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CaF/sub 2/:Mn thermoluminescence: a single glow peak not described by 1st or 2nd order kinetics

Description: The thermoluminescence (TL) of CaF/sub 2/:Mn has been studied using photon counting and digital recording. For doses of 10 rad or less the TL glow curves appear to consist of a single glow peak. However, there are indications - which are pronounced at larger doses - that one additional low intensity peak (area less than or equal to one percent) is superimposed on each side of the central peak. The intense peak is not described by 1st or 2nd order kinetics but is well described by the more general kinetics from which these kinetics are derived. These observations, and the results of additional kinetic analysis, demonstrate that retrapping is not negligible and may include all three peaks. In such systems, which are likely to include other dosimeter materials and minerals, peak height will not increase linearly with dose; an important factor for dosimetry and dating applications.
Date: December 1, 1984
Creator: Hornyak, W.F.; Levy, P.W. & Kierstead, J.A.
Partner: UNT Libraries Government Documents Department

Ultraviolet-spectrograph lens

Description: A 700-mm f/4.7 spectrograph camera lens was designed for imaging spectral lines in the 200- to 400-nm region on a 120-mm flat image field. Lens elements of fused silica and crystal calcium fluoride give such good achromatization that raytracing calculations predict a resolution limit of 30 lines/mm without refocusing in the 238- to 365-nm region. Light scattering at the polished calcium-fluoride surfaces is avoided by sandwiching the fluoride elements between fused silica and cementing with silicone fluid. The constructed lens makes good spectrograms.
Date: January 1, 1981
Creator: Brixner, B. & Winkler, M.A.
Partner: UNT Libraries Government Documents Department

Improved CO sub 2 enhanced oil recovery -- Mobility control by in-situ chemical precipitation

Description: The overall objective of this study has been to evaluate the feasibility of chemical precipitation to improve CO{sub 2} sweep efficiency and mobility control. The laboratory experiments have indicated that carbonate precipitation can alter the permeability of the core samples under reservoir conditions. Furthermore, the relative permeability measurements have revealed that precipitation reduces the gas permeability in favor of liquid permeability. This indicates that precipitation is occurring preferentially in the larger pores. Additional experimental work with a series of connected cores have indicated that the permeability profile can be successfully modified. However, Ph control plays a critical role in propagation of the chemical precipitation reaction. A numerical reservoir model has been utilized to evaluate the effects of permeability heterogeneity and permeability modification on the CO{sub 2} sweep efficiency. The computer simulation results indicate that the permeability profile modification can significantly enhance CO{sub 2} vertical and horizontal sweep efficiencies. The scoping studies with the model have further revealed that only a fraction of high permeability zones need to be altered to achieve sweep efficiency enhancement. 64 refs., 30 figs., 16 tabs.
Date: June 1, 1991
Creator: Ameri, S.; Aminian, K.; Wasson, J.A. & Durham, D.L.
Partner: UNT Libraries Government Documents Department

Thermal treatment for chlorine removal from coal

Description: It is the goal of this research to provide the technical basis for development of a process to remove chlorine from coal prior to combustion, based on a thermal treatment process. Through a bench scale study, mechanisms will be investigated, reaction rate constants and activation energies determined, and energy and mass balances performed. The recovery of the chlorine removed from the coal as a markable by-product, calcium chloride suitable for use as a road deicer, will be investigated using a novel absorption/crystallization device. The investigation of recovery of the chlorine as calcium chloride would also be applicable to the waste stream generated by a water leaching process, as well as the thermal process which is being investigated here. Although chlorine removal and utilization are the major thrusts of this research, data will also be obtained on the behavior during heating under controlled conditions of several other trace elements of growing concern (mercury, selenium etc.) since the enactment of the Clean Air Act Amendments last November.
Date: January 1, 1991
Creator: Muchmore, C.B.
Partner: UNT Libraries Government Documents Department

