Resource Type

1,497 Matching Results

Results open in a new window/tab.

Hard x-ray imaging and spectroscopy of long pulse NIF hohlraums (open access)

Hard x-ray imaging and spectroscopy of long pulse NIF hohlraums

None
Date: October 11, 2005
Creator: McDonald, J. W.; Kauffman, R. L.; Suter, L. J.; Celeste, J. R.; Schneider, M. B.; Holder, J. P. et al.
System: The UNT Digital Library
ULAS J234311.93-005034.0: A Gravitational Lens System Selected from UKIDSSand SDSS (open access)

ULAS J234311.93-005034.0: A Gravitational Lens System Selected from UKIDSSand SDSS

None
Date: April 11, 2008
Creator: Jackson, Neal; Ofek, Eran O. & Oguri, Masamune
System: The UNT Digital Library
Enhanced Chemical Cleaning: A New Process for Chemically Cleaning Savannah River Waste Tanks (open access)

Enhanced Chemical Cleaning: A New Process for Chemically Cleaning Savannah River Waste Tanks

At the Savannah River Site (SRS) there are 49 High Level Waste (HLW) tanks that eventually must be emptied, cleaned, and closed. The current method of chemically cleaning SRS HLW tanks, commonly referred to as Bulk Oxalic Acid Cleaning (BOAC), requires about a half million liters (130,000 gallons) of 8 weight percent (wt%) oxalic acid to clean a single tank. During the cleaning, the oxalic acid acts as the solvent to digest sludge solids and insoluble salt solids, such that they can be suspended and pumped out of the tank. Because of the volume and concentration of acid used, a significant quantity of oxalate is added to the HLW process. This added oxalate significantly impacts downstream processing. In addition to the oxalate, the volume of liquid added competes for the limited available tank space. A search, therefore, was initiated for a new cleaning process. Using TRIZ (Teoriya Resheniya Izobretatelskikh Zadatch or roughly translated as the Theory of Inventive Problem Solving), Chemical Oxidation Reduction Decontamination with Ultraviolet Light (CORD-UV{reg_sign}), a mature technology used in the commercial nuclear power industry was identified as an alternate technology. Similar to BOAC, CORD-UV{reg_sign} also uses oxalic acid as the solvent to dissolve the metal (hydr)oxide …
Date: February 11, 2009
Creator: Ketusky, Edward; Spires, Renee & Davis, Neil
System: The UNT Digital Library
Search For the Highly Suppressed Decays B- -> K+ pi- pi- and B- -> K- K- pi+ (open access)

Search For the Highly Suppressed Decays B- -> K+ pi- pi- and B- -> K- K- pi+

The authors report a search for the decays B{sup -} {yields} K{sup +}{pi}{sup -}{pi}{sup -} and B{sup -} {yields} K{sup -}K{sup -}{pi}{sup +}, which are highly suppressed in the Standard Model. Using a sample of (467 {+-} 5) x 10{sup 6} B{bar B} pairs collected with the BABAR detector, they do not see any evidence of these decays and determine 90% confidence level upper limits of {Beta}(B{sup -} {yields} K{sup +}{pi}{sup -}{pi}{sup -}) < 9.5 x 10{sup -7} and {Beta}(B{sup -} {yields} K{sup -}K{sup -}{pi}{sup +}) < 1.6 x 10{sup -7} on the corresponding branching fractions, including systematic uncertainties.
Date: August 11, 2008
Creator: Aubert, Bernard; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
System: The UNT Digital Library
EFFECTS OF OXYGEN AND AIR MIXING ON VOID FRACTIONS IN A LARGE SCALE SYSTEM (open access)

