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Laser supported solid state absorption fronts in silica (open access)

Laser supported solid state absorption fronts in silica

We develop a model based on simulation and experiment that explains the behavior of solid-state laser-supported absorption fronts generated in fused silica during high intensity (up to 5GW/cm{sup 2}) laser exposure. We find that the absorption front velocity is constant in time and is nearly linear in laser intensity. Further, this model can explain the dependence of laser damage site size on these parameters. This behavior is driven principally by the temperature-activated deep sub band-gap optical absorptivity, free electron transport and thermal diffusion in defect-free silica for temperatures up to 15,000K and pressures < 15GPa. The regime of parameter space critical to this problem spans and extends that measured by other means. It serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.
Date: February 9, 2010
Creator: Carr, C W & Bude, J D
System: The UNT Digital Library
Reevaluation Of Vitrified High-Level Waste Form Criteria For Potential Cost Savings At The Defense Waste Processing Facility (open access)

Reevaluation Of Vitrified High-Level Waste Form Criteria For Potential Cost Savings At The Defense Waste Processing Facility

At the Savannah River Site (SRS) the Defense Waste Processing Facility (DWPF) has been immobilizing SRS's radioactive high level waste (HLW) sludge into a durable borosilicate glass since 1996. Currently the DWPF has poured over 3,500 canisters, all of which are compliant with the U. S. Department of Energy's (DOE) Waste Acceptance Product Specifications for Vitrified High-Level Waste Forms (WAPS) and therefore ready to be shipped to a federal geologic repository for permanent disposal. Due to DOE petitioning to withdraw the Yucca Mountain License Application (LA) from the Nuclear Regulatory Commission (NRC) in 2010 and thus no clear disposal path for SRS canistered waste forms, there are opportunities for cost savings with future canister production at DWPF and other DOE producer sites by reevaluating high-level waste form requirements and compliance strategies and reducing/eliminating those that will not negatively impact the quality of the canistered waste form.
Date: January 9, 2013
Creator: Ray, J. W.; Marra, S. L. & Herman, C. C.
System: The UNT Digital Library
Developing of superconducting RF guns at BNL (open access)

Developing of superconducting RF guns at BNL

N/A
Date: September 9, 2012
Creator: Belomestnykh, S.; Altinbas, Z.; Ben-Zvi, Ilan; Boulware, C. H.; Brutus, J. C.; Burrill, A. et al.
System: The UNT Digital Library
Performance Modeling of Algebraic Multigrid on Blue Gene/Q: Lessons Learned (open access)

Performance Modeling of Algebraic Multigrid on Blue Gene/Q: Lessons Learned

None
Date: September 9, 2012
Creator: Gahvari, H.; Gropp, W.; Jordan, K. E.; Schulz, M. & Yang, U. M.
System: The UNT Digital Library
Next-to-Leading Order W 5-Jet Production at the LHC (open access)

Next-to-Leading Order W 5-Jet Production at the LHC

None
Date: April 9, 2013
Creator: Bern, Z.; Dixon, L. J.; Cordero, F. Febres; Hoeche, S.; Ita, H.; Kosower, D. A. et al.
System: The UNT Digital Library
Future Synchrotron Light Sources Based on Ultimate Storage Rings (open access)

Future Synchrotron Light Sources Based on Ultimate Storage Rings

The main purpose of this talk is to describe how far one might push the state of the art in storage ring design. The talk will start with an overview of the latest developments and advances in the design of synchrotron light sources based on the concept of an 'ultimate' storage ring. The review will establish how bright a ring based light source might be, where the frontier of technological challenges are, and what the limits of accelerator physics are. Emphasis will be given to possible improvements in accelerator design and developments in technology toward the goal of achieving an ultimate storage ring. An ultimate storage ring (USR), defined as an electron ring-based light source having an emittance in both transverse planes at the diffraction limit for the range of X-ray wavelengths of interest for a scientific community, would provide very high brightness photons having high transverse coherence that would extend the capabilities of X-ray imaging and probe techniques beyond today's performance. It would be a cost-effective, high-coherence 4th generation light source, competitive with one based on energy recovery linac (ERL) technology, serving a large number of users studying material, chemical, and biological sciences. Furthermore, because of the experience accumulated …
Date: April 9, 2012
Creator: Cai, Yunhai
System: The UNT Digital Library
Evaluation of Alternative Filter Media for the Rotary Microfilter (open access)

