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NATIONAL SYNCHROTRON LIGHT SOURCE ACTIVITY REPORT 1998.
In FY 1998, following the 50th Anniversary Year of Brookhaven National Laboratory, Brookhaven Science Associates became the new Managers of BNL. The new start is an appropriate time to take stock of past achievements and to renew or confirm future goals. During the 1998 NSLS Annual Users Meeting (described in Part 3 of this Activity Report), the DOE Laboratory Operations Board, Chaired by the Under Secretary for Energy, Ernest Moniz met at BNL. By chance all the NSLS Chairmen except Martin Blume (acting NSLS Chair 84-85) were present as recorded in the picture. Under their leadership the NSLS has improved dramatically: (1) The VUV Ring current has increased from 100 mA in October 1982 to nearly 1 A today. For the following few years 10 Ahrs of current were delivered most weeks - NSLS now exceeds that every day. (2) When the first experiments were performed on the X-ray ring during FY1985 the electron energy was 2 GeV and the current up to 100 mA - the X-Ray Ring now runs routinely at 2.5 GeV and at 2.8 GeV with up to 350 mA of current, with a very much longer beam half-life and improved reliability. (3) Starting in FY 1984 the proposal for the Phase II upgrade, mainly for a building extension and a suite of insertion devices and their associated beamlines, was pursued - the promises were delivered in full so that for some years now the NSLS has been running with two undulators in the VUV Ring and three wigglers and an undulator in the X-Ray Ring. In addition two novel insertion devices have been commissioned in the X13 straight. (4) At the start of FY 1998 the NSLS welcomed its 7000th user - attracted by the opportunity for pursuing research with high quality beams, guaranteed not to be interrupted by 'delivery failures', and welcomed by an efficient and caring user office and first class teams of PRT and NSLS staff. R & D have lead to the possibility of running the X-Ray Ring at the higher energy of 2.8 GeV. Figure 1 shows the first user beam, which was provided thereafter for half of the running time in FY 1998. In combination with the development of narrow gap undulators this mode opens the possibility of new undulators which could produce hard X-rays in the fundamental, perhaps up to 10 keV. On 27 September 1998, a low horizontal emittance lattice became operational at 2.584 GeV. This results in approximately a 50% decrease in the horizontal beam-size on dipole bending magnet beamlines, and somewhat less of a decrease on the insertion device lines. The beam lifetime is not degraded by the low emittance lattice. This represents an important achievement, enhancing for all users the x-ray ring brightness. The reduced horizontal emittance electron beam will produce brighter x-ray beams for all the beamlines, both bending magnets and insertion devices, adding to other recent increases in the X-Ray ring brightness. During FY 1999 users will gain experience of the new running mode and plans are in place to do the same at 2.8GeV during further studies sessions. Independent evidence of the reduced emittance is shown in Figure 2. This is a pinhole camera scan showing the X-ray beam profile, obtained on the diagnostic beamline X28. Finally, work has begun to update and refine the proposal of the Phase III upgrade endorsed by the Birgeneau panel and BESAC last year. With the whole NSLS facility in teenage years and with many demonstrated enhancements available, the time has come to herald in the next stage of life at the Light Source. digital.library.unt.edu/ark:/67531/metadc925998/
Radionuclide Coefficients for the BNL Site: For the Saturated and Unsaturated Zones
The partition coefficient (K{sub d}) is defined as the concentration of a species of interest on the solid phase divided by the concentration of that species in the liquid phase, at steady-state. Therefore the lower the K{sub d}, the less sorption takes place. It is a parameter that is readily incorporated in chemical transport models. The K{sub d} approach to the partitioning of contaminants between soil and water in groundwater flow systems, is based on the assumption that sorption reactions are in equilibrium and are reversible. As a contaminant plume advances along flow paths, the movement of the front is retarded (relative to the movement of the groundwater) as a result of transfer of part of the contamination mass to the solid phase. If the input of contaminant mass to the system is discontinued, contaminants will be transferred back to the liquid phase as lower-concentration water flushes through the previously contaminated zone. Several sets of soil/water partition coefficients (K{sub d}) have been measured using BNL site specific soils and groundwater (with tracers added). They were all reported earlier through internal memos or reports. The K{sub d}s obtained for various radionuclides are determined experimentally with soils taken from different locations and depths around site. In each experiment the site specific soil and water taken from that same geoprobe boring were used. Generally tracer radionuclides were used. However, for samples from the BGRR area, water taken from the sump was used for Cs-137 and Sr-90 Kd experiments. Values of K{sub d} in the saturated zone are summarized in Table 