The Fourth Users Meeting for the Advanced Photon Source (APS) was held on May 7--8, 1991 at Argonne National Laboratory. Scientists and engineers from universities, industry, and national laboratories came to review the status of the facility and to look ahead to the types of forefront science that will be possible when the APS is completed. The presentations at the meeting included an overview of the project; critical issues for APS operation; advances in synchrotron radiation applications; users perspectives, and funding perspectives. The actions taken at the 1991 Business Meeting of the Advanced Photon Source Users Organization are also documented.

Microstructure has a great influence on the mechanical and superconducting properties of YBCO. Mechanical properties of YBCO can be improved by both modifying the monolithic microstructure and developing composites of YBCO with silver (Ag). When monolithic YBCO was sintered to high densities ({approx} 91%) at a relatively low temperature ({approx} 910{degrees}C) by controlling oxygen partial pressure during sintering, the result was a small-grain microstructure (average grain size {approx} 5 {mu}m) and hence a high strength of 191 {plus_minus} 7 MPa. Addition of Ag as a second phase further improved the strength of YBCO. Composites of YBCO with 10 to 15 vol % Ag has a strength of 225 {plus_minus} 6 MPa and a fracture toughness of 3.3 {plus_minus} 0.2 MPa{radical}m. These improvements are believed to be due to compressive stresses in the YBCO matrix as a result of thermal mismatch between the YBCO and Ag phases. Furthermore, the Ag particles may provide increased resistance to crack propagation by pinning the crack. On the other hand, addition of Ag as a dopant to substitute for Cu sites in YBCO has a profound but nonmonotonic effect on grain microstructure and the resulting critical current density.

This report is a permanent record of a poster paper presented by the authors at the Third International Reservoir Characterization Technical Conference in Tulsa, Oklahoma on November 3--5, 1991. The subject is electromagnetic (EM) techniques that are being developed to monitor oil recovery processes to improve overall process performance. The potential impact of EM surveys is very significant, primarily in the areas of locating oil, identifying oil inside and outside the pattern, characterizing flow units, and pseudo-real time process control to optimize process performance and efficiency. Since a map of resistivity alone has little direct application to these areas, an essential part of the EM technique is understanding the relationship between the process and the formation resistivity at all scales, and integrating this understanding into reservoir characterization and simulation. First is a discussion of work completed on the core scale petrophysics of resistivity changes in an oil recovery process; a steamflood is used as an example. A system has been developed for coupling the petrophysics of resistivity with reservoir simulation to simulate the formation resistivity structure arising from a recovery process. Preliminary results are given for an investigation into the effect of heterogeneity and anisotropy on the EM technique, as …

The preparation of metal and ceramic atom clusters by means of the gas-condensation method, followed by their in situ collection and consolidation under high-vacuum conditions, has recently led to the synthesis of a new class of ultrafine-grained materials. These nanophase materials, with typical average grain sizes of 5 to 50 nm and, hence, a large fraction of their atoms in interfaces, exhibit properties that are often considerably improved relative to those of conventional materials. Furthermore, their synthesis and processing characteristics should enable the design of new materials with unique properties. Some examples are ductile ceramics that can be formed and sintered to full density at low temperatures without the need for binding or sintering aids, and metals with dramatically increased strength. The synthesis of these materials is briefly described along with what is presently known of their structure and properties. Their future impact on materials science and technology is also considered.

The induced current pulse from ionizing events occurring near contacts on each side of a p{sup +}-n-n{sup +} silicon junction detector may be used to map the electric field present in the detector. It is of interest to define the operative effects of fast neutron-induced displacement damage in detectors destined for high radiation environments in SSC or LHC. The hole current shape, in particular, has been useful to determine that the field maximum moves to the ``rear`` n{sup +} contact as the material apparently changes to p type at 8{times}10{sup 12} 1 MeV n/cm{sup 2}. Trapping times for both holes and electrons have been measured as a function of neutron fluence using the current pulse width to measure charge collection time as well as using calculated charge collection times. A clear linear relationship is found for the trapping probability (1/{tau}) versus neutron fluence. Current pulse shapes have been calculated for representative detector fields and mobility relationships and comparison with measured shapes is reasonable.

