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Some comments on manganin wire pressure gauges

Description: A standard manganin wire pressure gage was examined by comparing it with a recently developed 0.01% CaF/sub 2/ capacitive pressure gage. The effects of the Bridgman water kick'' and intrinsic time constant are clearly shown, and the results punctuate the usual assertion that manganin wire gages are extremely difficult to use approaching the 0.1% level. (auth)
Date: January 1, 1973
Creator: Andeen, C.; Schuele, D. & Fontanella, J.
Partner: UNT Libraries Government Documents Department

Report on the Study of Radiation Damage in Calcium Fluoride and Magnesium Fluoride Crystals for use in Excimer Laser Applications

Description: A study was performed to investigate the effects of radiation damage in calcium fluoride and magnesium fluoride crystals caused by gamma rays and UV photons from excimer lasers. The purpose was to study and correlate the damage caused by these two different mechanisms in various types of material used for fabricating optical elements in high power excimer lasers and lens systems of lithography tools. These optical systems are easily damaged by the laser itself, and it is necessary to use only the most radiation resistant materials for certain key elements. It was found that a clear correlation exists between the, radiation induced damage caused by high energy gamma rays and that produced by UV photons from the excimer laser. This correlation allows a simple procedure to be developed to select the most radiation resistant material at the ingot level, which would be later used to fabricate various components of the optical system. This avoids incurring the additional cost of fabricating actual optical elements with material that would later be damaged under prolonged use. The result of this screening procedure can result in a considerable savings in the overall cost of the lens and laser system.
Date: October 4, 1999
Partner: UNT Libraries Government Documents Department

BOTTOM-POUR RE-USABLE MELTING CRUCIBLES FOR PLUTONIUM CASTING

Description: 24p. Bottom-pour Ta and CaF/sub 2/-coated steel melt crucibles for Pu and Pu-rich alloys were developed. The controlled pour is effected by melting a Pu plug in the bottom spout of the crucible after the desired temperature and vacuum conditions are obtained. A description is given of the development of the crucibles which have replaced ceramic crucibles for casting work on the kilogram scale. (auth)
Date: October 1, 1960
Creator: Miley, F. & Anderson, J.W.
Partner: UNT Libraries Government Documents Department

Purex Processing of Dissolved Sand, Slag, and Crucible Containing High Levels of Boric Acid and Calcium Fluoride

Description: The plutonium solution obtained from the dissolution of SSC in F- Canyon will be high in fluoride. Flowsheet adjustments must be made to increase the plutonium extraction in the solvent extraction cycle to keep Pu losses from being excessive.
Date: May 1, 1998
Creator: Kyser, E.A.
Partner: UNT Libraries Government Documents Department

SETEC/Semiconductor Manufacturing Technologies Program: 1999 Annual and Final Report

Description: This report summarizes the results of work conducted by the Semiconductor Manufacturing Technologies Program at Sandia National Laboratories (Sandia) during 1999. This work was performed by one working group: the Semiconductor Equipment Technology Center (SETEC). The group's projects included Numerical/Experimental Characterization of the Growth of Single-Crystal Calcium Fluoride (CaF{sub 2}); The Use of High-Resolution Transmission Electron Microscopy (HRTEM) Imaging for Certifying Critical-Dimension Reference Materials Fabricated with Silicon Micromachining; Assembly Test Chip for Flip Chip on Board; Plasma Mechanism Validation: Modeling and Experimentation; and Model-Based Reduction of Contamination in Gate-Quality Nitride Reactor. During 1999, all projects focused on meeting customer needs in a timely manner and ensuring that projects were aligned with the goals of the National Technology Roadmap for Semiconductors sponsored by the Semiconductor Industry Association and with Sandia's defense mission. This report also provides a short history of the Sandia/SEMATECH relationship and a brief on all projects completed during the seven years of the program.
Date: December 2000
Creator: McBrayer, John D.
Partner: UNT Libraries Government Documents Department