EFFECTS OF OXYGEN AND AIR MIXING ON VOID FRACTIONS IN A LARGE SCALE SYSTEM

Oxygen and air mixing with spargers was performed in a 30 foot tall by 30 inch diameter column, to investigate mass transfer as air sparged up through the column and removed saturated oxygen from solution. The mixing techniques required to support this research are the focus of this paper. The fluids tested included water, water with an antifoam agent (AFA), and a high, solids content, Bingham plastic, nuclear waste simulant with AFA, referred to as AZ01 simulant, which is non-radioactive. Mixing of fluids in the column was performed using a recirculation system and an air sparger. The re-circulation system consisted of the column, a re-circulating pump, and associated piping. The air sparger was fabricated from a two inch diameter pipe concentrically installed in the column and open near the bottom of the column. The column contents were slowly re-circulated while fluids were mixed with the air sparger. Samples were rheologically tested to ensure effective mixing, as required. Once the fluids were adequately mixed, oxygen was homogeneously added through the re-circulation loop using a sintered metal oxygen sparger followed by a static mixer. Then the air sparger was re-actuated to remove oxygen from solution as air bubbled up through solution. To …
Date: September 11, 2008
Creator: Leishear, R; Hector Guerrero, H & Michael Restivo, M
System: The UNT Digital Library
Qualification of Automated Low-Field NMR Relaxometry for Quality Control of Polymers in a Production Setting (open access)

Qualification of Automated Low-Field NMR Relaxometry for Quality Control of Polymers in a Production Setting

Implementation of a low field time-domain NMR scanner as a diagnostic tool in the production of new polymer components is described in the context of qualification of a new QA/QC device. A study to determine the optimal experimental parameters was performed and a robotic autosampler was built to enable scanning of multiple pads. Relationships between T{sub 2} values and physical properties of DC745 slabs were investigated, and the appropriate sampling parameters for the production setting were determined. Two versions of a robotic autosampler were built, and for the component described here a fourth radial axis was required in addition to traditional X, Y, and Z movement to eliminate the large variability in T{sub 2} due to inconsistent sample coverage caused by complex rib geometry of the component. Data show that with appropriate choice of experimental conditions of the NMR detector and the detection geometry of the robotic autosampler, sufficient resolution of variations in crosslink density on the millimeter scale could be determined. All data to date demonstrates that low-field NMR devices are a feasible tool for use in production settings for non-destructive quality control of polymer components.
Date: May 11, 2007
Creator: Chinn, S; Cook-Tendulkar, A; Maxwell, R; Wheeler, H; Wilson, M & Xie, Z
System: The UNT Digital Library
Melting of Transition Metals (open access)

Melting of Transition Metals

We review the transition melting studies carried out at Mainz, and describe a recently developed model used to explain that the relatively low melting slopes are due to the partially filled d-bands, and the persistence of the pressure induced s-d transition. The basic tenets of the model have now been reconfirmed by new measurements for Cu and Ni. The measurements show that Cu which has a filled 3d-band, has a melt slope that is about 2.5 greater than its neighbor Ni. In the case of Mo, the apparent discrepancy of DAC melting measurements with shock melting can be explained by accounting for the change in melt slope due to the bcc-cp transition observed in the shock studies. The Fe melt curve is revisited. The possible relevance of the Jahn-Teller effect and recently observed transition metal melts with Icosahedral Short-Range Order (ISRO) is discussed.
Date: April 11, 2005
Creator: Ross, M; Japel, S & Boehler, R
System: The UNT Digital Library
Three-dimensional analysis of free-electron laser performance using brightness scaled variables (open access)

Three-dimensional analysis of free-electron laser performance using brightness scaled variables

A three-dimensional analysis of radiation generation in a free-electron laser (FEL) is performed in the small signal regime. The analysis includes beam conditioning, harmonic generation, flat beams, and a new scaling of the FEL equations using the six-dimensional beam brightness. The six-dimensional beam brightness is an invariant under Liouvillian flow; therefore, any nondissipative manipulation of the phase-space, performed, for example, in order to optimize FEL performance, must conserve this brightness. This scaling is more natural than the commonly-used scaling with the one-dimensional growth rate. The brightness-scaled equations allow for the succinct characterization of the optimal FEL performance under various additional constraints. The analysis allows for the simple evaluation of gain enhancement schemes based on beam phase space manipulations such as emittance exchange and conditioning. An example comparing the gain in the first and third harmonics of round or flat and conditioned or unconditioned beams is presented.
Date: June 11, 2008
Creator: Penn, Gregory; Gullans, M.; Penn, G.; Wurtele, J.S. & Zolotorev, M.
System: The UNT Digital Library
Linear scaling 3D fragment method for large-scale electronic structure calculations (open access)

Linear scaling 3D fragment method for large-scale electronic structure calculations

