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Infrasonic observation of earthquakes

Description: Infrasound signals generated by earthquakes have been detected at arrays operated by the Los Alamos National Laboratory. Three modes of propagation are possible and all have been observed by the authors. The observations suggest that regions remote from the epicenters are excited and may serve as secondary source regions. A relation is found between the normalized peak amplitudes and the seismic magnitudes.
Date: December 31, 1998
Creator: Mutschlecner, J.P. & Whitaker, R.W.
Partner: UNT Libraries Government Documents Department

Nucleon-nucleon interactions

Description: Nucleon-nucleon interactions are at the heart of nuclear physics, bridging the gap between QCD and the effective interactions appropriate for the shell model. We discuss the current status of {ital NN} data sets, partial-wave analyses, and some of the issues that go into the construction of potential models. Our remarks are illustrated by reference to the Argonne {ital v}{sub 18} potential, one of a number of new potentials that fit elastic nucleon-nucleon data up to 350 MeV with a {Chi}{sup 2} per datum near 1. We also discuss the related issues of three-nucleon potentials, two-nucleon charge and current operators, and relativistic effects. We give some examples of calculations that can be made using these realistic descriptions of {ital NN} interactions. We conclude with some remarks on how our empirical knowledge of {ital NN} interactions may help constrain models at the quark level, and hence models of nucleon structure.
Date: December 31, 1996
Creator: Wiringa, R.B.
Partner: UNT Libraries Government Documents Department

Vibration modal analysis using all-optical photorefractive processing

Description: A new experimental method for vibration modal analysis based on all- optical photorefractive processing is presented. The method utilizes an optical lock-in approach to measure phase variations in light scattered from optically rough, continuously vibrating surfaces. In this four-wave mixing technique, all-optical processing refers to mixing the object beam containing the frequency modulation due to vibration with a single frequency modulated pump beam in the photorefractive medium that processes the modulated signals. This allows for simple detection of the conjugate wavefront image at a CCD. The conjugate intensity is shown to be a function of the first-order ordinary Bessel function and linearly dependent on the vibration displacement induced phase. Furthermore, the results demonstrate the unique capabilities of the optical lock-in vibration detection technique to measure vibration signals with very narrow bandwidth (< 1 Hz) and high displacement sensitivity (sub-Angstrom). This narrow bandwidth detection can be achieved over a wide frequency range from the photorefractive response limit to the reciprocal of the photoinduced carrier recombination time. The technique is applied to determine the modal characteristics of a rigidly clamped circular disc from 10 kHz to 100 kHz.
Date: December 31, 1996
Creator: Hale, T. & Telschow, K.
Partner: UNT Libraries Government Documents Department

Amplitude and phase modulation with waveguide optics

Description: We have developed amplitude and phase modulation systems for glass lasers using integrated electro-optic modulators and solid state high- speed electronics. The present and future generation of lasers for Inertial Confinement Fusion require laser beams with complex temporal and phase shaping to compensate for laser gain saturation, mitigate parametric processes such as transverse stimulated Brillouin scattering in optics, and to provide specialized drive to the fusion targets. These functions can be performed using bulk optoelectronic modulators, however using high-speed electronics to drive low voltage integrated optical modulators has many practical advantages. In particular, we utilize microwave GaAs transistors to perform precision, 250 ps resolution temporal shaping. Optical bandwidth is generated using a microwave oscillator at 3 GHz amplified by a solid state amplifier. This drives an integrated electrooptic modulator to achieve laser bandwidths exceeding 30 GHz.
Date: December 17, 1996
Creator: Burkhart, S.C.; Wilcox, R.B.; Browning, D. & Penko, F.A.
Partner: UNT Libraries Government Documents Department

Prospects of a baryon instability search in neutron-antineutron oscillations

Description: The purpose of this article is to review the current status and the future prospects for an experimental neutron-antineutron transition search. Traditional and new experimental techniques are discussed here. In the n {r_arrow} {anti n} search in experiments at existing reactors, it would be possible to increase the discovery potential up to four orders of magnitude for vacuum n {r_arrow} {anti n} transitions relative to the existing experimental level or to achieve the limit of {tau}{sub n-{anti n}{sup {approximately}}} 10{sup 10}s.. With dedicated future reactors and an ultimate experimental layout, it might be possible to reach the limit of 10{sup 11}s. Significant progress in an intranuclear n {r_arrow} {anti n} transition search expected to be made during the next decade by the SuperKamiokande and Icarus detectors. It can be matched, or even exceeded, in a new alternative approach, where unstable long-lived isotopes of technetium are searched in non radioactive deep-mined ores.
Date: December 31, 1996
Creator: Efremenko, Yu. & Kamyshkov, Yu.
Partner: UNT Libraries Government Documents Department