Preliminary mode distortion measurements on the Jefferson Lab IRFEL

Description: We previously reported analytical calculations of mirror distortion in a high power FEL with a near-concentric cavity. Naive assumptions about the FEL power vs. distortion led us to believe that mirror losses were much lower than expected. Recently we have directly measured the mode size and beam quality as a function of power using a resonator with a center wavelength of 5 microns. The resonator mirrors were calcium fluoride. This material exhibits a large amount of distortion for a given power but, due to the negative slope of refractive index v temperature, adds almost no optical phase distortion on the laser output. The mode in the cavity can thus be directly calculated from the measurements at the resonator output. The presence of angular jitter produced results inconsistent with cold cavity expectations. Removing the effects of the angular jitter produces results in reasonable agreement with analytical models assuming mirror losses comparable to the original expectations.
Date: August 1, 2001
Creator: Benson, Stephen V.; Gubeli, Joe & Shinn, Michelle D.
Partner: UNT Libraries Government Documents Department

Formation and properties of silicon/fluorite heterostructures. Final report, June 1, 1994--May 31, 1997

Description: Our primary goal during the previous support periods was to determine the interrelationship among the structure of the CaF{sub 2}/Si interface, the growth kinetics, the structure and morphology of the overlying film, and the intrinsic dielectric properties of the interface itself. The experiments were designed (i) to determine the CaF{sub 2} overlayer structure and morphology as a function of kinetic conditions [Den93a, Den93b, Won93, Den95, Hes95], (ii) to develop and test models explaining the observed structures [Den95, Hes95], (iii) to investigate the stability of the interface structure [Les97] and (iv) to determine and interpret the photoelectron kinetic energy distributions as a function of the emitting atom location [Rot93, Rot94, Rot96]. As summarized below, we were successful in accomplishing these experiments and in largely fulfilling our original goal.
Date: October 1, 1997
Creator: Olmstead, M.A.
Partner: UNT Libraries Government Documents Department

Thermodynamics of the conversion of calcium and magnesium fluorides to the parent metal oxides and hydrogen fluoride

Description: The authors have used thermodynamic modeling to examine the reaction of calcium fluoride (CaF{sub 2}) and magnesium fluoride (MgF{sub 2}) with water (H{sub 2}O) at elevated temperatures. The calculated, equilibrium composition corresponds to the global free-energy minimum for the system. Optimum, predicted reaction temperatures and reactant mole ratios are reported for the recovery of hydrogen fluoride (HF), a valuable industrial feedstock. Complete conversion of MgF{sub 2} is found at 1,000 C and a ratio of 40 moles of H{sub 2}O per 1 mole of MgF{sub 2}. For CaF{sub 2}, temperatures as high as 1,400 C are required for complete conversion at a corresponding mole ratio of 40 moles of H{sub 2}O per 1 mole of CaF{sub 2}. The authors discuss the presence of minor chemical constituents as well as the stability of various potential container materials for the pyrohydrolysis reactions at elevated temperatures. CaF{sub 2} and MgF{sub 2} slags are available as wastes at former uranium production facilities within the Department of Energy Complex and other facilities regulated by the Nuclear Regulatory Commission. Recovery of HF from these wastes is an example of environmental remediation at such facilities.
Date: February 1, 1997
Creator: West, M.H. & Axler, K.M.
Partner: UNT Libraries Government Documents Department

