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Direct Digital Phase Shift by DDS rf Source
None
Date:
April 13, 1993
Creator:
A., Pei
Object Type:
Report
System:
The UNT Digital Library
Numerically Controlled Phase Locked Loop Using Direct Digital Synthesizer
None
Date:
April 13, 1993
Creator:
A., Pei
Object Type:
Report
System:
The UNT Digital Library
Impact of the LHC beam abort kicker prefire on high luminosity insertion and CMS detector performance
The effect of possible accidental beam loss in LHC on the IP5 insertion elements and CMS detector is studied via realistic Monte Carlo simulations. Such beam loss could be the consequence of an unsynchronized abort or � in worst case � an accidental prefire of one of the abort kicker modules. Simulations with the STRUCT code show that this beam losses would take place in the IP5 inner and outer triplets. MARS simulations of the hadronic and electro-magnetic cascades induced in such an event indicate severe heating of the inner triplet quadrupoles. In order to protect the IP5 elements, two methods are proposed: a set of shadow collimators in the outer triplet and a prefired module compensation using a special module charged with an opposite voltage (antikicker). The remnants of the accidental beam loss entering the experimental hall have been used as input for FLUKA simulations in the CMS detector. It is shown that it is vital to take measures to reliably protect the expensive CMS tracker components.
Date:
April 13, 1999
Creator:
A.I. Drozhdin, N.V. Mokhov and M. Huhtinen
Object Type:
Article
System:
The UNT Digital Library
On possible use of bent crystal to improve Tevatron beam scraping
A possibility to improve the Tevatron beam halo scraping using a bent channeling crystal instead of a thin scattering primary collimator is studied. To evaluate the efficiency of the system, realistic simulations have been performed using the CATCH and STRUCT Monte Carlo codes. It is shown that the scraping efficiency can be increased and the accelerator-related backgrounds in the CDF and DØ collider detectors can be reduced by about one order of magnitude. Results on scraping efficiency versus thickness of amorphous layer of the crystal, crystal alignment and its length are presented.
Date:
April 8, 1999
Creator:
A.I. Drozhdin, N.V. Mokhov and V.M. Biryukov
Object Type:
Article
System:
The UNT Digital Library
Radiation environment resulting from Main Injector beam extraction to the NuMI beam line
A 120 GeV Main Injector proton beam will be delivered to the NuMI beam line at Fermilab at the rate of 3.7x 10{sup 20} per year. Realistic Monte Carlo simulations have been performed to examine the radiation environment in the beam extraction system and NuMI beam line elements. A complete 3-D model of the 160 meter extraction region has been implemented utilizing the computer code MARS. The model includes a description of the field of the electrostatic septa and POISSON calculated field maps of the Lambertson magnets and the other lattice components in the area. The beam element alignment and the source term have been simulated using the code STRUCT. Results on beam losses in the system, energy deposition in the core elements and residual dose rates on the components are presented.
Date:
April 29, 1999
Creator:
A.I. Drozhdin, P.W. Lucas, N.V. Mokhov, C.D. Moore and S.I. Striganov
Object Type:
Article
System:
The UNT Digital Library
Advanced Emissions Control Development Program
The objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W).
Date:
April 1, 1998
Creator:
A.P.Evans; Redinger, K.E. & Holmes, M.J.
Object Type:
Report
System:
The UNT Digital Library
Nonforward parton distributions
Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive electroproduction processes require a generalization of usual parton distributions for the case when long-distance information is accumulated in nonforward matrix elements <p{prime}{vert_bar}O(0,x){vert_bar}p> of quark and gluon light-cone operators. They describe two types of nonperturbative functions parameterizing such matrix elements: double distributions F(x,y;t) and nonforward distribution functions F{_}/zeta (X;t), discuss their spectral properties, evolution equations which they satisfy, basic uses and general aspects of factorization for hard exclusive processes.