Evaluation of Alternative Filter Media for the Rotary Microfilter

The Savannah River Site is currently developing and testing several processes to treat high level radioactive liquid waste. Each of these processes has a solid-liquid separation process that limits its throughput. Savannah River National Laboratory researchers identified and tested the rotary microfilter as a technology to increase solid-liquid separation throughput. The authors believe the rotary microfilter throughput can be improved by using a better filter membrane. Previous testing showed that asymmetric filters composed of a ceramic membrane on top of a stainless steel support produced higher filter flux than 100% stainless steel symmetric filters in crossflow filter tests. Savannah River National Laboratory and Oak Ridge National Laboratory are working together to develop asymmetric ceramic ? stainless steel composite filters and asymmetric 100% stainless steel filters to improve the throughput of the rotary microfilter. The Oak Ridge National Laboratory Inorganic Membrane Group fabricated samples of alternative filter membranes. In addition, Savannah River National Laboratory obtained samples of filter membranes from Pall, Porvair, and SpinTek. They tested these samples in a static test cell with feed slurries containing monosodium titanate and simulated sludge.
Date: November 9, 2011
Creator: Poirier, M. R.; Herman, D. T. & Bhave, R.
System: The UNT Digital Library
Axisymmetric Simulations of the ITER Vertical Stability Coil (open access)

Axisymmetric Simulations of the ITER Vertical Stability Coil

The ITER in-vessel coil system includes Vertical Stability (VS) coils and Edge Localized Mode (ELM) coils. There are two large VS ring coils, one upper and one lower. Each has four turns which are independently connected. The VS coils are needed for successful operation of ITER for most all of its operating modes. The VS coils must be highly reliable and fault tolerant. The operating environment includes normal and disruption Lorentz forces. To parametrically address all these design conditions in a tractable analysis requires a simplified model. The VS coils are predominately axisymmetric, and this suggests that an axisymmetric model can be meaningfully used to address the variations in mechanical design, loading, material properties, and time dependency. The axisymmetric finite element analysis described in this paper includes simulations of the bolted frictional connections used for the mounting details. Radiation and elastic-plastic response are modeled particularly for the extreme faulted conditions. Thermal connectivity is varied to study the effects of partial thermal connection of the actively cooled conductor to the remaining structure.
Date: July 9, 2013
Creator: Titus, Peter H.
System: The UNT Digital Library
Efficient Laser-Induced 6 - 8 KeV X-Ray Production From Iron Oxide Aerogel and Foil-Lined Cavity Targets (open access)

Efficient Laser-Induced 6 - 8 KeV X-Ray Production From Iron Oxide Aerogel and Foil-Lined Cavity Targets

None
Date: May 9, 2012
Creator: Perez, F.; Kay, J. J.; Patterson, R.; Kane, J.; Villette, B.; Girard, F. et al.
System: The UNT Digital Library
Finding Regions of Interest on Toroidal Meshes (open access)

Finding Regions of Interest on Toroidal Meshes

Fusion promises to provide clean and safe energy, and a considerable amount of research effort is underway to turn this aspiration intoreality. This work focuses on a building block for analyzing data produced from the simulation of microturbulence in magnetic confinementfusion devices: the task of efficiently extracting regions of interest. Like many other simulations where a large amount of data are produced,the careful study of ``interesting'' parts of the data is critical to gain understanding. In this paper, we present an efficient approach forfinding these regions of interest. Our approach takes full advantage of the underlying mesh structure in magnetic coordinates to produce acompact representation of the mesh points inside the regions and an efficient connected component labeling algorithm for constructingregions from points. This approach scales linearly with the surface area of the regions of interest instead of the volume as shown with bothcomputational complexity analysis and experimental measurements. Furthermore, this new approach is 100s of times faster than a recentlypublished method based on Cartesian coordinates.
Date: February 9, 2011
Creator: Wu, Kesheng; Sinha, Rishi R; Jones, Chad; Ethier, Stephane; Klasky, Scott; Ma, Kwan-Liu et al.
System: The UNT Digital Library
Flux and Photon Spectral Index Distributions of Fermi-LAT Blazars and Contribution to the Extragalactic Gamma-ray Background (open access)