1, as ranges and an average. Soil sample identifications, locations, and descriptions are provided in Table 2 and Figure 1. Other experiments, specific to the unsaturated zone at the BGRR, are discussed below. In addition, each data source, including methods, is reproduced in Appendix A, including figures documenting isotherm experiments for the various soil samples used. The values of n above are the number of different locations or depths from which soil was sampled for K{sub d} evaluations. Each K{sub d} value (and n) may be the result of three to five individual experiments which are used to construct an isotherm. Average values reported above include skewed to high values. This is the result of preferential uptake of some elements on the fine-grained detritus, weathering products and Fe oxides found at the surface. The one set of measurements of K{sub d} of surface soil was made with soil from the 650 sump outfall. Best estimates for samples at the surface and at depth (in the saturated zone of the subsurface) are also given above. Please bear in mind that these values represent an average of samples from selected locations. Overall, for samples at depth, I believe they approach reasonable sitewide averages. However, the surface soil values should only be applied to the 650 sump outfall. Locally, values may vary depending on mineralogy and grain size of the soil, as well as composition of the water flowing through it. digital.library.unt.edu/ark:/67531/metadc929027/
A Pulsed Modulator Power Supply for the g-2 Muon Storage Ring Injection Kicker
This paper describes the pulse modulator power supplies used to drive the kicker magnets that inject the muon beam into the g-2 storage ring that has been built at Brookhaven. Three modulators built into coaxial structures consisting of a series circuit of an energy storage capacitor, damping resistor and a fast thyratron switch are used to energize three magnets that kick the beam into the proper orbit. A 100 kV charging power supply is used to charge the capacitor to 95 kV. the damping resistor shapes the magnet current waveform to a 450 nanosecond half-sine to match the injection requirements. this paper discusses the modulator design, construction and operation. digital.library.unt.edu/ark:/67531/metadc929328/
GENERIC, COMPONENT FAILURE DATA BASE FOR LIGHT WATER AND LIQUID SODIUM REACTOR PRAs
A comprehensive generic component failure data base has been developed for light water and liquid sodium reactor probabilistic risk assessments (PRAs) . The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) and the Centralized Reliability Data Organization (CREDO) data bases were used to generate component failure rates . Using this approach, most of the failure rates are based on actual plant data rather than existing estimates . digital.library.unt.edu/ark:/67531/metadc931741/
NATIONAL SYNCHROTRON LIGHT SOURCE ACTIVITY REPORT FOR THE PERIOD OCTOBER 1, 1996 THROUGH SEPTEMBER 30, 1997.
Phase IV Simulant Testing of Monosodium Titanate Adsorption Kinetics
The Salt Disposition Systems Engineering Team identified the adsorption kinetics of actinides and strontium onto monosodium titanate (MST) as a technical risk in several of the processing alternatives selected for additional evaluation in Phase III of their effort. digital.library.unt.edu/ark:/67531/metadc934991/
I: Low Frequency NMR and NQR Using a dc SQUID. II: Variable-temperature 13C CP/MAS of Organometallics
NMR and NQR at low frequencies are difficult prospects due to small nuclear spin polarization. Furthermore, the sensitivity'of the inductive pickup circuitry of standard spectrometers is reduced as the frequency is lowered. I have used a cw-SQUID (Superconducting QUantum Interference Device) spectrometer, which has no such frequency dependence, to study the local atomic environment of {sup 14}N via the quadrupolar interaction. Because {sup 14}N has spin I = 1 and a 0-6 MHz frequency range, it is not possible to obtain well-resolved spectra in high magnetic fields. I have used a technique to observe {sup 14}N NQR resonances via their effect on neighboring protons mediated by the heteronuclear dipolar interaction to study peptides and narcotics. The sensitivity of the SQUID is not enough to measure low-frequency surface (or other low spin density) systems. The application of spin-polarized xenon has been previously used to enhance polarization in conventional NMR experiments. Because xenon only polarizes spins with which it is in contact, it is surface selective. While differences in chemical shifts between surface and bulk spins are not large, it is expected that the differences in quadrupole coupling constant should be very large due to the drastic change of the electric field gradient surrounding spins at the surface. With this in mind, I have taken preliminary steps to measure SQUID detected polarization transfer from Xe to another spin species at 4.2 K and in small magnetic fields (&lt;50 G). In this regime, the spin-lattice relaxation of xenon is dependent on the applied magnetic field. The results of our efforts to characterize the relaxation of xenon are presented. The final section describes the solid-state variable-temperature (VT) one- and two-dimensional {sup 13}C cross polarization (CP)/magic angle spinning (MAS) NMR of Hf({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}({eta}{sup 1}-C{sub 5}H{sub 5}){sub 2}, Zr({eta}{sup 5}-C{sub 5}H{sub 5}){sub 3}({eta}{sup 1}-C{sub 5}H{sub 5}) and Sn({eta}{sup 1}-C{sub 5}H{sub 5}){sub 4}. This work was undertaken in the hope of gaining insight into the intramolecuhrr dynamics, specifically which fluxional processes exist in the solid state, by what mechanism rearrangements are occurring, and the activation energies by which these processes are governed. digital.library.unt.edu/ark:/67531/metadc934608/
