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1 - 24 of
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Prospects for physics at e/sup +/e/sup -/ linear colliders
The present thinking on high-energy e/sup /plus//e/sup /minus// linear colliders is reviewed, stressing those points that have consequences for detector design and physics analyses. Detector requirements are discussed. Experimental aspects of the physics that can be done at these colliders are discussed: first the general physics environment, then a standard process, W/sup /plus// W/sup /minus// detection, and finally four examples of the discovery potential of these colliders /emdash/ heavy quarks, heavy leptons, standard Higgs bosons, and charged Higgs bosons. The conclusions of this study will be stated. 23 refs., 40 figs.
Date:
March 1, 1988
Creator:
Feldman, G. J.
Object Type:
Article
System:
The UNT Digital Library
Di-leptons at the Bevalac
Recent results on the production of di-leptons measured by the Di-Lepton-Spectrometer (DLS) collaboration are discussed. Results are reported from observations made on p /plus/ Be collisions with proton beams from 1.0 to 4.9 GeV and on Ca collisions with calcium beams of 1.0 to 2.0 GeV/A. The shape of the distributions are similar to that at higher energies. The low mass cross section appears to be explained by ..pi..-..pi.. annihilation, but detailed calculations are needed to substantiate that hypothesis. (LEN)
Date:
March 1, 1988
Creator:
Matis, H.S.
Object Type:
Article
System:
The UNT Digital Library
Characterization of solids in the Three Mile Island Unit 2 Reactor defueling water: Addendum
Shortly after ORNL/TM-10362 was issued, it was discovered that a series of 31 figures had been inadvertently omitted. These figures, which consist of scanning electron microscope (SEM) photographs and energy-dispersive X-ray fluorescence scans, provide significant information about the results obtained in the tests performed with water sample W3. This Addendum includes these figures. Details of and comments on the SEM photographs may be found in ORNL/TM-10362.
Date:
March 1, 1988
Creator:
Campbell, D.O.
Object Type:
Report
System:
The UNT Digital Library
Field characterization and personal dosimetry at a high energy ion accelerator
The response of a variety of dosimeters was evaluated in the radiation field outside the shielding of the Lawrence Berkeley Laboratory Bevalac Biomedical Facility. The primary beam was 580 MeV/center dot/A neon ions, incident upon a 30.5-cm polyethylene cube. The field was characterized by a neutron spectrometer consisting of Bonner spheres and other detectors and by estimates of charged particle fluences in NTA film and in the Berklet spectrometer. The responses of American Acrylics CR-39 track-etch plastic detectors and AECL (Canada) type BD-100 Bubble Detectors were compared to those of NTA film, Andersson-Braun remmeter and recombination-chamber results as well as to reference dose equivalents based upon the unfolded neutron spectrum. Evaluations of these dosimeters are discussed. 7 refs., 4 figs.
Date:
March 1, 1988
Creator:
Greenhouse, N. A.; Busick, D. D.; de Castro, T. M.; Elwyn, A. J.; Hankins, D. E.; Ipe, N. E et al.
Object Type:
Article
System:
The UNT Digital Library
Anomalous rf magnetoresistance in copper at 4/degree/K
We have measured the effect of a magnetic field on the surface resistance of polycrystalline Cu at f = 1.2 GHz and at 4.4/degree/K; under these conditions the surface resistance is well into the anomalous skin effect regime but has not reached its limiting value. We find that the transverse and longitudinal magnetoresistance are an order of magnitude smaller than the DC magnetoresistance and depend quadratically on the field. At low fields we observe a decrease in surface resistance with increasing field which can be interpreted as a size effect of the TF surface current. 17 refs., 4 figs., 1 tab.
Date:
March 1, 1988
Creator:
Halama, H. J.; Prodell, A. G.; Rogers, J. T.; De Panfilis, S.; Melissinos, A. C.; Moskowitz, B. E. et al.