Date:
April 1, 1997
Creator:
A.Radyushkin
Object Type:
Article
System:
The UNT Digital Library
GEOTHERMAL HEAT PUMP GROUTING MATERIALS
The thermal conductivity of cementitious grouts has been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. The cement-sand grouts were also tested for rheological characteristics, bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the thermal conductivity, permeability, bonding and exotherm data for selected cementitious grouts. The theoretical reduction in bore length that could be achieved with the BNL-developed cement-sand grouts is examined. Finally, the FY 98 research and field trials are discussed.
Date:
April 1, 1998
Creator:
ALLAN,M.
Object Type:
Article
System:
The UNT Digital Library
Plutonium reclamation facility (PRF), building 236-Z layup plan
This document reviews each system inside PRF to determine the operation and maintenance requirements necessary to maintain safe and predictable system performance for facility systems needed to remain operational while minimizing the maintenance and surveillance being performed. Also covered are the actions required to place PRF in a safe layup configuration while minimizing hazards and taking into account the need for reactivation of certain equipment when cleanup work commences in the future.
Date:
April 6, 1999
Creator:
ANDERSON, R.N.
Object Type:
Report
System:
The UNT Digital Library
Fundamental studies of fusion plasmas
Work on ICRF interaction with the edge plasma is reported. ICRF generated convective cells have been established as an important mechanism for influencing edge transport and interaction with the H-mode, and for controlling profiles in the tokamak scrape-off-layer. Power dissipation by rf sheaths has been shown to be significant for some misaligned ICRF and IIBW antenna systems. Near-field antenna sheath work has been extended to the far-field case, important for experiments with low single pass absorption. Impurity modeling and Faraday screen design support has been provided for the ICRF community. In the area of core-ICRF physics, the kinetic theory of heating by applied ICRF waves has been extended to retain important geometrical effects relevant to modeling minority heated tokamak plasmas, thereby improving on the physics base that is standard in presently employed codes. Both the quasilinear theory of ion heating, and the plasma response function important in wave codes have been addressed. In separate studies, it has been shown that highly anisotropic minority heated plasmas can give rise to unstable field fluctuations in some situations. A completely separate series of studies have contributed to the understanding of tokamak confinement physics. Additionally, a diffraction formalism has been produced which will be …
Date:
April 27, 1993
Creator:
Aamodt, R. E.; Catto, P. J.; D'Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Object Type:
Report
System:
The UNT Digital Library
Fundamental studies of fusion plasmas. Annual performance report
Work on ICRF interaction with the edge plasma is reported. ICRF generated convective cells have been established as an important mechanism for influencing edge transport and interaction with the H-mode, and for controlling profiles in the tokamak scrape-off-layer. Power dissipation by rf sheaths has been shown to be significant for some misaligned ICRF and IIBW antenna systems. Near-field antenna sheath work has been extended to the far-field case, important for experiments with low single pass absorption. Impurity modeling and Faraday screen design support has been provided for the ICRF community. In the area of core-ICRF physics, the kinetic theory of heating by applied ICRF waves has been extended to retain important geometrical effects relevant to modeling minority heated tokamak plasmas, thereby improving on the physics base that is standard in presently employed codes. Both the quasilinear theory of ion heating, and the plasma response function important in wave codes have been addressed. In separate studies, it has been shown that highly anisotropic minority heated plasmas can give rise to unstable field fluctuations in some situations. A completely separate series of studies have contributed to the understanding of tokamak confinement physics. Additionally, a diffraction formalism has been produced which will be …
Date:
April 27, 1993
Creator:
Aamodt, R. E.; Catto, P. J.; D`Ippolito, D. A.; Myra, J. R. & Russell, D. A.
Object Type:
Report
System:
The UNT Digital Library
Analysis of neon soft x-ray spectra from short-pulse laser-produced plasmas
We report preliminary results from the analysis of streaked soft x-ray neon spectra obtained from the interaction of a picosecond Nd:glass laser with a gas jet target. In these experiments streaked spectra show prompt harmonic emission followed by longer time duration soft x-ray line emission. The majority of the line emission observed was found to originate from Li- and Be-like Ne and the major transitions in the observed spectra have been identified. Li-like emission lines were observed to decay faster in time than Be-like transitions, suggesting that recombination is taking place. Line ratios of n=4-2 and n=3-2 transitions supported the view that these lines were optically thin and thick, respectively. The time history of Li-like Ne 2p-4d and 2p-3d lines is in good agreement with a simple adiabatic expansion model coupled to a time dependent collisional-radiative code. Further x-ray spectroscopic analysis is underway which is aimed at diagnosing plasma conditions and assessing the potential of this recombining neon plasma as a quasi-steady-state recombination x-ray laser medium.
