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Breeding 10{sup 10}/s Radioactive Nuclei in a Compact Plasma Focus Device (open access)

Breeding 10{sup 10}/s Radioactive Nuclei in a Compact Plasma Focus Device

In the early 90's, it was discovered that a Plasma Focus (PF) system self-creates a plasma-tarp in which high energy-threshold nuclear-reactions occur at high reaction rates. Short life radioisotopes (SLR)s such as {sup 18}F, {sup 17}F, {sup 15}O, {sup 14}O, {sup 13}N have been generated (10{sup 6} - 10{sup 8} per pulse) with a PF-machine using 7 kJ energy storage to produce the plasmas. {beta}{sup -} radioactivity from the SLRs is measured with rugged, Geiger counters inserted into the PF-chamber, and a specific SLR is identified by its half-life. The PF chamber (before discharge) is filled with a mixture of gases that constitutes the latter plasma-target--beam system, e.g., the elements required to produce specific SLRs through nuclear reactions. In this paper, arguments are presented showing that a modest sized PF-machine, using a 50-75 kJ fast capacitor-bank, when operated at pulse frequencies of 1-10 Hz can produce {ge} 10{sup 9} SLRs/pulse. This paper reports the result s of testing a PF as a breeder of SLRs with dual applications for: (1) Secondary Radioactive Nuclear Beams ion-sources (Z < 35), and (2) as a breeder of radioisotopes for biomedicine (Z {le} 10) and/or PET imaging.
Date: July 27, 2001
Creator: Brzosko, JANS.
System: The UNT Digital Library
THE PHENIX EXPERIMENT AT RHIC. (open access)

THE PHENIX EXPERIMENT AT RHIC.

PHENIX is a large detector at the Relativistic Heavy Ion Collider (RHIC) at BNL. RHIC and PHENIX have recently operated for the first time, producing and detecting collisions of gold ions at beam energies of 30 and 65 GeV per nucleon. The current performance and future plans of PHENIX and of RHIC are presented.
Date: July 27, 2000
Creator: ARONSON,S. FOR THE PHENIX COLLABORATION
System: The UNT Digital Library
COUPLED THERMAL-HYDROLOGIC-CHEMICAL (THC) MODEL FOR PLUTONIUM MIGRATION FROM BENHAM UNDERGROUND NUCLEAR TEST. (open access)

COUPLED THERMAL-HYDROLOGIC-CHEMICAL (THC) MODEL FOR PLUTONIUM MIGRATION FROM BENHAM UNDERGROUND NUCLEAR TEST.

None
Date: July 27, 2000
Creator: LICHTNER, PETER C.; ANDREW V. WOLFSBERG, MAUREEN MC GRAW & GLASCOE, LEE
System: The UNT Digital Library
Unstructured Polyhedral Mesh Thermal Radiation Diffusion (open access)

Unstructured Polyhedral Mesh Thermal Radiation Diffusion

Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.
Date: July 27, 2000
Creator: Palmer, T. S.; Zika, M. R. & Madsen, N. K.
System: The UNT Digital Library
A case study in application I/O on Linux clusters. (open access)

A case study in application I/O on Linux clusters.

A critical but often ignored component of system performance is the I/O system. Today's applications expect a great deal from underlying storage systems and software, and both high performance distributed storage and high level interfaces have been developed to fill these needs. In this paper they discuss the I/O performance of a parallel scientific application on a Linux cluster, the FLASH astrophysics code. This application relies on three I/O software components to provide high performance parallel I/O on Linux clusters: the Parallel Virtual File System (PVFS), the ROMIO MPI-IO implementation, and the Hierarchical Data Format (HDF5) library. First they discuss the roles played by each of these components in providing an I/O solution. Next they discuss the FLASH I/O benchmark and point out its relevance. Following this they examine the performance of the benchmark, and through instrumentation of both the application and underlying system software code they discover the location of major software bottlenecks. They work around the most inhibiting of these bottlenecks, showing substantial performance improvement. Finally they point out similarities between the inefficiencies found here and those found in message passing systems, indicating that research in the message passing field could be leveraged to solve similar problems in …
Date: July 27, 2001
Creator: Ross, R.; Nurmi, D.; Cheng, A. & Zingale, M.
System: The UNT Digital Library
Radio-isotope production using laser Wakefield accelerators (open access)

