Accelerator physics and technology limitations to ultimate energy and luminosity in very large hadron colliders (open access)

Accelerator physics and technology limitations to ultimate energy and luminosity in very large hadron colliders

The following presents a study of the accelerator physics and technology limitations to ultimate energy and luminosity in very large hadron colliders (VLHCs). The main accelerator physics limitations to ultimate energy and luminosity in future energy frontier hadron colliders are synchrotron radiation (SR) power, proton-collision debris power in the interaction regions (IR), number of events-per-crossing, stored energy per beam and beam-stability [1]. Quantitative estimates of these limits were made and translated into scaling laws that could be inscribed into the particle energy versus machine size plane to delimit the boundaries for possible VLHCs. Eventually, accelerator simulations were performed to obtain the maximum achievable luminosities within these boundaries. Although this study aimed at investigating a general VLHC, it was unavoidable to refer in some instances to the recently studied, [2], 200 TeV center-of-mass energy VLHC stage-2 design (VLHC-2). A more thorough rendering of this work can be found in [3].
Date: December 5, 2002
Creator: al., P. Bauer et
System: The UNT Digital Library
Cross platform SCA component using C++ builder and KYLIX (open access)

Cross platform SCA component using C++ builder and KYLIX

A cross-platform component for EPICS Simple Channel Access (SCA) has been developed. EPICS client programs with GUI become portable at their C++ source-code level both on Windows and Linux by using Borland C++ Builder 6 and Kylix 3 on these platforms respectively.
Date: May 5, 2003
Creator: Nishimura, Hiroshi; Timossi, Chiris & McDonald, James L.
System: The UNT Digital Library
Performance and cost of particle air filtration technologies (open access)

Performance and cost of particle air filtration technologies

None
Date: May 5, 2001
Creator: Fisk, William J. & Faulkner, David
System: The UNT Digital Library
Properties of 20% cold-worked 316 stainless steel irradiated at low dose rate. (open access)

Properties of 20% cold-worked 316 stainless steel irradiated at low dose rate.

To assess the effects of long-term, low-dose-rate neutron exposure, tensile, hardness, and fracture properties were measured and microstructural characterization performed on irradiated 20% cold-worked Type 316 stainless steel. Samples were prepared from reactor core components retrieved from the EBR-II reactor following final shutdown. Sample locations were chosen to cover a dose range of 1-56 dpa at temperatures from 371-390 C and dose rates from 0.8-3.3 x 10{sup -7} dpa/s. Irradiation caused hardening, with the ultimate tensile strength (UTS) reaching about 800 MPa near 20 dpa and appearing to saturate at higher doses. The yield strength (YS) follows approximately the same trend as the ultimate tensile strength. At higher dose, the difference between the UTS and YS decreases, suggesting the work-hardening capability of the material is decreasing with increasing dose. The hardness and yield strength increases occur roughly over the same range of dose. While the material retained respectable ductility at 20 dpa, the uniform and total elongation decreased to <1 and <3%, respectively, at 47 dpa. Fracture in the 30 dpa specimen is mainly ductile but with local regions of mixed-mode failure, consisting mainly of dimples and microvoids. The fracture surface of the higher-exposure 47 dpa specimen displays more brittle …
Date: June 5, 2002
Creator: Allen, T. R.; Tsai, H.; Cole, J. I.; Ohta, J.; Dohi, K. & Kusanagi, H.
System: The UNT Digital Library
Radiation-induced segregation and the relationship to physical properties in irradiated austenitic alloys. (open access)

Radiation-induced segregation and the relationship to physical properties in irradiated austenitic alloys.