Optical modeling of the Jefferson Laboratory IR Demo FEL

Description: The Thomas Jefferson National Accelerator Facility (Jefferson Lab) is in the process of building a 1 kW free-electron laser operates at 3 microns. The details of the accelerator driver are given in other papers in these proceedings. The optical cavity consists of a near-concentric resonator with transmissive outcoupling. Though several free-electron lasers have used similar designs, they have not had to confront the high average-power loading present in this laser. It is useful to know the limits of this type of optical cavity design. The optical system of the laser has been modeled using the commercial code GLAD{reg_sign} by using a Beer`s-law region to mimic the FEL interaction. The effects of mirror heating have been calculated and compared with analytical treatments. The magnitude of the distortion for several materials and wave-lengths has been estimated. The model developed here allows one to quickly determine whether the mirror substrates and coatings are adequate for operation at a given optical power level once the absorption of the coatings, substrate, and transmission are known. Results of calculations of the maximum power level expected using several different sets of mirrors will be presented. Measurements of the distortion in calcium fluoride from absorption of carbon dioxide laser light are planned to benchmark the simulations. Multimode simulations using the code ELIXER have been carried out to characterize the saturated optical mode quality. The results will be presented.
Date: November 1, 1997
Creator: Benson, S.V.; Davidson, P.S.; Jain, R.; Kloeppel, P.K.; Neil, G.R. & Shinn, M.D.
Partner: UNT Libraries Government Documents Department

Laser-induced damage in dielectrics with nanosecond to subpicosecond pulses. I. Experimental. Part 1

Description: The authors report extensive laser-induced damage threshold measurements on pure and multilayer dielectrics at 1053 and 526 mm for pulse durations, {tau}, ranging from 140 fs to 1 ns. Qualitative differences in the morphology of damage and a departure from the diffusion-dominated {tau}{sup 1/2} scaling indicate that damage results from plasma formation and ablation for {tau}{le}10 ps and from conventional melting and boiling for {tau}>50 ps. A theoretical model based on electron production via multiphoton ionization, Joule heating, and collisional (avalanche) ionization is in good agreement with both the pulsewidth and wavelength scaling of experimental results.
Date: December 1, 1994
Creator: Stuart, B.C.; Herman, S. & Perry, M.D.
Partner: UNT Libraries Government Documents Department

Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-T(c) Superconductor

Description: We report the discovery of a self-doped multilayer high T{sub c} superconductor Ba{sub 2}Ca{sub 3}Cu{sub 4}O{sub 8}F{sub 2} (F0234) which contains distinctly different superconducting gap magnitudes along its two Fermi-surface sheets. While formal valence counting would imply this material to be an undoped insulator, it is a self-doped superconductor with a T{sub c} of 60 K, possessing simultaneously both electron- and hole-doped Fermi-surface sheets. Intriguingly, the Fermi-surface sheet characterized by the much larger gap is the electron-doped one, which has a shape disfavoring two electronic features considered to be important for the pairing mechanism: the van Hove singularity and the antiferromagnetic ({pi}/{alpha}, {pi}/{alpha}) scattering.
Date: February 12, 2007
Creator: Chen, Yulin; Iyo, Akira; Yang, Wanli; Zhou, Xingjiang; Lu, Donghui; Eisaki, Hiroshi et al.
Partner: UNT Libraries Government Documents Department

EXPERIMENTAL STUDY TO EVALUATE CORROSION OF THE F-CANYON DISSOLVER DURING THEUNIRRADIATED MARK-42 CAMPAIGN

Description: Unirradiated Mark 42 fuel tubes are to be dissolved in an upcoming campaign in F-canyon. Savannah River Technology Center (SRTC)/Chemical & Hydrogen Technology Section (CHTS) identified a flow sheet for the dissolution of these Mark 42 fuel tubes which required a more aggressive dissolver solution than previously required for irradiated Mark 42 fuel tubes. Subsequently, SRTC/MTS was requested to develop and perform a corrosion testing program to assess the impact of new flow sheets on corrosion of the dissolver wall. The two primary variables evaluated were the fluoride and aluminum concentrations of the dissolver solution. Fluoride was added as Calcium Fluoride (CaF{sub 2}) while the aluminum was added either as metallic aluminum, which was subsequently dissolved, or as the chemical aluminum nitrate (Al(NO{sub 3}){sub 3}). The dissolved aluminum metal was used to simulate the dissolution of the aluminum from the Mark 42 cladding and fuel matrix. Solution composition for the corrosion tests bracketed the flow sheet for the Mark 42. Corrosion rates of AISI Type 304 stainless steel coupons, both welded and non-welded coupons, were calculated from measured weight losses and post-test concentrations of soluble Fe, Cr and Ni. The corrosion rates, which ranged between 2.7 and 32.5 mpy, were calculated from both the one day and the one week weight losses. These corrosion rates indicated a relatively mild corrosion on the dissolver vessel. The welded coupons consistently had a higher corrosion rate than the non-welded coupons. The difference between the two decreased as the solution aggressiveness decreased. In these test solutions, aggressiveness corresponded with the fluoride concentration. Based on the results of this study, any corrosion occurring during the Mark 42 Campaign is not expected to have a deleterious effect on the dissolver vessel.
Date: August 1, 1999
Creator: Mickalonis, J & Kerry Dunn, K
Partner: UNT Libraries Government Documents Department