Radio-isotope production using laser Wakefield accelerators

A 10 Hz, 10 TW solid state laser system has been used to produce electron beams suitable for radio-isotope production. The laser beam was focused using a 30 cm focal length f/6 off-axis parabola on a gas plume produced by a high pressure pulsed gas jet. Electrons were trapped and accelerated by high gradient wakefields excited in the ionized gas through the self-modulated laser wakefield instability. The electron beam was measured to contain excesses of 5 nC/bunch. A composite Pb/Cu target was used to convert the electron beam into gamma rays which subsequently produced radio-isotopes through (gamma, n) reactions. Isotope identification through gamma-ray spectroscopy and half-life time measurements demonstrated that Cu{sup 61} was produced which indicates that 20-25 MeV gamma rays were produced, and hence electrons with energies greater than 25-30 MeV. The production of high energy electrons was independently confirmed using a bending magnet spectrometer. The measured spectra had an exponential distribution with a 3 MeV width. The amount of activation was on the order of 2.5 uCi after 3 hours of operation at 1 Hz. Future experiments will aim at increasing this yield by post-accelerating the electron beam using a channel guided laser wakefield accelerator.
Date: July 27, 2001
Creator: Leemans, W. P.; Rodgers, D.; Catravas, P. E.; Geddes, C. G. R.; Fubiani, G.; Toth, C. et al.
System: The UNT Digital Library
Technicolorful Supersymmetry (open access)

Technicolorful Supersymmetry

Technicolor achieves electroweak symmetry breaking (EWSB) in an elegant and natural way, while it suffers from severe model building difficulties. I propose to abandon its secondary goal to eliminate scalar bosons in exchange of solving numerous problems using supersymmetry. It helps to understand walking dynamics much better with certain exact results. In the particular model presented here, there is no light elementary Higgs boson and the EWSB is fully dynamical, hence explaining the hierarchy; There is no alignment problem and no light pseudo-Nambu-Goldstone bosons exist; The fermion masses are generated by a ultraviolet-complete renormalizable extended technicolor sector with techni-GIM mechanism and hence the sector is safe from flavor-changing-neutral-current constraints; The ''e{sup +}e{sup -}'' production of techni-states in the superconformal window is calculable; The electroweak precision observables are (un)fortunately not calculable.
Date: July 27, 2003
Creator: Murayama, Hitoshi
System: The UNT Digital Library
Numerical simulation of a premixed turbulent V-flame (open access)

Numerical simulation of a premixed turbulent V-flame

We present three-dimensional, time-dependent simulations of a full-size laboratory-scale rod-stabilized premixed turbulent V-flame. The computations use an adaptive projection method based on a low Mach number formulation that incorporates detailed chemical kinetics and transport. The simulations are performed without introducing models for turbulence or turbulence chemistry interaction. We outline the numerical procedure and experimental setup, and compare computed results to mean flame location and surface wrinkling statistics gathered from experiment.
Date: July 27, 2003
Creator: Bell, John B.; Day, Marc S.; Grcar, Joseph F.; Lijewski, Michael J.; Johnson, Matt R.; Cheng, Robert K. et al.
System: The UNT Digital Library
Analysis of carbon chemistry in numerical simulations of vortex flame interaction (open access)

Analysis of carbon chemistry in numerical simulations of vortex flame interaction

In this paper we discuss the application of a new diagnostic tool for analysis of flame simulations. This methodology is based on following specific chemical elements, e.g., carbon or nitrogen, as they move through the system. From this perspective an ''atom'' is a component of a molecule that is being transported through the simulation domain by advection and diffusion. Reactions cause the atom to shift from one species to another with the subsequent transport of the atom determined by the movement of the new species.
Date: July 27, 2003
Creator: Bell, John B.; Day, Marcus S.; Grcar, Joseph F. & Lijewski, Michael J.
System: The UNT Digital Library
Laboratory evaluation of fan/filter units' aerodynamic and energy performance (open access)

Laboratory evaluation of fan/filter units' aerodynamic and energy performance

The paper discusses the benefits of having a consistent testing method to characterize aerodynamic and energy performance of FFUs. It presents evaluation methods of laboratory-measured performance of ten relatively new, 1220 mm x 610 mm (or 4 ft x 2 ft) fan-filter units (FFUs), and includes results of a set of relevant metrics such as energy performance indices (EPI) based upon the sample FFUs tested. This paper concludes that there are variations in FFUs' performance, and that using a consistent testing and evaluation method can generate compatible and comparable FFU performance information. The paper also suggests that benefits and opportunities exist for our method of testing FFU energy performance to be integrated in future recommended practices.
Date: July 27, 2004
Creator: Xu, Tengfang & Jeng, Ming-Shan
System: The UNT Digital Library
Uranium Age Determination by Measuring the 230Th / 234U Ratio (open access)

