Carbon-14 Bomb Pulse Dating (open access)

Carbon-14 Bomb Pulse Dating

Abstract: Atmospheric testing of nuclear weapons during the 1950s and early 1960s doubled the concentration of carbon-14 in the atmosphere and created a pulse that labeled everything alive since 1955 as carbon moved up the food chain. The variation in carbon-14 concentration in time is well-documented and can be used to chronologically date all biological materials since the mid-1950s.
Date: June 15, 2012
Creator: Buchholz, Bruce A.
Object Type: Book Chapter
System: The UNT Digital Library
Scientific Opportunities for Monitoring at Environmental Remediation Sites (SOMERS): Integrated Systems-Based Approaches to Monitoring (open access)

Scientific Opportunities for Monitoring at Environmental Remediation Sites (SOMERS): Integrated Systems-Based Approaches to Monitoring

Through an inter-disciplinary effort, DOE is addressing a need to advance monitoring approaches from sole reliance on cost- and labor-intensive point-source monitoring to integrated systems-based approaches such as flux-based approaches and the use of early indicator parameters. Key objectives include identifying current scientific, technical and implementation opportunities and challenges, prioritizing science and technology strategies to meet current needs within the DOE complex for the most challenging environments, and developing an integrated and risk-informed monitoring framework.
Date: May 15, 2012
Creator: Bunn, Amoret L.; Wellman, Dawn M.; Deeb, Rula A.; Hawley, Elizabeth L.; Truex, Michael J.; Peterson, Mark et al.
Object Type: Report
System: The UNT Digital Library
AIP Conference Proceedings for the 19th Topical Conference on Radio Frequency Power in Plasmas (open access)

AIP Conference Proceedings for the 19th Topical Conference on Radio Frequency Power in Plasmas

An analytic model for single particle motion in the presence of a wave field and multiple cyclotron harmonics is developed and investigated. The model suggests that even in the absence of Doppler broadening, cyclotron harmonic layers have finite spatial extent. This allows for particles to interact with more than one harmonic layer simultaneously, provided the layers are tightly packed. The latter phenomenon is investigated in the context of the model using symplectic mapping techniques. Then the model behavior is compared with numerical simulations of neutral beam particle trajectories in NSTX using the full-orbit code SPIRAL
Date: August 15, 2012
Creator: Burby, J. W.; Kramer, G. J.; Phillips, C. K. & Valeo, E. J.
Object Type: Article
System: The UNT Digital Library
Canopy 2.1 User Guide (open access)

Canopy 2.1 User Guide

Its user guide for the Canopy system. Its design to be used electronically or printed out in conjunction with the application to teach users about the features.
Date: September 15, 2012
Creator: Burtner, Edwin R.
Object Type: Report
System: The UNT Digital Library
Construction and Development of a BF3 Neutron Detector At Brookhaven National Laboratory (BNL) (open access)

Construction and Development of a BF3 Neutron Detector At Brookhaven National Laboratory (BNL)

N/A
Date: July 15, 2012
Creator: C., Czajkowski; C., Finfrock; Philipsberg, P. & Ghosh, V.
Object Type: Article
System: The UNT Digital Library
Performance analysis of Darshan 2.2.3 on the Cray XE6 platform. (open access)

Performance analysis of Darshan 2.2.3 on the Cray XE6 platform.

None
Date: November 15, 2012
Creator: Carns, P.; Harms, K.; Latham, R. & Ross, R. (Mathematics and Computer Science)
Object Type: Report
System: The UNT Digital Library
Plasmonics Based Harsh Environment Compatible Chemical Sensors (open access)