Object Type:
Report
System:
The UNT Digital Library
A numerical study of Rayleigh-Taylor instability in aluminum and steel plates
The SCRAM code is applied to the study of Rayleigh-Taylor instability in metal plates, and comparisons of these computer results are made with experimental data for 1100-O aluminum, 6061-T6 aluminum and 304 stainless steel. Various models for the pressure, temperature, and strain-rate dependencies of the flow stress are compared in the computer calculations. The coefficients that are required in these models to give good agreement with the experimental results are generally close to values that were determined from previous experimental comparisons. The sensitivity of the computed results to modeling parameters, to variations in the hardening modulus, and to the amplitude and wavelength of the perturbations in the plate surface is examined. Very little growth in amplitude occurs if either the initial amplitude or the wavelength is sufficiently small. The growth rate increases monotonically with increasing initial amplitude. There appears to exist a wavelength of maximum growth, such that the growth rate increases rapidly with wavelength up to this wavelength, but then decreases slowly as the wavelength is further increased.
Date:
March 1, 1988
Creator:
Daly, B.J.
Object Type:
Report
System:
The UNT Digital Library
Pion scattering to 8/sup -/ stretched states in /sup 60/Ni
Using the Energetic Pion Channel and Spectrometer at the Los Alamos Meson Physics Facility, differential cross sections for pion scattering were measured for ten previously known J/sup ..pi../ = 8/sup /minus// stretched states in /sup 60/Ni. A possible new pure isoscalar stretched state was also found. The data were taken near the /DELTA//sub 3,3/-resonance using 162 MeV incident pions and scattering angles of 65/degree/, 80/degree/, and 90/degree/ for ..pi../sup +/ and 65/degree/ and 80/degree/ for ..pi../sup /minus//. The analysis of the /sup 60/Ni data found that the use of Woods-Saxon wave functions in the theoretical calculations gave much better agreement with data than the use of the usual harmonic oscillator wave functions. The WS theory gave better predictions of: the angle at which the ..pi../sup /minus// and ..pi../sup +/ angular distributions are maximum, the ratios of ..pi../sup /minus// to ..pi../sup +/ cross sections for pure isovector states (which were much larger than unity), and the absolute size of the cross sections for all states (so that the normalization factor necessary to arrive at agreement of theory with data was closer to unity). The theoretical calculations used the distorted wave impulse approximation, including new methods for unbound states. The sensitivities of …
Date:
March 1, 1988
Creator:
Clausen, B.L.
Object Type:
Report
System:
The UNT Digital Library
Interaction of impurity ions with a weakly non-Maxwellian simple hydrogenic plasma. [None]
The average acceleration of an ensemble of /open quotes/test particles/close quotes/ in a plasma is called the /open quotes/dynamical friction/close quotes/; the average rate at which their velocity vectors spread out in velocity-space diffusion-rate tensor. These quantities are derived for impurity ions intereacting with a weakly non-Maxwellian simple hydrogenic plasma. The distribution functions for the plasma ions and electrons are written explicitly.
Date:
March 1, 1988
Creator:
Terry, W.K.
Object Type:
Report
System:
The UNT Digital Library
Detection of charged particles in thick hydrogenated amorphous silicon layers
We show our results in detecting particles of various linear energy transfer, including minimum ionizing electrons from a Sr-90 source with 5 to 12 micron thick n-i-p and p-i-n diodes. We measured W ( average energy to produce one electron-hole pair) using 17keV filtered xray pulses with a result W = 6.0 /+-/ 0.2eV. This is consistent with the expected value for a semiconductor with band gap of 1.7 to 1.9eV. With heavily ionizing particles such as 6 MeV alphas and 1 to 2 MeV protons, there was some loss of signal due to recombination in the particle track. The minimum ionizing electrons showed no sign of recombination. Applications to pixel and strip detectors for physics experiments and medical imaging will be discussed. 7 refs., 8 figs.
