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[Aerial View of California Crossing Park and Surrounding Area]
Photograph of California Crossing Park and its surrounding area in Dallas, Texas. The park, which sits in front of California Crossing Road, is located in the center of the photo, just to the right of the National Guard building. It contains part of the Elm Fork Trinity River, which extends up the right side of the picture. Lake Carolyn is visible in the top right corner.
Date:
April 28, 1997
Creator:
Loftin, Reginald G.
Object Type:
Photograph
System:
The Portal to Texas History
Mechanisms and genetic control of interspecific crossing barriers in Lycopersicon. Final report
Deficiency of Lycopersicon esculentum allele (E) was observed from the RFLP and isozyme data of the F{sub 2} populations derived from the cross L. esculentum x L. pennellii. The genome composition of the F{sub 2} populations containing L. pennellii cytoplasm (F{sub 2}{sup Lp4}) has a lower proportion of the homozygous L. pennellii (PP) genotypes and a higher proportion of heterozygote (EP) genotypes than that of the F{sub 2} populations containing L. esculentum cytoplasm (F{sub 2}{sup Le}). A lower proportion of the L. pennellii alleles (P) was also observed in F{sub 2}{sup Lp4} as compared to F{sub 2}{sup Le} when each marker locus was tested individually. To study the effects of gametic and zygotic selection on segregation distortion, the expected patterns of segregation at a marker locus were derived for ten selection models with gametic or zygotic selection at a hidden linked locus. Segregation distortion caused by four of the selection models studied can be uniquely identified by the patterns of significance expected for the likelihood ratio tests at the marker loci. Comparison of the chromosomal regions associated with specific selection models across populations (of this experiment and previous publications) indicated that the segregation distortion observed in chromosome 10 is associated …
Date:
April 30, 1997
Creator:
Mutschler, M.A.
Object Type:
Report
System:
The UNT Digital Library
Increasing Heavy Oil Reserves in the Wilmington Oil Field Through Advanced Reservoir Characterization and Thermal Production Technologies
The project involves improving thermal recovery techniques in a slope and basin clastic (SBC) reservoir in the Wilmington field, Los Angeles Co., Calif. using advanced reservoir characterization and thermal production technologies. The existing steamflood in the Tar zone of Fault Block (FB) II-A has been relatively inefficient because of several producibility problems which are common in SBC reservoirs. Inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil, and nonuniform distribution of remaining oil have all contributed to poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated formation sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. The advanced technologies to be applied include: (1) Develop three-dimensional (3-D) deterministic and stochastic geologic models. (2) Develop 3-D deterministic and stochastic thermal reservoir simulation models to aid in reservoir management and subsequent development work. (3) Develop computerized 3-D visualizations of the geologic and reservoir simulation models to aid in analysis. (4) Perform detailed study on the geochemical interactions between the steam and the formation rock and fluids. (5) Pilot …
Date:
August 8, 1997
Creator:
Hara, Scott
Object Type:
Report
System:
The UNT Digital Library
Increasing heavy oil reservers in the Wilmington oil Field through advanced reservoir characterization and thermal production technologies, technical progress report, October 1, 1996--December 31, 1996
The project involves improving thermal recovery techniques in a slope and basin clastic (SBC) reservoir in the Wilmington field, Los Angeles Co., Calif. using advanced reservoir characterization and thermal production technologies. The existing steamflood in the Tar zone of Fault Block (FB) 11-A has been relatively inefficient because of several producibility problems which are common in SBC reservoirs. Inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil, and nonuniform distribution of remaining oil have all contributed to poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated formation sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. The advanced technologies to be applied include: (1) Develop three-dimensional (3-D) deterministic and stochastic geologic models. (2) Develop 3-D deterministic and stochastic thermal reservoir simulation models to aid in reservoir management and subsequent development work. (3) Develop computerized 3-D visualizations of the geologic and reservoir simulation models to aid in analysis. (4) Perform detailed study on the geochemical interactions between the steam and the formation rock and fluids. (5) Pilot …
Date:
May 11, 1997
Creator:
Hara, S.
