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Front-end data processing the SLD data acquisition system

Description: The data acquisition system for the SLD detector will make extensive use of parallel at the front-end level. Fastbus acquisition modules are being built with powerful processing capabilities for calibration, data reduction and further pre-processing of the large amount of analog data handled by each module. This paper describes the read-out electronics chain and data pre-processing system adapted for most of the detector channels, exemplified by the central drift chamber waveform digitization and processing system.
Date: July 1, 1986
Creator: Nielsen, B.S.
Partner: UNT Libraries Government Documents Department

AutoCAD discipline layering convention. Revision 1

Description: This document is a user`s guide to establishing layering standards for drawing development. Uniform layering standards are established to exchange of AutoCAD datasets between organizations and companies. Consistency in the layering conventions assists the user through logical separation and identification of drawing data. This allows the user to view and plot related aspects of a drawing separately or in combination. The use of color and Linetype by layer is the preferred layering convention method, however to accommodate specific needs, colors and linetypes can also be assigned on an entity basis. New drawing setup files (also identified in AutoCAD documentation as Prototype drawings) use this layering convention to establish discipline drawing layers that are routinely used. Additions, deletions or revisions to the layering conventions are encourage.
Date: May 17, 1995
Creator: Nielsen, B.L.
Partner: UNT Libraries Government Documents Department

Controlling company drawing symbology

Description: Fluor Daniel Hanford. Inc., is the prime contractor for the US, Department of Energy, Richland Operations Office at the Hanford Site, which is located near Richland, Washington, in the southeastern portion of the state. Six major subcontractors for Fluor Daniel Hanford, Inc., provide operations and maintenance in waste management, environmental restoration, science and energy for 24 major facilities, programs or utilities on the Site that covers 1,465 square kilometers (560 square miles). Hanford was established in secrecy during the Second World War to produce plutonium for America's nuclear weapons. Peak production was reached in the 1960s when nine production reactors were in operation at the Site. All weapons material production was halted in the late 1980s and the Site is now engaged in the world's largest environmental cleanup project. The mission at Hanford is to manage waste products; researching, developing, applying, and commercializing technologies; waste management; cleanup and environmental restoration. Engineering, scientific and research programs are conducted on environmental restoration, tank waste remediation, waste management, nuclear energy, and energy research.
Date: June 6, 1999
Creator: NIELSEN, B.L.
Partner: UNT Libraries Government Documents Department

Positron diffusion in Si

Description: Positron diffusion in Si(100) and Si(111) has been studied using a variable energy positron beam. The positron diffusion coefficient is found to be D/sub +/ = 2.7 +- 0.3 cm/sup 2//sec using a Makhov-type positron implantation profile, which is demonstrated to fit the data more reliably than the more commonly applied exponential profile. The diffusion related parameter, E/sub 0/, which results from the exponential profile, is found to be 4.2 +- 0.2 keV, significantly longer than previously reported values. A drastic reduction in E/sub 0/ is found after annealing the sample at 1300 K, showing that previously reported low values of E/sub 0/ are probably associated with the thermal history of the sample.
Date: June 1, 1985
Creator: Nielsen, B.; Lynn, K.G.; Vehanen, A. & Schultz, P.J.
Partner: UNT Libraries Government Documents Department

Positron reemission: measurement of thin single crystal W(100) films to be used as transmission moderator or re-moderators

Description: It has been shown that one can produce thin single crystal W films capable of reemitting positrons at a sufficiently high fraction to be used either as a moderator or as a re-moderator. Both the impurities and the defects could be removed by the appropriate cleaning and annealing procedures, and narrow beam emission could be attained when the films were cleaned. This technique would also be a good method for characterizing defect concentration at interfaces or in thin films.
Date: November 1, 1984
Creator: Chen, D.M.; Lynn, K.G.; Pareja, R. & Nielsen, B.
Partner: UNT Libraries Government Documents Department