Date:
April 1, 1993
Creator:
Abare, A. C.; Keane, C. J.; Crane, J. K.; DaSilva, L. B.; Lee, R. W.; Perry, M. D. et al.
Object Type:
Article
System:
The UNT Digital Library
Comparison of a constraint directed search to a genetic algorithm in a scheduling application
Scheduling plutonium containers for blending is a time-intensive operation. Several constraints must be taken into account; including the number of containers in a dissolver run, the size of each dissolver run, and the size and target purity of the blended mixture formed from these runs. Two types of algorithms have been used to solve this problem: a constraint directed search and a genetic algorithm. This paper discusses the implementation of these two different approaches to the problem and the strengths and weaknesses of each algorithm.
Date:
April 1, 1993
Creator:
Abbott, L.
Object Type:
Article
System:
The UNT Digital Library
Toxic vapor cloud impacts from accidental releases of anhydrous ammonia and nitrogen dioxide at the ICPP NO{sub x} Abatement Facility
This report evaluates potential atmospheric and human health impacts that may result from accidental releases of anhydrous ammonia and nitrogen dioxide at the Idaho Chemical Processing Plant (ICPP) NO{sub x} Abatement Facility. Excess process gas releases are evaluated using a traditional Gaussian puff model. Dense two-phase aerosol releases from an 18,000 gallon liquefied ammonia storage tank and a 6,000 gallon tanker truck accident are evaluated using the refined vapor dispersion model, SLAB. The SLAB results are also compared to those using the neutral-buoyancy puff model. A SLAB sensitivity analysis is presented which examines various combinations of ambient temperatures and wind speeds in order to determine worst-case downwind air concentrations. The results from the storage tank releases indicated that potentially serious ammonia concentrations (greater than 1000 ppm) could result at downwind distances ranging from 150 meters (relief valve malfunction) to approximately 3 kilometers (catastrophic tank failure). The tank failure scenario produced concentrations that could be rapidly fatal (greater than 5000 ppm) out to 1.3 kilometers. Under worst-case meteorological dispersion conditions, recognized exposure limits (IDLH, TLV-STEL) were exceeded for very large distances (greater than 15 kilometers).
Date:
April 1, 1992
Creator:
Abbott, M. L.
Object Type:
Report
System:
The UNT Digital Library
Toxic vapor cloud impacts from accidental releases of anhydrous ammonia and nitrogen dioxide at the ICPP NO sub x Abatement Facility
This report evaluates potential atmospheric and human health impacts that may result from accidental releases of anhydrous ammonia and nitrogen dioxide at the Idaho Chemical Processing Plant (ICPP) NO{sub x} Abatement Facility. Excess process gas releases are evaluated using a traditional Gaussian puff model. Dense two-phase aerosol releases from an 18,000 gallon liquefied ammonia storage tank and a 6,000 gallon tanker truck accident are evaluated using the refined vapor dispersion model, SLAB. The SLAB results are also compared to those using the neutral-buoyancy puff model. A SLAB sensitivity analysis is presented which examines various combinations of ambient temperatures and wind speeds in order to determine worst-case downwind air concentrations. The results from the storage tank releases indicated that potentially serious ammonia concentrations (greater than 1000 ppm) could result at downwind distances ranging from 150 meters (relief valve malfunction) to approximately 3 kilometers (catastrophic tank failure). The tank failure scenario produced concentrations that could be rapidly fatal (greater than 5000 ppm) out to 1.3 kilometers. Under worst-case meteorological dispersion conditions, recognized exposure limits (IDLH, TLV-STEL) were exceeded for very large distances (greater than 15 kilometers).