Date:
March 1, 1988
Creator:
Fujieda, I.; Cho, G.; Kaplan, S. N.; Perez-Mendez, V.; Qureshi, S.; Ward, W. et al.
Object Type:
Article
System:
The UNT Digital Library
Spectra in the 60 )angstrom) to 345 )angstrom) wavelength region of elements injected into the PLT tokamak
High resolution spectra of the elements Fe, Ni, Zn, Ge, Se, and Mo injected into the PLT tokamak were recorded by the 2-meter Schwob-Fraenkel soft X-ray multichannel spectrometer (SOXMOS). Spectra were recorded every 50 ms during the time before and after injection. The spectral lines of the injected element were very strong in the spectrum recorded immedately after injection, and the transition in the injected element were easily distinguished from the transitions in te intrinsic elements (C, O, Ti, Cr, Fe, and Ni). An accurate wavelength scale was established using well-known reference transitions in the intrinsic elements. The spectra recorded just prior to injection were substracted from the spectra recorded after injection, and the resulting spectrum was composed almost entirely of transitions from the injected element. A large number of ..delta..n + 0 transitions between the ground and the first excited configurations in the Li I through K I isoelectronic sequences of the injected elements were identified in the wavelength region 60 )angstrom) to 345 )angstrom). 33 refs., 5 figs., 1 tab.
Date:
March 1, 1988
Creator:
Wouters, A.; Schwob, J.L.; Suckewer, S.; Seely, J.F.; Feldman, U. & Dave, J.H.
Object Type:
Report
System:
The UNT Digital Library
Capture reactions of /sup 40/Ca and /sup 48/Ca with targets of /sup 197/Au and /sup 208/Pb
The reactions of /sup 40/Ca and /sup 48/Ca with targets of /sup 197/Au and /sup 208/Pb have been measured in the region from below the interaction barrier to about twice the barrier energy. The fission-like fragments were detected in a pair of position-sensitive, multi-wire proportional counters and were identified from measurements of position and time using two-body kinematics. In the region above the barrier the cross sections for capture are less than those given by the touching condition, indicating that an /open quotes/extra push/close quotes/ is required to induce capture. The observations for /sup 40/Ca and /sup 48/Ca show different fissilities for the onset of the extra push and indicate that charge equilibration may be an important factor governing capture reactions. Below the barrier the cross sections show an enhancement relative to the prediction for a one dimensional barrier. The enhancements are larger for /sup 40/Ca than for /sup 48/Ca (for both targets) and this is in qualitative agreement with predictions based on the coupling of the relative motion to low-lying collective states. Both above and below the barrier, we find that the change in the light partner, from /sup 48/Ca to /sup 40/Ca, has a larger effect on the …
Date:
March 1, 1988
Creator:
Stokstad, R.; Chan, Y.; Chavez, E.; Di Gregorio, D.; di Tada, M.; Gazes, S. et al.
Object Type:
Article
System:
The UNT Digital Library
An outdoor test facility for the large-scale production of microalgae
The goal of the US Department of EnergySolar Energy Research Institute's Aquatic Species Program is to develop the technology base to produce liquid fuels from microalgae. This technology is being initially developed for the desert Southwest. As part of this program an outdoor test facility has been designed and constructed in Roswell, New Mexico. The site has a large existing infrastructure, a suitable climate, and abundant saline groundwater. This facility will be used to evaluate productivity of microalgae strains and conduct large-scale experiments to increase biomass productivity while decreasing production costs. Six 3-m/sup 2/ fiberglass raceways were constructed. Several microalgae strains were screened for growth, one of which had a short-term productivity rate of greater than 50 g dry wt m/sup /minus/2/ d/sup /minus/1/. Two large-scale, 0.1-ha raceways have also been built. These are being used to evaluate the performance trade-offs between low-cost earthen liners and higher cost plastic liners. A series of hydraulic measurements is also being carried out to evaluate future improved pond designs. Future plans include a 0.5-ha pond, which will be built in approximately 2 years to test a scaled-up system. This unique facility will be available to other researchers and industry for studies on microalgae …
Date:
March 1, 1988
Creator:
Johnson, D.A.; Weissman, J. & Goebel, R.