New insight into damage-related phenomena in Si implanted under extreme conditions

Description: New insight into damage formation in Si(100) during self-ion irradiation is gained from processing under extreme conditions. Dislocations form in the near-surface as a result of lattice relaxation in response to strain produced by precursor defects which are shown to be vacancy-type by positron analysis. A model to account for these defects and their distribution is presented. A novel technique is demonstrated which utilizes a subsequent implantation as a depth specific probe to manipulate the vacancy-type defects. Aspects of damage growth which emerge from the probe results are discussed.
Date: January 1996
Creator: Holland, O. W.; Budai, J. D. & Nielsen, B.
Partner: UNT Libraries Government Documents Department

Annealing studies of visible light emission from silicon nanocrystals produced by implantation

Description: The annealing behavior of silicon implanted SiO{sub 2} layers is studied using continuous and time-gated photoluminescence (PL). Two PL emission bands are observed. A band centered at 560 nm is present in as implanted samples and it is still observed after 1000 {degrees}C annealing. The emission time is fast (0.2 -2 ns). A second band centered at 780 nm further increases when hydrogen annealing was performed. The emission time is long (1 {mu}s - 0.3 ms).
Date: December 31, 1996
Creator: Ghislotti, G.; Nielsen, B. & Di Mauro, L.F.
Partner: UNT Libraries Government Documents Department

Vacancy related defects in La{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}} thin films

Description: Laser ablated La{sub 0.5}Sr{sub 0.5}CoO{sub 3-{delta}} thin films have been studied by Doppler-broadening-detected positron annihilation using a variable-energy positron beam. The oxygen partial pressure during cooling from the growth temperature was altered through the range 760 torr to 10{sup -5} torr to change the oxygen non-stoichiometry of the films. The measured Doppler broadened lineshape parameter S was found to increase with increasing oxygen nonstoichiometry. For films cooled with an oxygen partial pressure of {le} 10{sup -4} Torr positron trapping to monovacancy type defects is inferred. For the film cooled in 10{sup -5} torr oxygen the magnitude of the increase in S, with respect to that measured from the film cooled in 760 Torr oxygen, showed positron trapping to vacancy cluster defects was occurring.
Date: 1997
Creator: Keeble, D. J.; Krishnan, A. & Nielsen, B.
Partner: UNT Libraries Government Documents Department

Vacancies in thermal equilibrium in Nb

Description: We have measured the diffusion of positrons in Nb(110) in the temperature range from 300K to 2450K utilizing a variable energy positron beam. The purpose was to study the vacancy formation. However, no significant sign of vacancy trapping was observed. This could be due to a high detrapping rate caused by a low positron binding energy or due to a high vacancy formation enthalpy H/sub IV//sup F/. The last possibility is consistent with recent studies of the vacancy migration and with calculation of the positron binding energy. In this case we find the H/sub IV//sup F/ > 3 eV.
Date: June 1, 1985
Creator: Nielsen, B.; Lynn, K.G.; Hurst, J.; Vehanen, A. & Schultz, P.J.
Partner: UNT Libraries Government Documents Department

Surveys of forest bird populations found in the vicinity of proposed geothermal project subzones in the district of Puna, Hawaii

Description: This report presents data on the distribution and status of forest bird species found within the vicinity of proposed geothermal resource development on the Island of Hawaii. Potential impacts of the proposed development on the native bird populations found in the project are are addressed.
Date: October 1, 1994
Creator: Jacobi, J.D.; Reynolds, M.; Ritchotte, G.; Nielsen, B.; Viggiano, A. & Dwyer, J.
Partner: UNT Libraries Government Documents Department