Date:
April 1, 1992
Creator:
Abbott, M.L.
Object Type:
Report
System:
The UNT Digital Library
An automated vacuum gauge calibration system
An automated system for calibrating vacuum gauges over the pressure range of 10{sup {minus}6} to 0.1 Pa was designed and constructed at the National Institute of Standards and Technology (NIST) for the Department of Energy (DOE) Primary Standards Laboratory at Sandia National Laboratories (SNL). Calculable pressures are generated by passing a known flow of gas through an orifice of known conductance. The orifice conductance is derived from dimensional measurements and accurate flows are generated using metal capillary leaks. The expanded uncertainty (k = 2) in the generated pressure is estimated to be between 1% and 4% over the calibration range. The design, calibration results. and component uncertainties will be discussed.
Date:
April 1, 1998
Creator:
Abbott, P. J. & Benner, M. S.
Object Type:
Article
System:
The UNT Digital Library
Flywheel energy storage using superconducting magnetic bearings
Storage of electrical energy on a utility scale is currently not practicable for most utilities, preventing the full utilization of existing base-load capacity. A potential solution to this problem is Flywheel Energy Storage (FES), made possible by technological developments in high-temperature superconducting materials. Commonwealth Research Corporation (CRC), the research arm of Commonwealth Edison Company, and Argonne National Laboratory are implementing a demonstration project to advance the state of the art in high temperature superconductor (HTS) bearing performance and the overall demonstration of efficient Flywheel Energy Storage. Currently, electricity must be used simultaneously with its generation as electrical energy storage is not available for most utilities. Existing storage methods either are dependent on special geography, are too expensive, or are too inefficient. Without energy storage, electric utilities, such as Commonwealth Edison Company, are forced to cycle base load power plants to meet load swings in hourly customer demand. Demand can change by as much as 30% over a 12-hour period and result in significant costs to utilities as power plant output is adjusted to meet these changes. HTS FES systems can reduce demand-based power plant cycling by storing unused nighttime capacity until it is needed to meet daytime demand.
Date:
April 1, 1994
Creator:
Abboud, R. G.; Uherka, K.; Hull, J. & Mulcahy, T.
Object Type:
Article
System:
The UNT Digital Library
Multiphoton physics with x-rays: Two photon K-shell ionization of chlorine
A calculation of the two X-ray K-shell photoionization cross section of chlorine will be presented and the feasibility of an experiment will be discussed.
Date:
April 1, 1993
Creator:
Abdallah, J.; Collins, L. A.; Csanak, G.; Kyrala, G. A. & Schappert, G. T.
Object Type:
Article
System:
The UNT Digital Library
Chamber and target technology development for inertial fusion energy
Fusion chambers and high pulse-rate target systems for inertial fusion energy (IFE) must: regenerate chamber conditions suitable for target injection, laser propagation, and ignition at rates of 5 to 10 Hz; extract fusion energy at temperatures high enough for efficient conversion to electricity; breed tritium and fuel targets with minimum tritium inventory; manufacture targets at low cost; inject those targets with sufficient accuracy for high energy gain; assure adequate lifetime of the chamber and beam interface (final optics); minimize radioactive waste levels and annual volumes; and minimize radiation releases under normal operating and accident conditions. The primary goal of the US IFE program over the next four years (Phase I) is to develop the basis for a Proof-of-Performance-level driver and target chamber called the Integrated Research Experiment (IRE). The IRE will explore beam transport and focusing through prototypical chamber environment and will intercept surrogate targets at high pulse rep-rate. The IRE will not have enough driver energy to ignite targets, and it will be a non-nuclear facility. IRE options are being developed for both heavy ion and laser driven IFE. Fig. 1 shows that Phase I is prerequisite to an IRE, and the IRE plus NIF (Phase II) is prerequisite …
Date:
April 7, 1999
Creator:
Abdou, M.; Besenbruch, G.; Duke, J.; Forman, L.; Goodin, D.; Gulec, K. et al.