Direct oxide reduction demonstration, small-scale studies

Description: This project was initiated to provide process design information to the Plutonium Recovery Project (PRP). Although direct oxide reduction (DOR) has been operated in a production mode both at the Rocky Flats Plant (now operated by EG G, Inc.) and Los Alamos National Laboratory, many aspects of the process are ill-defined. Because the PRP plans include significant DOR capability, a well-defined process should minimize capital cost and maximize productivity. Reduced radiation exposure may also be realized. A detailed, statistically valid investigation of the direct oxide reduction process was carried out utilizing 100 grams or less of plutonium dioxide per experiment. Conditions were established for obtaining 95% + yields. Conclusions drawn from the results of the experimental work were utilized to make recommendations for future large-scale investigative and confirmative work as well large-scale production demonstration work. 4 refs., 5 figs., 14 tabs.
Date: December 9, 1991
Creator: Long, J.L.; Santi, D.J.; Fisher, D.C. & Humiston, T.J.
Partner: UNT Libraries Government Documents Department

Measurement of roughness-induced wavelength corrections to the surface plasmon resonance in silver

Description: A systematic study was made of the wavelength position of the surface plasma resonance in roughened silver foils. Frequency shifts in the resonance peak, produced by varying surface roughness parameters, were interpreted using a model calculation. A self-consistent comparison was made to angular scattered-light distributions from the same foils. Remarks are given concerning changes in silver reflectivity due to annealing.
Date: January 1, 1979
Creator: Bush, J.A.; Cohen, D.K.; Scherkoske, K.D. & Sari, S.O.
Partner: UNT Libraries Government Documents Department

Production-scale Direct Oxide Reduction demonstration

Description: A detailed, statistically valid, examination of the direct oxide reduction parameters affecting process yield and purity was planned and executed. Guidelines for attaining yields approaching 100% are presented. Feed oxide, percent excess calcium, and stirrer design affected yield and product purity. Experiments were performed in production-scale equipment utilizing 800 grams of plutonium dioxide per charge. 1 ref., 9 figs., 3 tabs.
Date: January 23, 1989
Creator: Humiston, T.J.; Santi, D.J.; Long, J.L.; Thomas, R.L. (ed.) & Delaney, I.C. (comp.)
Partner: UNT Libraries Government Documents Department

Fundamental studies of metal fluorination reactions. Third annual progress report

Description: Results are presented of investigations of the solubility and diffusivity of fluorine in copper. Other research is reported on the electronic conductivity of CaF/sub 2/ electrolyte and mixed electrode reactions in solid electrolyte cells. (JRD)
Date: January 1, 1978
Creator: Rapp, R.A.; Reddy, S.N.S.; Chou, S.F. & Lee, B.S.
Partner: UNT Libraries Government Documents Department

Evaluation of a thin CaF/sub 2/(Eu) scintillator for detecting tritium

Description: The primary objective of this project was to investigate the feasibility of using a CaF/sub 2/(Eu) scintillator for detecting low-energy beta particles from tritium. A proof-of-principle detector was designed to flow tritium-spiked nitrogen gas across the surface of a thin scintillator, which was optically coupled between two low-noise photomultiplier tubes. Electronics for operating two photomultiplier tubes in coincidence eliminated most of the tube noise pulses and allowed detection of small pulses from the low-energy tritium beta particles.
Date: January 1, 1986
Creator: Chiles, M.M.
Partner: UNT Libraries Government Documents Department

RIMS diagnostics for laser desorption/laser ablation

Description: Laser desorption mass spectrometry is a useful method for interrogating materials and events at or near surfaces. Laser desorption/ablation combined with Resonance Ionization Mass Spectrometry (RIMS) provides a powerful tool to obtain information on chemical composition and speciation and, in some cases, internal and translational energy distributions. The application of this technique to the interrogation of materials and interfaces is discussed for several systems, including the analysis of conventional analytical samples, and the study of optical damage events. 8 refs., 2 figs., 1 tab.
Date: January 1, 1986
Creator: Apel, E.C.; Nogar, N.S.; Miller, C.M. & Estler, R.C.
Partner: UNT Libraries Government Documents Department

Viscosity of NaCl and other solutions up to 350{sup 0}C and 50 MPa pressures

Description: Experimental values for the viscosity of sodium chloride solutions are critically reviewed for application to geothermal energy. Data published recently by Kestin, Los, Pepinov, and Semenyuk as well as earlier data are included. A theoretically based equation for calculating relative viscosity was developed, and used to generate tables of smoothed values over the ranges 20{sup 0}C to 350{sup 0}C, 0 to 5 m and pressures up to 50 MPa. The equation reproduces selected data to an average of better than 2 percent over the entire range of temperatures and pressures. Selected tables of data are included for KCl up to 150{sup 0}C, CaCl{sub 2} solutions up to 100{sup 0}C, and for mixtures of NaCl with KCl and CaCl{sub 2}. Recommendations are given for additional data needs.
Date: November 1, 1980
Creator: Phillips, S.L.; Ozbek, H.; Igbene, A. & Litton, G.
Partner: UNT Libraries Government Documents Department