Recent progress in molecular-dynamics studies of radiation-induced crystalline-to-amorphous transition in the ordered intermetallic compounds of the Cu-Ti system is discussed. The effect of irradiation was simulated by the generation of Frenkel pairs,which resulted in both the formation of stable point defects and chemical disorder upon defect recombination. The thermodynamic, structural and mechanical responses of the compounds during irradiation were determined by monitoring changes in the system potential energy, volume expansion, pair correlation function, diffraction patterns, and elastic constants. It was found that the intermetallics Cu{sub 4}Ti{sub 3}, CuTi, and CuTi{sub 2} could be rendered amorphous by the creation of Frenkel pairs, but Cu{sub 4}Ti could not, consistent with experimental observations during electron irradiation. However, the simulations showed that Cu{sub 4}Ti did become amorphous when clusters of Frenkel pairs were introduced, indicating that this compound may be susceptible to amorphization by heavy-ion bombardment. A generalization of the Lindemann criterion was used to develop a thermodynamic description of solid-state amorphization as a disorder- induced melting process.

X-ray probes are capable of determining the spatial structure of an atom in a specific chemical state, over length scales from about a micron all the way down to atomic resolution. Examples of these probes include photoemission microscopy, energy-dependent photoemission diffraction, photoelectron holography, and X-ray absorption microspectroscopy. Although the method of image formation, chemical-state sensitivity, and length scales can be very different, these X-ray techniques share a common goal of combining a capability for structure determination with chemical-state specificity. This workshop will address recent advances in holographic, diffraction, and direct imaging techniques using X-ray photoemission on both theoretical and experimental fronts. A particular emphasis will be on novel structure determinations with atomic resolution using photoelectrons.

As the old saying goes, ``If you have no objective, any road will take your there.`` So it is with the audit checklist. The checklist is the primary tool for providing order to Quality Assurance audit activities. With a well-planned and well-defined checklist, success is achievable. Without a checklist, the auditor has a disjointed, disorganized activity and no place to document his or her failed efforts. A number of formal quality programs which include audits as one of their program elements require the audit to be performed using a checklist or procedures to document what the auditor reviewed and what he or she found. It is the intent of this paper to provide the reader with the some insight as to the value of the checklist; the varieties of checklists that can be constructed; the pitfalls of improper application; and the success that can be achieved when the checklist has been properly researched, developed, and deployed.

We present new results in axiomatic group theory obtained by using automated deduction programs. The results include single axioms, some with the identity and others without, for groups of exponents 3, 4, 5 and 7, and a general form for single axioms for groups of odd exponent. The results were obtained by using the programs in three separate ways: as a symbolic calculator, to search for proofs,and to search for couterexamples. We also touch on relations between logic programming and automated reasoning.

Despite the enormous personal and social cost Of substance abuse, there is very little knowledge with respect to the mechanisms by which these drugs produce addiction as well as to the mechanisms of toxicity. Similarly, there is a lack of effective therapeutic intervention to treat the drug abusers. In this respect, nuclear medicine could contribute significantly by helping to gather information using brain imaging techniques about mechanisms of drug addiction which, in turn, could help design better therapeutic interventions, and by helping in the evaluation and diagnosis of organ toxicity from the use of drugs of abuse. This volume contains six short descriptions of presentations made at the 18th Meeting of the American College of Nuclear Physicians -- DOE Day: Substance Abuse and Nuclear Medicine.

The symmetry and density of unoccupied states of YBa{sub 2}Cu{sub 3}O{sub 7} YBa{sub 2}Cu{sub 4}O{sub 8} have been investigated by orientation dependent x-ray absorption spectroscopy on the O 1s edge using a bulk-sensitive fluorescence-yield-detection method. It has been found that the O 2p holes are distributed equally between the CuO{sub 2} planes and CuO chains and that the partial density of unoccupied O 2p states in the CuO{sub 2} planes are identical in both systems investigated. The upper Hubbard band has been observed in the planes but not in the chains in both systems. 18 refs.

