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Sigma: Web Retrieval Interface for Nuclear Reaction Data (open access)

Sigma: Web Retrieval Interface for Nuclear Reaction Data

The authors present Sigma, a Web-rich application which provides user-friendly access in processing and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The main interface includes browsing using a periodic table and a directory tree, basic and advanced search capabilities, interactive plots of cross sections, angular distributions and spectra, comparisons between evaluated and experimental data, computations between different cross section sets. Interactive energy-angle, neutron cross section uncertainties plots and visualization of covariance matrices are under development. Sigma is publicly available at the National Nuclear Data Center website at www.nndc.bnl.gov/sigma.
Date: June 24, 2008
Creator: Pritychenko,B. & Sonzogni, A.A.
System: The UNT Digital Library
Long-range and head-on beam-beam compensation studies in RHIC with lessons for the LHC (open access)

Long-range and head-on beam-beam compensation studies in RHIC with lessons for the LHC

Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are also important consideration for the LHC upgrades. To mitigate long-range effects current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. To reduce the head-on beam-beam effect electron lenses were proposed for both RIDC and the LHC. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.
Date: November 24, 2008
Creator: Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G. et al.
System: The UNT Digital Library
Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator (open access)

Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator

In recent experiments plasma electrons became trapped in a plasma wakefield accelerator (PWFA). The transverse size of these trapped electrons on a downstream diagnostic yields an upper limit measurement of transverse normalized emittance divided by peak current, {var_epsilon}{sub N,x}/I. The lowest upper limit for {var_epsilon}{sub N,x}/I measured in the experiment is 1.3 {center_dot} 10{sup -10} m/A.
Date: September 24, 2008
Creator: Kirby, N.; Blumenfeld, I.; Clayton, C. E.; Decker, F. J.; Hogan, M. J.; Huang, C. et al.
System: The UNT Digital Library
Measurement of the tau- to eta pi-pi+pi-nu tau Branching Fraction and a Search for a Second-Class Current in the tau- to eta'(958)pi-nu tau Decay (open access)

Measurement of the tau- to eta pi-pi+pi-nu tau Branching Fraction and a Search for a Second-Class Current in the tau- to eta'(958)pi-nu tau Decay

The {tau}{sup -} {yields} {eta}{pi}{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}} decay with the {eta} {yields} {gamma}{gamma} mode is studied using 384 fb{sup -1} of data collected by the BABAR detector. The branching fraction is measured to be (1.60 {+-} 0.05 {+-} 0.11) x 10{sup -4}. It is found that {tau}{sup -} {yields} f{sub 1}(1285){pi}{sup -} {nu}{sub {tau}} {yields} {eta}{pi}{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}} is the dominant decay mode with a branching fraction of (1.11 {+-} 0.06 {+-} 0.05) x 10{sup -4}. The first error on the branching fractions is statistical and the second systematic. In addition, a 90% confidence level upper limit on the branching fraction of the {tau}{sup -} {yields} {eta}{prime}(958){pi}{sup -}{nu}{sub {tau}} decay is measured to be 7.2 x 10{sup -6}. This last decay proceeds through a second-class current and is expected to be forbidden in the limit of isospin symmetry.
Date: March 24, 2008
Creator: Aubert, B.; Bona, M.; Boutigny, D.; Karyotakis, Y.; Lees, J. P.; Poireau, V. et al.
System: The UNT Digital Library
The impact of retail rate structures on the economics of commercial photovoltaic systems in California (open access)

The impact of retail rate structures on the economics of commercial photovoltaic systems in California