We present a new linearly scaling three-dimensional fragment (LS3DF) method for large scale ab initio electronic structure calculations. LS3DF is based on a divide-and-conquer approach, which incorporates a novel patching scheme that effectively cancels out the artificial boundary effects due to the subdivision of the system. As a consequence, the LS3DF program yields essentially the same results as direct density functional theory (DFT) calculations. The fragments of the LS3DF algorithm can be calculated separately with different groups of processors. This leads to almost perfect parallelization on tens of thousands of processors. After code optimization, we were able to achieve 35.1 Tflop/s, which is 39% of the theoretical speed on 17,280 Cray XT4 processor cores. Our 13,824-atom ZnTeO alloy calculation runs 400 times faster than a direct DFT calculation, even presuming that the direct DFT calculation can scale well up to 17,280 processor cores. These results demonstrate the applicability of the LS3DF method to material simulations, the advantage of using linearly scaling algorithms over conventional O(N{sup 3}) methods, and the potential for petascale computation using the LS3DF method.
Date: July 11, 2008
Creator: Wang, Lin-Wang; Wang, Lin-Wang; Lee, Byounghak; Shan, HongZhang; Zhao, Zhengji; Meza, Juan et al.
System: The UNT Digital Library
Rapid, Absolute Calibration of X-ray Filters Employed By Laser-Produced Plasma Diagnostics (open access)

Rapid, Absolute Calibration of X-ray Filters Employed By Laser-Produced Plasma Diagnostics

The electron beam ion trap (EBIT) facility at the Lawrence Livermore National Laboratory is being used to absolutely calibrate the transmission efficiency of X-ray filters employed by diodes and spectrometers used to diagnose laser-produced plasmas. EBIT emits strong, discrete monoenergetic lines at appropriately chosen X-ray energies. X-rays are detected using the high-resolution EBIT calorimeter spectrometer (ECS), developed for LLNL at the NASA/Goddard Space Flight Center. X-ray filter transmission efficiency is determined by dividing the X-ray counts detected when the filter is in the line of sight by those detected when out of the line of sight. Verification of filter thickness can be completed in only a few hours, and absolute efficiencies can be calibrated in a single day over a broad range from about 0.1 to 15 keV. The EBIT calibration lab has been used to field diagnostics (e.g., the OZSPEC instrument) with fully calibrated X-ray filters at the OMEGA laser. Extensions to use the capability for calibrating filter transmission for the DANTE instrument on the National Ignition Facility are discussed.
Date: May 11, 2008
Creator: Brown, G. V.; Beiersdorfer, P.; Emig, J.; Frankel, M.; Gu, M. F.; Heeter, R. F. et al.
System: The UNT Digital Library
Massively Parallel QCD (open access)

Massively Parallel QCD

The theory of the strong nuclear force, Quantum Chromodynamics (QCD), can be numerically simulated from first principles on massively-parallel supercomputers using the method of Lattice Gauge Theory. We describe the special programming requirements of lattice QCD (LQCD) as well as the optimal supercomputer hardware architectures that it suggests. We demonstrate these methods on the BlueGene massively-parallel supercomputer and argue that LQCD and the BlueGene architecture are a natural match. This can be traced to the simple fact that LQCD is a regular lattice discretization of space into lattice sites while the BlueGene supercomputer is a discretization of space into compute nodes, and that both are constrained by requirements of locality. This simple relation is both technologically important and theoretically intriguing. The main result of this paper is the speedup of LQCD using up to 131,072 CPUs on the largest BlueGene/L supercomputer. The speedup is perfect with sustained performance of about 20% of peak. This corresponds to a maximum of 70.5 sustained TFlop/s. At these speeds LQCD and BlueGene are poised to produce the next generation of strong interaction physics theoretical results.
Date: April 11, 2007
Creator: Soltz, R.; Vranas, P.; Blumrich, M.; Chen, D.; Gara, A.; Giampap, M. et al.
System: The UNT Digital Library
EFFECTIVENESS OF USING DILUTE OXALIC ACID TO DISSOLVEHIGH LEVEL WASTE IRON BASED SLUDGE SIMULANT (open access)

