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Physics of Polarity at RHIC-Volume 10 (open access)

Physics of Polarity at RHIC-Volume 10

The RBRC Workshop on Physics of Polarimetry at RHIC was held from Aug 4 to 7, 1998 at BNL. The primary motive of the workshop is (1) to discuss the RHIC polarimeter using the elastic proton-carbon scattering at Coulomb-nuclear interference region (p-C CNI polarimeter) in detail and write a proposal for the test experiment a t the AGS, (2) to discuss the related physics, (3) and to discuss other options for the RHIC polarimetry. The idea of the p-C CNI polarimeter was proposed last year as a simple, inexpensive and efficient polarimeter for RHIC. In order to establish this polarimeter, we have decided to carry out a test experiment by using a polarized beam at the AGS. We have made a draft of the proposal during the workshop. For the p-C CNI polarimeter, a telescope detector using both the micro-channel plate (MCP) and the SSD was proposed to detect low energy recoil carbon ions, based on the test measurements at IUCF and Kyoto, where the carbon ions as low as 200 keV were successfully detected. The kinetic energy of carbon ion is measured with the SSD, and the velocity is measured by TOF between the two detectors and between the …
Date: August 4, 1998
Creator: Imai, K. & Fields, D.
System: The UNT Digital Library
Microstructural examination of irradiated V-(4-5%)Cr-(4-5%)Ti. (open access)

Microstructural examination of irradiated V-(4-5%)Cr-(4-5%)Ti.

Microstructural examination results are reported for two heats of V-(4-5%) Cr-(4-5%)Ti irradiated in the EBR-II X530 experiment to 4.5 dpa at {approximately}400 C to provide an understanding of the microstructural evolution that may be associated with degradation of mechanical properties. Fine precipitates were observed in high density intermixed with small defect clusters for all conditions examined following the irradiation. The irradiation-induced precipitation does not appear to be affected by preirradiation heat treatment at 950-1125 C. There was no evidence for a significant density of large (diameter >10 nm) dislocation loops or network dislocations. Analytical investigations successfully demonstrated that the precipitates were enriched in titanium, depleted in vanadium and contained no nitrogen. These results are discussed in terms of future alloy development options.
Date: May 4, 1998
Creator: Gelles, D. S.
System: The UNT Digital Library
Solving QCD via multi-Regge theory. (open access)

Solving QCD via multi-Regge theory.

A high-energy, transverse momentum cut-off, solution of QCD is outlined. Regge pole and single gluon properties of the pomeron are directly related to the confinement and chiral symmetry breaking properties of the hadron spectrum. This solution, which corresponds to a supercritical phase of Reggeon Field Theory, may only be applicable to QCD with a very special quark content.
Date: November 4, 1998
Creator: White, A. R.
System: The UNT Digital Library
Inductively Coupled Plasma Etching of III-V Antimonides in BCl(3)/Ar and Cl(2)/Ar (open access)

Inductively Coupled Plasma Etching of III-V Antimonides in BCl(3)/Ar and Cl(2)/Ar

Inductively coupled plasma (ICP) etching characteristics of GaSb and AIGaAsSb have been investigated in BC13/Ar and Clz/Ar plasmas. The etch rates and selectivity between GaSb and AIGaAsSb are reported as functions of plasma chemistry, ICP power, RF self-bias, and chamber pressure. It is found that physical sputtering resorption of the etch products plays a dominant role in BC13/Ar ICP etching, while in Clz/Ar plasma, the chemical reaction dominates the etching. GaSb etch rates exceeding 2 ~rnhnin are achieved in Clz/Ar plasmas with smooth surfaces and anisotropic profiles. In BC13/Ar plasmas, etch rates of 5100 Mmin and 4200 Mmin are obtained for GaSb and AIGaAsSb, respectively. The surfaces of both GaSb and AIGaAsSb etched in BC13/Ar plasmas remain smooth and stoichiometric over the entire range of plasma conditions investigated. This result is attributed to effective removal of etch products by physical sputtering. For a wide range of plasma conditions, the selectivity between GaSb and AIGaAsSb is close to unity, which is desirable for fabricating etched mirrors and gratings for Sb-based mid-IR laser diodes.
Date: November 4, 1998
Creator: Leavitt, R.P.; Lester, L.F.; Shul, R.J.; Willison, C.G. & Zhang, L.
System: The UNT Digital Library
The Production and Acceleration of Radioactive Ion Beams at the HRIBF (open access)