In this seminar we will review some of the characteristics of the major classes of ground motion in order to determine whether their effects must be considered or place fundamental limits on the sitting and/or design of modern storage rings and linear colliders. The classes discussed range in frequency content from tidal deformation and tectonic motions through earthquakes and microseisms. Countermeasures currently available are briefly discussed.

Magneto-optical multilayers are of interest to the optical data storage community as a possible second-generation medium of the future. The important Co/Pt-superlattice system is introduced in this respect, and an extensive reference listing is provided to previous research. Magneto-optical modeling studies of Co/Pt are presented, and it is concluded that the interfacial Pt is magnetized and is magneto-optically active at the short wavelengths of interest ({approximately}4 eV) for applications. Magneto-optics in the ultrathin limit are discussed, and an additivity law is presented and verified experimentally utilizing data for epitaxial Fe/Ag(111) superlattices. Finally, the surface magnetic anisotropy that provides the vertical easy axes of magnetization in candidate superlattice systems is discussed and illustrated experimentally using ultrathin epitaxial films of Fe grown on a variety of substrates. It is concluded that magneto-optic multilayers will provide many stimulating basic and applied challenges in the years ahead.

The Atmospheric Neutrino Deficit defines a region in {Delta}m{sup 2}-sin{sup 2}2{theta} space which ought to be conclusively tested in a long-baseline experiment. This talk sets out a region to cover (which may change as more data is analyzed) and translates that region into an L/E. I present exclusion curves for different experiments based on their distance and their precision; I conclude that an experiment which can detect oscillations down to 1% located at 1200 km will cleanly test the allowed region from Kamioka and IMB. I then describe the techniques which can perform such a measurement and outline both a detector capable of performing such an experiment and some of the systematic problems we might expect.

We review the current and future accelerator technologies for generation of high brightness radiation beam.

Relation merging is employed in relational databases in order to reduce the need for joining relations. Merging, however, can create unnormalized relations. In this paper we propose a merging technique that preserves the high (Boyce-Codd) normal form of relational schemas consisting of relation-schemes, key dependencies, referential integrity constraints, and null constraints. The additional constraints generated by this merging technique can be effectively maintained using the mechanisms provided by several relational database management systems.

In the study of geographic disease clusters, an alternative to traditional methods based on rates is to analyze case locations on a transformed map in which population density is everywhere equal. Although the analyst`s task is thereby simplified, the specification of the density equalizing map projection (DEMP) itself is not simple and continues to be the subject of considerable research. Here a new DEMP algorithm is described, which avoids some of the difficulties of earlier approaches. The new algorithm (a) avoids illegal overlapping of transformed polygons; (b) finds the unique solution that minimizes map distortion; (c) provides constant magnification over each map polygon; (d) defines a continuous transformation over the entire map domain; (e) defines an inverse transformation; (f) can accept optional constraints such as fixed boundaries; and (g) can use commercially supported minimization software. Work is continuing to improve computing efficiency and improve the algorithm.

Efficiencies of interstitial absorption during pulsed ND:YAG laser welding of vanadium were compared for nitrogen, oxygen, hydrogen, and water vapor. Influence of interstitial levels on the embrittlement of vanadium laser welds was also measured. For 1000 ppM contaminant levels in the weld atmosphere, weld hydrogen content increased 9 ppM, nitrogen content increased 190 ppM, and oxygen content increased from 500 ppM relative to baseplate levels. Welds in ultrahigh-purity argon atmospheres contained 3 ppM hydrogen, 40 ppM nitrogen, and 250 ppM oxygen. Longitudinal all-weld tensile specimens and notched-plate specimens were used to measure weld metal tensile properties at {minus}55C. All of the laser weld notch-strength ratios exceeded unity and weld metal tensile strengths all exceeded the baseplate values. For 1000 ppM atmosphere contaminant levels, the only significant decrease in ductility, as measured by reduction-in-area at fracture was for the weld atmosphere containing oxygen. Weld atmospheres containing 1% nitrogen also reduced the weld ductility, and resulted in the onset of cleavage fracture.