Object Type:
Article
System:
The UNT Digital Library
Radioactive Waste Isolation in Salt: A Method for Evaluating the Effectiveness of Site Characterization Measurements
The approach presumes that measurements are undertaken to support performance predictions. A quantitative performance objective like groundwater travel time is compared with performance predictions. The approach recognizes that such predictions are uncertain because the measurements upon which they are based are uncertain. The effectiveness of measurement activities is quantified by an index, ..beta.., that reflects the number of standard deviations separating the best estimate of performance from the performance objective. Measurements that reduce the uncertainty in predictions lead to increased values of ..beta... Evaluating ..beta.. for a particular measurement scheme requires identifying the measured quantities that significantly affect prediction uncertainty. Sources of uncertainty are spatial variation, noise, estimation error, and measurement bias. Changing the measurement scheme to increase ..beta.. increases the likelihood of a performance objective being achieved or exceeded. The application of the ..beta..-index method to the Richton dome site in Mississippi focuses on uncertainties in hydraulic conductivity data in relation to groundwater travel time predictions. The ..beta.. values for four different measurement schemes for hydraulic conductivity are determined. 44 refs., 14 figs., 15 tabs.
Date:
March 1, 1988
Creator:
Ditmars, J. D.; Baecher, G. B.; Edgar, D. E. & Dowding, C. H.
Object Type:
Report
System:
The UNT Digital Library
Electron-positron physics at 1 TeV
We discuss the motivation for TeV e/sup +/ e/sup )minus/) linear colliders, some aspects of their design, and the experimental consequences that follow from the design. After a brief discussion of the general physics environment, we consider the discovery potential of these colliders by examining three sample processes: the detection of new heavy leptons, standard Higgs bosons, and charged Higgs bosons. 13 refs., 22 figs., 5 tabs.
Date:
March 1, 1988
Creator:
Feldman, G. J.
Object Type:
Article
System:
The UNT Digital Library
Development of biomass gasification to produce substitute fuels
The development of an efficient pressurized, medium-Btu steam-oxygen-blown fluidized-bed biomass gasification process was conducted. The overall program included initial stages of design-support research before the 12-ton-per-day (TPD) process research unit (PRU) was built. These stages involved the characterization of test-specific biomass species and the characteristics and limits of fluidization control. Also obtained for the design of the adiabatic PRU was information from studies with bench-scale equipment on the rapid rates of biomass devolatilization and on kinetics of the rate-controlling step of biomass char and steam gasification. The development program culminated with the sucessful operation of the PRU through 19 parametric-variation tests and extended steady-state process-proving tests. the program investigated the effect of gasifier temperature, pressure, biomass throughput rate, steam-to-biomass ratio, type of feedstock, feedstock moisture, and fludized-bed height on gasification performance. A long-duration gasification test of 3 days steady-state operation was conducted with the whole tree chips to indentify long-term effects of fluidized process conditions; to establish gasifier material and energy balances; to determine the possible breakthrough of low concentration organic species; and to evaluate the mechanical performance of the system components. Results indicate that the pressurized fludizied-bed process, can achieve carbon conversions of about 95% with cold gas thermal …
Date:
March 1, 1988
Creator:
Evans, R. J.; Knight, R. A.; Onischak, M. & Babu, S. P.
Object Type:
Report
System:
The UNT Digital Library
Introduction to human factors
Some background is given on the field of human factors. The nature of problems with current human/computer interfaces is discussed, some costs are identified, ideal attributes of graceful system interfaces are outlined, and some reasons are indicated why it's not easy to fix the problems. (LEW)
Date:
March 1, 1988
Creator:
Winters, J. M.