The Production and Acceleration of Radioactive Ion Beams at the HRIBF

The Holifield Radioactive Ion Beam Facility (HRIBF) includes a cyclotron (ORIC) which provides high-intensity light-ions for producing radioactive atoms, and a 25 MV tandem electrostatic accelerator which is used to accelerate the radioactive-ions for nuclear structure and nuclear astrophysics research. Ion sources and targets suitable for the production of various radioactive ion beams (RIBs) have been developed. Operational experiences, problem areas, and plans for future beam development are discussed.
Date: November 4, 1998
Creator: Auble, R. L.
System: The UNT Digital Library
Advances in fabrication of Ag-clad Bi-2223 superconductors. (open access)

Advances in fabrication of Ag-clad Bi-2223 superconductors.

Powder-in-tube (PIT) processing was used to fabricate multifilamentary Ag-clad Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) superconductors for various electric power applications. Enhancements in the transport current properties of long lengths of multifilament tapes were achieved by increasing the packing density of the precursor powder, improving the mechanical deformation, and adjusting the cooling rate. The dependence of the critical current density on magnetic field and temperature for the optimally processed tapes was measured. J{sub c} was greater than 10{sup 4} (A/cm{sup 2}) at 20 K for magnetic field up to 3 T and parallel to the c-axis which is of interest for use in refrigerator coded magnets. An attempt was made to combine the good alignment of Bi-2223 grains in Ag-sheathed superconducting tapes to obtain high J{sub c} values at high temperature and low field, and good intrinsic pinning of YBa{sub 2}Cu{sub 3}O{sub 7{minus}d} (Y-123) thin film to maintain high J{sub c} values in high fields. A new composite multifilament tape was fabricated such that the central part contained Bi-2223 filaments, with the primary function of conducting the transport current. The central Bi-2223 filaments were surrounded by Y-123 thin film to shield the applied magnetic field and protect the Bi-2223 …
Date: September 4, 1998
Creator: Balachandran, U.
System: The UNT Digital Library
Lithium-endohedral C{sub 60} complexes. (open access)

Lithium-endohedral C{sub 60} complexes.

High capacity, reversible, lithium intercalated carbon anodes have been prepared, 855 m.Ah/g, which exceed the capacity for stage 1 lithium intercalated carbon anodes, 372 mAh/g. Since there is very little hydrogen content in the high capacity anode, the fullerene C{sub 60} lattice is used to investigate the nature of lithium ion bonding and spacing between lithiums in endohedral lithium complexes of C{sub 60}. Three lithium-endohedral complexes have been investigated using ab initio molecular orbital calculations involving 2,3 and 5 lithium. The calculated results suggest that lithium cluster formation may be important for achieving the high capacity lithium carbon anodes.
Date: May 4, 1998
Creator: Scanlon, L. G.
System: The UNT Digital Library
Statistical Tests of System Linearity Based on the Method of Surrogate Data (open access)

Statistical Tests of System Linearity Based on the Method of Surrogate Data

When dealing with measured data from dynamic systems we often make the tacit assumption that the data are generated by linear dynamics. While some systematic tests for linearity and determinism are available - for example the coherence fimction, the probability density fimction, and the bispectrum - fi,u-ther tests that quanti$ the existence and the degree of nonlinearity are clearly needed. In this paper we demonstrate a statistical test for the nonlinearity exhibited by a dynamic system excited by Gaussian random noise. We perform the usual division of the input and response time series data into blocks as required by the Welch method of spectrum estimation and search for significant relationships between a given input fkequency and response at harmonics of the selected input frequency. We argue that systematic tests based on the recently developed statistical method of surrogate data readily detect significant nonlinear relationships. The paper elucidates the method of surrogate data. Typical results are illustrated for a linear single degree-of-freedom system and for a system with polynomial stiffness nonlinearity.
Date: November 4, 1998
Creator: Hunter, N.; Paez, T. & Red-Horse, J.
System: The UNT Digital Library
EPR detection of light-generated nuclear coherences in photosynthetic reaction centers. (open access)