EFFECTIVENESS OF USING DILUTE OXALIC ACID TO DISSOLVEHIGH LEVEL WASTE IRON BASED SLUDGE SIMULANT

At the Savannah River Site (SRS), near Aiken South Carolina, there is a crucial need to remove residual quantities of highly radioactive iron-based sludge from large select underground storage tanks (e.g., 19,000 liters of sludge per tank), in order to support tank closure. The use of oxalic acid is planned to dissolve the residual sludge, hence, helping in the removal. Based on rigorous testing, primarily using 4 and 8 wt% oxalic acid solutions, it was concluded that the more concentrated the acid, the greater the amount of residual sludge that would be dissolved; hence, a baseline technology on using 8 wt% oxalic acid was developed. In stark contrast to the baseline technology, reports from other industries suggest that the dissolution will most effectively occur at 1 wt% oxalic acid (i.e., maintaining the pH near 2). The driver for using less oxalic acid is that less (i.e., moles) would decrease the severity of the downstream impacts (i.e., required oxalate solids removal efforts). To determine the initial feasibility of using 1 wt% acid to dissolve > 90% of the sludge solids, about 19,000 liters of representative sludge was modeled using about 530,000 liters of 0 to 8 wt% oxalic acid solutions. With …
Date: July 11, 2008
Creator: Ketusky, E
System: The UNT Digital Library
A divide-and-conquer linear scaling three dimensional fragment method for large scale electronic structure calculations (open access)

A divide-and-conquer linear scaling three dimensional fragment method for large scale electronic structure calculations

We present a new linear scaling ab initio total energy electronic structure calculation method based on the divide-and-conquer strategy. This method is simple to implement, easily to parallelize, and produces very accurate results when compared with the direct ab initio method. The method has been tested using up to 8,000 processors, and has been used to calculate nanosystems up to 15,000 atoms.
Date: July 11, 2008
Creator: Wang, Lin-Wang; Zhao, Zhengji; Meza, Juan & Wang, Lin-Wang
System: The UNT Digital Library
The Effectiveness of HCl and HF Cleaning of Si0.85Ge0.15 Surface (open access)

The Effectiveness of HCl and HF Cleaning of Si0.85Ge0.15 Surface

The cleaning of Si{sub 0.85}Ge{sub 0.15} surfaces using HCl and HF solutions is studied using synchrotron radiation photoelectron spectroscopy. The HF solution is found to be effective in removing both the Si oxide and the Ge oxide while the HCl solution can only remove part of the Ge oxide. For samples treated with HF, four spectral components are needed to fit the Ge 3d photoemission spectra. One is the bulk component and the other three are attributed to the surface Ge atoms with mono-hydride, di-hydride and tri-hydride terminations, respectively.
Date: July 11, 2008
Creator: Sun, Y.; Liu, Z.; Sun, S. & Pianetta, P.
System: The UNT Digital Library
Vacuum Chamber Design of NSLS-II Storage Ring (open access)

Vacuum Chamber Design of NSLS-II Storage Ring

National Synchrotron Light Source II (NSLS II) will be a 3-GeV, 792-meter circumference, 3rd generation synchrotron radiation facility, with ultra low emittance and extremely high brightness. the storage ring has 30 Double-Bend-Achromatic (DBA) cells. in each cell, there are five magnets and chamber girders, and one straight section for insertion devices or Radio Frequency (RF) cavities or injection. Most vacuum chambers are made from extruded aluminum with two different cross sections: one fitted in the dipole magnets, and the other surrounded by multipole magnets. They discuss the layout of the DBA cells, the detailed design of the cell's vacuum chambers, the mounting of the Beam-Position-Monitor (BPM) buttons, discrete absorbers, lumped pumps and the distributed Non-Evaporable Getter (NEG) strips, and describe the fabrication and testing of these prototype cell chambers. The account also details the development of the chamber bakeout process, the NEG stri's supports, and the RF shielded bellows.
Date: June 11, 2008
Creator: Doom,L.; Ferreira, M.; Hseuh, H. C.; Lincoln, F.; Longo, C.; Ravindranath, V. et al.
System: The UNT Digital Library
Repassivation Potential of Alloy 22 in Sodium and Calcium Chloride Brines (open access)

