spare. The source configuration is described in detail and its projected operating power curves are presented. Although the CPI tube has been shown to be stable under high power operating conditions on many facilities, a test of the combined FPA source arrangement is in preparation using existing high power 30 MHz amplifiers to assure that this configuration …
Date:
October 4, 2005
Creator:
Hosea, J.; Brunkhorst, C.; Fredd, E.; Goulding, R. H.; Greenough, N.; Kung, C. et al.
Object Type:
Report
System:
The UNT Digital Library
Enhanced Infrared Surveillance Imaging Report for NA-22
The purpose of this report is to describe our work on enhanced infrared (IR) surveillance using speckle imaging for NA-22. Speckle imaging in this context is an image post-processing algorithm that aims to solve the atmospheric blurring problem of imaging through horizontal or slant path turbulence. We will describe the IR imaging systems used in our data collections and show imagery before and after speckle processing. We will also compare IR imagery with visible wavelength imagery of the same target in the same conditions and demonstrate how going to longer wavelengths can be beneficial in the presence of strong turbulence.
Date:
October 4, 2005
Creator:
Carrano, C J
Object Type:
Report
System:
The UNT Digital Library
Spin distribution in neutron induced preequilibrium reactions
The preequilibrium reaction mechanism makes an important contribution to neutron-induced reactions above E{sub n} {approx} 10 MeV. The preequilibrium process has been studied exclusively via the characteristic high energy neutrons produced at bombarding energies greater than 10 MeV. They are expanding the study of the preequilibrium reaction mechanism through {gamma}-ray spectroscopy. Cross-section measurements were made of prompt {gamma}-ray production as a function of incident neutron energy (E{sub n} = 1 to 250 MeV) on a {sup 48}Ti sample. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the Los Alamos Neutron Science Center facility. The prompt-reaction {gamma} rays were detected with the large-scale Compton-suppressed Germanium Array for Neutron Induced Excitations (GEANIE). Neutron energies were determined by the time-of-flight technique. The {gamma}-ray excitation functions were converted to partial {gamma}-ray cross sections taking into account the dead-time correction, target thickness, detector efficiency and neutron flux (monitored with an in-line fission chamber). Residual state population was predicted using the GNASH reaction code, enhanced for preequilibrium. The preequilibrium reaction spin distribution was calculated using the quantum mechanical theory of Feshback, Kerman, and Koonin (FKK). The multistep direct part of the FKK theory was calculated for a one-step process. …
Date:
October 4, 2005
Creator:
Dashdorj, D.; Kawano, T.; Chadwick, M.; Devlin, M.; Fotiades, N.; Nelson, R. O. et al.
Object Type:
Article
System:
The UNT Digital Library
Circuit Design to Stabilize the Reflectometer Local Oscillator Signals
Reflectometry, which uses the microwave radar technique to probe the magnetically confined fusion plasmas, is a very powerful tool to observe the density fluctuations in the fusion plasmas. Typically, two or more microwave beams of different frequencies are used to study the plasma density fluctuations. The frequency separation between these two beams of the PPPL designed reflectometer system upgrade on the DIII-D tokamak can be varied over 18 GHz. Due to the performance of the associated electronics, the local oscillator (LO) power level at the LO port of the I/Q demodulator suffers more than 12 dB of power fluctuations when the frequency separation is varied. Thus, the I/Q demodulator performance is impaired. In order to correct this problem, a power leveling circuit is introduced in the PPPL upgrade. According to the test results, the LO power fluctuation was regulated to be within 1 dB for greater than 16 dB of input power variation over the full dynamic bandwidth of the receiver.
Date:
October 4, 2005
Creator:
Kung CC, Kramer GJ, Johnson E, Solomon W, Nazikian R
Object Type:
Report
System:
The UNT Digital Library
X-ray Pulse Length Characterization using the Surface Magneto Optic Kerr Effect
It will be challenging to measure the temporal profile of the hard X-ray SASE beam independently from the electron beam in the LCLS and other 4th generation light sources. A fast interaction mechanism is needed that can be probed by an ultrafast laser pulse in a pump-probe experiment. It is proposed to exploit the rotation in polarization of light reflected from a thin magnetized film, known as the surface magneto optic Kerr effect (SMOKE), to witness the absorption of the x-ray pulse in the thin film. The change in spin orbit coupling induced by the x-ray pulse occurs on the subfemtosecond time scale and changes the polarization of the probe beam. The limitation to the technique lies with the bandwidth of the probe laser pulse and how short the optical pulse can be made. The SMOKE mechanism will be described and the choices of materials for use with 1.5 {angstrom} x-rays. A schematic description of the pump-probe geometry for x-ray diagnosis is also described.
Date:
October 4, 2006
Creator:
Krejcik, P.
Object Type:
Article
System:
The UNT Digital Library
Electron Bunch Length Measurement for LCLS at SLAC
At Stanford Linear Accelerator Center (SLAC) a Bunch Length Measurement system has been developed to measure the length of the electron bunch for its new Linac Coherent Light Source (LCLS). This destructive measurement uses a transverse-mounted RF deflector (TCAV) to vertically streak the electron beam and an image taken with an insertable screen and a camera. The device control software was implemented with the Experimental Physics and Industrial Control System (EPICS) toolkit. The analysis software was implemented in Matlab{trademark} using the EPICS/Channel Access Interface for Scilab{trademark} and Matlab{trademark} (labCA). This architecture allowed engineers and physicists to develop and integrate their control and analysis without duplication of effort.
Date:
October 4, 2007
Creator:
Zelazny, M.; Allison, S.; Chevtsov, Sergei; Emma, P.; Kotturi, K. D.; Loos, H. et al.