EPR detection of light-generated nuclear coherences in photosynthetic reaction centers.

In this study we first discuss a pulsed EPR experiment designed to establish the mechanism of coherence generation [1]. The pulse sequence employed, flash-t-({pi}/2){sub x}-{tau}, consists of a short laser pulse at time zero, followed by a variable period t. At the end of this period a non-ideal ({pi}/2) microwave pulse is applied. The resulting free-induction decay at fixed detection time {tau} is then monitored as a function of successively incremented values of t. For P{sub 700}{sup +} A{sub 1}{sup {minus}} in deuterated and {sup 15}N-substituted PSI preparations, the transverse magnetization shows an oscillatory dependence on the delay between the laser and the microwave pulse [1]. Apparently, there are fast initial oscillations which disappear 250 ns after the laser pulse. In addition, slow persisting oscillations with frequencies of a few MHz can be observed. Basically, these slow oscillations represent nuclear coherences initiated by the laser pulse [1].
Date: May 4, 1998
Creator: Bechtold, M.
System: The UNT Digital Library
Chemically Selective Coated Quartz Crystal Microbalance (QCM) Array for Detection of Volatile Organic Chemicals (open access)

Chemically Selective Coated Quartz Crystal Microbalance (QCM) Array for Detection of Volatile Organic Chemicals

Liquid flow cells have been fabricated to prepare an array of QCMS operating simultaneously for detection and identification of VOCS in water. TWO signals, a tlequency response and a damping voltage response, were obtained per resonator. A blank QCM was used as a reference to account for changes in liquid density and viscosity. Nine different polymer coatings applied using a spin coat technique have been examined for VOC response under liquid flow conditions. A matrix of three classes of VOCS were examined for each coating with four chemicals in each class. The three classes of VOCS are polar, nonpolar and chlorinated. A pattern recognition technique, called visually empirical region of influence (VERI), was used to cluster the responses in n-dimensional space. Chemicals within a class varying by only one methyl group (e.g., toluene and xylene) are easily discriminated using only two different coatings with three different QCM responses. All chemicak were easily separated and detected with a total of 5 films and 6 responses with >99% accuracy.
Date: November 4, 1998
Creator: Bohuszewicz, T. V.; Frye-Mason, G. C.; Martin, S. J.; Osbourn, G. C.; Schneider, T. W. & Spates, J. J.
System: The UNT Digital Library
Characterization of spent EBR-II driver fuel. (open access)

Characterization of spent EBR-II driver fuel.

Operations and material control and accountancy requirements for the Fuel Conditioning Facility demand accurate prediction of the mass flow of spent EBR-II driver fuel into the facility. This requires validated calculational tools that can predict the burnup and isotopic distribution in irradiated Zr-alloy fueled driver assemblies. Detailed core-follow depletion calculations have been performed for an extensive series of EBR-II runs to produce a database of material inventories for the spent fuel to be processed. As this fuel is processed, comparison of calculated values with measured data obtained from samples of this fuel is producing a growing set of validation data. A more extensive set of samples and measurements from the initial processing of irradiated driver fuel has produced valuable estimates of the biases and uncertainties in both the measured and calculated values. Results of these comparisons are presented herein and indicate the calculated values adequately predict the mass flows.
Date: May 4, 1998
Creator: McKnight, R. D.
System: The UNT Digital Library
A Methodology to Validate 3-D Arbitrary Lagrangian Eulerian Codes with Applications to Alegra (open access)