Uranium Age Determination by Measuring the 230Th / 234U Ratio

A radiochemical isotope dilution mass spectrometry method has been developed to determine the age of uranium materials. The amount of 230Th activity, the first progeny of 234U, that had grown into a small uranium metal sample was used to determine the elapsed time since the material was last radiochemically purified. To preserve the sample, only a small amount of oxidized uranium was removed from the surface of the sample and dissolved. Aliquots of the dissolved sample were spiked with 233U tracer and radiochemically purified by anion-exchange chromatography. The 234U isotopic concentration was then determined by thermal ionization mass spectrometry. Additional aliquots of the sample were spiked with 229Th tracer, and the thorium was purified using two sequential anion-exchange chromatography separations. The isotopic concentrations of 230Th and 232Th were determined by TIMS. The lack of any 232Th confirmed the assumption that all thorium was removed from the uranium sample at the time of purification. The 230Th and 234U mass concentrations were converted to activities and the 230Th/234U ratio for the sample was calculated. The experimental 230Th/234U ratio showed the uranium in this sample was radiochemically purified in about 1945. Isotope dilution thermal ionization mass spectrometry has sufficient sensitivity to determine the …
Date: July 27, 2004
Creator: LAMONT, STEPHENP.
System: The UNT Digital Library
Development of superconducting magnet systems for HIFExperiments (open access)

Development of superconducting magnet systems for HIFExperiments

The U.S. Heavy Ion Fusion program is developing superconducting focusing quadrupoles for near-term experiments and future driver accelerators. Following the fabrication and testing of several models, a baseline quadrupole design was selected and further optimized. The first prototype of the optimized design achieved a conductor-limited gradient of 132 T/m in a 70 mm bore, with measured field harmonics within 10 parts in 10{sup 4}. In parallel, a compact focusing doublet was fabricated and tested using two of the first-generation quadrupoles. After assembly in the cryostat, both magnets reached their conductor-limited quench current. Further optimization steps are currently underway to improve the performance of the magnet system and reduce its cost. They include the fabrication and testing of a new prototype quadrupole with reduced field errors as well as improvements of the cryostat design for the focusing doublet. The prototype units will be installed in the HCX beamline at LBNL, to perform accelerator physics experiments and gain operational experience. Successful results in the present phase will make superconducting magnets a viable option for the next generation of integrated beam experiments.
Date: July 27, 2004
Creator: Sabbi, Gian Luca; Faltens, A.; Leitzke, A.; Seidl, P.; Lund, S.; Martovets ky, N. et al.
System: The UNT Digital Library
Helium Release Behavior of Aged Titanium Tritides (open access)

Helium Release Behavior of Aged Titanium Tritides

One sample of bulk Ti has been loaded with a 50 per cent / 50 per cent deuterium/tritium mixture and statically aged for 6.5 years. Thermal desorption of the sample shows an initial release of hydrogen isotopes followed by 3He release. Subsequent D2 loading/desorption was used to quantify the trapped tritium heel. The sample shows an excess hydrogen capacity as a second thermal desorption peak that partially disappears and shifts with annealing at 923-973K. The main hydrogen desorption peak also shifts to higher temperature, indicating a partial reversal of the tritium-decay induced damage by annealing.
Date: July 27, 2004
Creator: SHANAHAN, KIRKL.
System: The UNT Digital Library
Systems analysis for modular versus multi-beam HIF drivers (open access)

Systems analysis for modular versus multi-beam HIF drivers

None
Date: July 27, 2004
Creator: Meier, W. R. & Logan, B. G.
System: The UNT Digital Library
Numerical simulations of shock-induced mixing and combustion (open access)

Numerical simulations of shock-induced mixing and combustion

In this paper we use numerical simulation to investigate shock-induced ignition and combustion of a hydrocarbon gas. The focus of this paper is on quantifying the effect of fidelity in the chemical kinetics on the overall solution. We model the system using the compressible Navier Stokes equations for a reacting mixture. These equations express conservation of species mass, momentum, total energy.
Date: July 27, 2003
Creator: Bell, John B.; Day, Marc S. & Kuhl, A.
System: The UNT Digital Library
SUMAC: A monitor and control tree for multi-FPGA systems (open access)