Unified Einstein-Virasoro Master Equation in the General Non-Linear Sigma Model
The Virasoro master equation (VME) describes the general affine-Virasoro construction $T=L^abJ_aJ_b+iD^a \dif J_a$ in the operator algebra of the WZW model, where $L^ab$ is the inverse inertia tensor and $D^a$ is the improvement vector. In this paper, we generalize this construction to find the general (one-loop) Virasoro construction in the operator algebra of the general non-linear sigma model. The result is a unified Einstein-Virasoro master equation which couples the spacetime spin-two field $L^ab$ to the background fields of the sigma model. For a particular solution $L_G^ab$, the unified system reduces to the canonical stress tensors and conventional Einstein equations of the sigma model, and the system reduces to the general affine-Virasoro construction and the VME when the sigma model is taken to be the WZW action. More generally, the unified system describes a space of conformal field theories which is presumably much larger than the sum of the general affine-Virasoro construction and the sigma model with its canonical stress tensors. We also discuss a number of algebraic and geometrical properties of the system, including its relation to an unsolved problem in the theory of $G$-structures on manifolds with torsion. digital.library.unt.edu/ark:/67531/metadc930700/
Twining characters and orbit Lie algebras
We associate to outer automorphisms of generalized Kac-Moody algebras generalized character-valued indices, the twining characters. A character formula for twining characters is derived which shows that they coincide with the ordinary characters of some other generalized Kac-Moody algebra, the so-called orbit Lie algebra. Some applications to problems in conformal field theory, algebraic geometry and the theory of sporadic simple groups are sketched. digital.library.unt.edu/ark:/67531/metadc932245/
Wakimoto realizations of current algebras: an explicit construction
A generalized Wakimoto realization of $\widehat\cal G_K$ can be associated with each parabolic subalgebra $\cal P=(\cal G_0 +\cal G_+)$ of a simple Lie algebra $\cal G$ according to an earlier proposal by Feigin and Frenkel. In this paper the proposal is made explicit by developing the construction of Wakimoto realizations from a simple but unconventional viewpoint. An explicit formula is derived for the Wakimoto current first at the Poisson bracket level by Hamiltonian symmetry reduction of the WZNW model. The quantization is then performed by normal ordering the classical formula and determining the required quantum correction for it to generate $\widehat\cal G_K$ by means of commutators. The affine-Sugawara stress-energy tensor is verified to have the expected quadratic form in the constituents, which are symplectic bosons belonging to $\cal G_+$ and a current belonging to $\cal G_0$. The quantization requires a choice of special polynomial coordinates on the big cell of the flag manifold $P\backslash G$. The effect of this choice is investigated in detail by constructing quantum coordinate transformations. Finally, the explicit form of the screening charges for each generalized Wakimoto realization is determined, and some applications are briefly discussed. digital.library.unt.edu/ark:/67531/metadc930038/
Monopole Condensation and Confining Phase of N=1 Gauge Theories Via M Theory Fivebrane
The fivebrane of M theory is used in order to study the moduli space of vacua of confining phase N=1 supersymmetric gauge theories in four dimensions. The supersymmetric vacua correspond to the condensation of massless monopoles and confinement of photons. The monopole and meson vacuum expectation values are computed using the fivebrane configuration. The comparison of the fivebrane computation and the field theory analysis shows that at vacua with a classically enhanced gauge group SU(r) the effective superpotential obtained by the&quot;integrating in&quot; method is exact for r=2 but is not exact for r&gt; 2. The fivebrane configuration corresponding to N=1 gauge theories with Landau-Ginzburg type superpotentials is studied. N=1 non-trivial fixed points are analyzed using the brane geometry. digital.library.unt.edu/ark:/67531/metadc932349/
Target space supersymmetric sigma model techniques
We briefly review the covariant formulation of the Green-Schwarz superstring by Berkovits, and describe how a detailed tree-level and one-loop analysis of this model leads, for the first time, to a derivation of the low-energy effective action of the heterotic superstring while keeping target-space supersymmetry manifest. The resulting low-energy theory is old-minimal supergravity coupled to tensor multiplet. The dilaton is part of the compensator multiplet. digital.library.unt.edu/ark:/67531/metadc928320/
Squarks in Tevatron dilepton events?