Optimized readout system for cooled optically stimulated luminescence

Description: Cooled Optically Stimulated Luminescence (COSL) in CaF{sub 2}:Mn is an ionizing radiation dosimetry method recently developed at the Pacific Northwest Laboratory (PNL). In this method CaF{sub 2}:Mn crystals irradiated by gamma radiation at room temperature are cooled to liquid nitrogen temperature (77K), stimulated by ultraviolet laser light at 326 nm, and allowed to warm to room temperature. Light emission proportional to the gamma exposure occurs as the TLD warms from liquid nitrogen temperature to room temperature. The new method is an example of a highly sensitive phototransfer technique which could form the basis for future radiation dosimetry applications. Measurements to date have shown high potential for measuring gamma exposures in the range of 10 {mu}R. The high sensitivity of the COSL technique is due in part to the larger quantum efficiency of radiative recombination at low temperatures and to the complete absence of the incandescent background associated with conventional thermoluminescent readout methods. Along with the potential for a system which is more sensitive than thermoluminescent readers, multiple COSL readouts can be performed with minimal reduction in the COSL intensity. The multiple readout capability can serve as a possible permanent dosimetry record, thus allowing the reanalysis of a questionable reading. In an attempt to optimize the sensitivity of the COSL method, a new readout system is being developed. 8 refs., 7 figs.
Date: September 1, 1990
Creator: Miller, S.D. & Eschbach, P.A.
Partner: UNT Libraries Government Documents Department

PINEX (Pinhold Neutron Experiment) fluor characteristics

Description: This report will describe recent experiments to characterize four fluors: BC-400, 408, 422, 430. Each fluor sample was 0.5 cm thick commensurate with our standard Electronic Pinhole Neutron Experiment (EL-PINEX) fluors. The important results are that the neutron-gamma sensitivity ratios did not change significantly, although the absolute gamma and neutron sensitivities decreased. 6 figs., 4 tabs.
Date: July 1, 1988
Creator: Koehler, H.; Kammeraad, J.; Davis, B. & Burns, E.
Partner: UNT Libraries Government Documents Department

Theoretical and practical implications of the effects of temperature during irradiation and during pre- and post-irradiation storage on the response of thermoluminescence dosimeters

Description: Experiments have been conducted to determine the applicability of the Randall-Wilkins theory for describing the behavior of CaF/sub 2/:Mn thermoluminescence dosimeters (Harshaw TLD-400 chips). Results were obtained for four different conditions: irradiation followed by storage, irradiation after storage, irradiation both preceded and followed by storage, and continuous simultaneous irradiation and storage. The experiments were performed for storage intervals of approximately 1, 2, 3, 5, 6 and 7 days at five different storage temperatures: -25, +20, +65, +150 and +175/sup 0/C. The results indicate fading that is described not by the Randall-Wilkins theory but rather as a linear function of the logarithm of the storage time. While the results suggest that the trapping efficiency is independent of temperature, they do demonstrate a small decrease in TL response with storage time prior to irradiation which is independent of temperature and time (>17 hours) and hence probably not dosimetric in origin but perhaps optically related. Glow curve analyses support the concept of a band of traps rather than a single trap. The overall results are compared to other data available in the literature most of which is for room-temperature storage. These data, for storage periods ranging from minutes to one year, can also be described as a linear function of the logarithm of the storage time and are remarkably consistent when uniformly normalized. Although peripheral experiments revealed problems associated with self-irradiation as well as a decline in sensitivity with use, the stability experiment results verify the highly favorable stability properties of CaF/sub 2/:Mn for widespread application.
Date: January 1, 1984
Creator: Gail de Planque, E.
Partner: UNT Libraries Government Documents Department