Flux and Photon Spectral Index Distributions of Fermi-LAT Blazars and Contribution to the Extragalactic Gamma-ray Background

We present a determination of the distributions of gamma-ray flux - the so called LogN-LogS relation - and photon spectral index for the 352 blazars detected with a greater than approximately seven sigma detection threshold and located above {+-} 20{sup o} Galactic latitude by the Large Area Telescope of the Fermi Gamma-ray Space Telescope in its first year catalog. Because the flux detection threshold depends on the photon index, the observed raw distributions do not provide the true LogN-LogS counts or the true distribution of the photon index. We use the non-parametric methods developed by Efron and Petrosian to reconstruct the intrinsic distributions from the observed ones which account for the data truncations introduced by observational bias and includes the effects of the possible correlation among the two variables. We demonstrate the robustness of our procedures using a simulated data set of blazars and then apply these to the real data and find that for the population as a whole the intrinsic flux distribution can be represented by a broken power law of slopes -2.37 {+-} 0.13 and -1.70 {+-} 0.26, and the intrinsic photon index distribution can be represented by a Gaussian with mean 2.41 {+-} 0.13 and 1{sigma} …
Date: December 9, 2011
Creator: Singal, J.; /KIPAC, Menlo Park /SLAC /Stanford U.; Petrosian, V.; /KIPAC, Menlo Park /SLAC /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Ajello, M. & /KIPAC, Menlo Park /SLAC /Stanford U.
System: The UNT Digital Library
Strongly Interacting Matter Matter at Very High Energy Density: 3 Lectures in Zakopane (open access)

Strongly Interacting Matter Matter at Very High Energy Density: 3 Lectures in Zakopane

These lectures concern the properties of strongly interacting matter at very high energy density. I begin with the Color Glass Condensate and the Glasma, matter that controls the earliest times in hadronic collisions. I then describe the Quark Gluon Plasma, matter produced from the thermalized remnants of the Glasma. Finally, I describe high density baryonic matter, in particular Quarkyonic matter. The discussion will be intuitive and based on simple structural aspects of QCD. There will be some discussion of experimental tests of these ideas.
Date: June 9, 2010
Creator: McLerran, L.
System: The UNT Digital Library
COMFEN 3.0 - Evolution of an Early Design Tool for Commercial Facades and Fenestration Systems (open access)

COMFEN 3.0 - Evolution of an Early Design Tool for Commercial Facades and Fenestration Systems

Achieving a net-zero energy building cannot be done solely by improving the efficiency of the engineering systems. It also requires consideration of the essential nature of the building including factors such as architectural form, massing, orientation and enclosure. Making informed decisions about the fundamental character of a building requires assessment of the effects of the complex interaction of these factors on the resulting performance of the building. The complexity of these interactions necessitates the use of modeling and simulation tools to dynamically analyze the effects of the relationships, yet decisions about the building fundamentals are often made in the earliest stages of design, before a `building? exists to model. To address these issues, Lawrence Berkeley National Laboratory (LBNL) has developed an early-design energy modeling tool (COMFEN) specifically to help make informed decisions about building facade fundamentals by considering the design of the building envelope, orientation and massing on building performance. COMFEN focuses on the concept of a ?space? or ?room? and uses the EnergyPlus, and RadianceTM engines and a simple, graphic user interface to allow the user to explore the effects of changing key early-design input variables on energy consumption, peak energy demand, and thermal and visual comfort. Comparative results …
Date: March 9, 2011
Creator: McClintock Facade Consulting LLC, Walnut Creek, CA; McQuillen Interactive LLC, Santa Cruz, CA; Selkowitz, Stephen; Mitchell, Robin; McClintock, Maurya; McQuillen, Daniel et al.
System: The UNT Digital Library
SRF Test Areas Cryogenic System Controls Graphical User Interface (open access)