We consider unusual events in the CDF and D0 dilepton+jets sample with very high ET(lepton) and ET(missing). It is possible, but very unlikely, that these events originate from top quark pair production; however, they have characteristics that are better accounted for by decays of supersymmetric quarks with mass in the region of 300 GeV. digital.library.unt.edu/ark:/67531/metadc928380/
Nucleon decay in GUT and nonGUT SUSY models
I first emphasize the importance of searching for nucleon decay in the context of supersymmetric models. The status of minimal SUSY SU(5) model is reviewed, which can be definitively ruled out by a combination of superKamiokande andLEP-2 experiments. Non-minimal models may provide some suppression in the nucleon decay rates, but there is still a good chance for superKamiokande. I point out that the operators suppressed even by the Planck-scale are too large. We need a suppression mechanism for the operators at the level of 10-7, and the mechanism, I argue, may well be a flavor symmetry. A particular example predicts p --&gt; K0e+ to be the dominant mode which does not arise in GUT models. digital.library.unt.edu/ark:/67531/metadc934617/
F-Theory, T-Duality on K3 Surfaces and N = 2 Supersymmetric Gauge Theories in Four Dimensions
We construct T-duality on K3 surfaces. The T-duality exchanges a 4-brane R-R charge and a O-brane R-R charge. We study the action of the T-duality on the moduli space of O-branes located at points of K3 and 4-branes wrapping it. We apply the construction to F-theory compactified on a Calabi-Yau 4-fold and study the duality of N = 2 SU(N{sub c}) gauge theories in four dimensions. We discuss the generalization to the N = 1 duality scenario. digital.library.unt.edu/ark:/67531/metadc930126/
Current Experiments in Particle Physics (September 1996)
This report contains summaries of current and recent experiments in Particle Physics. Included are experiments at BEPC (Beijing), BNL, CEBAF, CERN, CESR, DESY, FNAL, Frascati, ITEP (Moscow), JINR (Dubna), KEK, LAMPF, Novosibirsk, PNPI (St. Petersburg), PSI, Saclay, Serpukhov, SLAC, and TRIUMF, and also several proton decay and solar neutrino experiments. Excluded are experiments that finished taking data before 1991. Instructions are given for the World Wide Web (WWW) searching of the computer database (maintained under the SLAC-SPIRES system) that contains the summaries. This report contains full summaries of 180 approved current and recent experiments in elementary particle physics. The focus of the report is on selected experiments which directly contribute to our better understanding of elementary particles and their properties such as masses, widths or lifetimes, and branching fractions. digital.library.unt.edu/ark:/67531/metadc930566/
Will at least one of the Higgs bosons of the next-to-minimal supersymmetric extension of the standard model be observable at LEP2 or the LHC?
We demonstrate that there are regions of parameter space in the next-to-minimal (i.e. two-Higgs-doublet, one-Higgs-singlet superfield) supersymmetric extension of the SM for which none of the Higgs bosons are observable either at LEP2 with $\sqrt{s}=192 GeV$ and an integrated luminosity of $L=1000inverse pb$ or at the LHC with $L=600 inverse fb$. digital.library.unt.edu/ark:/67531/metadc926500/
Independent Evaluaton of Air Filter Media From Chornobyl
Independent Evaluation of Air Filter Media from Chornobyl Research performed for the U.S. Department of Energy under Cooperative Agreement DE-FC04-96AL76406 Edited by Lovelace Respiratory Research Institute digital.library.unt.edu/ark:/67531/metadc933319/
CORROSION STUDY OF REPLACEMENT MATERIALS FOR HAZARDOUS LOW LEVEL WASTE PROCESSING TANKS
New waste tanks are to be constructed in H-area to store hazardous low level wastes. AISI Type 304L (304L) stainless steel was recommended as a suitable material of construction for these tanks. Cyclic polarization and coupon tests were performed to evaluate the corrosion resistance of 304L over a wide range of waste tank environments. The results of both tests indicated that 304L was not susceptible to attack under any of these conditions. Comparison tests were also performed with ASTM A537 carbon steel (A537) and Incoloy 825. The carbon steel corroded severely in some of the environments, while Incoloy 825 did not corrode. These tests, along with those for 304L, verified the correlation between cyclic polarization and coupon tests. Electrochemical Impedance Spectroscopy (EIS) was performed to monitor the breakdown of the protective oxide film on the surface of the material as a function of time and temperature. These results also correlated with those from the cyclic polarization and coupon tests. digital.library.unt.edu/ark:/67531/metadc931390/
COUPON IMMERSION TESTING IN SIMULATED HAZARDOUS LOW LEVEL WASTE
AISI Type 304L (304L) stainless steel was recommended as a suitable material of construction for the new Hazardous Low Level Waste Processing Tanks (HLLWPT). This report documents the second phase of a coupon immersion test program to determine the susceptibility of 304L to localized attack in a variety of simulated wastes. The coupon test results confirmed the conclusions that were made from the first phase of the test program. First, 304L is a suitable material of construction for the new waste tanks. Second, the agreement between the cyclic polarization tests and the coupon immersion tests demonstrates that cyclic polarization can be used to predict the susceptibility of a material to localized corrosion in these wastes. In addition to the tests performed on 304L, tests were performed on ASTM A537 carbon steel (A537) and Incoloy 825 (I825). Neither 304L nor I825 was susceptible to attack, while A537 experienced varying degrees of attack in the different wastes. Observations on the surface attack and corrosion products on A537 were used to elucidate the mechanism by which A537 corrodes in these wastes. digital.library.unt.edu/ark:/67531/metadc929820/