Plasmonics Based Harsh Environment Compatible Chemical Sensors

Au-YSZ, Au-TiO{sub 2} and Au-CeO{sub 2} nanocomposite films have been investigated as a potential sensing element for high-temperature plasmonic sensing of H{sub 2}, CO, and NO{sub 2} in an oxygen containing environment. The Au-YSZ and Au-TiO{sub 2} films were deposited using PVD methods, while the CeO{sub 2} thin film was deposited by molecular beam epitaxy (MBE) and Au was implanted into the as-grown film at an elevated temperature followed by high temperature annealing to form well-defined Au nanoclusters. Each of the films were characterized by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). For the gas sensing experiments, separate exposures to varying concentrations of H{sub 2}, CO, and NO{sub 2} were performed at a temperature of 500°C in oxygen backgrounds of 5.0, 10, and ~21% O{sub 2}. Changes in the localized surface plasmon resonance (LSPR) absorption peak were monitored during gas exposures and are believed to be the result of oxidation-reduction processes that fill or create oxygen vacancies in the respective metal oxides. This process affects the LSPR peak position either by charge exchange with the Au nanoparticles or by changes in the dielectric constant surrounding the particles. Hyperspectral multivariate analysis was used to gauge the inherent selectivity of the …
Date: January 15, 2012
Creator: Carpenter, Michael
Object Type: Report
System: The UNT Digital Library
Development of Transparent Ceramic Ce-Doped Gadolinium Garnet Gamma Spectrometers (open access)

Development of Transparent Ceramic Ce-Doped Gadolinium Garnet Gamma Spectrometers

None
Date: November 15, 2012
Creator: Cherepy, N J; Seeley, Z M; Payne, S A; Beck, P R; Drury, O B; O'Neal, S P et al.
Object Type: Article
System: The UNT Digital Library
Atomic data for the ITER Core Imaging X-ray Spectrometer (open access)

Atomic data for the ITER Core Imaging X-ray Spectrometer

The parameters of the ITER core plasmas will be measured using the Core Imaging X-ray Spectrometer (CIXS), a high-resolution crystal spectrometer focusing on the L-shell spectra of highly ionized tungsten atoms. In order to correctly infer the plasma properties accurate atomic data are required. Here, some aspects of the underlying physics are discussed using experimental data and theoretical predictions from modeling.
Date: June 15, 2012
Creator: Clementson, J.; Beiersdorfer, P.; Biedermann, C.; Bitter, M.; Delgado-Aparicio, L. F.; Graf, A. et al.
Object Type: Article
System: The UNT Digital Library
Singlet-Doublet Dark Matter (open access)

Singlet-Doublet Dark Matter

In light of recent data from direct detection experiments and the Large Hadron Collider, we explore models of dark matter in which an SU(2){sub L} doublet is mixed with a Standard Model singlet. We impose a thermal history. If the new particles are fermions, this model is already constrained due to null results from XENON100. We comment on remaining regions of parameter space and assess prospects for future discovery. We do the same for the model where the new particles are scalars, which at present is less constrained. Much of the remaining parameter space for both models will be probed by the next generation of direct detection experiments. For the fermion model, DeepCore may also play an important role.
Date: February 15, 2012
Creator: Cohen, Timothy; /SLAC /Michigan U., MCTP; Kearney, John; Pierce, Aaron; /Michigan U., MCTP; Tucker-Smith, David et al.
Object Type: Report
System: The UNT Digital Library
Electroweak Baryogenesis and Colored Scalars (open access)

Electroweak Baryogenesis and Colored Scalars

We consider the 2-loop finite temperature effective potential for a Standard Model-like Higgs boson, allowing Higgs boson couplings to additional scalars. If the scalars transform under color, they contribute 2-loop diagrams to the effective potential that include gluons. These 2-loop effects are perhaps stronger than previously appreciated. For a Higgs boson mass of 115 GeV, they can increase the strength of the phase transition by as much as a factor of 3.5. It is this effect that is responsible for the survival of the tenuous electroweak baryogenesis window of the Minimal Supersymmetric Standard Model. We further illuminate the importance of these 2-loop diagrams by contrasting models with colored scalars to models with singlet scalars. We conclude that baryogenesis favors models with light colored scalars. This motivates searches for pair-produced di-jet resonances or jet(s) + = E{sub T}.
Date: February 15, 2012
Creator: Cohen, Timothy; /SLAC /Michigan U., MCTP; Pierce, Aaron & /Michigan U., MCTP
Object Type: Article
System: The UNT Digital Library
Comments on Gaugino Screening (open access)