Object Type:
Report
System:
The UNT Digital Library
Ground fracturing at the southern end of Summit Ridge caused by October 17, 1989 Loma Prieta, California, earthquake sequence (maps of Summit Ridge Shear Zones, en echelon tension cracks, complex and compound fractures, and small faults that formed coactively with the earthquake sequence)
The Loma Prieta earthquake of 17 October 1989 was the first of three large earthquakes that occurred in California in less than 5 years. The main shock of the Loma Prieta earthquake was deep-seated, the rupture zones of the main shock did not reach the surface, and the earthquake produced enigmatic surface ruptures along the frontal faults of the Coast Range and in the epicentral area that were explained in several quite different ways. The Landers earthquake of 28 June 1992 was near surface and produced more than 80 km of spectacular surface rupture of many different kinematic expressions. Detailed study of fractures at Landers has provided a basis for re-evaluating earlier work on fractures produced by the Loma Prieta earthquake. This paper is a description of some of the fractures produced by the Loma Prieta earthquake and a discussion of their causes. Detailed mapping (scale of 1:250) in an area on either side of Summit Road and between Morrell Cutoff Road in the northwest and the intersection of Summit Road and San Jose-Soquel Road in the southeast has provided documentation of fracture orientations and differential displacements required to decipher the ground deformation in that area during the Loma Prieta …
Date:
December 31, 1997
Creator:
Martosudarmo, S.Y.; Johnson, A.M. & Fleming, R.W.
Object Type:
Report
System:
The UNT Digital Library
Joint environmental assessment 1997--2001 of the California Department of Food and Agriculture Curly Top Virus Control Program for Bureau of Land Management and Department of Energy
The DOE, Naval Petroleum reserves in California (NPRC), proposes to sign an Amendment to the Cooperative Agreement and Supplement with the California Department of Food and Agriculture (CDFA) to extend the term of the Curly Top Virus Control Program (CTVCP) in California. This program involves Malathion spraying on NPRC lands to control the beet leafhopper, over a five year period from 1997 through 2001. It is expected that approximately 330 acres on Naval Petroleum Reserve Number 1 (NPR-1) and approximately 9,603 acres on Naval Petroleum Reserve Number 2 (NPR-2) will be treated with Malathion annually by CDFA during the course of this program. The actual acreage subject to treatment can vary from year to year. Pursuant to the requirements of the National Environmental Policy Act of 1969 (NEPA), as amended, the potential impacts of the proposed action were analyzed in a Joint Environmental Assessment (DOE/EA-1011) with the US Department of Interior, Bureau of Land Management (BLM) acting as lead agency, in consultation with the CDFA, and the DOE acting as a cooperating agency. Based on the analysis in the EA, DOE has determined that the conduct of the Curly Top Virus Control Program in California is not a major Federal …
Date:
March 1, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Increasing heavy oil reserves in the Wilmington Oil Field through advanced reservoir characterization and thermal production technologies. Annual report, March 30, 1995--March 31, 1996
The objective of this project is to increase heavy oil reserves in a portion of the Wilmington Oil Field, near Long Beach, California, by implementing advanced reservoir characterization and thermal production technologies. Based on the knowledge and experience gained with this project, these technologies are intended to be extended to other sections of the Wilmington Oil Field, and, through technology transfer, will be available to increase heavy oil reserves in other slope and basin clastic (SBC) reservoirs. The project involves implementing thermal recovery in the southern half of the Fault Block II-A Tar zone. The existing steamflood in Fault Block II-A has been relatively inefficient due to several producibility problems which are common in SBC reservoirs. Inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil, and nonuniform distribution of remaining oil have all contributed to poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated formation sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. A suite of advanced reservoir characterization and thermal production technologies are being …
Date:
September 1, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Growth of a tectonic ridge
The 28 June 1992 Landers, California, earthquake of M 7.6 created an impressive record of surface rupture and ground deformation. Fractures extend over a length of more than 80 km including zones of right-lateral shift, steps in the fault zones, fault intersections and vertical changes. Among the vertical changes was the growth of a tectonic ridge described here. In this paper the authors describe the Emerson fault zone and the Tortoise Hill ridge including the relations between the fault zone and the ridge. They present data on the horizontal deformation at several scales associated with activity within the ridge and belt of shear zones and show the differential vertical uplifts. And, they conclude with a discussion of potential models for the observed deformation.