EXPERIMENTAL STUDY TO EVALUATE CORROSION OF THE F-CANYON DISSOLVER DURING THEUNIRRADIATED MARK-42 CAMPAIGN
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. digital.library.unt.edu/ark:/67531/metadc932064/
GLASS FEASIBILITY STUDY: VITRIFICATION OF OAK RIDGE NATIONAL LABORATORY GUNITE WASTE USING IRON PHOSPHATE GLASS (U)
This report describes the results of a glass feasibility study on vitrification of Oak Ridge National Laboratory (ORNL) Gunite waste into an Iron Phosphate glass. This glass feasibility study is part of a larger ORNL Gunite and Associated Tanks Treatability program (TTPSR1-6-WT-31). The treatability program explores different immobilization techniques of placing Gunite waste into a glass or grout form for long term storage. ORNL Gunite tanks contain waste that originated from years of various ORNL Research and Development programs. The available analyses of the Gunite Waste Tanks indicate, uranium and/or thorium as the dominant chemical constituent (50% +) and Cs{sup 137} the primary radionuclide. This information was utilized in determining a preliminary iron phosphate glass formulation. Chemical and physical properties: processing temperature, waste loading capability, chemical durability, density and redox were determined. digital.library.unt.edu/ark:/67531/metadc926692/
Calculations of Higher Multipole Components in a Large Superconducting Quadrupole Magnet
We analyze the magnetic field of a finite length, large bore superconducting quadrupole magnet for use in a large aperture, high momentum magnetic spectrometer.In particular, we study the 12-pole and 20-pole components which would contribute to geometric aberations.The magnet is 130 cm long, has a pole radius of 4.3 cm, and the field is largely iron dominated.We analyze the magnet with a nominal field gradient of 276 gauss/cm.The field and/or the scalar potential is calculated with the program TOSCA and decomposed consistent with magnetostatic theory.We establish that the small multipole components are determined reliably and consistently.We find that although the absolute magnitude of the higher order multipoles can become quite large near the ends of the magnet, they reverse sign in this region and their contributions to the field integral are quite small.At the pole radius the integral contributions of the 12-pole (n=6) and 20-pole (n=10) are ~ 1.2*10^-2 and ~ 2.4*10^- digital.library.unt.edu/ark:/67531/metadc931069/
Calculation of the Conditions for Bunched-Beam e-p Instability in the Los Alamos Proton Storage Ring (PSR)
Recent observations are consistent with the possibility of an digital.library.unt.edu/ark:/67531/metadc931833/
Chemical Relaxation Times in a Hadron Gas at Finite Temperature
The relaxation time of particle numbers in hot hadronic matter with vanishing baryon number are estimated using the ideal gas approximation and taking into account resonance decays and annihilation processes as the only sources of particle number fluctuations.Near the QCD critical temperature the longest relaxation times turn out to be of the order of 10 fm and grow roughly exponentially to become of the order of 10^3 fm at temperatures around 100 MeV.As a consequence of such long relaxation times, a clear departure from chemical equilibrium must be observed in the momentum distribution of secondary particles produced in high energy nuclear collisions. digital.library.unt.edu/ark:/67531/metadc926826/
Duals for SU(N) SUSY Gauge Theories with an Antisymmetric Tensor: Five Easy Flavors
I consider N = 1 supersymmetric SU(N{sub c}) gauge theories with matter fields consisting of one antisymmetric representation, five flavors, and enough antifundamental representations to cancel the gauge anomaly. Previous analyses are extended to the case of even N{sub c} with no superpotential. Using holomorphy I show that the theory has an interacting infrared fixed point for sufficiently large N{sub c}. These theories are interesting due to the fact that in going from five to four flavors the theory goes from a non-trivial infrared fixed point to confinement, in contradistinction to SUSY QCD, but in analogy to the behavior expected in non-SUSY QCD. digital.library.unt.edu/ark:/67531/metadc933660/
Dynamics of N = 2 Supersymmetric Gauge Theories in Three Dimensions
We study the structure of the moduli spaces of vacua and superpotentials of N = 2 supersymmetric gauge theories in three dimensions. By analyzing the instanton corrections, we compute the exact superpotentials and determine the quantum Coulomb and Higgs branches of the theories in the weak coupling regions. We find candidates for non-trivial N = 2 superconformal field theories at the singularities of the moduli spaces. The analysis is carried out explicitly for gauge groups U(N{sub c}) and SU(N{sub c}) with N{sub f} flavors. We show that the field theory results are in complete agreement with the intersecting branes picture. We also compute the exact superpotentials for arbitrary gauge groups and arbitrary matter content. digital.library.unt.edu/ark:/67531/metadc927194/
A Radiological Survey Approach to use Prior to Decommissioning: Results from a Technology Scanning & Assessment Project Focused on the Chornobyl NPP
Results from a technology scanning and assessment project focused on the Chornobyl npp. digital.library.unt.edu/ark:/67531/metadc928244/
Lake Roosevelt Fisheries Evaluation Program, Assessment of the Lake Roosevelt Walleye Population 1998 Annual Report, Part D.