Vacancy supersaturations produced by high-energy ion implantation

Description: A new technique for detecting the vacancy clusters produced by high-energy ion implantation into silicon is proposed and tested. This technique takes advantage of the fact that metal impurities, such as Au, are gettered near one-half of the projected range ({1/2}R{sub p}) of MeV implants. The vacancy clustered region produced by a 2 MeV Si{sup +} implant into silicon has been labeled with Au diffused in from the front surface. The trapped Au was detected by Rutherford backscattering spectrometry (RBS) to profile the vacancy clusters. Cross section transmission electron microscopy (XTEM) analysis shows that the Au in the region of vacancy clusters is in the form of precipitates. By annealing MeV implanted samples prior to introduction of the Au, changes in the defect concentration within the vacancy clustered region were monitored as a function of annealing conditions.
Date: January 1, 1998
Creator: Venezia, V.C.; Eaglesham, D.J.; Jacobson, D.C.; Gossmann, H.J.; Haynes, T.E.; Agarwal, A. et al.
Partner: UNT Libraries Government Documents Department

Characterization of silicon implanted SiO{sub 2} layers using positron annihilation spectroscopy

Description: Silicon implanted thermal SiO{sub 2} layers were studied using depth-resolved positron annihilation spectroscopy (PAS) and transmission electron microscopy (TEM). TEM observations show the presence of silicon nanocrystals (Si{sub nc}) in the region between 200 nm and 200 nm. The defect annealing behavior is studied by means of PAS. For 1000{degrees}C annealed samples at a depth for which Si{sub nc} are observed, a distinctive PAS signal is detected and ascribed to the Si{sub nc}/SiO{sub 2} interface.
Date: August 1, 1995
Creator: Ghislotti, G.; Nielsen, B.; Asoka-Kumar, P.; Lynn, K.G.; Szeles, C.; Bottani, C.E. et al.
Partner: UNT Libraries Government Documents Department

Performance of the SLD Central Drift Chamber prototype

Description: A two-cell prototype of the SLD Central Drift Chamber has been tested using CO/sub 2/-isobutane (92%-8%) at one atmosphere. Average single wire resolution of 55 ..mu..m was achieved. Charge division tests indicate a resolution for the final design of less than or equal to 0.5% of wire length. dE/dx separation of ..pi../e should be useful up to at least 7 GeV/c. 100 MHz waveform digitizers were used in parallel with conventional timing and integration techniques. The results show equivalent performance for single tracks and a two pulse resolution better than 1 mm. 7 refs., 7 figs., 1 tab.
Date: March 1, 1986
Creator: Atwood, W.B.; Carr, J.; Chadwick, G.; Csorna, S.; Hansl-Kozanecka, T.; Hodges, C. et al.
Partner: UNT Libraries Government Documents Department

Nitrogen vacancy complexes in nitrogen irradiated metals

Description: Gas desorption and positron annihilation techniques have been employed to study the evolution of nitrogen associated defects in nitrogen irradiated metals: Fe, Ni, Mo and W. Nitrogen in these metals has a rather high affinity to vacancy type defects. The results obtained for low irradiation dose show that substitutional nitrogen (NV; with V = vacancy) is formed. The nitrogen vacancy complex dissociates at temperatures ranging from 350 K for Ni to 900 K for Mo and 1,100 K for W. At high doses defects are formed which can be characterized as nitrogen saturated vacancy clusters. These defect, as observed by helium probing, disappear during annealing for nickel at 800 K, and for Mo at 1,100 K. The direct observation of the desorbing nitrogen for nickel and molybdenum reveals a very fast desorption transient at the dissociation temperature of the clusters. This is the characteristic desorption transient of a small nitride cluster, e.g., by shrinkage with constant rate. For iron the nitrogen desorption is more complicated because of a general background that continuously rises with temperature. With the positron beam technique depth information was obtained for defects in iron and the defect character could be established with the help of the information provided on annihilation with conduction and core electrons of the defect trapped positrons.
Date: December 31, 1996
Creator: Veen, A. van; Westerduin, K.T.; Schut, H.; Melker, E.J.E.; Thijsse, B.J.; Nielsen, B. et al.
Partner: UNT Libraries Government Documents Department