Date:
December 31, 1997
Creator:
Fleming, Robert W.; Messerich, James A. & Johnson, Arvid M.
Object Type:
Report
System:
The UNT Digital Library
A High shear stress segment along the San Andreas Fault: Inferences based on near-field stress direction and stress magnitude observations in the Carrizo Plain Area
Nearly 200 new in-situ determinations of stress directions and stress magnitudes near the Carrizo plain segment of the San Andreas fault indicate a marked change in stress state occurring within 20 km of this principal transform plate boundary. A natural consequence of this stress transition is that if the observed near-field ``fault-oblique`` stress directions are representative of the fault stress state, the Mohr-Coulomb shear stresses resolved on San Andreas sub-parallel planes are substantially greater than previously inferred based on fault-normal compression. Although the directional stress data and near-hydrostatic pore pressures, which exist within 15 km of the fault, support a high shear stress environment near the fault, appealing to elevated pore pressures in the fault zone (Byerlee-Rice Model) merely enhances the likelihood of shear failure. These near-field stress observations raise important questions regarding what previous stress observations have actually been measuring. The ``fault-normal`` stress direction measured out to 70 km from the fault can be interpreted as representing a comparable depth average shear strength of the principal plate boundary. Stress measurements closer to the fault reflect a shallower depth-average representation of the fault zone shear strength. If this is true, only stress observations at fault distances comparable to the seismogenic …
Date:
January 30, 1997
Creator:
Castillo, D. A., & Younker, L.W.
Object Type:
Report
System:
The UNT Digital Library
Increasing waterflood reserves in the Wilmington Oil Field through improved reservoir characterization and reservoir management. Annual report, March 21, 1995--March 20, 1996
This project uses advanced reservoir characterization tools, including the pulsed acoustic cased-hole logging tool, geologic three- dimensional (3-D) modeling software, and commercially available reservoir management software to identify sands with remaining high oil saturation following waterflood. Production from the identified high oil saturation sands will be stimulated by recompleting existing production and injection wells in these sands using conventional means as well as short radius and ultra-short radius laterals. Although these reservoirs have been waterflooded over 40 years, researchers have found areas of remaining oil saturation. Areas such as the top sand in the Upper Terminal Zone Fault Block V, the western fault slivers of Upper Terminal Zone Fault Block V, the bottom sands of the Tar Zone Fault Block V, and the eastern edge of Fault Block IV in both the Upper Terminal and Lower Terminal Zones all show significant remaining oil saturation. Each area of interest was uncovered emphasizing a different type of reservoir characterization technique or practice. This was not the original strategy but was necessitated by the different levels of progress in each of the project activities.
Date:
August 1, 1997
Creator:
Sullivan, D.; Clarke, D.; Walker, S.; Phillips, C.; Nguyen, J.; Moos, D. et al.
Object Type:
Report
System:
The UNT Digital Library
Feral burro populations: Distribution and damage assessment
This report was prepared to document (1) regional use of the National Training Center (NTC), Fort Irwin, CA, by burros, (2)influence of available water sources for burro use, (3) burro-related damage at several NTC sensitive habitat areas, and (4) management recommendations. All work described in this report was conducted in 1996 and 1997. Roadside transects were conducted and mapped using Geographical Positioning Systems/Geographical Information Systems (GPS/GIS) to indirectly measure relative abundance of feral burros (scat per mile) and to examine the spatial relationship of burro use to permanent or semi-permanent water sources that exist on the NTC. The authors also surveyed several permanent springs for burro-related damage and mapped the impact areas using GPS/GIS to quantify the extent of damage and to provide guidance on size and extent of burro exclosures in those areas. Photographs of the spring sites were also archived and permanent photo points were established for long-term monitoring of feral burro damage areas. In addition, aquatic invertebrate data collected during another spring site study were summarized and discussed in relation to burro-related impacts on the NTC`s sensitive habitats. Several water-quality parameters were also obtained from each spring, including temperature, dissolved oxygen, pH, and total dissolved solids.
Date:
December 1, 1997
Creator:
Tiller, B. L.