A walleye mark-recapture experiment was initiated on Lake Roosevelt in 1997, with the primary objective of estimating the size of the walleye population. The project was continued in 1998 with a revised sampling regime. The primary goals during 1998 were to estimate the size of the walleye population in Lake Roosevelt, estimate the size of the spawning run in the Spokane River Arm, and describe the age structure of the population for use in managing the population and developing a kokanee bioenergetics model. Secondary objectives included: determining walleye movements, back-calculating growth rates, estimating mortality rates, determining walleye condition, and estimating walleye young-of-the-year (YOY) production in the Spokane River Arm. All walleye, {ge} 150 mm TL, were marked with individually numbered Floy{reg_sign} tags, during five passes through the reservoir. The passes occurred between April 1st and September 16th, 1998. The most unbiased estimate of walleye abundance in Lake Roosevelt, 186,482 (40,113 {le} N {le} 943,213), was obtained using the Mtb model of the CAPTURE program. The most unbiased estimate of the size of the walleye spawning run in the Spokane River Arm, 27,345 (1,535 {le} N {le} 57,519), was calculated using the Jolly-Seber model. The abundance estimates appeared reasonable, but they had wide 95 % confidence intervals. Wide confidence intervals were attributed to low capture probabilities. Coefficient of variation (CV) values for both estimates indicated that they were not acceptable for general management, not to mention research. Despite the CV value, we felt that the reservoir estimate was reasonable and that it was the best possible, without a large increase in effort and money. The spawning run estimate could have been improved by a small increase in effort. Ages of walleye in Lake Roosevelt ranged from 0 to 13 years. Growth, mortality, and condition were all average when compared to other walleye producing waters. We recommended that there be no changes in the management of the Lake Roosevelt walleye population and that three separate values of walleye abundance be used in the calculation of the kokanee bioenergetics model. digital.library.unt.edu/ark:/67531/metadc929890/
Lake Roosevelt Fisheries Evaluation Program : Limnological and Fisheries Monitoring Annual Report 1999.
Quark-Hadron Duality and Intrinsic Transverse Momentum
It is demonstrated in several exclusive processes involving the pion that a local quark-hadron duality prescription is equivalent to using an effective (bar)qq (two-body) light-cone wave function Psi (sup) (LD) (x, k (sub)perpendicular) for the pion. This wave function models soft dynamics of all higher (bar)qG...Gq Fock components of the standard light-cone approach. Contributions corresponding to higher Fock components in a hard regime appear in this approach as radiative corrections and are suppressed by powers of alpha(sub)s / Pi. digital.library.unt.edu/ark:/67531/metadc927774/
Soft Contribution to Form Factors of Gamma<sup>*</sup> p -> Delta<sup>+</sup> Transition
The purely nonperturbative soft contribution to the gamma<sup>*</sup> p -> delta<sup>+</sup> transition form factors is estimated using the local quark-hadron duality approach. Our results show that the soft contribution is dominated by the magnetic transition: the ratio G<sup>*</sup> <sub>E</sub> Q<sup>2</sup>/ G<sup>*</sup><sub>M</sub> Q<sup>2</sup> is small for all accessible Q<sup>2</sup>, in contrast to pQCD expectations that G<sup>*</sup><sub>E</sub> (Q<sup>2</sup>) -> -G<sup>*</sup><sub>M</sub> (Q<sup>2</sup>). We also found that the soft contribution to the magnetic form factor is large enough to explain the magnitude of existing experimental data. digital.library.unt.edu/ark:/67531/metadc934213/
Soft modes contribution into path integral
A method for nonperturbative path integral calculation is proposed. Quantum mechanics as a simplest example of a quantum field theory is considered. All modes are decomposed into hard (with frequencies $omega^2 >omega^2_0$) and soft (with frequencies $omega^2 <omega^2_0$) ones, $omega_0$ is a some parameter. Hard modes contribution is considered by weak coupling expansion. A low energy effective Lagrangian for soft modes is used. In the case of soft modes we apply a strong coupling expansion. To realize this expansion a special basis in functional space of trajectories is considered. A good convergency of proposed procedure in the case of potential $V(x)=lambda x^4$ is demonstrated. Ground state energy of the unharmonic oscillator is calculated. digital.library.unt.edu/ark:/67531/metadc928192/
RF Control System for CEBAF
The design goal of 2.5*10^-5 rms energy spread for the CEBAF electron beam demands strict control of the phase and amplitude of the 1.5 GHz accelerating field.To achieve such control in the presence of microphonic excitations, a separate system for each of the 338 superconducting cavities is required.The RF control system employs a heterodyne scheme which allows the use of high precision analog circuits operating at 70 MHz.Presently, the 45 MeV CEBAF injector with 18 superconducting cavities is being commissioned, and this effort provides the first full integrated test in the accelerator tunnel, including cryogenics, RF, beam transport, and beam diagnostics.The RF control system design and objectives are discussed and compared to measured performance during the first commissioning phase.Hardware reliability and operational challenges experienced for RF control are presented. digital.library.unt.edu/ark:/67531/metadc934292/
Technique of Measuring Bunch Length by Phasing an RF Cavity.