SRF Test Areas Cryogenic System Controls Graphical User Interface

Fermi National Accelerator Laboratory has constructed a superconducting 1.3 GHz cavity test facility at Meson Detector Building (MDB) and a superconducting 1.3 GHz cryomodule test facility located at the New Muon Lab Building (NML). The control of these 2K cryogenic systems is accomplished by using a Synoptic graphical user interface (GUI) to interact with the underlying Fermilab Accelerator Control System. The design, testing and operational experience of employing the Synoptic client-server system for graphical representation will be discussed. Details on the Synoptic deployment to the MDB and NML cryogenic sub-systems will also be discussed. The implementation of the Synoptic as the GUI for both NML and MDB has been a success. Both facilities are currently fulfilling their individual roles in SCRF testing as a result of successful availability of the cryogenic systems. The tools available for creating Synoptic pages will continue to be developed to serve the evolving needs of users.
Date: June 9, 2011
Creator: DeGraff, B. D.; Ganster, G.; Klebaner, A.; Petrov, A. D. & Soyars, W. M.
System: The UNT Digital Library
Emittance Studies of the BNL/SLAC/UCLA 1.6 Cell Photocathode RF Gun (open access)

Emittance Studies of the BNL/SLAC/UCLA 1.6 Cell Photocathode RF Gun

The symmetrized 1.6 cell S-band photocathode gun developed by the BNL/SLAC/UCLA collaboration is in operation at the Brookhaven Accelerator Test Facility (ATF). A novel emittance compensation solenoid magnet has also been designed, built and is in operation at the ATF. These two subsystems form an emittance compensated photoinjector used for beam dynamics, advanced acceleration and free electron laser experiments at the ATF. The highest acceleration field achieved on the copper cathode is 150 MV/m, and the guns normal operating field is 130 MV/m. The maximum rf pulse length is 3 {mu}s. The transverse emittance of the photoelectron beam were measured for various injection parameters. The 1 nC emittance results are presented along with electron bunch length measurements that indicated that at above the 400 pC, space charge bunch lengthening is occurring. The thermal emittance, {epsilon}{sub o}, of the copper cathode has been measured.
Date: September 9, 2011
Creator: Palmer, D. T.; Wang, X. J.; Miller, R. H.; Babzien, M.; Ben-Zvi, Ilan; Pellegrini, C. et al.
System: The UNT Digital Library
Electrical Resistance Tomography for Monitoring of Underground Coal Gasification (open access)

Electrical Resistance Tomography for Monitoring of Underground Coal Gasification

None
Date: August 9, 2011
Creator: Yang, X; Wagoner, J; Ramirez, A; Hunter, S; Mellors, R; Camp, D et al.
System: The UNT Digital Library
Stop the Top Background of the Stop Search (open access)

Stop the Top Background of the Stop Search

None
Date: July 9, 2013
Creator: Bai, Yang; Cheng, Hsin-Chia; Gallicchio, Jason & Gu, Jiayin
System: The UNT Digital Library
Event-by-Event Fission with FREYA (open access)

Event-by-Event Fission with FREYA

The recently developed code FREYA (Fission Reaction Event Yield Algorithm) generates large samples of complete fission events, consisting of two receding product nuclei as well as a number of neutrons and photons, all with complete kinematic information. Thus it is possible to calculate arbitrary correlation observables whose behavior may provide unique insight into the fission process. The presentation first discusses the present status of FREYA, which has now been extended up to energies where pre-equilibrium emission becomes significant and one or more neutrons may be emitted prior to fission. Concentrating on {sup 239}Pu(n,f), we discuss the neutron multiplicity correlations, the dependence of the neutron energy spectrum on the neutron multiplicity, and the relationship between the fragment kinetic energy and the number of neutrons and their energies. We also briefly suggest novel fission observables that could be measured with modern detectors.
Date: November 9, 2010
Creator: Randrup, J. & Vogt, R.
System: The UNT Digital Library
APPLICATIONS OF CURRENT TECHNOLOGY FOR CONTINUOUS MONITORING OF SPENT FUEL (open access)