Experiments on the interaction of intense femtosecond radiation with dense plasmas. Final report

Description: An upgraded KrF{sup {asterisk}} (248 nm) system producing a pulse energy of {approximately} 400 mJ, a pulse width of {approximately} 220 fs, and focal intensities above 10{sup 19} W/cm{sup 2}, has been constructed, tested, operated, and used in experimental studies. The spatial morphology of channeled radiation in plasmas has been measured with a spatial resolution of {approximately} 30 {mu}m and damage studies of fused silica indicate that femtosecond (200 - 300 fs) 248 nm radiation has a damage limit not exceeding {approximately} 50 GW/cm{sup 2}, an unfavorably low level. 2 figs.
Date: January 24, 1996
Creator: Rhodes, C. K.
Partner: UNT Libraries Government Documents Department

Criteria determining the selection of slags for the melt decontamination of radioactively contaminated stainless steel by electroslag remelting

Description: Electroslag remelting is an excellent process choice for the melt decontamination of radioactively contaminated metals. ESR furnaces are easily enclosed and do not make use of refractories which could complicate thermochemical interactions between molten metal and slag. A variety of cleaning mechanisms are active during melting; radionuclides may be partitioned to the slag by means of thermochemical reaction, electrochemical reaction, or mechanical entrapment. At the completion of melting, the slag is removed from the furnace in solid form. The electroslag process as a whole is greatly affected by the chemical and physical properties of the slag used. When used as a melt decontamination scheme, the ESR process may be optimized by selection of the slag. In this research, stainless steel bars were coated with non-radioactive surrogate elements in order to simulate surface contamination. These bars were electroslag remelted using slags of various chemistries. The slags investigated were ternary mixtures of calcium fluoride, calcium oxide, and alumina. The final chemistries of the stainless steel ingots were compared with those predicted by the use of a Free Energy Minimization Modeling technique. Modeling also provided insight into the chemical mechanisms by which certain elements are captured by a slag. Slag selection was also shown to have an impact on the electrical efficiency of the process as well as the surface quality of the ingots produced.
Date: March 1, 1997
Creator: Buckentin, J.M.R.; Damkroger, B.K.; Shelmidine, G.J. & Atteridge, D.G.
Partner: UNT Libraries Government Documents Department