This article examines the impact of retail electricity rate design on the economic value of grid-connected photovoltaic (PV) systems, focusing on commercial customers in California. Using 15-min interval building load and PV production data from a sample of 24 actual commercial PV installations, we compare the value of the bill savings across 20 commercial-customer retail electricity rates currently offered in the state. Across all combinations of customers and rates, we find that the annual bill savings from PV, per kWh generated, ranges from $0.05 to $0.24/kWh. This sizable range in rate-reduction value reflects differences in rate structures, revenue requirements, the size of the PV system relative to building load, and customer load shape. The most significant rate design issue for the value of commercial PV is found to be the percentage of total utility bills recovered through demand charges, though a variety of other factors are also found to be of importance. The value of net metering is found to be substantial, but only when energy from commercial PV systems represents a sizable portion of annual customer load. Though the analysis presented here is specific to California, our general results demonstrate the fundamental importance of retail rate design for the …
Date: June 24, 2008
Creator: Mills, Andrew D.; Wiser, Ryan; Barbose, Galen & Golove, William
System: The UNT Digital Library
Can cross sections be accurately known for priori? (open access)

Can cross sections be accurately known for priori?

Distinct maxima and minima in the neutron total cross section uncertainties were observed in our large scale covariance calculations using a spherical optical potential. In this contribution we investigate the physical origin of this oscillating structure. Specifically, we analyze the case of neutron reactions on {sup 56}Fe, for which total cross section uncertainties are characterized by the presence of five distinct minima at 0.1, 1.1, 5, 25, and 70 MeV. To investigate their origin, we calculated total cross sections by perturbing the real volume depth V{sub v} by its expected uncertainty {+-}{Delta}V{sub v}. Inspecting the effect of this perturbation on the partial wave cross sections we found that the first minimum (at 0.1 MeV) is exclusively due to the contribution of the s-wave. On the other hand, the same analysis at 1.1 MeV showed that the minimum is the result of the interplay between s-, p-, and d-waves; namely the change in the s-wave happens to be counterbalanced by changes in the p- and d-waves. Similar considerations can be extended for the third minimum, although it can be also explained in terms of the Ramsauer effect as well as the other ones (at 25 and 70 MeV). We discuss the …
Date: June 24, 2008
Creator: Pigni, M. T.; Dietrich, F. S.; Herman, M. & Oblozinsky, P.
System: The UNT Digital Library
Depth-resolved soft x-ray photoelectron emission microscopy in nanostructures via standing-wave excited photoemission (open access)

Depth-resolved soft x-ray photoelectron emission microscopy in nanostructures via standing-wave excited photoemission

We present an extension of conventional laterally resolved soft x-ray photoelectron emission microscopy. A depth resolution along the surface normal down to a few {angstrom} can be achieved by setting up standing x-ray wave fields in a multilayer substrate. The sample is an Ag/Co/Au trilayer, whose first layer has a wedge profile, grown on a Si/MoSi2 multilayer mirror. Tuning the incident x-ray to the mirror Bragg angle we set up standing x-ray wave fields. We demonstrate the resulting depth resolution by imaging the standing wave fields as they move through the trilayer wedge structure.
Date: November 24, 2008
Creator: Kronast, F.; Ovsyannikov, R.; Kaiser, A.; Wiemann, C.; Yang, S. -H.; Locatelli, A. et al.
System: The UNT Digital Library
Measurement of electron clouds in large accelerators by microwave dispersion (open access)

Measurement of electron clouds in large accelerators by microwave dispersion

Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation at high currents. Furthermore, it is difficult to probe their density over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave transmitted over a section of the accelerator and used it to measure the average electron cloud density over a 50 m section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center.
Date: January 24, 2008
Creator: Desantis, Stefano; De Santis, Stefano; Byrd, John M.; Sonnad, Kiran G.; Pivi, Mauro T.F.; Krasnykh, Anatoly et al.
System: The UNT Digital Library
Analyses of Oxyanion Materials by Prompt Gamma Activation Analysis (open access)