Radiation-induced changes in composition are studied because these changes can degrade failure of materials irradiated in nuclear reactors. In this work, the effect of alloy composition on radiation-induced segregation, hardening, and void swelling is presented. Five alloys, Fe-18Cr-8Ni, Fe-16Cr-13Ni, Fe-18Cr-40Ni, Fe-16Cr-13Ni+Mo, and Fe-16Cr-13Ni+Mo+P (all compositions in wt. %), were irradiated with 3.2 MeV protons at 400 C to a dose of 0.5 displacements per atom. The change in grain boundary composition was measured using field emission gun scanning transmission electron microscopy and the hardening was measured using Vickers indentation. Void swelling is calculated from the void size distribution measured using transmission electron microscopy. After irradiation, Cr depletes and Ni enriches at grain boundaries. Increasing bulk Ni concentration causes greater Cr depletion and Ni enrichment at grain boundaries. For alloys with 16 Cr, the addition of P reduces the Cr depletion and Ni enrichment. Hardening does not directly correlate with composition, but a framework for isolating the effect of hardening and segregation on cracking is suggested. The amount of void swelling in the irradiated material is shown to correspond inversely with segregation. Those alloys with greater segregation tend to swell less.
Date: June 5, 2002
Creator: Allen, T. R.; Cole, J. I.; Was, G. S. & Kenik, E. A.
System: The UNT Digital Library
Going Where No Man Can Go (open access)

Going Where No Man Can Go

This paper discusses the successful remote visual inspection of a contaminated air exhaust tunnel running beneath the Savannah River Site's H-Canyon nuclear material separations facility. The air exhaust tunnel has been in operation since the 1950's, and the portion of the tunnel inspected has not been seen or accessed since startup. Numerous challenges were overcome in the deployment of the vehicle, including an initial 10-ft drop, travelling a long distance through harsh environmental conditions, surviving and recovering from a second vertical drop, turning 90 degrees, and subsequently travelling further. Video of the entire inspection was transmitted back to a control station, and the vehicle was abandoned in place for possible future use.
Date: February 5, 2004
Creator: Robinson, C.W.
System: The UNT Digital Library
The precision of higgs boson measurements and their implications (open access)

The precision of higgs boson measurements and their implications

The prospects for a precise exploration of the properties of a single or many observed Higgs bosons at future accelerators are summarized, with particular emphasis on the abilities of a Linear Collider (LC). Some implications of these measurements for discerning new physics beyond the Standard Model (SM) are also discussed.
Date: December 5, 2002
Creator: Conway, J.; Desch, K.; Gunion, J. F.; Mrenna, S. & Zeppenfeld, D.
System: The UNT Digital Library
Thermodynamics of Combustion in a Confined Explosion (open access)

Thermodynamics of Combustion in a Confined Explosion

Considered here are explosions from condensed TNT charges--where the expanded detonation products gases are rich in C and CO [1]. Mixing with air causes oxidation/combustion [2], which dramatically increases the pressure in confined systems (vid. Fig. 1). We treat this as an Inverse Problem: infer fuel consumption from the measured pressure P {triple_bond} {bar p}(t)/p{sub i}. The Model expounded here represents a valuable tool for extracting the evolution of combustion system from a readily measurable quantity (pressure). The Model establishes the fuel consumption history as well as the evolution of thermodynamic solution (specific volumes, energies and densities) of the components that will generate the observed pressure profile. This solution in Thermodynamic (State) Space provides extraordinarily clear insight into the combustion process, which is normally clouded by a myriad of transport processes that occur in physical space.
Date: February 5, 2000
Creator: Kuhl, A.L.; Oppenheim, A.K. & Ferguson, R.E.
System: The UNT Digital Library
Monitoring Carbon Dioxide Sequestration Using Electrical Resistance Tomography (ERT): A Minimally Invasive Method (open access)

Monitoring Carbon Dioxide Sequestration Using Electrical Resistance Tomography (ERT): A Minimally Invasive Method

Successful geologic sequestration of carbon dioxide (CO{sub 2}), will require monitoring the CO{sub 2} injection to confirm the performance of the caprock/reservoir system, assess leaks and flow paths, and understand the geophysical and geochemical interactions between the CO{sub 2} and the geologic minerals and fluids. Electrical methods are especially well suited for monitoring processes involving fluids, as electrical properties are sensitive to the presence and nature of the formation fluids. High resolution tomographs of electrical properties are now used for site characterization and to monitor subsurface migration of fluids (i.e., leaking underground tanks, infiltration events, steam floods, contaminant movement, and to assess the integrity of engineered barriers). When electrical resistance tomography (ERT) imaging can be performed using existing well casings as long electrodes, the method is nearly transparent to reservoir operators, and reduces the need for additional drilling. Using numerical simulations and laboratory experiments, we have conducted sensitivity studies to determine the potential of ERT methods to detect and monitor the migration of CO{sub 2} in the subsurface. These studies have in turn been applied to the design and implementation of the first field casing surveys conducted in an oil field undergoing a CO{sub 2} flood.
Date: August 5, 2002
Creator: Newmark, R. L.; Ramirez, A. L. & Daily, W. D.
System: The UNT Digital Library
Optical Sensing of Microsystem Motion and Performance (open access)