Mechanisms of enhanced ionic conduction at interfaces in ceramics

Description: A large enhancement in the ionic conductivity of certain compounds occurs when the compound is produced as a composite material containing a finely-dispersed non-conductor such as SiO{sub 2} or Al{sub 2}O{sub 3}. This paper describes recent experiments which proposes that extended defects such as dislocations and grain boundaries, either resulting from or stabilized by the interface, are responsible for the enhancement. The ionic conductivities of LiI and CaF{sub 2} thin films grown on sapphire(0001) substrates were monitored in-situ during deposition as a function of film thickness and deposition conditions. LiI films grown at 27{degrees}C exhibited a region of enhanced conduction within 100 nm of the substrate and a lesser enhancement as the film thickness was increased further. This conduction enhancement was not stable but annealed out with a characteristic log(time) dependence. The observed annealing behavior was fit with a model based on dislocation motion which implies that the increase in conduction near the interface is due to extended defects generated during the growth process. CaF{sub 2} films grown at 200{degrees}C showed a behavior similar to the 27{degrees}C LiI films, with a region of thermally unstable enhanced conduction that occurs within 10 nm of the substrate. Amorphous Al{sub 2}O{sub 3} films deposited over the CaF{sub 2} layers created no additional enhancement but did increase the stability of the conduction, consistent with an extended defect model. Simultaneous deposition of CaF{sub 2} and Al{sub 2}O{sub 3} produced films consisting of very-fine-grained CaF{sub 2} and particles of amorphous Al{sub 2}O{sub 3} (5-10 nm grain and particle size) and a high defect density which was stable even well above the growth temperature. Measured conduction in the composite at 200{degrees}C was approximately 360 times that of bulk CaF{sub 2}.
Date: November 1, 1994
Creator: Lubben, D. & Modine, F.A.
Partner: UNT Libraries Government Documents Department

Electron-irradiation-induced crystallization of amorphous orthophosphates

Description: Amorphous LaPO{sub 4}, EuPO{sub 4}, GdPO{sub 4}, ScPO{sub 4}, and fluorapatite [Ca{sub 5}(PO{sub 4}){sub 3}F] were irradiated by electron beam in a TEM. Irradiations were done at -150 to 300 C, 80 to 200 keV, and current densities from 0.3 to 16 A/cm{sup 2}. In all cases, the materials crystallized to form a randomly oriented polycrystalline assemblage. Crystallization is driven dominantly by inelastic processes, although ballistic collisions with target nuclei can be important above 175 keV, particularly in apatite. Using a high current density, crystallization is so fast that continuous lines of crystallites can be ``drawn`` on the amorphous matrix.
Date: December 1, 1996
Creator: Meldrum, A.; Ewing, R.C. & Boatner, L.A.
Partner: UNT Libraries Government Documents Department

Flow sheet development for the dissolution of unirradiated Mark 42 fuel tubes in F-Canyon, Part II

Description: Two dissolution flow sheets were tested for the desorption of unirradiated Mark 42 fuel tubes. Both the aluminum (from the can, cladding, and fuel core) and the plutonium oxide (PuO{sub 2}) are dissolved simultaneously, i.e., a co-dissolution flow sheet. In the first series of tests, 0.15 and 0.20 molar (M) potassium fluoride (KF) solutions were used and the dissolution extended over several days. In the other series of tests, solutions with higher concentrations of fluoride (0.25 to 0.30 M) were used. Calcium fluoride (CaF{sub 2}) was used in those tests as the fluoride source.
Date: September 20, 1999
Creator: Murray, A.M.
Partner: UNT Libraries Government Documents Department

CALIBRATION OF PHOTOELASTIC MODULATORS IN THE VACUUM UV.

Description: Measurements of circular dichroism (CD) in the UV and vacuum UV have used photoelastic modulators (PEMs) for high sensitivity (to about 10{sup -6}). While a simple technique for wavelength calibration of the PEMs has been used with good results, several features of these calibration curves have not been understood. The authors have calibrated a calcium fluoride PEM and a lithium fluoride PEM using the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory as a light source. These experiments showed calibration graphs that are linear bit do not pass through the graph origin. A second ''multiple pass'' experiment with laser light of a single wavelength, performed on the calcium fluoride PEM, demonstrates the linearity of the PEM electronics. This implies that the calibration behavior results from intrinsic physical properties of the PEM optical element material. An algorithm for generating calibration curves for calcium fluoride and lithium fluoride PEMs has been developed. The calibration curves for circular dichroism measurement for the two PEMs investigated in this study are given as examples.
Date: February 15, 2000
Creator: Oakberg, T. C.; Trunk, J. & Sutherland, J. C.
Partner: UNT Libraries Government Documents Department