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in creator/contributor: "National Science Foundation U.S."

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Numerical simulation of a short RFQ resonator using the MAFIA codes

The electrical characteristics of a short (2{beta}{lambda}=0.4 m) resonator with large modulation (m=4) have been studied using the three dimensional codes, MAFIA. The complete resonator, including the modulated electrodes and a complex support structure, has been simulated using {approximately} 350,000 mesh points. Important characteristics studied include the resonant frequency, electric and magnetic fields distributions, quality factor and stored energy. The results of the numerical simulati… more

Date: January 1, 1991

Creator: Wang, H.; Ben-Zvi, Ilan; Jain, A.; Paul, P. (State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics) & Lombardi, A. (Istituto Nazionale di Fisica Nucleare, Legnaro (Italy). Lab. Nazionale di Legnaro)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Nonlinear optical properties of new KTiOPO sub 4 isostructures

The atomic structures of the nonlinear optical materials potassium titanyl phosphate (KTiOPO{sub 4}, or KTP) and potassium titanyl arsenate (KTiOAsO{sub 4}) feature one-dimensional channels through which the potassium ions are relatively free to migrate. Ion exchange results when these materials are immersed in molten salts containing alkali metal ions. Sodium, lithium and silver all exchange readily for K{sup +} single crystals of both KTP and KTA to yield the exchanged derivatives Na{sub .95}… more

Date: January 1, 1991

Creator: Phillips, M. L. F.; Harrison, W. T. A. & Stucky, G. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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ADIFOR: Automatic differentiation in a source translator environment

The numerical methods employed in the solution of many scientific computing problems require the computation of derivatives of a function f: R{sup n} {yields} R{sup m}. ADIFOR (Automatic Differentiation in FORtran) is a source transformation tool that accepts Fortran 77 code for the computation of a function and writes portable Fortran 77 code for the computation of the derivatives. In contrast to previous approaches, ADIFOR views automatic differentiation as a source transformation problem and… more

Date: January 1, 1992

Creator: Bischof, C.; Corliss, G.; Griewank, A. (Argonne National Lab., IL (United States)) & Carle, A. (Rice Univ., Houston, TX (United States). Center for Research on Parallel Computation)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Time-Dependent Two-Dimensional Radiation Hydrodynamics of Accreting Matter Onto Highly Magnetized Neutron Stars

We present for the first time, the self-consistent solution of the two-dimensional, time-dependent equations of radiation-hydrodynamics governing the accretion of matter onto the highly magnetized polar caps of luminous x-ray pulsars. The calculations show a structure in the accretion column very different from previous one-zone uniform models. We have included all the relevant magnetic field corrections to both the hydrodynamics and the radiative transport. We include a new theory for the diff… more

Date: November 24, 1989

Creator: Klein, R.I. (California Univ., Los Angeles, CA (USA). Dept. of Astronomy Lawrence Livermore National Lab., CA (USA) California Univ., Los Angeles, CA (USA). Inst. of Geophysics and Planetary Physics) & Arons, J. (California Univ., Berkeley, CA (USA). Dept. of Astronomy California Univ., Los Angeles, CA (USA). Inst. of Geophysics and Planetary Physics CEA Centre d'Etudes Nucleaires de Saclay, 91 -

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Spectral weight changes at the superconducting transition of Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8+. delta

An overview of our gap studies in high-{Tc} superconductors is presented for the workshop on Fermiology of high-{Tc}'s. The work is centered on the study of single crystal Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}. In a conventional BCS superconductor, a superconducting gap {Delta} is formed when the near Fermi edge electrons condense to form Cooper pairs at low temperatures. As the material goes superconducting the density of states is modified such that the spectral intensity in the regio… more

Date: January 1, 1991

Creator: Dessau, D. S.; Shen, Z. X.; Wells, B. O.; Spicer, W. E. (Stanford Univ., CA (United States). Stanford Electronics Labs.) & Arko, A. J. (Los Alamos National Lab., NM (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Cosmology and the weak interaction

The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N{sub {nu}} {approximately} 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the … more

Date: December 1, 1989

Creator: Schramm, D. N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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ADIFOR: Fortran source translation for efficient derivatives

The numerical methods employed in the solution of many scientific computing problems require the computation of derivatives of a function f: R{sup n} {yields} R{sup m}. Both the accuracy and the computational requirements of the derivative computation are usually of critical importance for the robustness and speed of the numerical method. ADIFOR (Automatic Differentiation In FORtran) is a source translation tool implemented using the data abstractions and program analysis capabilities of the Pa… more

Date: January 1, 1992

Creator: Bischof, C.; Corliss, G.; Griewank, A.; Hovland, P. (Argonne National Lab., IL (United States)) & Carle, A. (Rice Univ., Houston, TX (United States). Center for Research on Parallel Computation)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Static and dynamic spin fluctuations in the spin glass doping regime in La sub 2-x Sr sub x CuO sub 4+y