Solid state laser driver for an ICF reactor

Description: A conceptual design is presented of the main power amplifier of a multi-beamline, multi-megawatt solid state ICF reactor driver. Simultaneous achievement of useful beam quality and high average power is achieved by a proper choice of amplifier geometry. An amplifier beamline consists of a sequence of face-pumped rectangular slab gain elements, oriented at the Brewster angle relative to the beamline axis, and cooled on their large faces by helium gas that is flowing subsonically. The infrared amplifier output radiation is shifted to an appropriately short wavelength (<500 nm) using nonlinear crystals that are also gas cooled. We project an overall driver efficiency >10% (including all flow cooling input power) when the amplifiers are pumped by efficient high-power AlGaAs semiconductor laser diode arrays. 11 refs., 3 figs., 7 tabs.
Date: January 1, 1988
Creator: Krupke, W.F.
Partner: UNT Libraries Government Documents Department

Molecular dynamics studies of superionic conductors

Description: Over the last fifteen years computer modeling of liquids and solids has become a useful method of understanding the structural and dynamical correlations in these systems. Some characteristics of the method are presented with an example from work on homogeneous nucleation in monoatomic liquids; the interaction potential determines the structure: a Lennard--Jones system nucleates a close packed structure while an alkali metal potential nucleates a bcc packing. In the study of ionic systems like CaF/sub 2/ the Coulomb interaction together with the short range repulsion is enough to produce a satisfactory model for the motion of F/sup -/ ions in CaF/sub 2/ at approx. 1600/sup 0/K. Analysis of this motion shows that F/sup -/ ions reside at their fluorite sites for about 6 x 10/sup -12/ s and that the diffusion is mainly due to F/sup -/ jumps in the 100 direction. The motion can be analyzed in terms of the generation and annihilation of anti-Frenkel pairs. The temperature dependence of the F/sup -/ diffusion constant at two different densities has also been calculated. The computer model does not correspond with experiment in this regard.
Date: January 1, 1979
Creator: Rahman, A.
Partner: UNT Libraries Government Documents Department

High-resolution laser and rf spectroscopy of atomic and molecular beams

Description: Most of the effort during the past year has been applied to continuing our systematic study of the hyperfine (hfs) and spin-rotation interactions in the calcium monohalide family of radicals. The work is now about 75% complete. The systematic, high-precision measurements will ultimately enable theorists to test the quality of wave functions obtained in ab initio calculations of the structure of these small molecules. Progress is described. (WHK)
Date: January 1, 1982
Creator: Childs, W.J.; Cok, D.R. & Goodman, L.S.
Partner: UNT Libraries Government Documents Department

Fast neutron dosimeter using Cooled Optically Stimulated Luminescence (COSL)

Description: Data is presented that demonstrates the concept of a fast neutron dosimeter using Cooled Optically Stimulated Luminescence. CaF{sub 2}:Mn powder, compounded with polyethylene, was injection molded and pressed into 0.1-cm-thick sheets. The sheets were then cut to form dosimeters with dimensions, 1.25 cm by 1.25 cm. After a laser anneal, the dosimeters were exposed to various amounts (from 10 mSv to 100 mSv) of fast {sup 252}Cf neutrons. The exposed dosimeters were cooled to liquid nitrogen temperature, stimulated with laser light, and then allowed to warm up to room temperature whereupon the dose dependent luminescence was recorded with a photon counting system. When the control and gamma components were subtracted from the {sup 252}Cf response, a dose-dependent neutron response was observed. The design, construction, and preliminary performance of an automated system for the dose interrogation of individual CaF{sub 2}:Mn grains within the polyethylene matrix will also be discussed. The system uses a small CO{sub 2} laser to heat areas of the cooled dosimeter to room temperature. If the readout of very small grain within the plastic matrix is successful, it will enhance the neutron to gamma response of the dosimeter.
Date: October 1, 1991
Creator: Eschbach, P.A. & Miller, S.D.
Partner: UNT Libraries Government Documents Department

Use of precalciners to remove alkali from raw material in the cement industry. Quarterly technical progress report, August-October 1978

Description: A literature survey assisted in defining the role of CaCl/sub 2/ and limitations on its applicability to alkali reduction experimentation. Additional insight into the mechanism and parameters of heat exchange in the precalciner-type kiln systems has been gained from the literature search, which culminated in the preparation of the bibliography covering thermal treatment of raw materials. Experiments investigating the efficiency of alkali volatization from pure argillaceous minerals are underway. Initial results have been encouraging, as significant fractions of total alkali were volatilized even under the static conditions employed. Clay minerals were, rather surprisingly, more resistant to alkali removal than feldspars when CaCl/sub 2/ was used. This may indicate that their structure collapsed upon removal of some alkali, and that CaCO/sub 3/ should be added to the clay burns.
Date: November 1, 1978
Creator: Miller, F.M.
Partner: UNT Libraries Government Documents Department