Analyses of Oxyanion Materials by Prompt Gamma Activation Analysis

Prompt gamma activation analysis (PGAA) has been used to analyze metal ion oxyanion materials that have multiple applications, including medicine, materials, catalysts, and electronics. The significance for the need for accurate, highly sensitive analyses for the materials is discussed in the context of quality control of end products containing the parent element in each material. Applications of the analytical data for input to models and theoretical calculations related to the electronic and other properties of the materials are discussed.
Date: March 24, 2008
Creator: Firestone, Richard B.; Perry, D. L.; English, G. A.; Firestone, R. B.; Leung, K. N.; Garabedian, G. et al.
System: The UNT Digital Library
Experimental Tests of Cooling: Expectations and Additional Needs (open access)

Experimental Tests of Cooling: Expectations and Additional Needs

Cooling is a critical aspect for a high-performance Neutrino Factory or a MuonCollider. For this reason, considerable effort is being put toward theexperimental verification of this technique. The international Muon IonizationCooling Experiment, MICE, was approved to operate at Rutherford AppletonLaboratory (RAL) in the UK and beam line commissioning commenced in March, 2008. The MICE collaboration comprises about 130 scientists and engineers from Asia, Europe, and the U.S. In this paper we present the motivation and goals for thisexperiment and describe its present status. MICE is scheduled for completion in2011. We will also indicate the prospects for a future 6D muon coolingexperiment and discuss its possible time schedule.
Date: September 24, 2008
Creator: Zisman, Michael S
System: The UNT Digital Library
Development of a Multi Megawatt Circulator for X Band (open access)

Development of a Multi Megawatt Circulator for X Band

Research is in progress on a TeV-scale linear collider that will operate at 5-10 times the energy of present-generation accelerators. This will require development of high power RF sources generating of 50-100 MW per source. Transmission of power at this level requires overmoded waveguide to avoid breakdown. In particular, the TE{sub 01} circular waveguide mode is currently the mode of choice for waveguide transmission at Stanford Linear Accelerator Center (SLAC) in the Multimode Delay Line Distribution System (MDLDS). A common device for protecting an RF source from reflected power is the waveguide circulator. A circulator is typically a three-port device that allows low loss power transmission from the source to the load, but diverts power coming from the load (reflected power) to a third terminated port. To achieve a low loss, matched, three port junction requires nonreciprocal behavior. This is achieved using ferrites in a static magnetic field which introduces a propagation constant dependent on RF field direction relative to the static magnetic field. Circulators are currently available at X-Band for power levels up to 1 MW in fundamental rectangular waveguide; however, the next generation of RF sources for TeV-level accelerators will require circulators in the 50-100 MW range. Clearly, …
Date: March 24, 2008
Creator: Neilson, J.; Ives, L. & Tantawi, S. G.
System: The UNT Digital Library
Vacuum-Ultraviolet (VUV) Photoionization of Small Methanol and Methanol-Water Clusters (open access)

Vacuum-Ultraviolet (VUV) Photoionization of Small Methanol and Methanol-Water Clusters

In this work, we report on the vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters. Clusters of methanol with water are generated via co-expansion of the gas phase constituents in a continuous supersonic jet expansion of methanol and water seeded in Ar. The resulting clusters are investigated by single photon ionization with tunable vacuum-ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Protonated methanol clusters of the form (CH3OH)nH+(n = 1-12) dominate the mass spectrum below the ionization energy of the methanol monomer. With an increase in water concentration, small amounts of mixed clusters of the form (CH3OH n(H2O)H+ (n = 2-11) are detected. The only unprotonated species observed in this work are the methanol monomer and dimer. Appearance energies are obtained from the photoionization efficiency (PIE) curves for CH3OH+, (CH3OH)2+, (CH3OH)nH+ (n = 1-9), and (CH3OH)n(H2O)H+ (n = 2-9) as a function of photon energy. With an increasein the water content in the molecular beam, there is an enhancement of photoionization intensity for the methanol dimer and protonated methanol monomer at threshold. These results are compared and contrasted to previous experimental observations.
Date: April 24, 2008
Creator: Kostko, Oleg; Belau, Leonid; Wilson, Kevin R. & Ahmed, Musahid
System: The UNT Digital Library
Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study (open access)

Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study

We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 = z = 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of theabsorption minimum in Ca ii H&K, we show that the spectra of the high-redshift SNe Ia are quantitatively similar to spectra of nearby SNe Ia (z< 0.15). One supernova in our high redshift sample, SN 2002fd at z = 0.279, is found to have spectral characteristics that are associated with peculiar SN 1991T/SN 1999aa-like supernovae.
Date: March 24, 2008
Creator: Supernova Cosmology Project
System: The UNT Digital Library
Parametric Modeling of Transverse Phase Space of an RF Photoinjector (open access)

Parametric Modeling of Transverse Phase Space of an RF Photoinjector

High brightness electron beam sources such as rf photo-injectors as proposed for SASE FELs must consistently produce the desired beam quality. We report the results of a study in which a combined neural network (NN) and first-principles (FP) model is used to model the transverse phase space of the beam as a function of quadrupole strength, while beam charge, solenoid field, accelerator gradient, and linac voltage and phase are kept constant. The parametric transport matrix between the exit of the linac section and the spectrometer screen constitutes the FP component of the combined model. The NN block provides the parameters of the transport matrix as functions of quad current. Using real data from SLAC Gun Test Facility, we will highlight the significance of the constrained training of the NN block and show that the phase space of the beam is accurately modeled by the combined NN and FP model, while variations of beam matrix parameters with the quad current are correctly captured. We plan to extend the combined model in the future to capture the effects of variations in beam charge, solenoid field, and accelerator voltage and phase.
Date: January 24, 2008
Creator: Hartman, E.; Sayyar-Rodsari, B.; Schweiger, C. A.; Lee, M. J.; Lui, P.; Paterson, Ewan et al.
System: The UNT Digital Library
PBXN-9 Ignition Kinetics and Deflagration Rates (open access)

PBXN-9 Ignition Kinetics and Deflagration Rates

The ignition kinetics and deflagration rates of PBXN-9 were measured using specially designed instruments at LLNL and compared with previous work on similar HMX based materials. Ignition kinetics were measured based on the One Dimensional Time-to-Explosion combined with ALE3D modeling. Results of these experiments indicate that PBXN-9 behaves much like other HMX based materials (i.e. LX-04, LX-07, LX-10 and PBX-9501) and the dominant factor in these experiments is the type of explosive, not the type of binder/plasticizer. In contrast, the deflagration behavior of PBXN-9 is quite different from similar high weight percent HMX based materials (i.e LX-10, LX-07 and PBX-9501). PBXN-9 burns in a laminar manner over the full pressure range studied (0-310 MPa) unlike LX-10, LX-07, and PBX-9501. The difference in deflagration behavior is attributed to the nature of the binder/plasticizer alone or in conjunction with the volume of binder present in PBXN-9.
Date: April 24, 2008
Creator: Glascoe, E; Maienschein, J; Burnham, A; Koerner, J; Hsu, P & Wemhoff, A.
System: The UNT Digital Library
Absolute Bunch Length Measurements at the ALS by Incoherent Synchrotron Radiation Fluctuation Analysis (open access)

Absolute Bunch Length Measurements at the ALS by Incoherent Synchrotron Radiation Fluctuation Analysis

By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial distribution of the beam. At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, we have developed and tested a simple scheme based on this principle that allows for the absolute measurement of the bunch length. A description of the method and the experimental results are presented.
Date: January 24, 2008
Creator: Filippetto, D.; /Frascati; Sannibale, F.; Zolotorev, Max Samuil; /LBL, Berkeley; Stupakov, G.V. et al.
System: The UNT Digital Library
Deformed Matrix Models, Supersymmetric Lattice Twists and N=1/4 Supersymmetry (open access)