Object Type:
Report
System:
The UNT Digital Library
Pattern of Thermal Fluctuations in a Recovery Boiler Floor
The floor of a black liquor recovey boiler at a mill in central Canada has experienced cracking and delamination of the composite tubing near the spout wall and deformation of the floor panels that is most severe in the vicinity of the spout wall. One possible explanation for the observed damage is impacts of salt cake falling from the convective section onto the floor. In order to determine if such impacts do occur, strain gauges and thermocouples were installed on the boiler floor in areas where cracking and deformation were most frequent. The data obtained from these instruments indicate that brief, sudden temperature fluctuations do occur, and changes in the strain experienced by the affected tube occur simultaneously. These fluctuations appear to occur less often along the spout wall and more frequently with increasing distance from the wall. The frequency of these temperature fluctuations is insufficient for thermal fatigue to be the sole cause of the cracking observed on the tubes, but the data are consistent with what might be expected from pieces of falling salt cake.
Date:
April 25, 1999
Creator:
Abdullah, Z.; Gorog, J. P.; Keiser, J. R.; Meyers, L. E. & Swindeman, R. W.
Object Type:
Article
System:
The UNT Digital Library
Results from Sage
The Russian-American Gallium Solar Neutrino Experiment (SAGE) is described. Beginning in September 1992, SAGE II data were taken with 55 tons of Ga and with significantly reduced backgrounds. The solar neutrino flux measured by 31 extractions through October 1993 is presented. The result of 69 {+-} 10 +5/{minus}7 SNU is to be compared with a Standard Solar Model prediction of 132 SNU.
Date:
April 1, 1996
Creator:
Abdurashitov, J. N.; Gavrin, V. N. & Girin, S. V.
Object Type:
Report
System:
The UNT Digital Library
Electrostatic design of the barrel CRID (Cherenkov Ring Imaging Detector) and associated measurements
We report on the electrostatic design and related measurements of the barrel Cherenkov Ring Imaging Detector for the Stanford Large Detector experiment at the Stanford Linear Accelerator Center Linear Collider. We include test results of photon feedback in TMAE-laden gas, distortion measurements in the drift boxes and corona measurements. 13 refs., 21 figs.
Date:
April 1, 1990
Creator:
Abe, K.; Hasegawa, K.; Suekane, F.; Yuta, H. (Tohoku Univ., Sendai (Japan). Dept. of Physics); Antilogus, P.; Aston, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Scintillating glass fiber neutron senors
Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched {sup 6} Li , these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over {sup 3}He or BF{sub 3} proportional tubes include flexibility in geometric configuration, ruggedness in high-vibration environments, and less detector weight for the same neutron sensitivity. This paper describes the performance of these scintillating fibers with regard to count rates, pulse height spectra, absolute efficiencies, and neutron/gamma discrimination. Fibers with light transmission lengths (1/e) of greater than 2 m have been produced at PNL. Neutron sensors in fiber form allow development of a variety of neutron detectors packaged in previously unavailable configurations. Brief descriptions of some of the devices already produced are included to illustrate these possibilities.
Date:
April 1, 1994
Creator:
Abel, K. H.; Arthur, R. J. & Bliss, M.
Object Type:
Article
System:
The UNT Digital Library
Scintillating glass fiber-optic neutron sensors
Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate scintillating fibers via a hot-downdraw process. These fibers, which, as produced, typically have a transmission length (e{sup {minus}1} length) of greater than 2 meters, are found to undergo aging when subjected to room air. The aging, which is complete in a few weeks, reduces the transmission length to the order of 0.5 meter. Because of the high alkali content of the glass (on the order of 20--30 mole % lithia), we have attributed this aging to aqueous corrosion oat the polymer cladding/glass interface. changes in transmission with chemical treatment of the surface support the corrosion model. Fiber transmission performance has been preserved by modifying the hot-downdraw to a double crucible to produce glass-on-glass waveguides.
Date:
April 1, 1994
Creator:
Abel, K. H.; Arthur, R. J. & Bliss, M.
Object Type:
Article
System:
The UNT Digital Library