Experiments which are planned for the Superconducting Super Collider and the Relativistic Heavy Ion Collider will involve interactions in which detectors will need to identify and localize hundreds or even thousands of particle tracks simultaneously. Most types of conventional position sensitive, proportional detectors with projective geometry are not able to unravel the individual tracks in these environments. We have been investigating several forms of sub-divided cathode readout to address this problem. We report here on geometric charge division using chevron shaped cathode pads which lie in rows underneath each anode wire. Investigations have quantified the non-linear effects due to avalanche angular localization, and how these become negligible with proper design of the pad. Differential nm-linearity of {plus_minus}5%, and position resolution in the region of 50{mu}m rms, have been achieved.

Distributions of the A-center (oxygen-vacancy) in neutron silicon detectors have been studied using Deep Level Transient Spectroscopy. A-centers have been found to be nearly uniformly distributed in the silicon water depth for medium resistivity (0.1 {minus} 0.2 k{Omega}-cm) silicon detectors. A positive filling pulse was needed to detect the A-centers in high resistivity (>4 k{Omega}-cm) silicon detectors, and this effect was found to be dependent on the oxidation temperature. A discussion of this effect is presented. 16 refs.

The steady-state distribution of natural stratospheric ozone is primarily maintained through production by ultraviolet photolysis of molecular oxygen, destruction by a catalytic cycle involving nitrogen oxides (NO{sub x}), and relocation by air motions within the stratosphere. Nitrogen oxides from the exhausts of a commercially viable fleet of supersonic transports would exceed the natural source of stratospheric nitrogen oxides if the t should be equipped with 1990 technology jet engines. This model-free comparison between a vital natural global ingredient and a proposed new industrial product shows that building a large fleet of passenger stratospheric aircraft poses a significant global problem. NASA and aircraft industries have recognized this problem and are studying the redesign of jet aircraft engines in order to reduce the nitrogen oxides emissions. In 1989 atmospheric models identified two other paths by which the ozone destroying effects of stratospheric aircraft might be reduced or eliminated: (1) Use relatively low supersonic Mach numbers and flight altitudes. For a given rate of nitrogen oxides injection into the stratosphere, the calculated reduction of total ozone is a strong function of altitude, and flight altitudes well below 20 kilometers give relatively low calculated ozone reductions. (2) Include heterogeneous chemistry in the two-dimensional model …

We review the current and future accelerator technologies for generation of high brightness radiation beam.

Relation merging is employed in relational databases in order to reduce the need for joining relations. Merging, however, can create unnormalized relations. In this paper we propose a merging technique that preserves the high (Boyce-Codd) normal form of relational schemas consisting of relation-schemes, key dependencies, referential integrity constraints, and null constraints. The additional constraints generated by this merging technique can be effectively maintained using the mechanisms provided by several relational database management systems.

The steady-state distribution of natural stratospheric ozone is primarily maintained through production by ultraviolet photolysis of molecular oxygen, destruction by a catalytic cycle involving nitrogen oxides (NO{sub x}), and relocation by air motions within the stratosphere. Nitrogen oxides from the exhausts of a commercially viable fleet of supersonic transports would exceed the natural source of stratospheric nitrogen oxides if the t should be equipped with 1990 technology jet engines. This model-free comparison between a vital natural global ingredient and a proposed new industrial product shows that building a large fleet of passenger stratospheric aircraft poses a significant global problem. NASA and aircraft industries have recognized this problem and are studying the redesign of jet aircraft engines in order to reduce the nitrogen oxides emissions. In 1989 atmospheric models identified two other paths by which the ozone destroying effects of stratospheric aircraft might be reduced or eliminated: (1) Use relatively low supersonic Mach numbers and flight altitudes. For a given rate of nitrogen oxides injection into the stratosphere, the calculated reduction of total ozone is a strong function of altitude, and flight altitudes well below 20 kilometers give relatively low calculated ozone reductions. (2) Include heterogeneous chemistry in the two-dimensional model …