Optical Sensing of Microsystem Motion and Performance

None
Date: July 5, 2000
Creator: Holswade, Scott C. & Dickey, Fred M.
System: The UNT Digital Library
Overview of the Coupled Model Intercomparison Project (CMIP) (open access)

Overview of the Coupled Model Intercomparison Project (CMIP)

The Coupled Model Intercomparison Project (CMIP) is designed to allow study and intercomparison of multi-model simulations of present-day and future climate. The latter are represented by idealized forcing of compounded 1% per year CO2 increase to the time of CO2 doubling near year 70 in simulations with global coupled models that contain, typically, components representing atmosphere, ocean, sea ice and land surface. Results from CMIP diagnostic subprojects were presented at the Second CMIP Workshop held at the Max Planck Institute for Meteorology in Hamburg, Germany, in September, 2003. Significant progress in diagnosing and understanding results from global coupled models has been made since the First CMIP Workshop in Melbourne, Australia in 1998. For example, the issue of flux adjustment is slowly fading as more and more models obtain stable multi-century surface climates without them. El Nino variability, usually about half the observed amplitude in the previous generation of coupled models, is now more accurately simulated in the present generation of global coupled models, though there are still biases in simulating the patterns of maximum variability. Typical resolutions of atmospheric component models contained in coupled models is now usually around 2.5 degrees latitude-longitude, with the ocean components often having about twice …
Date: August 5, 2004
Creator: Meehl, Gerald A.; Covey, Curt; McAvaney, Bryant; Latif, Mojib & Stouffer, Ronald J.
System: The UNT Digital Library
A Compact High Gradient Pulsed Magnetic Quadpole (open access)

A Compact High Gradient Pulsed Magnetic Quadpole

A design for a high gradient, low inductance pulsed quadrupole magnet is presented. The magnet is a circular current dominated design with a circular iron return yoke. Conductor angles are determined by a method of direct multipole elimination which theoretically eliminates the first four higher order multipole field components. Coils are fabricated from solid round film-insulated conductor, wound as a single layer ''non-spiral bedstead'' coil having a diagonal leadout entirely within one upturned end. The coils are wound and stretched straight in a special winder, then bent in simple fixtures to form the upturned ends.
Date: July 5, 2005
Creator: Shuman, D.; Faltens, A.; Kajiyama, Y.; Kireeff-Covo, M. & Seidl, P.
System: The UNT Digital Library
Solenoid-free Plasma Start-up in NSTX using Transient CHI (open access)

Solenoid-free Plasma Start-up in NSTX using Transient CHI

Experiments in NSTX have now demonstrated the coupling of toroidal plasmas produced by the technique of Coaxial Helicity Injection (CHI) to inductive sustainment and ramp-up of the toroidal plasma current. In these discharges, the central Ohmic transformer was used to apply an inductive loop voltage to discharges with a toroidal current of about 100 kA created by CHI. The coupled discharges have ramped up to >700 kA and transitioned into an H-mode demonstrating compatibility of this startup method with conventional operation. The electron temperature in the coupled discharges reached over 800 eV and the resulting plasma had low inductance, which is preferred for long-pulse high performance discharges. These results from NSTX in combination with the previously obtained record 160 kA non-inductively-generated startup currents in an ST or tokamak in NSTX demonstrate that CHI is a viable solenoid-free plasma startup method for future STs and tokamaks.
Date: January 5, 2009
Creator: Raman, R.; Jarboe, T.; Nelson, B.; Mueller, D. & Soukhanovskii, V. A.
System: The UNT Digital Library
Compressible Multiphase Flows in an ALE Framework (open access)

Compressible Multiphase Flows in an ALE Framework

None
Date: December 5, 2003
Creator: Stevens, David; Nelson, B.; Fogarty, P.; Eberle, C. & Ulrickson, M.
System: The UNT Digital Library
ENVIRONMENTAL MONITORING OF LEAKS USING TIME LAPSED LONG ELECTRODE ELECTRICAL RESISTIVITY (open access)