Object Type:
Report
System:
The UNT Digital Library
The Growth of Thin Epitaxial Copper Films on Ruthenium (0001)and Oxygen-Precovered Ruthenium (0001) as studied by x-rayphotoelectron diffraction. University of California, Davis, Department of Physics, Ph.D. Thesis
In the first part of this dissertation, the variation of mean emitter depths with direction for core photoelectron emission from single crystals, including the effects of both isotropic inelastic scattering and single and multiple elastic scattering was theoretically studied. The mean emitter depth was found to vary by as much as ±30% with direction. In the second part of this dissertation, x-ray photoelectron diffraction (XPD) was used to study the structure and growth mechanisms of Cu films grown on a clean and an oxygen-precovered Ru(OOO1) surface. Experimental Cu 2p3/2 (E<sub>kin</sub> = 556 eV) and Ru 3d (E<sub>kin</sub> = 1205 eV) intensities were measured for Cu coverages from submonolayer up to several monolayer (ML) on the clean Ru(OOO1) surface. In addition, the O 1s (E<sub>kin</sub> = 958 eV) intensity was measured for Cu grown on oxygen precovered Ru(OOO1). These XPD intensities have been analyzed using single scattering cluster (SSC) and multiple scattering cluster (MSC) models. The first Cu layer has been found to grow pseudomorphically on the Ru(OOO1) surface in agreement with prior studies of the Cu/Ru(OOO 1) system. Thus, the initial growth is layer-by-layer. For higher coverages, XPD shows that the short-range structure of the Cu films is fcc Cu(l …
Date:
June 1, 1997
Creator:
Ruebush, Scott Daniel
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Final cost reduction study for the Geysers Recharge Alternative. Volume 1
The purpose of this study is to determine whether or not cost reduction opportunities exist for the Geysers Recharge Alternative as defined in the Santa Rosa Subregional Long-Term Wastewater Project EIR/EIS. The City of Santa Rosa has been directed to have a plan for reclaimed water disposal in place by 1999 which will meet future capacity needs under all weather conditions. A Draft EIR/EIS released in July 1996 and a Final EIR certified in June 1997 examine four primary alternatives plus the No Action Alternative. Two of the primary alternatives involve agricultural irrigation with reclaimed water, either in western or southern Sonoma County. Another involves increased discharge of reclaimed water into the Russian River. The fourth involves using reclaimed water to replenish the geothermal reservoir at the Geysers. The addition of this water source would enable the Geysers operators to produce more steam from the geothermal area and thereby prolong the life and economic production level of the steamfield and the geothermal power plants supplied by the steamfield. This study provides additional refined cost estimates for new scenarios which utilize an alternative pipeline alignment and a range of reclaimed water flows, which deliver less water to the Geysers than proposed …
Date:
November 1, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Changing Oceans and Changing Fisheries: Environmental Data for Fisheries Research and Management
The following report is the proceedings of a workshop convened at NOAA's Pacific Fisheries Environmental Group in Pacific Grove, California, on July 16-18 1996, to examine the uses of environmental data for fisheries.
Date:
April 1997
Creator:
Boehlert, George W. & Schumacher, James D.
Object Type:
Report
System:
The UNT Digital Library
Oral History Interview with Lloyd C. Cross, April 9, 1997
Access:
Use of this item is restricted to the UNT Community
Interview with Lloyd C. Cross, a Navy veteran, concerning his experiences while aboard the submarines USS S-45 USS Sunfish, USS Spearfish, USS Pogy in the Pacific Theater during World War II. Pre-war duty aboard the USS California and the heavy cruiser USS Vincennes, 1935-39; Submarine School, New London, Connecticut, 1940; his responsibilities as a fireman; various patrols in the Sea of Japan.
Date:
April 9, 1997
Creator:
Maglaughlin, Barry & Cross, Lloyd C.
Object Type:
Book
System:
The UNT Digital Library
Recent developments on the STAR detector system at RHIC
The STAR detector system is designed to provide tracking, momentum analysis and particle identification for many of the mid-rapidity charged particles produced in collisions at the RHIC collider. A silicon vertex detector (SVT) provides three layers of tracking near the interaction point. This is followed by the main time projection chamber (TPC), which continues tracking out to 200 cm radial distance from the interaction region. The detector design also includes an electromagnetic calorimeter, various trigger detectors, and radial TPCs in the forward region. The entire system is enclosed in a 0.5 T solenoid magnet. A progress report is given for the various components of the STAR detector system. The authors report on the recent developments in the detector proto-typing and construction, with an emphasis on the main TPC, recent TPC cosmic ray testing and shipping to Brookhaven National Laboratory.