Comments on Gaugino Screening

Gauge mediated models of supersymmetry breaking often exhibit 'gaugino screening,' where to leading order in F, gaugino masses are unaffected by higher dimensional Kahler potential interactions between the supersymmetry breaking spurion and the messengers. We provide a derivation of this phenomenon which utilizes the gaugino counterterm originally proposed in the context of anomaly mediation by Dine and Seiberg. We argue that this counterterm is present when there are non-zero messenger F-terms, and can cancel the leading order Feynman diagram contribution to the gaugino mass. We provide a nontrivial check of the regulator independence of our results by performing the computation using both dimensional reduction and Pauli-Villars. This analysis reconciles an apparent contradiction between diagrammatics and analytic continuation into superspace.
Date: February 15, 2012
Creator: Cohen, Timothy; Hook, Anson & Wecht, Brian
Object Type: Article
System: The UNT Digital Library
Constraints on the pMSSM from LAT Observations of Dwarf Spheroidal Galaxies (open access)

Constraints on the pMSSM from LAT Observations of Dwarf Spheroidal Galaxies

We examine the ability for the Large Area Telescope (LAT) to constrain Minimal Supersymmetric Standard Model (MSSM) dark matter through a combined analysis of Milky Way dwarf spheroidal galaxies. We examine the Lightest Supersymmetric Particles (LSPs) for a set of {approx}71k experimentally valid supersymmetric models derived from the phenomenological-MSSM (pMSSM). We find that none of these models can be excluded at 95% confidence by the current analysis; nevertheless, many lie within the predicted reach of future LAT analyses. With two years of data, we find that the LAT is currently most sensitive to light LSPs (mLSP < 50 GeV) annihilating into {tau}-pairs and heavier LSPs annihilating into b{bar b}. Additionally, we find that future LAT analyses will be able to probe some LSPs that form a sub-dominant component of dark matter. We directly compare the LAT results to direct detection experiments and show the complementarity of these search methods.
Date: March 15, 2012
Creator: Cotta, R. C.; Drlica-Wagner, A.; Murgia, S.; Bloom, E. D.; Hewett, J. L. & Rizzo, T. G.
Object Type: Article
System: The UNT Digital Library
Americans in International Organizations in Vienna Workshop Summary Report (open access)

Americans in International Organizations in Vienna Workshop Summary Report

N/A
Date: September 15, 2012
Creator: D., Occhiogrosso; S., Pepper & MacArthur, L. and Collins, T.
Object Type: Report
System: The UNT Digital Library
U.S. Citizens Working in International Organizations in Vienna, Austria (open access)

U.S. Citizens Working in International Organizations in Vienna, Austria

N/A
Date: July 15, 2012
Creator: D., Occhiogrosso; S., Pepper; MacArthur, L. & Collins, T.
Object Type: Article
System: The UNT Digital Library
CRADA Final Report for NFE-08-01826: Development and application of processing and processcontrol for nano-composite materials for lithium ion batteries (open access)

CRADA Final Report for NFE-08-01826: Development and application of processing and processcontrol for nano-composite materials for lithium ion batteries

Oak Ridge National Laboratory and A123 Systems, Inc. collaborated on this project to develop a better understanding, quality control procedures, and safety testing for A123 System’s nanocomposite separator (NCS) technology which is a cell based patented technology and separator. NCS demonstrated excellent performance. x3450 prismatic cells were shown to survive >8000 cycles (1C/2C rate) at room temperature with greater than 80% capacity retention with only NCS present as an alternative to conventional polyolefin. However, for a successful commercialization, the coating conditions required to provide consistent and reliable product had not been optimized and QC techniques for being able to remove defective material before incorporation into a cell had not been developed. The work outlined in this report addresses these latter two points. First, experiments were conducted to understand temperature profiles during the different drying stages of the NCS coating when applied to both anode and cathode. One of the more interesting discoveries of this study was the observation of the large temperature decrease experienced by the wet coating between the end of the infrared (IR) drying stage and the beginning of the exposure to the convection drying oven. This is not a desirable situation as the temperature gradient could have …
Date: December 15, 2012
Creator: Daniel, C.; Armstrong, B.; Maxey, C.; Sabau, A.; Wang, H.; Hagans, P. (A123 Systems, Inc.) et al.
Object Type: Report
System: The UNT Digital Library
Ultrafast Photovoltaic Response in Ferroelectric Nanolayers (open access)

Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond timescales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.
Date: February 15, 2012
Creator: Daranciang, Dan
Object Type: Article
System: The UNT Digital Library
Single-cycle Terahertz Pulses with >0.2 V/A Field Amplitudes via Coherent Transition Radiation (open access)

Single-cycle Terahertz Pulses with >0.2 V/A Field Amplitudes via Coherent Transition Radiation

We demonstrate terahertz pulses with field amplitudes exceeding 0.2 V/{angstrom} generated by coherent transition radiation. Femtosecond, relativistic electron bunches generated at the Linac Coherent Light Source are passed through a beryllium foil, and the emitted radiation is characterized as a function of the bunch duration and charge. Broadband pulses centered at a frequency of 10 THz with energies of 140 {mu}J are measured. These far-below-bandgap pulses drive a nonlinear optical response in a silicon photodiode, with which we perform nonlinear autocorrelations that yield information regarding the terahertz temporal profile. Simulations of the spatiotemporal profile agree well with experimental results.
Date: February 15, 2012
Creator: Daranciang, Dan; Goodfellow, John; Fuchs, Matthias; Wen, Haidan; Ghimire, Shambhu; Reis, David A. et al.
Object Type: Article
System: The UNT Digital Library
Testing the OPERA Superluminal Neutrino Anomaly at the LHC (open access)

Testing the OPERA Superluminal Neutrino Anomaly at the LHC

The OPERA collaboration has reported the observation of superluminal muon neutrinos, whose speed v{sub {nu}} exceeds that of light c, with (v{sub {nu}}-c)/c {approx_equal} 2.5 x 10{sup -5}. In a recent work, Cohen and Glashow (CG) have refuted this claim by noting that such neutrinos will lose energy, by pair-emission of particles, at unacceptable rates. Following the CG arguments, we point out that pair-emissions consistent with the OPERA anomaly can lead to detectable signals for neutrinos originating from decays of highly boosted top quarks at the LHC, allowing an independent test of the superluminal neutrino hypothesis.
Date: March 15, 2012
Creator: Davoudiasl, Hooman; /Brookhaven & Rizzo, Thomas G.
Object Type: Article
System: The UNT Digital Library
Advances in Superresolution Optical Fluctuation Imaging (SOFI) (open access)

Advances in Superresolution Optical Fluctuation Imaging (SOFI)

None
Date: May 15, 2012
Creator: Dertinger, T.; Pallaoro, A.; Braun, G.; Ly, S.; Laurence, T. A. & Weiss, S.
Object Type: Article
System: The UNT Digital Library
Analytic Result for the Two-loop Six-point NMHV Amplitude in N = 4 Super Yang-Mills Theory (open access)

Analytic Result for the Two-loop Six-point NMHV Amplitude in N = 4 Super Yang-Mills Theory

We provide a simple analytic formula for the two-loop six-point ratio function of planar N = 4 super Yang-Mills theory. This result extends the analytic knowledge of multi-loop six-point amplitudes beyond those with maximal helicity violation. We make a natural ansatz for the symbols of the relevant functions appearing in the two-loop amplitude, and impose various consistency conditions, including symmetry, the absence of spurious poles, the correct collinear behavior, and agreement with the operator product expansion for light-like (super) Wilson loops. This information reduces the ansatz to a small number of relatively simple functions. In order to fix these parameters uniquely, we utilize an explicit representation of the amplitude in terms of loop integrals that can be evaluated analytically in various kinematic limits. The final compact analytic result is expressed in terms of classical polylogarithms, whose arguments are rational functions of the dual conformal cross-ratios, plus precisely two functions that are not of this type. One of the functions, the loop integral {Omega}{sup (2)}, also plays a key role in a new representation of the remainder function R{sub 6}{sup (2)} in the maximally helicity violating sector. Another interesting feature at two loops is the appearance of a new (parity odd) …
Date: February 15, 2012
Creator: Dixon, Lance J.; Drummond, James M. & Henn, Johannes M.
Object Type: Article
System: The UNT Digital Library
FRW Solutions and Holography from Uplifted AdS/CFT (open access)