A Methodology to Validate 3-D Arbitrary Lagrangian Eulerian Codes with Applications to Alegra

In this study we provided an experimental test bed for validating features of the Arbitrary Lagrangian Eulerian Grid for Research Applications (ALEGRA) code over a broad range of strain rates with overlapping diagnostics that encompass the multiple responses. A unique feature of the ALEGRA code is that it allows simultaneous computational treatment, within one code, of a wide range of strain-rates varying from hydrodynamic to structural conditions. This range encompasses strain rates characteristic of shock-wave propagation (107/s) and those characteristics of structural response (102/s). Most previous code validation experimental &udies, however, have been restricted to simulating or investigating a single strain-rate regime. What is new and different in this investigation is that we have performed well-controlled and well-instrumented experiments, which capture features relevant to both hydrodynamic and structural response in a single experiment. Aluminum was chosen for use in this study because it is a well-characterized material. The current experiments span strain rate regimes of over 107/s to less than 102/s in a single experiment. The input conditions were extremely well defined. Velocity interferometers were used to record the high' strain-rate response, while low strain rate data were collected using strain gauges. Although the current tests were conducted at a …
Date: November 4, 1998
Creator: Chhabildas, L. C.; Duggins, B. D.; Konrad, C. H.; Mosher, D. A.; Perry, J. S.; Reinhart, W. D. et al.
System: The UNT Digital Library
Analysis of Decentralized Variable Structure Control for Collective Search by Mobile Robots (open access)

Analysis of Decentralized Variable Structure Control for Collective Search by Mobile Robots

This paper presents an analysis of a decentralized coordination strategy for organizing and controlling a team of mobile robots performing collective search. The alpha-beta coordination strategy is a family of collective search algorithms that allow teams of communicating robots to implicitly coordinate their search activities through a division of labor based on self-selected roIes. In an alpha-beta team. alpha agents are motivated to improve their status by exploring new regions of the search space. Beta a~ents are conservative, and reiy on the alpha agents to provide advanced information on favorable regions of the search space. An agent selects its current role dynamically based on its current status value relative to the current status values of the other team members. Status is determined by some function of the agent's sensor readings, and is generally a measurement of source intensity at the agent's current location. Variations on the decision rules determining alpha and beta behavior produce different versions of the algorithm that lead to different global properties. The alpha-beta strategy is based on a simple finite-state machine that implements a form of Variable Structure Control (VSC). The VSC system changes the dynamics of the collective system by abruptly switching at defined states …
Date: November 4, 1998
Creator: Feddema, J.; Goldsmith, S. & Robinett, R.
System: The UNT Digital Library
Solving QCD via multi-Regge theory. (open access)

Solving QCD via multi-Regge theory.

To solve QCD at high-energy the authors must simultaneously find the hadronic states and the exchanged pomeron (IP) giving UNITARY scattering amplitudes. Experimentally, the IP {approximately} a Regge pole at small Q{sup 2} and a single gluon at larger Q{sup 2}. (F{sub 2}{sup D}-H1, dijets-ZEUS). In the solution which the author describes, these non-perturbative properties of the IP are directly related to the non-perturbative confinement and chiral symmetry breaking properties of hadrons.
Date: November 4, 1998
Creator: White, A. R.
System: The UNT Digital Library
Microscale chemistry technology exchange at Argonne National Laboratory - east. (open access)

Microscale chemistry technology exchange at Argonne National Laboratory - east.