Repassivation Potential of Alloy 22 in Sodium and Calcium Chloride Brines

A comprehensive matrix of 60 tests was designed to explore the effect of calcium chloride vs. sodium chloride and the ratio R of nitrate concentration over chloride concentration on the repassivation potential of Alloy 22. Tests were conducted using the cyclic potentiodynamic polarization (CPP) technique at 75 C and at 90 C. Results show that at a ratio R of 0.18 and higher nitrate was able to inhibit the crevice corrosion in Alloy 22 induced by chloride. Current results fail to show in a consistent way a different effect on the repassivation potential of Alloy 22 for calcium chloride solutions than for sodium chloride solutions.
Date: August 11, 2007
Creator: Rebak, R B; Ilevbare, G O & Carranza, R M
System: The UNT Digital Library
Effect of chemical etching on the surface roughness of CdZnTe and CdMnTe gamma radiation detectors (open access)

Effect of chemical etching on the surface roughness of CdZnTe and CdMnTe gamma radiation detectors

Generally, mechanical polishing is performed to diminish the cutting damage followed by chemical etching to remove the remaining damage on crystal surfaces. In this paper, we detail the findings from our study of the effects of various chemical treatments on the roughness of crystal surfaces. We prepared several CdZnTe (CZT) and CdMnTe (CMT) crystals by mechanical polishing with 5 {micro}m and/or lower grits of Al{sub 2}O{sub 3} abrasive papers including final polishing with 0.05-{micro}m particle size alumina powder and then etched them for different periods with a 2%, 5% Bromine-Methanol (B-M) solution, and also with an E-solution (HNO{sub 3}:H{sub 2}O:Cr{sub 2}O{sub 7}). The material removal rate (etching rate) from the crystals was found to be 10 {micro}m, 30 {micro}m, and 15 {micro}m per minute, respectively. The roughness of the resulting surfaces was determined by the Atomic Force Microscopy (AFM) to identify the most efficient surface processing method by combining mechanical and chemical polishing.
Date: August 11, 2008
Creator: Hossain, A.; Babalola, S.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Yang, G. et al.
System: The UNT Digital Library
Seismic Source and Path Calibration in the Korean Peninsula, Yellow Sea (open access)

Seismic Source and Path Calibration in the Korean Peninsula, Yellow Sea

Two significant seismic events were analyzed using the crustal velocity model developed under this contract. The M{sub W} = 4.55 Korea earthquake of January 20, 2007 occurred in the Republic of Korea on land and within the dense digital seismic network. Using P-wave arrivals from 60 broadband, short-period and acceleration stations, the event occurred at 37.68N, 128.58E at a depth of 7.5 km at 20070120115653.8. Source inversion was performed using the accelerometer recordings in the 0.05-0.20 Hz band the broadband data in the 0.02-0.10 Hz band, with identical focal mechanisms and source depths of 9 and 11 km, respectively. This is the largest event on land in South Korea since the M{sub W} 4.7 event on December 13, 1996. Forward modeling of the waveforms at INCN and MDJ indicates the ability of the current model to match observations on the Korean Peninsula and the effect of significant pulse shape modification for paths that partially cross the Sea of Japan. The results of using the local network data provide a ground truth point for other studies analyzing seismic events on the peninsula. The isotropic seismic moment of the October 9, 2006 North Korea explosion was estimated from the Rayleigh-wave spectral amplitudes …
Date: July 11, 2007
Creator: Herrmann, R. B.; Walter, W. R. & Pasyanos, M.
System: The UNT Digital Library
Tools for neuroanatomy and neurogenetics in Drosophila (open access)

Tools for neuroanatomy and neurogenetics in Drosophila

We demonstrate the feasibility of generating thousands of transgenic Drosophila melanogaster lines in which the expression of an exogenous gene is reproducibly directed to distinct small subsets of cells in the adult brain. We expect the expression patterns produced by the collection of 5,000 lines that we are currently generating to encompass all neurons in the brain in a variety of intersecting patterns. Overlapping 3-kb DNA fragments from the flanking noncoding and intronic regions of genes thought to have patterned expression in the adult brain were inserted into a defined genomic location by site-specific recombination. These fragments were then assayed for their ability to function as transcriptional enhancers in conjunction with a synthetic core promoter designed to work with a wide variety of enhancer types. An analysis of 44 fragments from four genes found that >80% drive expression patterns in the brain; the observed patterns were, on average, comprised of <100 cells. Our results suggest that the D. melanogaster genome contains >50,000 enhancers and that multiple enhancers drive distinct subsets of expression of a gene in each tissue and developmental stage. We expect that these lines will be valuable tools for neuroanatomy as well as for the elucidation of neuronal …
Date: August 11, 2008
Creator: Pfeiffer, Barret D.; Jenett, Arnim; Hammonds, Ann S.; Ngo, Teri-T B.; Misra, Sima; Murphy, Christine et al.
System: The UNT Digital Library
A New Chicane Experiment in PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders (open access)