Deformed Matrix Models, Supersymmetric Lattice Twists and N=1/4 Supersymmetry

A manifestly supersymmetric nonperturbative matrix regularization for a twisted version of N = (8, 8) theory on a curved background (a two-sphere) is constructed. Both continuum and the matrix regularization respect four exact scalar supersymmetries under a twisted version of the supersymmetry algebra. We then discuss a succinct Q = 1 deformed matrix model regularization of N = 4 SYM in d = 4, which is equivalent to a non-commutative A*{sub 4} orbifold lattice formulation. Motivated by recent progress in supersymmetric lattices, we also propose a N = 1/4 supersymmetry preserving deformation of N = 4 SYM theory on R{sup 4}. In this class of N = 1/4 theories, both the regularized and continuum theory respect the same set of (scalar) supersymmetry. By using the equivalence of the deformed matrix models with the lattice formulations, we give a very simple physical argument on why the exact lattice supersymmetry must be a subset of scalar subalgebra. This argument disagrees with the recent claims of the link approach, for which we give a new interpretation.
Date: September 24, 2008
Creator: Unsal, Mithat
System: The UNT Digital Library
Actinic EUV mask inspection beyond 0.25 NA (open access)

Actinic EUV mask inspection beyond 0.25 NA

The SEMATECH Berkeley Actinic Inspection Tool (AIT) is an EUV-wavelength mask inspection microscope designed for direct aerial image measurements, and pre-commercial EUV mask research. Operating on a synchrotron bending magnet beamline, the AIT uses an off-axis Fresnel zoneplate lens to project a high-magnification EUV image directly onto a CCD camera. We present the results of recent system upgrades that have improved the imaging resolution, illumination uniformity, and partial coherence. Benchmarking tests show image contrast above 75% for 100-nm mask features, and significant improvements and across the full range of measured sizes. The zoneplate lens has been replaced by an array of user-selectable zoneplates with higher magnification and NA values up to 0.0875, emulating the spatial resolution of a 0.35-NA 4x EUV stepper. Illumination uniformity is above 90% for mask areas 2-{micro}m-wide and smaller. An angle-scanning mirror reduces the high coherence of the synchrotron beamline light source giving measured {sigma} values of approximately 0.125 at 0.0875 NA.
Date: March 24, 2008
Creator: Goldberg, Kenneth A.; Mochi, Iacopo; Anderson, Erik H.; Rekawa, Seno. B.; Kemp, Charles D.; Huh, S. et al.
System: The UNT Digital Library
Neutron Cross Section Uncertainties in the Thermal and Resonance Regions (open access)

Neutron Cross Section Uncertainties in the Thermal and Resonance Regions

In the 'Atlas of Neutron Resonances', special care was expended to ensure that the resonance parameter information reproduces the various measured thermal cross sections, as well as the infinite dilute resonance integrals for Z = 1-100. In contrast, the uncertainties of the recommended quantities do not match those generated from the uncertainties of the resonance parameters. To address this problem, the present study was initiated to achieve consistency for 15 actinides and 21 structural and coolant moderator materials. This is realized by assigning uncertainties to the parameters of the negative-energy resonances and changing, if necessary, significantly the uncertainties of the low-lying positive-energy resonances. The influence of correlations between parameters on the derived uncertainties is examined and discussed.
Date: June 24, 2008
Creator: Mughabghab, S. F. & Oblozinsky, P.
System: The UNT Digital Library
Development of covariance capabilities in EMPIRE code (open access)

Development of covariance capabilities in EMPIRE code

The nuclear reaction code EMPIRE has been extended to provide evaluation capabilities for neutron cross section covariances in the thermal, resolved resonance, unresolved resonance and fast neutron regions. The Atlas of Neutron Resonances by Mughabghab is used as a primary source of information on uncertainties at low energies. Care is taken to ensure consistency among the resonance parameter uncertainties and those for thermal cross sections. The resulting resonance parameter covariances are formatted in the ENDF-6 File 32. In the fast neutron range our methodology is based on model calculations with the code EMPIRE combined with experimental data through several available approaches. The model-based covariances can be obtained using deterministic (Kalman) or stochastic (Monte Carlo) propagation of model parameter uncertainties. We show that these two procedures yield comparable results. The Kalman filter and/or the generalized least square fitting procedures are employed to incorporate experimental information. We compare the two approaches analyzing results for the major reaction channels on {sup 89}Y. We also discuss a long-standing issue of unreasonably low uncertainties and link it to the rigidity of the model.
Date: June 24, 2008
Creator: Herman, M.; Pigni, M. T.; Oblozinsky, P.; Mughabghab, S. F.; Mattoon, C. M.; Capote, R. et al.
System: The UNT Digital Library
High gain FEL amplification of charge modulation caused by a hadron (open access)