The Division of Educational Programs (DEP) at Argonne National Laboratory-East interacts with the education community at all levels to improve science and mathematics education and to provide resources to instructors of science and mathematics. DEP conducts a wide range of educational programs and has established an enormous audience of teachers, both in the Chicago area and nationally. DEP has brought microscale chemistry to the attention of this huge audience. This effort has been supported by the U.S. Department of Energy through the Environmental Management Operations organization within Argonne. Microscale chemistry is a teaching methodology wherein laboratory chemistry training is provided to students while utilizing very small amounts of reagents and correspondingly small apparatus. The techniques enable a school to reduce significantly the cost of reagents, the cost of waste disposal and the dangers associated with the manipulation of chemicals. The cost reductions are achieved while still providing the students with the hands-on laboratory experience that is vital to students who might choose to pursue careers in the sciences. Many universities and colleges have already begun to switch from macroscale to microscale chemistry in their educational laboratories. The introduction of these techniques at the secondary education level will lead to freshman …
Date: June 4, 1998
Creator: Pausma, R.
System: The UNT Digital Library
Resonance Control Cooling System for the APT/LEDA RFQ (open access)

Resonance Control Cooling System for the APT/LEDA RFQ

The Radio Frequency Quadrupole (RFQ) resonance control cooling system (RCCS) for the Low Energy Demonstration Accelerator (LEDA) in support of the Accelerator Production of Tritium (APT) is described. Constant flow regulating valves to distribute the required flow to the 424 channels and to permit use of centrifugal pumps is discussed. Control system schema are described to regulate resonance frequency during steady state operation.
Date: November 4, 1998
Creator: Domer, G. A. & Floersch, R. H.
System: The UNT Digital Library
Nucleation of nanocrystalline diamond by fragmentation of fullerene precursors. (open access)

Nucleation of nanocrystalline diamond by fragmentation of fullerene precursors.

Growth of diamond films from C{sub 60}/Ar microwave discharges results in a nanocrystalline microstructure with crystallite sizes in the range 3-10 nm. Heterogeneous nucleation rates of 10{sup 10} cm{sup {minus}2} sec are required to account for the results. The nucleation mechanism presented here fulfills this requirement and is based on the insertion of carbon dimer, C{sub 2}, molecules, produced by fragmentation of C{sub 60}, into the n-bonded dimer rows of the reconstructed (100) surface of diamond. Density functional theory is used to calculate the energetic of C{sub 2} insertion into carbon clusters that model the (100) surface. The reaction of singlet C{sub 2} with the double bond of the C{sub 9}H{sub 12} cluster leads to either carbene structures or a cyclobutynelike structure. At the HF/6-31G* level, the carbene product has a C{sub 2v} structure, while at the B3LYP/6-31G* levels of theory, it has a C{sub s} structure with the inserted C{sub 2} tilted. No barrier for insertion into the C=C double bond of the C{sub 9}H{sub 12} cluster was found at the HF/6-31G* and B3LYP/6-31G* levels of theory. Thus, calculations including correlation energy and geometry optimization indicate that insertion of C{sub 2} into a C=C double bond leads to a …
Date: May 4, 1998
Creator: Gruen, D. M.
System: The UNT Digital Library
Modeling Nonlinear Optical Properties of Transition Metal Complexes. Basis Set, Effective Core Potential, and Geometry Effects (open access)

Modeling Nonlinear Optical Properties of Transition Metal Complexes. Basis Set, Effective Core Potential, and Geometry Effects

Article discussing modeling nonlinear optical properties of transition metal complexes and the basis set, effective core potential, and geometry effects.
Date: April 4, 1998
Creator: Cundari, Thomas R., 1964-; Kurtz, Henry A. & Zhou, Tie
System: The UNT Digital Library
Kinetic studies of the reaction of atomic hydrogen with trifluoroiodomethane (open access)

Kinetic studies of the reaction of atomic hydrogen with trifluoroiodomethane

This article discusses kinetic studies of the reaction of atomic hydrogen with trifluoroiodomethane.
Date: December 4, 1998
Creator: Yuan, Jessie; Wells, Leah & Marshall, Paul
System: The UNT Digital Library
Neutron Tube Design Study for Boron Neutron Capture TherapyApplication (open access)