A New Chicane Experiment in PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders

Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders [1-3]. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine.
Date: June 11, 2008
Creator: Pivi, M. T.; Pivi, M. T. F.; Ng, J. S. T.; Arnett, D.; Cooper, F.; Kharakh, D. et al.
System: The UNT Digital Library
Determining Transition State Geometries in Liquids Using 2D-IR (open access)

Determining Transition State Geometries in Liquids Using 2D-IR

Many properties of chemical reactions are determined by the transition state connecting reactant and product, yet it is difficult to directly obtain any information about these short-lived structures in liquids. We show that two-dimensional infrared (2D-IR) spectroscopy can provide direct information about transition states by tracking the transformation of vibrational modes as a molecule crossed a transition state. We successfully monitored a simple chemical reaction, the fluxional rearrangement of Fe(CO)5, in which the exchange of axial and equatorial CO ligands causes an exchange of vibrational energy between the normal modes of the molecule. This energy transfer provides direct evidence regarding the time scale, transition state, and mechanism of the reaction.
Date: December 11, 2007
Creator: Harris, Charles; Cahoon, James F.; Sawyer, Karma R.; Schlegel, Jacob P. & Harris, Charles B.
System: The UNT Digital Library
Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling (open access)

Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling

Electron clouds and gas pressure rise limit the performance of many major accelerators. A multi-laboratory effort to understand the underlying physics via the combined application of experiment, theory, and simulation is underway. We present here the status of the simulation capability development, based on a merge of the three-dimensional parallel Particle-In-Cell (PIC) accelerator code WARP and the electron cloud code POSINST, with additional functionalities. The development of the new capability follows a ''roadmap'' describing the different functional modules, and their inter-relationships, that are ultimately needed to reach self-consistency. Newly developed functionalities include a novel particle mover bridging the time scales between electron and ion motion, a module to generate neutrals desorbed by beam ion impacts at the wall, and a module to track impact ionization of the gas by beam ions or electrons. Example applications of the new capability to the modeling of electron effects in the High Current Experiment (HCX) are given.
Date: October 11, 2005
Creator: Vay, J; Furman, M A; Seidl, P A; Cohen, R H; Friedman, A; Grote, D P et al.
System: The UNT Digital Library
Search for CP Violation in Neutral D Meson Cabibbo-suppressedThree-body Decays (open access)

Search for CP Violation in Neutral D Meson Cabibbo-suppressedThree-body Decays

Using 385 fb{sup -1} of e{sup +}e{sup -} collision data collected at center-of-mass energies around 10.6 GeV, we search for time-integrated CP violation in the Cabibbo-suppressed decays D{sup 0}/{bar D}{sup 0} {yields} {pi}{sup -}{pi}{sup +}{pi}{sup 0} and D{sup 0}/{bar D}{sup 0} {yields} K{sup -}K{sup +}{pi}{sup 0} with both model-independent and model-dependent methods. Measurements of the asymmetries in amplitudes of flavor states and CP eigenstates provide constraints on theories beyond the Standard Model, some of which predict CP violation in amplitudes at the 1% level or higher. We find no evidence of CP violation and hence no conflict with the Standard Model.
Date: March 11, 2008
Creator: Aubert, B.
System: The UNT Digital Library
Damage Detection System with Sub-microsecond Resolution (open access)

Damage Detection System with Sub-microsecond Resolution

Fiber optic grating sensors have been used to measure multi-dimensional strain, pressure, temperature, corrosion and moisture. This paper presents a method of using fiber grating sensors to measure the position and velocity of a very fast event associated with a blast wave. A chirped fiber grating of 50 mm length is placed in a highly energetic material. The action of the shock wave is to destroy the fiber grating as it propagates along it. By using a spectral filter such as a chirped fiber grating in combination with high speed detectors the position and velocity of the shock wave may be determined. A layout of a system used to experimentally verify this technique is described and results presented for two different highly energetic materials.
Date: February 11, 2008
Creator: Udd, E & Benterou, J
System: The UNT Digital Library