Date:
December 1997
Creator:
Argonne National Laboratory
Object Type:
Article
System:
The UNT Digital Library
Experimental investigation of the compressible Richtmyer-Meshkov instability from a broad-spectrum, multimode initial perturbation
Experiments have been conducted using the Nova laser system to investigate the growth of the Richtmyer-Meshkov (RM) instability resuling from a strong shock wave (M{approximately}30) crossing a prescribed well-defined initial multimode perturbation. The perturbation was a 100 mode superposition of 1 {micro}m amplitude sine waves with randomly generated phases between 0 and 2{pi}. The two working fluids were fluidized brominated plastic and carbon resorcinol foam, giving a post-shock Atwood number of approximately 0.6. The present experimental results give a power-law coefficient of 0.87 {+-} 0.2 for the growth of the interface. This value is higher than results previously published.
Date:
November 1, 1997
Creator:
Farley, D.; Peyser, T.; Miller, P.; Logory, L.; Stry, P. & Burke, E., LLNL
Object Type:
Article
System:
The UNT Digital Library
Hydrogen local vibrational modes in semiconductors
Following, a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient. exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen. the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the [111] direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the …
Date:
June 1, 1997
Creator:
McCluskey, M. D.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Experimental study of the richtmyer-meshkov instability, including amplitude and wavelength variations
We report on results of an experimental study of the Richtmyer- Meshkov instability. The growth of the mixing region in the nonlinear regime is measured for a set of cases in which the amplitude and wavelength of the initial perturbation are varied systematically. The experiments are conducted on the Nova laser facility, and use a Nova hohlraum as a driver source to launch a high-Mach-number shock into a miniature shock tube attached to the hohlraum. The shock tube contains brominated plastic and low-density carbon foam as the two working fluids, with a micro-machined, triangular sawtooth interface between them serving as the initial perturbation. The sawtooth perturbation waveform is dominated by a single mode, and the perturbation amplitudes are chosen to expedite transition into the nonlinear phase of the instability. The shock, upon crossing the perturbation at the interface, instigates the Richtmyer- Meshkov instability. The resulting growth of the mixing region is diagnosed radiographically. Quantitative measurements of the temporal growth of the width of the mixing region are made for six different combinations of amplitude and wavelength, building upon previous results which employed a single amplitude/wavelength combination. Data from both experiment and supporting simulations suggest that the nonlinear growth of the …
Date:
July 1, 1997
Creator:
Miller, P. L.; Logory, L. M.; Peyser, T. A.; Farley, D. R.; Murray, S. D.; Burke, E. W. et al.
Object Type:
Article
System:
The UNT Digital Library
An experimental study of the richtmyer-meshkov instability, including amplitude and wave length variations
We report on results of an experimental study of the Richtmyer- Meshkov instability. The growth of the mixing region in the nonlinear regime is measured for a set of cases in which the amplitude and wavelength of the initial perturbation are varied systematically. The experiments are conducted on the Nova laser facility, and use a Nova hohlraum as a driver source to launch a high-Mach number shock into a miniature shock tube attached to the hohlraum. The shock tube contains brominated plastic and low density carbon foam as the two working fluids, with a micro-machined, triangular sawtooth interface between them serving as the initial perturbation. The sawtooth perturbation waveform is dominated by a single mode, and the perturbation amplitudes are chosen to expedite transition into the nonlinear phase of the instability. The shock, upon crossing the perturbation at the interface, instigates the Richtmyer-Meshkov instability. The resulting growth of the mixing region is diagnosed radiographically. Quantitative measurements of the temporal growth of the width of the mixing region are made for six different combinations of amplitude and wavelength, building upon previous results which employed a single amplitude/wavelength combination. Data from both experimental and supporting simulations suggest that the nonlinear growth of …
Date:
June 12, 1997
Creator:
Logory, L. M.; Miller, P. L.; Peyser, T. A.; Murray, S. D.; Farley, D. R.; Burke, E. W. et al.