Object Type:
Article
System:
The UNT Digital Library
The Wylie News (Wylie, Tex.), Vol. 59, No. 20, Ed. 1 Wednesday, October 4, 2006
Weekly newspaper from Wylie, Texas that includes local, state and national news along with advertising.
Date:
October 4, 2006
Creator:
Engbrock, Chad B.
Object Type:
Newspaper
System:
The Portal to Texas History
Automatic Alignment System for the National Ignition Facility
The automatic alignment system for the National Ignition Facility (NIF) is a large-scale parallel system that directs all 192 laser beams along the 300-m optical path to a 50-micron focus at target chamber in less than 30 minutes. The system commands 9,000 stepping motors to adjust mirrors and other optics. Twenty-two control loops per beamline request image processing services running on a LINUX cluster to analyze high-resolution images of the beam and references. Process-leveling assures the computational load is evenly spread on the cluster. Algorithms also estimate measurement accuracy and reject off-normal images. One challenge to achieving rapid alignment of beams in parallel is the efficient coordination of shared laser devices, such as sensors that are configurable to monitor multiple beams. Contention for shared resources is managed by the Component Mediation System, which precludes deadlocks and optimizes device motions using a hierarchical component structure. A reservation service provided by the software framework prevents interference from competing instances of automated controls or from the actions of system operators. The design, architecture and performance of the system will be discussed.
Date:
October 4, 2007
Creator:
Wilhlelmsen, K. C.; Awwal, A. S.; Ferguson, S. W.; Horowitz, B.; Miller Kamm, V. J. & Reynolds, C. A.
Object Type:
Article
System:
The UNT Digital Library
A New Lorentz Violating Nonlocal Field Theory From String-Theory
A four-dimensional field theory with a qualitatively new type of nonlocality is constructed from a setting where Kaluza-Klein particles probe toroidally compactified string theory with twisted boundary conditions. In this theory fundamental particles are not pointlike and occupy a volume proportional to their R-charge. The theory breaks Lorentz invariance but appears to preserve spatial rotations. At low energies, it is approximately N=4 Super Yang-Mills theory, deformed by an operator of dimension seven. The dispersion relation of massless modes in vacuum is unchanged, but under certain conditions in this theory, particles can travel at superluminal velocities.
Date:
October 4, 2007
Creator:
Ganor, Ori J.
Object Type:
Article
System:
The UNT Digital Library
Seminole Sentinel (Seminole, Tex.), Vol. 97, No. 103, Ed. 1 Wednesday, October 4, 2006
Semiweekly newspaper from Seminole, Texas that includes local, state, and national news along with extensive advertising.
Date:
October 4, 2006
Creator:
Wright, Dustin
Object Type:
Newspaper
System:
The Portal to Texas History
Archer County News (Archer City, Tex.), No. 40, Ed. 1 Thursday, October 4, 2007
Weekly newspaper from Archer City, Texas that includes local, state, and national news along with advertising.
Date:
October 4, 2007
Creator:
Lewis, Shelley
Object Type:
Newspaper
System:
The Portal to Texas History
Seminole Sentinel (Seminole, Tex.), Vol. 93, No. 101, Ed. 1 Wednesday, October 4, 2000
Semiweekly newspaper from Seminole, Texas that includes local, state, and national news along with advertising.
Date:
October 4, 2000
Creator:
Dow, M. Gene & Fisher, David
Object Type:
Newspaper
System:
The Portal to Texas History
Lexington Observer (Lexington, Okla.), Vol. 12, No. 25, Ed. 1 Thursday, October 4, 2007
Weekly newspaper from Lexington, Oklahoma that includes local, state, and national news along with advertising.
Date:
October 4, 2007
Creator:
Edwards, Olvis
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
The Ranger (San Antonio, Tex.), Vol. 77, No. 4, Ed. 1 Friday, October 4, 2002
Weekly student newspaper from San Antonio College in San Antonio, Texas that includes campus news along with advertising.
Date:
October 4, 2002
Creator:
San Antonio College
Object Type:
Newspaper
System:
The Portal to Texas History
Polk County Enterprise (Livingston, Tex.), Vol. 127, No. 82, Ed. 1 Sunday, October 4, 2009
Semi-weekly newspaper from Livingston, Texas that includes local, state and national news along with advertising.
Date:
October 4, 2009
Creator:
Reddell, Valerie
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 22, No. 40, Ed. 1 Thursday, October 4, 2007
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
October 4, 2007
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Comanche Chief (Comanche, Tex.), No. 23, Ed. 1 Thursday, October 4, 2007
Weekly newspaper from Comanche, Texas that includes local, state, and national news along with advertising.
Date:
October 4, 2007
Creator:
Wilkerson, James C., III
Object Type:
Newspaper
System:
The Portal to Texas History
Yoakum Herald-Times (Yoakum, Tex.), Vol. 114, No. 40, Ed. 1 Wednesday, October 4, 2006
Weekly newspaper from Yoakum, Texas that includes local, state, and national news along with advertising.
Date:
October 4, 2006
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 16, No. 40, Ed. 1 Thursday, October 4, 2001
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
October 4, 2001
Creator:
Ritch, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
The Clifton Record (Clifton, Tex.), Vol. 111, No. 40, Ed. 1 Wednesday, October 4, 2006
Weekly newspaper from Clifton, Texas that includes local, state, and national news along with advertising.
Date:
October 4, 2006
Creator:
Smith, W. Leon
Object Type:
Newspaper
System:
The Portal to Texas History