Neutron Tube Design Study for Boron Neutron Capture TherapyApplication

Radio-frequency (RF) driven ion sources are being developed in Lawrence Berkeley National Laboratory (LBNL) for sealed-accelerator-tube neutron generator application. By using a 5-cm-diameter RF-driven multicusp source H{sup +} yields over 95% have been achieved. These experimental findings will enable one to develop compact neutron generators based on the D-D or D-T fusion reactions. In this new neutron generator, the ion source, the accelerator and the target are all housed in a sealed metal container without external pumping. Recent moderator design simulation studies have shown that 14 MeV neutrons could be moderated to therapeutically useful energy ranges for boron neutron capture therapy (BNCT). The dose near the center of the brain with optimized moderators is about 65% higher than the dose obtained from a typical neutron spectrum produced by the Brookhaven Medical Research Reactor (BMRR), and is comparable to the dose obtained by other accelerator-based neutron sources. With a 120 keV and 1 A deuteron beam, a treatment time of {approx}35 minutes is estimated for BNCT.
Date: January 4, 1998
Creator: Verbeke, J. M.; Lee, Y.; Leung, K. N.; Vujic, J.; Williams, M. D.; Wu, L. K. et al.
System: The UNT Digital Library
A Three Dimensional Beam Profile Monitor Based on Residual Gas Ionization (open access)

A Three Dimensional Beam Profile Monitor Based on Residual Gas Ionization

A three-dimensional beam profile monitor based on tracking the ionization of the residual gas molecules in the evacuated beam pipe is described. Tracking in position and time of the ions and electrons produced in the ionization enables simultaneous position sampling in three dimensions. Special features which make it possible to sample very low beam currents were employed.
Date: November 4, 1998
Creator: Lewis, T. A. & Shapira, D.
System: The UNT Digital Library
Low Intensity Beam Imaging - Position Sensitive Avalanche Counter (open access)

Low Intensity Beam Imaging - Position Sensitive Avalanche Counter

Monitors of this type are mostly intended for the lowest intensity beams at the HRIBF at ORNL. They are used to aid the accelerator operator in focusing and steering the beam and by the experimenters at the focal plane of the spectrometers.
Date: November 4, 1998
Creator: Mas, J.; Shapira, Dan & Lewis, T. A.
System: The UNT Digital Library
Query estimation and order-optimized iteration in very large federations (open access)

Query estimation and order-optimized iteration in very large federations

Objectivity federated databases may contain many terabytes of data and span thousands of files. In such an environment, it is often easy for a user to pose a query that may return an iterator over millions of objects, requiring opening thousands of databases. This presentation describes several technologies developed for such settings: (1) a query estimator, which tells the user how many objects satisfy the query, and how many databases will be touched, prior to opening all of those files; (2) an order-optimized iterator, which behaves like an ordinary iterator except that elements are returned in an order optimized for efficient access, presorted by the database (and container) in which they reside; (3) a parallel implementation of the order-optimized iterator, allowing any number of processes in a parallel or distributed system to iterate over disjoint subcollections of terms satisfying the query, partitioned by the database or container in which the items reside. These technologies have been developed for scientific experiments that will require handling thousands of terabytes of data annually, but they are intended to be applicable in other massive data settings as well. In such environments, significant amounts of data will reside on tertiary storage, accessible via Objectivity`s recently-announced …
Date: May 4, 1998
Creator: Malon, David M.
System: The UNT Digital Library
Electrochemical cell for in-situ x-ray characterization (open access)

Electrochemical cell for in-situ x-ray characterization

An electrochemical cell suitable for in-situ XRD analysis is presented. Qualitative information such as phase formation and phase stability can be easily monitored using the in-situ cell design. Quantitative information such as lattice parameters and kinetic behavior is also straightforward. Analysis of the LiMn&sub2;O&sub4; spinel using this cell design shows that the lattice undergoes two major structural shrinkages at approx. 4.0 V and approx. 4.07 V during charging. These shrinkages correlate well with the two electrochemical waves observed and indicate the likelihood of two separate redox processes which charging and discharging.
Date: August 4, 1998
Creator: Doughty, Daniel H.; Ingersoll, David & Rodriguez, Mark A.
System: The UNT Digital Library