FRW Solutions and Holography from Uplifted AdS/CFT

Starting from concrete AdS/CFT dual pairs, one can introduce ingredients which produce cosmological solutions, including metastable de Sitter and its decay to non-accelerating FRW. We present simple FRW solutions sourced by magnetic flavor branes and analyze correlation functions and particle and brane dynamics. To obtain a holographic description, we exhibit a time-dependent warped metric on the solution and interpret the resulting redshifted region as a Lorentzian low energy effective field theory in one fewer dimension. At finite times, this theory has a finite cutoff, a propagating lower dimensional graviton and a finite covariant entropy bound, but at late times the lower dimensional Planck mass and entropy go off to infinity in a way that is dominated by contributions from the low energy effective theory. This opens up the possibility of a precise dual at late times. We reproduce the time-dependent growth of the number of degrees of freedom in the system via a count of available microscopic states in the corresponding magnetic brane construction.
Date: February 15, 2012
Creator: Dong, Xi; Horn, Bart; /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC; Matsuura, Shunji; /Santa Barbara, KITP /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC; Silverstein, Eva et al.
Object Type: Report
System: The UNT Digital Library
Advanced, Integrated Control for Building Operations to Achieve 40% Energy Saving (open access)

Advanced, Integrated Control for Building Operations to Achieve 40% Energy Saving

we developed and demonstrated a software based integrated advanced building control platform called Smart Energy Box (SEB), which can coordinate building subsystem controls, integrate variety of energy optimization algorithms and provide proactive and collaborative energy management and control for building operations using weather and occupancy information. The integrated control system is a low cost solution and also features: Scalable component based architecture allows to build a solution for different building control system configurations with needed components; Open Architecture with a central data repository for data exchange among runtime components; Extendible to accommodate variety of communication protocols. Optimal building control for central loads, distributed loads and onsite energy resource Uses web server as a loosely coupled way to engage both building operators and building occupants in collaboration for energy conservation. Based on the open platform of SEB, we have investigated and evaluated a variety of operation and energy saving control strategies on Carnegie Mellon University Intelligent Work place which is equipped with alternative cooling/heating/ventilation/lighting methods, including radiant mullions, radiant cooling/heating ceiling panels, cool waves, dedicated ventilation unit, motorized window and blinds, and external louvers. Based on the validation results of these control strategies, they were integrated in SEB in a collaborative …
Date: October 15, 2012
Creator: Dr. Zhen Song, Prof. Vivian Loftness, Dr. Kun Ji, Dr. Sam Zheng, Mr. Bertrand Lasternas, Ms. Flore Marion, Mr. Yuebin Yu
Object Type: Report
System: The UNT Digital Library
Hydrogen Production and Purification from Coal and Other Heavy Feedstocks Year 6 - Activity 1.4 - Development of a National Center for Hydrogen Technology (open access)

Hydrogen Production and Purification from Coal and Other Heavy Feedstocks Year 6 - Activity 1.4 - Development of a National Center for Hydrogen Technology

Air Products and Chemicals, Inc., is developing the sour pressure swing adsorption (PSA) technology which can be used to reject acid gas components (hydrogen sulfide [H{sub 2}S] and carbon dioxide [CO{sub 2}]) from sour syngas streams such as coal gasification syngas. In the current work, tests were conducted to investigate the impact of continuous exposure of real sour syngas and dilute levels of hydrochloric acid (HCl) and ammonia (NH{sub 3}) on the preferred adsorbent of that process. The results show a modest (~10%–15%) decrease in CO{sub 2} adsorption capacity after sour syngas exposure, as well as deposition of metals from carbonyl decomposition. Continuous exposure to HCl and NH{sub 3} yield a higher degree of CO{sub 2} capacity degradation (up to 25%). These tests represent worst-case approaches since the exposure is continuous and the HCl and NH{sub 3} levels are relatively high compare to an industrial sour syngas stream. Long-term PSA tests are needed to unequivocally evaluate the impact of cyclic exposure to these types of streams.
Date: March 15, 2012
Creator: Dunham, Grant
Object Type: Report
System: The UNT Digital Library