We review the results of neutron scattering studies of the static and dynamic spin fluctuations crystals of La{sub 2-x}Sr{sub x}CuO{sub 4+{delta}} in the doping regime intermediate between the Neel and superconducting regions. In this regime the in-plane resistance is linear in temperature down to {approximately}80 K with a crossover due to logarithmic conductance effects at lower temperatures. The static spin correlations are well-described by a simple model in which the inverse correlation le… more

Date: January 1, 1991

Creator: Birgeneau, R.J.; Belk, N.; Kastner, M.A.; Keimer, B. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics); Endoh, Y. (Tohoku Univ., Sendai (Japan). Dept. of Physics); Erwin, R.W. (National Inst. of Standards and Technology, Gaithersburg, MD (United States)) et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The influence of anharmonic phonons on the isotope effect in high- Tc oxides

Anharmonic phonons are examined to study the unusual isotope effect exponents for the high-{Tc} oxides. Within a simple model of anharmonicity, the mass dependences of the electron-phonon coupling constant {lambda} and the phonon frequency determine the isotope effect exponent {alpha} as a function of coupling strength. A model in which the outer wells of a multiple-well potential deepen as the orthorhombic/low temperature tetragonal phase transition in La{sub 2-x}M{sub x}CuO{sub 4} is approach… more

Date: January 1, 1992

Creator: Crespi, V.H. & Cohen, M.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Thermal Conductivity of Quasi-One Dimensional Conductors

The thermal conductivity of K{sub 0.3}M{sub 0}O{sub 3}, (TaSe{sub 4}){sub 2}I and TaS{sub 3} have been studied. Together with the specific heat measurement, the anomaly observed in thermal conductivity around the Peierls transition is believed to be due to extra heat carried by the 2k{sub F} soft phonons. The field dependent thermal conductivity of the blue bronze and TaS{sub 3} have also been measured by two distinct methods, and found to be independent of applied electric field. 17 refs., 3 f… more

Date: January 1, 1989

Creator: Kwok, R.S. (California Univ., Los Angeles, CA (USA). Dept. of Physics) & Brown, S.E. (Los Alamos National Lab., NM (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Benchmark problems in which equality plays the major role

We have recently heard rumors that researchers are again studying paramodulation (Wos87) in the context of strategy for its control. In part to facilitate such research, and in part to provide test problems for evaluating other approaches to equality-oriented reasoning, we offer in this article a set of benchmark problems in which equality plays the dominant role. The test problems are taken from group theory, Robbins algebra, combinatory logic, and other areas. For each problem, we include app… more

Date: January 1, 1992

Creator: Lusk, E. & Wos, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron positron factories

In this paper, we will first indicate the key issues in designing a B-factory and a {phi}-factory, and illustrate the approaches that are being followed to address them. In general, reaching the B-factory parameter regime offers the most challenges, so we will emphasize it here. Then we will consider an extrapolation of our present understanding of collider performance and assess the maximum luminosity that could be anticipated. To reach extremely high luminosity, it may be necessary to conside… more

Date: December 1, 1990

Creator: Zisman, M. S.; Chattopadhyay, S.; Garren, A. A.; Lambertson, G. (Lawrence Berkeley Lab., CA (United States)); Bloom, E.; Corbett, W. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Quark matter and cosmology

The possible implications of the quark-hadron transition for cosmology are explored. Possible surviving signatures are discussed. In particular, the possibility of generating a dark matter candidate such as strange nuggets or planetary mass black holes is noted. Much discussion is devoted to the possible role of the transition for cosmological nucleosynthesis. It is emphasized that even an optimized first order phase transition will not significantly alter the nucleosynthesis constraints on the… more

Date: January 1, 1992

Creator: Schramm, D.N. (Chicago Univ., IL (United States) Fermi National Accelerator Lab., Batavia, IL (United States)); Fields, B. & Thomas, D. (Chicago Univ., IL (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Momentum-dependent mean field and the nuclear equation of state

We study the momentum distribution of nucleons in nuclear matter and calculate the incompressibility analytically in the presence of a momentum-dependent mean field. An equivalent mass is introduced for calculational purposes. The effect of the momentum-dependence of the mean field on the hadronic equation of state is examined and the conditions for equilibrium with a quark phase described by a bag model equation of state are investigated. 12 refs., 4 figs.