Object Type:
Article
System:
The UNT Digital Library
A study of low Q/sup 2/ radiative Bhabha scattering
This thesis presents a study of electron-positron scattering, via nearly real photon exchange, where in the process one or more high energy photons are produced. The motivations behind the work are twofold. Firstly, the study is a sensitive test of the theory of electron-photon interactions, quantum electrodynamics. A deviation from the theory could indicate that the electron is a composite particle. Secondly, a thorough understanding of this process is necessary for experiments to be done in the near future at the Stanford Linear Collider and the LEP facility at CERN. Calculations for the process to third and fourth order in pertubation theory are described. Methods for simulating the process by a Monte Carlo event generator are given. Results from the calculations are compared to data from the Mark II experiment at the PEP storage ring. The ratio of measured to calculated cross sections are 0.993 /+-/ 0.017 /+-/ 0.015 and 0.99 /+-/ 0.16 /+-/ 0.08 for final states with one and two observed photons respectively, where the first errors are statistical and the second systematic. The excellent agreement verifies the calculations of the fourth order radiative correction. No evidence for electron substructure is observed.
Date:
March 1, 1988
Creator:
Karlen, D.A.
Object Type:
Report
System:
The UNT Digital Library
Environmental assessment of the potential effects of aquifer thermal energy storage systems on microorganisms in groundwater
The primary objective of this study was to evaluate the potential environmental effects (both adverse and beneficials) of aquifer thermal energy storage (ATES) technology pertaining to microbial communities indigenous to subsurface environments (i.e., aquifers) and the propagation, movement, and potential release of pathogenic microorganisms (specifically, Legionella) within ATES systems. Seasonal storage of thermal energy in aquifers shows great promise to reduce peak demand; reduce electric utility load problems; contribute to establishing favorable economics for district heating and cooling systems; and reduce pollution from extraction, refining, and combustion of fossil fuels. However, concerns that the widespread implementation of this technology may have adverse effects on biological systems indigeneous to aquifers, as well as help to propagate and release pathogenic organisms that enter thee environments need to be resolved. 101 refs., 2 tabs.
Date:
March 1, 1988
Creator:
Hicks, R. J. & Stewart, D. L.
Object Type:
Report
System:
The UNT Digital Library
Assessing waste management systems using reginalt software
A method for assessing management systems for low-level radioactive waste is being developed for US Department of Energy. The method is based on benefit-cost-risk analysis. Waste management is broken down into its component steps, which are generation, treatment, packaging, storage, transportation, and disposal. Several different alternatives available for each waste management step are described. A particular waste management system consists of a feasible combination of alternatives for each step. Selecting an optimal waste management system would generally proceed as follows: (1) qualitative considerations are used to narrow down the choice of waste management system alternatives to a manageable number; (2) the costs and risks for each of these system alternatives are evaluated; (3) the number of alternatives is further reduced by eliminating alternatives with similar risks but higher costs, or those with similar costs but higher risks; (4) a trade-off factor between cost and risk is chosen and used to compute the objective function (sum of the cost and risk); and (5) the selection of the optimal waste management system among the remaining alternatives is made by choosing the alternative with the smallest value for the objective function. The authors propose that the REGINALT software system, developed by EG and …
Date:
March 1, 1988
Creator:
Meshkov, N. K.; Camasta, S. F. & Gilbert, T. L.