Object Type:
Article
System:
The UNT Digital Library
Ground penetrating radar results at the Box Canyon Site - 1996 survey as part of infiltration test
This data report presents a discussion of the borehole radar tomography experiment conducted at Box Canyon, Idaho. Discussion concentrates on the survey methodology, data acquisition procedures, and the resulting tomographic images and interpretations. The entire geophysics field effort for FY96 centered around the collection of the borehole radar data within the inclined boreholes R1, R2, R3, and R4 before, during, and after the ponded infiltration experiment. The well pairs R1-R2, R2-R4, and R3-R4 comprised the bulk of the field survey; however, additional data were collected between vertical boreholes within and around the infiltration basin. The intent of the inclined boreholes was to allow access beneath the infiltration basin and to enhance the ability of the radar method to image both vertical and horizontal features where flow may dominate. This data report will concentrate on the inclined borehole data and the resulting tomograms. The borehole radar method is one in which modified ground penetrating radar antennas are lowered into boreholes and high frequency electromagnetic signals are transmitted through subsurface material to a receiving antenna. The transmitted signals may be represented as multiple raypaths crossing through the zone of interest. If sufficient raypaths are recorded, a tomographic image may be obtained through …
Date:
August 1, 1997
Creator:
Peterson, J.E. Jr. & Williams, K.H.
Object Type:
Report
System:
The UNT Digital Library
Los Alamos Neutron Science Center (LANSCE) accelerator timing system upgrade
The Los Alamos Neutron Science Center (LANSCE) 800 MeV proton linear accelerator (linac) operates at a maximum repetition rate of twice the AC power line frequency, i.e. 120 Hz. The start of each machine cycle occurs a fixed delay after each zero-crossing of the AC line voltage. Fluctuations in the AC line frequency and phase are therefore present on all linac timing signals. Proper beam acceleration along the linac requires that the timing signals remain well synchronized to the AC line. For neutron chopper spectrometers, e.g., PHAROS at the Manuel Lujan Jr. Neutron Scattering Center, accurate neutron energy selection requires that precise synchronization be maintained between the beam-on-target arrival time and the neutron chopper rotor position. This is most easily accomplished when the chopper is synchronized to a stable, fixed frequency signal. A new zero-crossing circuit which employs a Phase-Locked Loop (PLL) has been developed to increase the phase and frequency stability of the linac timing signals and thereby improve neutron chopper performance while simultaneously maintaining proper linac operation. Results of timing signal data analysis and modeling and a description of the PLL circuit are presented.
Date:
October 1, 1997
Creator:
Rybarcyk, L.J. & Shelley, F.E. Jr.
Object Type:
Article
System:
The UNT Digital Library
Minimizing the Pacman effect
The Pacman bunches will experience two deleterious effects: tune shift and orbit displacement. It is known that the tune shift can be compensated by arranging crossing planes 900 relative to each other at successive interaction points (lPs). This paper gives an analytical estimate of the Pacman orbit displacement for a single as well as for two crossings. For the latter, it can be minimized by using equal phase advances from one IP to another. In the LHC, this displacement is in any event small and can be neglected.
Date:
October 1, 1997
Creator:
Ritson, D.
Object Type:
Report
System:
The UNT Digital Library
Intercampus Institute for Research at Particle Accelerators. Final Report, March 15, 1992--September 30, 1995
This is the final report to the DOE for the Intercampus Institute for Research at Particle Accelerators, or IIRPA, at least for the San Diego branch. Over the years that DOE supported IIRPA, we were told that yearly reports (and the final report) were not necessary because the previous year`s summary in our annual request for funds constituted those reports. Therefore, it has taken some effort, and a corresponding long time, to put something together, after the fact. The IIRPA was born as an idea that arose during discussions at the 1974 PEP summer study, and began to be funded by DoE during the early stages of PEP detector design and construction. The intent was for the members of the Institute to be responsible for the PEP-9 Facility; all of the PEP experiments were supposed to be facilities, rather than just experimental setups for a particular group or research goal. IIRPA was approved as a Multicampus Research Unit (MRU) in 1977 by the University of California, and it was active on the UCD, UCSB and UCSD campuses for 10 years. This report concentrates on the period of time when the Directorship of IIRPA was once again at the San Diego …
Date:
September 22, 1997
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library