ENVIRONMENTAL MONITORING OF LEAKS USING TIME LAPSED LONG ELECTRODE ELECTRICAL RESISTIVITY

Highly industrialized areas pose significant challenges for surface based electrical resistivity characterization and monitoring due to the high degree of metallic infrastructure. The infrastructure is typically several orders of magnitude more conductive than the desired targets, preventing the geophysicist from obtaining a clear picture of the subsurface. These challenges may be minimized if steel-cased wells are used as long electrodes. We demonstrate a method of using long electrodes in a complex nuclear waste facility to monitor a simulated leak from an underground storage tank. The leak was simulated by injecting high conductivity fluid in a perforated well and the resistivity measurements were made before and after the leak test. The data were processed in four dimensions, where a regularization procedure was applied in both the time and space domains. The results showed a lowered resistivity feature develop south of the injection site. The time lapsed regularization parameter had a strong influence on the differences in inverted resistivity between the pre and post datasets, potentially making calibration of the results to specific hydrogeologic parameters difficult.
Date: November 5, 2009
Creator: Rucker, D. F.; Fink, J. B.; Loke, M. H. & Myers, D. A.
System: The UNT Digital Library
NUCLEAR DATABASES FOR REACTOR APPLICATIONS. (open access)

NUCLEAR DATABASES FOR REACTOR APPLICATIONS.

The National Nuclear Data Center (NNDC): An overview of nuclear databases, related products, nuclear data Web services and publications. The NNDC collects, evaluates, and disseminates nuclear physics data for basic research and applied nuclear technologies. The NNDC maintains and contributes to the nuclear reaction (ENDF, CSISRS) and nuclear structure databases along with several others databases (CapGam, MIRD, IRDF-2002) and provides coordination for the Cross Section Evaluation Working Group (CSEWG) and the US Nuclear Data Program (USNDP). The Center produces several publications and codes such as Atlas of Neutron Resonances, Nuclear Wallet Cards booklets and develops codes, such as nuclear reaction model code Empire.
Date: June 5, 2006
Creator: Pritychenko, B.; Arcilla, R.; Burrows, T.; Herman, M. W.; Mughabghab, S.; Oblozinsky, P. et al.
System: The UNT Digital Library
Molecular Dynamics Simulations of Collisional Cooling and Ordering of Multiply Charged Ions in a Penning Trap (open access)

Molecular Dynamics Simulations of Collisional Cooling and Ordering of Multiply Charged Ions in a Penning Trap

Molecular dynamics simulations are used to help design new experiments by modeling the cooling of small numbers of trapped multiply charged ions by Coulomb interactions with laser-cooled Be{sup +} ions. A Verlet algorithm is used to integrate the equations of motion of two species of point ions interacting in an ideal Penning trap. We use a time step short enough to follow the cyclotron motion of the ions. Axial and radial temperatures for each species are saved periodically. Direct heating and cooling of each species in the simulation can be performed by periodically rescaling velocities. Of interest are Fe{sup 11+} due to a EUV-optical double resonance for imaging and manipulating the ions, and Ca{sup 14+} since a ground state fine structure transition has a convenient wavelength in the tunable laser range.
Date: October 5, 2000
Creator: Holder, J. P.; Church, D. A.; Gruber, L.; DeWitt, H. E.; Beck, B. R. & Schneider, D.
System: The UNT Digital Library
Progress in Target Design for IFE for Ion Beams and Lasers (open access)

Progress in Target Design for IFE for Ion Beams and Lasers

Critical to the success of high gain ion beam driven targets for IFE is the tradeoff between target gain and the required focal spot size. A target design has been developed which uses the internal structure of the hohlraum to achieve radiation symmetry using beam spots with almost triple the allowed focal spot area relative to the earlier distributed radiator designs at comparable driver energy. An analysis is presented of the tradeoff between implosion robustness and the target fabrication specifications for survival against hydrodynamic instabilities during the implosion. A key issue for laser driven direct drive (DD) targets is control of hydrodynamic instability growth while achieving adequate gain for IFE. The goal of DD targets for IFE is to maximize gain through use of features such as wetted foams and laser zooming to increase absorption and use of a high-z coating to reduce laser imprint and achieve optimal control of instability growth. Because of advances in hohlraum design, laser driven indirect drive targets may have adequate gain for IFE for laser drivers with an efficiency of 10% or more. A key issue for the fast ignition concept is the ability to couple the hot electrons produced in high intensity laser …
Date: November 5, 2001
Creator: Lindl, John D.; Tabak, Max; Callahan-Miller, Debbie; Herrmann, Mark & Hatchett, Steve
System: The UNT Digital Library
Modeling Efforts to Aid in the Determination of Process Enrichment Levels for Identifying Potential Material Diversion (open access)