High gain FEL amplification of charge modulation caused by a hadron

In scheme of coherent electron cooling (CeC) [1,2], a modulation of electron beam density induced by a copropagation hadron is amplified in high gain FEL. The resulting amplified modulation of electron beam, its shape, form and its lethargy determine number of important properties of the coherent electron cooling. In this talk we present both analytical and numerical (using codes RON [3] and Genesis [4]) evaluations of the corresponding Green functions. We also discuss influence of electron beam parameters on the FEL response.
Date: August 24, 2008
Creator: Litvinenko, V.; Ben-Zvi, Ilan; Hao, Y.; Kayran, D.; Pozdeyev, E.; Wang, G. et al.
System: The UNT Digital Library
Formic Acid Dehydrogenation on Au-Based Catalysts at Near-Ambient Temperatures (open access)

Formic Acid Dehydrogenation on Au-Based Catalysts at Near-Ambient Temperatures

Formic acid (HCOOH) is a convenient hydrogen carrier in fuel cells designed for portable use. Recent studies have shown that HCOOH decomposition is catalyzed with Ru-based complexes in the aqueous phase at near-ambient temperatures. HCOOH decomposition reactions are used frequently to probe the effects of alloying and cluster size and of geometric and electronic factors in catalysis. These studies have concluded that Pt is the most active metal for HCOOH decomposition, at least as large crystallites and extended surfaces. The identity and oxidation state of surface metal atoms influence the relative rates of dehydrogenation (HCOOH {yields} H{sub 2} + CO{sub 2}) and dehydration (HCOOH {yields} H{sub 2}O + CO) routes, a selectivity requirement for the synthesis of CO-free H{sub 2} streams for low-temperature fuel cells. Group Ib and Group VIII noble metals catalyze dehydrogenation selectively, while base metals and metal oxides catalyze both routes, either directly or indirectly via subsequent water-gas shift (WGS) reactions.
Date: November 24, 2008
Creator: Ojeda, Manuel & Iglesia, Enrique
System: The UNT Digital Library
CP Violation in B0 decays to Charmonium and Charm Final States (open access)

CP Violation in B0 decays to Charmonium and Charm Final States

We report on measurements of time-dependent CP-violation asymmetries in neutral B meson decays to charmonium and charm final states. The results are obtained from a data sample of (467 {+-} 5) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II B factory.
Date: September 24, 2008
Creator: Chen, Chunhui
System: The UNT Digital Library
NUCLEAR WASTE GLASSES CONTINUOUS MELTING AND BULK VITRIFICAITON (open access)

NUCLEAR WASTE GLASSES CONTINUOUS MELTING AND BULK VITRIFICAITON

This contribution addresses various aspects of nuclear waste vitrification. Nuclear wastes have a variety of components and composition ranges. For each waste composition, the glass must be formulated to possess acceptable processing and product behavior defined in terms of physical and chemical properties that guarantee the glass can be easily made and resist environmental degradation. Glass formulation is facilitated by developing property-composition models, and the strategy of model development and application is reviewed. However, the large variability of waste compositions presents numerous additional challenges: insoluble solids and molten salts may segregate; foam may hinder heat transfer and slow down the process; molten salts may accumulate in container refractory walls; the glass on cooling may precipitate crystalline phases. These problems need targeted exploratory research. Examples of specific problems and their possible solutions are discussed.
Date: March 24, 2008
Creator: AA, KRUGER & PR, HRMA
System: The UNT Digital Library