SUMAC: A monitor and control tree for multi-FPGA systems

The BTeV pixel trigger is a data acquisition system capable of finding tracks and vertices in real time in the BTeV pixel detector array. The trigger uses some 3000 processing elements (DSPs) arranged in three processing levels to handle a raw data rate of nearly 100 Gigabytes per second and bring the trigger rate down to 10 KHz. The trigger system has more than 6000 programmable elements, including Field Programmable Logic Arrays (FPGAs), microprocessors (DSPs, interface to the monitor and control tree through FPGAs), and others. Sumac (Serial Utility Monitor and Control tree) is used for configuring and monitoring of these devices. Its primary function is the downloading of FPGA bit streams, microprocessor programs, chip configurations, and test data. In addition, remote cpus and other devices can send messages and status back to the host. The Sumac system is capable of handling several thousand remote devices from a single host PC. Because it stores configuration data in local flash eeproms, it will be capable of achieving a complete system reboot in less than 1 second. The Sumac system is a tree hierarchy connected via high-speed serial links. Typically each board in the system will have a control node which accepts …
Date: July 27, 1999
Creator: Gao, Mingshen
System: The UNT Digital Library
CAMAC Driver Support for Windows NT{trademark} and Lunux{trademark} (open access)

CAMAC Driver Support for Windows NT{trademark} and Lunux{trademark}

CAMAC is a Modular Instrumentation and Digital Interface System defined as a standardized instrumentation system for Computer Automated Measurement and Control. CAMAC hardware and software has been defined by the NIM Committee (National Instrumentation Methods Committee) of the US Department of Energy and the ESONE Committee (European Standards on Nuclear Electronics Committee) of European Laboratories. Fermi National Accelerator Laboratory has for many years produced software packages that follow the ANSI/IEEE standard 758-1979 for a variety of computers, CAMAC controller interfaces, and operating systems. In order to enable the re-use of existing hardware and software, Fermilab now supports standard routine libraries and drivers for Windows NT 4.0 and the Linux operating systems for the Jorway 411s SCSI Bus CAMAC Driver[l] and the Jorway73A SCSI Bus CAMAC Crate Controller. A number of test stands and small experiments both on-site and off-site are using this software for their CAMAC data acquisition needs.
Date: July 27, 1999
Creator: Streets, D.A. Slimmer and J.M.
System: The UNT Digital Library
B {0 over d} mixing and CP violation measurements at the Tevatron (open access)

B {0 over d} mixing and CP violation measurements at the Tevatron

We present six time-dependent B<sup>0</sup><sub>d</sub> mixing measurements of {Delta}m<sub>d</sub> from the CDF Run I data. The CDF average is {Delta}m<sub>d</sub> = .494<sup>&plusmn;.026</sup><sub>&plusmn;.026</sub>(ps)<sup>-1</sup>. We also present a measurement of the CP-violating asymmetry sin(2{beta}) using a sample of B<sup>0</sup>/{anti B}<sup>0</sup> {yields} J/{psi} K<sup>0</sup><sub>s</sub> decays and report sin(2{beta}) = .79 <sup>+41</sup><sub>-.44</sub>.
Date: July 27, 1999
Creator: Byrum, K.
System: The UNT Digital Library
A Numerical Analysis of 3D EM Imaging from a Single Borehole (open access)

A Numerical Analysis of 3D EM Imaging from a Single Borehole

In this study we analyze the feasibility of three dimensional (3D) electromagnetic (EM) imaging from a single borehole. The proposed logging tool consists of three mutually orthogonal magnetic dipole sources and multiple three component magnetic field receivers. A sensitivity analysis indicates that the most important sensor configuration for providing 3D geological information about the borehole consists of a transmitter with moment aligned parallel to the axis of the borehole, and receivers aligned perpendicular to the axis. The standard coaxial logging configuration provides the greatest depth of sensitivity compared to other configurations, but offers no information regarding 3D structure. Two other tool configurations in which both the source and receiver are aligned perpendicular to the borehole axis provide some directional information and therefore better image resolution, but not true 3D information. A 3D inversion algorithm has been employed to demonstrate the plausibility of 3D inversion using data collected with the proposed logging tool. This study demonstrates that an increase in image resolution results when three orthogonal sources are incorporated into the logging tool rather than a single axially aligned source.
Date: July 27, 1999
Creator: Alumbaugh, David L. & Wilt, Michael J.
System: The UNT Digital Library
Polymer Aging Techniques Applied to Degradation of a Polyurethane Propellant Binder (open access)

Polymer Aging Techniques Applied to Degradation of a Polyurethane Propellant Binder