Modeling Efforts to Aid in the Determination of Process Enrichment Levels for Identifying Potential Material Diversion

None
Date: June 5, 2006
Creator: Guenther, C. F.; Elayat, H. A. & O'Connell, W. J.
System: The UNT Digital Library
Autophosphorylation of the DNA-Dependent Protein Kinase Catalyticsubunit is Required for Rejoining of DNA Double-Strand Breaks (open access)

Autophosphorylation of the DNA-Dependent Protein Kinase Catalyticsubunit is Required for Rejoining of DNA Double-Strand Breaks

This report is a descriptive journey of the Autophosphorylation of the DNA-Dependent Protein Kinase Catalyticsubunit is Required for Rejoining of DNA Double-Strand Breaks.
Date: June 5, 2002
Creator: Chan, Doug W.; Chen, Benjamin Ping-Chi; Yang, Shun-Jen; Singh,Sheela; Murphy, Michael B.; Kurimasa, Akihiro et al.
System: The UNT Digital Library
Solid-state modulators for RF and fast kickders (open access)

Solid-state modulators for RF and fast kickders

As the switching capabilities of solid-state devices increase, these devices are being incorporated into modulator designs for high voltage accelerator applications. Solid-state modulators based on inductive adder circuit topology have demonstrated great versatility with regard to pulse width and pulse repetition rate while maintaining fast pulse rise and fall times. Additionally, these modulators are capable of being scaled to higher output voltage and power levels. An explanation of the basic circuit operation will be presented as well as test data of several different hardware systems.
Date: May 5, 2005
Creator: Cook, E. G.; Akana, G.; Gower, E. J.; Hawkins, S. A.; Hickman, B. C.; Brooksby, C. A. et al.
System: The UNT Digital Library
Evidence for B Semileptonic Decays into the Lambda_c Charm Baryon (open access)

Evidence for B Semileptonic Decays into the Lambda_c Charm Baryon

We present the first evidence for B semileptonic decays into the charmed baryon {Lambda}{sub c}{sup +} based on 420 fb{sup -1} of data collected at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II e{sup +}e{sup -} storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We measure the relative branching fraction {Beta}({bar B} {yields} {Lambda}{sub c}{sup +} X{ell}{sup -}{bar {nu}}{sub {ell}})/{Beta}({bar B} {yields} {Lambda}{sub c}{sup +}/{bar {Lambda}}{sub c}{sup -}X) = (3.2 {+-} 0.9{sub stat.} {+-} 0.9{sub syst.})%. The significance of the signal including the systematic uncertainty is 4.9 standard deviations.
Date: November 5, 2008
Creator: Aubert, Bernard; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
System: The UNT Digital Library
Band anticrossing in Group II-Ox-VI1-x highly mismatched alloys: Cd1-yMnyOxTe1-x quaternaries synthesized by O ion implantation (open access)

Band anticrossing in Group II-Ox-VI1-x highly mismatched alloys: Cd1-yMnyOxTe1-x quaternaries synthesized by O ion implantation

None
Date: November 5, 2001
Creator: Yu, K. M.; Walukiewicz, W.; Wu, J.; Beeman, J. W.; Ager, J. W., III; Haller, E. E. et al.
System: The UNT Digital Library
Prototype Laser-Activated Shape Memory Polymer Foam Device for Embolic Treatment of Aneurysms (open access)

Prototype Laser-Activated Shape Memory Polymer Foam Device for Embolic Treatment of Aneurysms

None
Date: February 5, 2007
Creator: Maitland, D. J.; Small, W., IV; Ortega, J. M.; Buckley, P. R.; Rodriguez, J.; Hartman, J. et al.
System: The UNT Digital Library