Transition Form Factor gamma gamma* -> pi(sup)0 and QCD sum rules
We extend the QCD sum rule analysis of the form factor F(sub)(gamma*gamma* -> pi^0)(q(sub)1^2, q(sub)2^2) into the region of small virtuality of one of the photons: digital.library.unt.edu/ark:/67531/metadc927099/
Large Acceptance Detectors for Electromagnetic Nuclear Physics
The physics program and the requirements for large acceptance detectors in electromagnetic nuclear physics are discussed. As a specific example, the CEBAF Large Acceptance Spectrometer is presented. digital.library.unt.edu/ark:/67531/metadc928825/
Once More on the Applicability of Perturbative QCD to Elastic Form Factors
The long-standing problem of the applicability of perturbative QCD to hadronic elastic form factors is discussed. The basic ingredients both of the asymptotic large-Q<sup>2</sup> treatment and of the QCD sum rule approach are analyzed. The main conclusion is that for accessible energies and momentum transfers the soft (nonperturbative) contributions dominate over those due to the hard quark rescattering subprocesses. digital.library.unt.edu/ark:/67531/metadc930585/
Superconducting Cavities from High Thermal Conductivity Niobium for CEBAF
The Continuous Electron Beam Accelerator Facility (CEBAF) is presently under construction in Newport News, VA.The accelerator consists of approximately 169 meters of 5-cell niobium cavities made from high thermal conductivity niobium with RRR values > 250.Cavities have been manufactured of material from three different suppliers.The material properties like thermal conductivity, residual resistivity and tensile behavior are compared.Results on the performance of these cavities in the presence of high rf fields are reported.Q(sub)0 values as high as 10^10 at 2 K and accelerating gradient of E > 14 MV/m have been achieved. digital.library.unt.edu/ark:/67531/metadc932177/
Physics at CEBAF with High Resolution Spectrometers
We present here the physics program planned for Hall A at CEBAF.It encompasses exclusive as well as inclusive electromagnetic measurements requiring both high precision and accuracy.The program includes measurements of the elementary form factors of the nucleon, systematic studies of the few nucleon systems (d, (sup)3.4 He), high momentum structure of nuclei, their structure at high Q^2 to look for hadronization and quark effects, spin response of nuclei via (vector-e, e', vector-p) reactions and the study of nuclear pion fields. digital.library.unt.edu/ark:/67531/metadc930860/
The Inclusive Muon Neutrino Reaction In 12C
We calculate the charged current inclusive cross section for the reaction, v(sub)u +12C ->u^- + X, from the threshold to 300 MeV.In addition we obtain the average cross section over the spectrum currently being produced at LAMPF.We discuss our results with respect to the current experimental work and consider the possible contributions from higher l states. digital.library.unt.edu/ark:/67531/metadc934886/
Inclusive Scattering and Dynamics in Light Nuclei
Inclusive scattering offers a unique opportunity to study nuclear dynamics in the regime of moderate momentum and energy transfers. We show that realistic models of nuclear interactions and current operators provide a quantitive description of the Alpha particle longitudinal and transverse responses measured in electron scattering. A consistend picture of in-medium nucleon dynamics naturally emerges from an analysis of these (e, e') data and quasi-elastic data from hadronic reactions on heavier nuclei. Its essential features are : (1) a significant quenching of the longitudinal strength; (2) a substantial enhancement of the transverse strength due to the two-nucleon currents required by gauge invariance; and (3) a large shift to higher energies of the isovector strength as observed in the charge-exchange response to hadronic probes. Within this theoretical framework the interactions and currents due to pion exchange play an absolutely crucial role. digital.library.unt.edu/ark:/67531/metadc934151/
Isoscalar Meson Exchange Currents and the Deuteron Form Factors
The electromagnetic form factors for the RhoPiGamma and wSigmaGamma vertices are calculated from quark loop diagrams which take the qq structure of the Pi, Sigma, Rho, w mesons into account.The resulting form factors decrease with increasing Q<sup>2</sup> (the square of the four-momentum of the off-shell photon) considerably more rapidly than the monopole form factors obtained from vector meson dominance.The implications of this behavior, which has a significant effect on the elastic electromagnetic form factors of deuteron, is discussed. digital.library.unt.edu/ark:/67531/metadc928481/