Investigation of optical damage via resonance ionization mass spectrometry

Description: Resonance ionization mass spectrometry (RIMS) has been used as a diagnostic for interrogating optical damage events. RIMS involves multistep laser photoionization, generally through real intermediate states, followed by mass separation and detection. It is a sensitive and selective means of detection, and has the potential for detection of ultratrace inclusions in substrates and/or coatings. In initial experiments, damage on uncoated CaF/sub 2/ substrates was initiated by pulses of 1.06-..mu..m light from a Q-switched Nd/sup +3/:YAG laser. Interrogation of the spalled plume revealed CaF radicals only when damage events occurred. No Ca atoms were observed, and no attempt was made to detect F atoms or CaF/sub 2/. In subsequent experiments conducted at laser intensities below the damage threshold, we observed the presence of surface adsorbents and a correlation between the presence of the adsorbents and the occurrence of optical damage. 34 refs., 3 figs.
Date: January 1, 1985
Creator: Estler, R.C. & Nogar, N.S.
Partner: UNT Libraries Government Documents Department

Regeneration and recycle of spent oxide reduction solvent salts used in pyrochemical plutonium recovery operations at Los Alamos

Description: One method used at Los Alamos for producing plutonium metal is to chemically reduce the oxide with calcium metal in molten CaCl/sub 2/ at 850/sup 0/C. The solvent CaCl/sub 2/ from this reduction step is currently discarded as low-level radioactive waste because it is saturated with the reaction by-product, CaO. We have developed and demonstrated a molten salt technique for rechlorinating the CaO, thereby regenerating the CaCl/sub 2/ and incorporating solvent recycle into the batch PuO/sub 2/ reduction process. We discuss results from salt regeneration and recycle experiments, and present our plans for incorporating the technique into an advanced design for semi-continuous plutonium metal production.
Date: January 1, 1986
Creator: Fife, K.W.; Bowersox, D.F.; Simpson, J.J.; Davis, C.C.; Phillips, B.J. & McCormick, E.D.
Partner: UNT Libraries Government Documents Department

Fundamental studies of metal fluorination reactions. Fourth annual progress report

Description: In order to investigate the effects of oxygen on the electrical characteristics of the bulk and the electrode/electrolyte interface of CaF/sub 2/ electrochemical cells separately, the equivalent electrical circuits for the following cells were determined, and the geometric capacitances, the double-layer capacitances, the bulk conductivities and the interface conductivities were examined: Ni + NiF/sub 2//CaF/sub 2//Ni + NiF/sub 2/, Ni + NiO/CaF/sub 2//Ni + NiO, and Cu + Cu/sub 2/O/CaF/sub 2//Cu + Cu/sub 2/O. After understanding the behavior of oxygen at the electrode/electrolyte interface and in the bulk of a CaF/sub 2/ electrochemical cell, a theory was developed to rationalize the emf values of the Ni + NiO/CaF/sub 2//Cu + Cu/sub 2/O cell.
Date: January 1, 1979
Creator: Rapp, R.A.
Partner: UNT Libraries Government Documents Department

The free energy of formation of CaCsCl/sub 3/

Description: The free energy of formation of the compound CaCsCl/sub 3/ from CaCl/sub 2/ and CsCl has been determined by measuring the sublimation pressure of CsCl(g) over CaCsCl/sub 3/(s) and over CsCl(s) using Knudsen effusion mass spectrometry. The free energy change for the reaction CaCl/sub 2/(s) + CsCl(s) = CaCsCl/sub 3/(s) at 298 K is /minus/40.7 +/- 6.4 kJ mol/sup /minus/1/. The enthalpy change is /minus/33.5 +//minus/ 5.2 kJ mol /sup /minus/1/ and the entropy change is 23.4 +//minus/ 3.7 J K/sup /minus/1/ mol/sup /minus/1/. Comparisons are made with determinations of these quantities by other investigators. 15 refs., 2 figs., 6 tabs.
Date: January 1, 1989
Creator: Kleinschmidt, P.D. & Axler, K.M.
Partner: UNT Libraries Government Documents Department