The oxidative thermal aging of a crosslinked hydroxy-terminated polybutadiene (HTPB)/isophorone diisocyanate (IPDI) polyurethane rubber, commonly used as the polymeric binder matrix in solid rocket propellants, was studied at temperatures of RT to 125 C. We investigate changes in tensile elongation, mechanical hardening, polymer network properties, density, O{sub 2} permeation and molecular chain dynamics using a range of techniques including solvent swelling, detailed modulus profiling and NMR relaxation measurements. Using extensive data superposition and highly sensitive oxygen consumption measurements, we critically evaluate the Arrhenius methodology, which normally assumes a linear extrapolation of high temperature aging data. Significant curvature in the Arrhenius diagram of these oxidation rates was observed similar to previous results found for other rubber materials. Preliminary gel/network properties suggest that crosslinking is the dominant process at higher temperatures. We also assess the importance of other constituents such as ammonium perchlorate or aluminum powder in the propellant formulation.
Date: July 27, 1999
Creator: Assink, R. A.; Celina, M.; Graham, A. C. & Minier, L. M.
System: The UNT Digital Library
Highly-Efficient Laser with Self-Aligned Waveguide and Current Confinement by Selective Oxidation (open access)

Highly-Efficient Laser with Self-Aligned Waveguide and Current Confinement by Selective Oxidation

We report highly efficient, low-threshold-current edge-emitting lasers where both the optical waveguide and lateral current confinement are achieved by lateral selective oxidation of AlGaAs. External differential quantum efficiency in excess of 95% and 40% wall-plug efficiency are demonstrated in 600 {micro}m-long devices without facet coatings. Shorter, 300-{micro}m-long, uncoated devices have &lt;6 mA threshold currents. This high-performance is a combined result of placement of the oxide layers so as to achieve the minimum optical mode volume and bi-parabolic grading of the Al{sub x}Ga{sub 1{minus}x}As heteroepitaxy for minimum height/potential barriers, less than 15 meV, created by the wide-energy-gap layers required for selective wet oxidation. Since the initial development of wet AlGaAs oxidation methods, a number of oxidized edge-emitting laser concepts have been tried. The most successful of these have used lateral selective oxidation of AlGaAs layers between 100 and 300 nm thickness. These layers have been used as current restricting apertures or for both current restriction and lateral waveguiding. Use of an oxide layer above and below the laser active region offers the ability to create a self-aligned waveguide with current apertures on both sides of the pn-junction in a process requiring only one epitaxial growth step. Previous use apertures for these …
Date: July 27, 1999
Creator: Allerman, A.; Blum, O.; Gao, Y. & Vawter, G. A.
System: The UNT Digital Library
SYNTHESIZING PRECISION FLEXURES THAT DECOUPLE DISPLACEMENT-BASED ACTUATORS (open access)

SYNTHESIZING PRECISION FLEXURES THAT DECOUPLE DISPLACEMENT-BASED ACTUATORS

None
Date: July 27, 2012
Creator: Hopkins, J B & McCalib, D B
System: The UNT Digital Library
Ideal MHD Stability of ITER Steady State Scenarios with ITBs (open access)

Ideal MHD Stability of ITER Steady State Scenarios with ITBs

One of ITER goals is to demonstrate feasibility of continuous operations using non-inductive current drive. Two main candidates have been identified for advanced operations: the long duration, high neutron fluency hybrid scenario and the steady state scenario, both operating at a plasma current lower than the reference ELMy scenario [1][2] to minimize the required current drive. The steady state scenario targets plasmas with current 7-10 MA in the flat-top, 50% of which will be provided by the self-generated, pressure-driven bootstrap current. It has been estimated that, in order to obtain a fusion gain Q &gt; 5 at a current of 9 MA, it should be ΒN &gt; 2.5 and H &gt; 1.5 [3]. This implies the presence of an Internal Transport Barrier (ITB). This work discusses how the stability of steady state scenarios with ITBs is affected by the external heating sources and by perturbations of the equilibrium profiles.
Date: July 27, 2011
Creator: Poli, F. M.; Kessel, C. E.; Jardin, S.; Manickam, J.; Chance, M. & Chen, J.
System: The UNT Digital Library
Organization by Gordon Research Conferences of the 2012 Plasma Processing Science Conference 22-27 July 2012 (open access)

Organization by Gordon Research Conferences of the 2012 Plasma Processing Science Conference 22-27 July 2012

The 2012 Gordon Research Conference on Plasma Processing Science will feature a comprehensive program that will highlight the most cutting edge scientific advances in plasma science and technology as well as explore the applications of this nonequilibrium medium in possible approaches relative to many grand societal challenges. Fundamental science sessions will focus on plasma kinetics and chemistry, plasma surface interactions, and recent trends in plasma generation and multi-phase plasmas. Application sessions will explore the impact of plasma technology in renewable energy, the production of fuels from renewable feedstocks and carbon dioxide neutral solar fuels (from carbon dioxide and water), and plasma-enabled medicine and sterilization.
Date: July 27, 2012
Creator: Chang, Jane
System: The UNT Digital Library