APPLICATIONS OF CURRENT TECHNOLOGY FOR CONTINUOUS MONITORING OF SPENT FUEL

Advancements in technology have opened many opportunities to improve upon the current infrastructure surrounding the nuclear fuel cycle. Embedded devices, very small sensors, and wireless technology can be applied to Security, Safety, and Nonproliferation of Spent Nuclear Fuel. Security, separate of current video monitoring systems, can be improved by integrating current wireless technology with a variety of sensors including motion detection, altimeter, accelerometer, and a tagging system. By continually monitoring these sensors, thresholds can be set to sense deviations from nominal values. Then alarms or notifications can be activated as needed. Safety can be improved in several ways. First, human exposure to ionizing radiation can be reduced by using a wireless sensor package on each spent fuel cask to monitor radiation, temperature, humidity, etc. Since the sensor data is monitored remotely operator stay-time is decreased and distance from the spent fuel increased, so the overall radiation exposure is reduced as compared to visual inspections. The second improvement is the ability to monitor continuously rather than periodically. If changes occur to the material, alarm thresholds could be set and notifications made to provide advanced notice of negative data trends. These sensor packages could also record data to be used for scientific …
Date: June 9, 2013
Creator: Drayer, R.
System: The UNT Digital Library
Characterization of Slow Orbit Motion in the SPEAR3 (open access)

Characterization of Slow Orbit Motion in the SPEAR3

SPEAR3 is a third-generation synchrotron light source storage ring. The beam stability requirements are {approx}10% of the beam size, which is about 1 micron in the vertical plane. Hydrostatic level system (HLS) measurements show that the height of the SPEAR3 tunnel floor varies by tens of microns daily. We present analysis of the HLS data, including accounting for common-mode tidal motion. We discuss the results of experiments done to determine the primary driving source of ground motion. We painted the accelerator tunnel walls white; we temporarily installed Mylar over the asphalt in the center of the accelerator; and we put Mylar over a section of the tunnel walls.
Date: July 9, 2012
Creator: Sunilkumar, Nikita; Gassner, Georg; Safranek, James & Yan, Yiton
System: The UNT Digital Library
Improvements at the BNL 200 MeV LINAC (open access)

Improvements at the BNL 200 MeV LINAC

N/A
Date: September 9, 2012
Creator: Raparia, D.; Alessi, J.; Briscoe, B.; Fite, J.; Gould, O.; LoDestro, V. et al.
System: The UNT Digital Library
Novel Perspectives for Hadron Physics (open access)

Novel Perspectives for Hadron Physics

I discuss several novel and unexpected aspects of quantum chromodynamics. These include: (a) the nonperturbative origin of intrinsic strange, charm and bottom quarks in the nucleon at large x; the breakdown of pQCD factorization theorems due to the lensing effects of initial- and final-state interactions; (b) important corrections to pQCD scaling for inclusive reactions due to processes in which hadrons are created at high transverse momentum directly in the hard processes and their relation to the baryon anomaly in high-centrality heavy-ion collisions; and (c) the nonuniversality of quark distributions in nuclei. I also discuss some novel theoretical perspectives in QCD: (a) light-front holography - a relativistic color-confining first approximation to QCD based on the AdS/CFT correspondence principle; (b) the principle of maximum conformality - a method which determines the renormalization scale at finite order in perturbation theory yielding scheme independent results; (c) the replacement of quark and gluon vacuum condensates by 'in-hadron condensates' and how this helps to resolve the conflict between QCD vacuum and the cosmological constant.
Date: March 9, 2012
Creator: Brodsky, Stanley J.
System: The UNT Digital Library
Beam Measurements at LCLS (open access)

Beam Measurements at LCLS

None
Date: May 9, 2012
Creator: Frisch, J.; Akre, R.; Decker, F. J.; Ding, Y.; Dowell, D.; Emma, P. et al.
System: The UNT Digital Library
120-Channel, Chronically Implantable, Wireless, Polymer Neural Interface (open access)

120-Channel, Chronically Implantable, Wireless, Polymer Neural Interface

None
Date: May 9, 2012
Creator: Tooker, A; Shah, K; Tolosa, V; Sheth, H; Felix, S; Delima, T et al.
System: The UNT Digital Library