Orbit Correction Techniques for a Multipass Linac
The CEBAF accelerator includes a linac section which accelerates multiple beams with different energies. Problems arise when performing orbit correction, due to the fact that correction of higher energy passes disturb lower energy trajectories. Therefore, a perfect orbit correction cannot be obtained for all energy beams at the same time.\nWe present methods and performance (using simulation results) for performing orbit corrections in such a system. Limitations to the correction methods are also addressed.\n digital.library.unt.edu/ark:/67531/metadc928182/
Cooperative Pre-College Educational Programs at the Continuous Electron Beam Accelerator Facility (CEBAF)
The Continuous Electron Beam Accelerator Facility (CEBAF), under construction in Newport News, Virginia, is a particle accelerator laboratory for nuclear physics research funded by the U.S. Department of Energy. CEBAF's research and supporting technologies offer a rich environment for capturing the interest of and augmenting the experience of pre-college teachers and students. This paper describes some of the pre-college educational programs underway at CEBAF in collaboration with schools, colleges, and business partners. The BEAMS program -- Becoming Enthusiastic About Math and Science -- is highlighted. BEAMS brings entire classes of fifth and sixth grade students with their teachers into CEBAF for a full school week of special science and math activities. A pilot program involving seven inner-city classes was conducted in spring 1991. The 1991/1992 program is well underway with fifty classes scheduled to visit CEBAF. digital.library.unt.edu/ark:/67531/metadc926485/
Covariant Quark Model of Pion Structure
A relativistic quark model wave function of the pion is obtained from a fit to the experimental data, including the charge radius, charge form factor and weak decay constant.The results are quite stable for different choices of quark mass.The two-photon decay width of the neutral pion and the asymptotic form factor for the gamma*+ pi^0 -> gamma transition are estimated. digital.library.unt.edu/ark:/67531/metadc926275/
A General Analysis of Thin Wire Pickups for High Frequency Beam Position Monitors
In many particle accelerators, a large number of high frequency beam position monitors (BPMs) are required to track and correct the orbit of the beam. Therefore, simple, sensitive, low cost pickup designs for such BPMs are of widespread interest. In this paper, a general analysis of arbitrarily terminated thin wire stripline or digital.library.unt.edu/ark:/67531/metadc933929/
CEBAF: The Continuous Electron Beam Accelerator Facility and its Physics Program
With the 4 GeV Continuous Electron Beam Accelerator Facility presently under construction in Newport News, Virginia, a new domain of nuclear and subnuclear phenomena can be investigated, mainly through coincidence experiments. An overview of the characteristic features of the accelerator and associated experimental equipment is given. Some examples of the physics programs are briefly described. digital.library.unt.edu/ark:/67531/metadc932180/
CEBAF Transfer Line Systems
The Continuous Electron Beam Accelerator Facility (CEBAF) has three refrigeration systems which supply many users with liquid and gaseous helium and liquid nitrogen at different state points. Static vacuum transfer lines of varying sizes and geometries transport the cryogens. The simplest has 2 flow paths and the most complex has 5 flow paths including a 4.5 K subcooler. CEBAF will have nearly 2 km of transfer line varying in size from 11.4 cm to 40.6 cm outside diameter. The transfer lines have eccentric flow shield circuits which convey LN(sub)2 or 40 K to 50 K helium gas to intercept the main 300 K heat leak. All of the transfer lines have been designed and fabricated at CEBAF. digital.library.unt.edu/ark:/67531/metadc933565/
Hadronic loops and the OZI rule
Arguments based on unitarity indicate that hadronic loop diagrams should produce large violations of the OZI (Okubo-Zweig-Iizuka) rule. The mechanism by which these corrections are evaded has long been a mystery. We have found that there is an exact cancellation of all such loops in a particular (quark model) limit and that, at least for the rho-->omega system which we have studied in detail, the cancellation is maintained in a realistic calculation which takes into account departures from this limit. digital.library.unt.edu/ark:/67531/metadc934166/
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