Object Type:
Report
System:
The UNT Digital Library
Bird associations with shrubsteppe plant communities at the proposed reference repository location in southeastern Washington
This report provides information on te seasonal use of shrubsteppe vegetation by bird species at the RRL. Bird abundance and distribution were studied at the RRL to ensure that the DOE monitored migratory bird species pursuant to the Migratory Bird Treaty Act and to assess potential impacts of site characterization activities on bird populations. Birds were counted on two transects that together sampled an areas of 1.39 km/sup 2/. The relative abundance of birds, species richness, seasonal distribution, and the association of breeding shrubsteppe birds with major vegetation types were determined from Janurary through December 1987. Only 38 species were counted during 82 surveys. Total bird density during the nesting season (March-June) was 42.96 birdskm/sup 2/ and the density for the entire year was 26.74 birdskm/sup 2/. The characteristic nesting birds in shrubsteppe habitats were western meadowlark, sage sparrow, burrowing owl, mourning dove, horned lark, long-billed curlew, lark sparrow, and loggerhead shrike. Western meadowlark and sage sparrows were the most abundant breeding birds with an average density of 11.25 and 7.76 birdskm/sup 2/, respectively. Seasonal distribution of birds varied with species, but most species were present from March to September. Distribution and abunandance of nesting birds were correlated with habitat …
Date:
March 1, 1988
Creator:
Schuler, C. A.; Rickard, W. H. & Sargeant, G. A.
Object Type:
Report
System:
The UNT Digital Library
Breakdown phenomena in high power klystrons
In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e. pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. …
Date:
March 1, 1988
Creator:
Vlieks, A. E.; Allen, M. A.; Callin, R. S.; Fowkes, W. R.; Hoyt, E. W.; Lebacqz, J. V. et al.
Object Type:
Article
System:
The UNT Digital Library
Geother Evaluation and Improvement: A Progress Report Including Test Cases for Two-Dimensional BWIP (Basalt Waste Isolation Project) Analysis
The objective of the work is to evaluate the GEOTHER code and peform necessary improvements to make it specifically suitable for predicting the environmental conditions of the waste package for the Basalt Waste Isolation Project (BWIP); and to perform resaturation analyses, that is, the analyses of steam formation and condensation, for the repository and waste package using the improved GEOTHER code. This is a progress report to BWIP documenting the status of GEOTHER code testing, evaluation, and improvements. The computational results documented in this report reflect the current condition of the code and the condition before code improvements. The test cases used are intended for examining the code features in sufficient detail and are not intended to be taken as final conclusions for BWIP applications.
Date:
March 1, 1988
Creator:
Bian, S. H.; Budden, M. J.; Bartley, C. L. & Yung, S. C.
Object Type:
Report
System:
The UNT Digital Library
Automated MCNP photon source generation for arbitrary configurations of radioactive materials and first-principles calculations of photon detector responses
A patch to the Los Alamos Monte Carlo code MCNP has been developed that automates the generation of source descriptions for photons from arbitrary mixtures and configurations of radioactive isotopes. Photon branching ratios for decay processes are obtained from national and international data bases and accesed directly from computer files. Code user input is generally confined to readily available information such as density, isotopic weight fractions, atomic numbers, etc. of isotopes and material compositions. The availbility of this capability in conjunction with the ''generalized source'' capability of MCNP Version 3A makes possible the rapid and accurate description of photon sources from complex mixtures and configurations of radioactive materials, resulting in imporved radiation transport predictive capabilities. This capability is combined with a first - principles calculation of photon spectrometer response - functions for NaI, BGO, and HPGe for E..gamma.. )approxreverse arrowlt) 1 MeV. 25 refs., 1 fig., 4 tabs.
Date:
March 1, 1988
Creator:
Estes, G.P.; Schrandt, R.G. & Kriese, J.T.
Object Type:
Report
System:
The UNT Digital Library
Fuel performance annual report for 1986
This annual report, the ninth in a series, provides a brief description of fuel performance during 1986 in commercial nuclear power plants and an indication of trends. Brief summaries of fuel design changes, fuel surveillance programs, fuel operating experience, fuel problems, high-burnup fuel experience, and items of general significance are provided. References to more detailed information and related U.S. Nuclear Regulatory Commission evaluations are included. 550 refs., 12 figs., 31 tabs.
Date:
March 1, 1988
Creator:
Bailey, W.J. & Wu, S.
Object Type:
Report
System:
The UNT Digital Library