Date: 1991-01~

Creator: Csernai, László P.; Fai, George; Gale, Charles & Osnes, Eivind

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Studies of heavy-ion reactions and transuranic nuclei

The development of the cold-fusion'' episode is reviewed. Ongoing studies of compound-nucleus formation and decay via the neutron multiplicity distribution confirm the validity of conventional statistical theory. The excitation energy partition in near-barrier damped {sup 58}Ni + {sup 208}Pb collisions is found to be largely independent of the direction of net mass transfer, supporting a diffusion-like nucleon-exchange mechanism. Exclusive experiments on the heavy reaction systems {sup 197}Au +… more

Date: August 1, 1991

Creator: Schroeder, W. U. & Huizenga, J. R.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Electron energies in metals

The modern era of electron-electron interactions began a decade ago. Plummer's group initiated a program of using angular resolved photoemission to examine the band structure of the simple metals. Beginning with aluminum, and carrying on to sodium and potassium, they always found that the occupied energy bands were much narrower than expected. For example, the compressed energy bands for metallic potassium suggest a band effective mass of m* = 1.33m{sub e}. This should be compared to the band m… more

Date: July 10, 1991

Creator: Mahan, G.D. (Oak Ridge National Lab., TN (United States) Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Quantum cosmology on the worldsheet

Two-dimensional quantum gravity coupled to conformally invariant matter central c > 25 provides a toy model for quantum gravity in four dimensions. Two-dimensional quantum cosmology can thus be studied in terms of string theory in background fields. The large scale cosmological constant depends on non-linear dynamics in the string theory target space and does not appear to be suppressed by wormhole effects. 13 refs.

Date: August 1, 1991

Creator: Cooper, A.R.; Susskind, L. & Thorlacius, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electronic states in systems of reduced dimensionality

This report briefly discusses the following research: magnetically modulated systems, inelastic magnetotunneling, ballistic transport review, screening in reduced dimensions, raman and electron energy loss spectroscopy; and ballistic quantum interference effects. (LSP).

Date: April 15, 1992

Creator: Ulloa, S.E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Capillary surfaces in exotic containers

A survey is presented of results to date for capillary surfaces in exotic'' containers. These containers have the property that each one admits a continuum of distinct equilibrium free surfaces, all bounding with the container walls the same volume of fluid, making the same contact angle at the trip interface curve, and having identical mechanical energies. The containers can be so designed that they are themselves axially symmetric but that the fluid configurations of minimizing energy cannot … more

Date: July 1, 1991

Creator: Concus, P. (Lawrence Berkeley Lab., CA (United States)) & Finn, R. (Stanford Univ., CA (United States). Dept. of Mathematics)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Particle detection using superfluid helium

We have observed 5 MeV {alpha} particles stopped in volumes-up to two liters of liquid helium at 70 mK. A fraction of the kinetic energy of an {alpha} particle is converted to elementary excitations (rotons and phonons), which progagate ballistically in isotopically pure {sup 4}He below 0.1 K. Most of these excitations have sufficient energy to evaporate helium atoms on hitting a free surface. The evaporated helium atoms can be detected calorimetrically when adsorbed on a thin silicon wafer ({a… more

Date: January 1, 1991

Creator: Bandler, S. R.; Lanou, R. E.; Maris, H. J.; More, T.; Porter, F. S.; Seidel, G. M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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High l state population in O sup 7+ produced in ion-solid collisions

The high {ell}-state population of fast ions excited in ion-solid interactions is very different from {ell}-state populations produced under single collision conditions. A study of the population dynamics of electronic excitation and transport within the framework of a classical transport theory for O{sup 2+} (2 MeV/u) ions traversing carbon foils shows food agreement with experimental results from delayed photon emission spectroscopy. We investigate the dependence of the characteristic exponen… more

Date: January 1, 1991

Creator: Kemmler, J. (Centre Interdisciplinaire de Recherches avec les Ions Lourds, 14 - Caen (France)); Bourgdoerfer, J. & Reinhold, C.O. (Tennessee Univ., Knoxville, TN (United States) Oak Ridge National Lab., TN (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Michigan State Cyclotron Laboratory Annual Report: 1972

No Description Available.

Date: November 1972

Creator: Michigan State University. Cyclotron Laboratory.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Status of the SUNY superconducting RFQ

A RFQ resonator is presently being developed at SUNY. This resonator is a prototype for a chain of six short ({approximately}0.5m long), superconducting (Pb plated Cu), 50 MHz resonators designed to accelerate beam from {beta} = 0.01 to 0.05. The chain accepts a prebunched beam to save on superconducting length. The resonators are of four-rods type with vane-like electrodes. The prototype resonator is designed to accelerate ions of q/A = 1/6 from {beta} = 0.030 to 0.036, operating at a peak sur… more

Date: January 1, 1991

Creator: Jain, A.; Ben-Zvi, Ilan; Paul, P.; Wang, H. (Brookhaven National Lab., Upton, NY (United States)) & Lombardi, A. (Istituto Nazionale di Fisica Nucleare, Legnaro (Italy). Lab. Nazionale di Legnaro)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Recent developments in the Virasoro master equation

The Virasoro master equation collects all possible Virasoro constructions which are quadratic in the currents of affine Lie g. The solution space of this system is immense, with generically irrational central charge, and solutions which have so far been observed are generically unitary. Other developments reviewed include the exact C-function, the superconformal master equation and partial classification of solutions by graph theory and generalized graph theories. 37 refs., 1 fig., 1 tab.

Date: September 3, 1991

Creator: Halpern, M.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department