Phase synchronization of multiple klystrons in RF system

Description: The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of the Acceleration Production of Tritium (APT) accelerator. The first LEDA RF system includes three, 1.2 MW, 350 MHz, continuous wave, klystrons driving a radio frequency quadrupole (RFQ). A phase control loop is necessary for each individual klystron in order to guarantee the phase matching of these klystrons. To meet this objective, they propose adaptive PI controllers which are based on simple adaptive control. These controllers guarantee not only phase matching but also amplitude matching.
Date: December 31, 1998
Creator: Kwon, S.; Regan, A.; Wang, Y.M. & Rohlev, T.
Partner: UNT Libraries Government Documents Department

Infrasound from the El Paso super-bolide of October 9, 1997

Description: During the noon hour on October 9, 1997 an extremely bright fireball ({approx}-21.5 in stellar magnitude putting it into the class of a super-bolide) was observed over western Texas with visual sightings from as far away as Arizona to northern Mexico and even in northern New Mexico over 300 miles away. This event produced tremendously loud sonic boom reports in the El Paso area. It was also detected locally by 4 seismometers which are part of a network of 5 seismic stations operated by the University of Texas at El Paso (UTEP). Subsequent investigations of the data from the six infrasound arrays used by LANL (Los Alamos National Laboratory) and operated for the DOE (Department of Energy) as a part of the CTB (Comprehensive Test Ban) Research and Development program for the IMS (International Monitoring System) showed the presence of an infrasonic signal from the proper direction at the correct time for this super-bolide from two of the six arrays. Both the seismic and infrasound recordings indicated that an explosion occurred in the atmosphere at source heights from 28--30 km, having its epicenter slightly to the northeast of Horizon City, Texas. The signal characteristics, analyzed from {approx}0.1 to 5.0 Hz, include a total duration of {approx}4 min (at Los Alamos, LA) to &gt;{approx}5 min at Lajitas, Texas, TXAR, another CTB IMS array operated by E. Herrin at Southern Methodist University (SMU) for a source directed from LA toward {approx}171--180 deg and from TXAR of {approx}321-4 deg respectively from true north. The observed signal trace velocities (for the part of the recording with the highest cross-correlation) at LA ranged from 300--360 m/sec with a signal velocity of 0.30 {+-} 0.03 km/sec, implying a Stratospheric (S Type) ducted path. The dominant signal frequency at LA was from 0.20 to 0.80 Hz, with ...
Date: December 31, 1998
Creator: ReVelle, D.O.; Whitaker, R.W. & Armstrong, W.T.
Partner: UNT Libraries Government Documents Department

Nonlinear Pulsation Modeling of Luminous Blue Variables

Description: Using an updated version of the Ostlie and Cox (1993) nonlinear hydrodynamics code, we show the results of Luminous Blue Variable (LBV) envelope models based on evolution models of initial mass 50-80 M solar. including mass loss. The models use OPAL opacities, contain 60-120 Lagrangian zones, include time dependent convection, and are given an initial photospheric radial velocity amplitude of 1 km/sec. Our goal is to explain the reason for the LBV instability strip and suggest a cause for LBV outbursts observed in massive stars in our Galaxy as well as the LMC and SMC.
Date: December 31, 1997
Creator: Despain, Kate M.; Guzik, Joyce A. & Cox, Arthur N.
Partner: UNT Libraries Government Documents Department

Amplitude path corrections for regional phases in China

Description: The authors investigate the effectiveness of amplitude path corrections for regional phases on seismic event discrimination and magnitude estimation. Waveform data from digital stations in China for regional, shallow (< 50 km) events were obtained from the IRIS Data Management Center (DMC) for years 1986 to 1996 using the USGS Preliminary Determination of Epicenters (PDE) and the Chinese State Seismological Bureau (SSB) catalogs. For each event, the amplitudes for each regional phase (P{sub n}, P{sub g}, S{sub n}, L{sub g}) were measured, as well as the P{sub g} and L{sub g} coda. Measured amplitudes were corrected for source scaling using estimates of m{sub b} and for distance using a power law that accounts for attenuation and spreading. The amplitude residuals were interpolated and mapped as 2-D amplitude correction surfaces. The authors employ several methods to create the amplitude correction surfaces: a waveguide method, and two interpolation methods (Baysian kriging and a circular moving window mean smoother). They explore the sensitivities of the surfaces to the method and to regional propagation, and apply these surfaces to correct amplitude data to reduce scatter in discrimination ratios and magnitude estimates.
Date: December 31, 1998
Creator: Phillips, W.S.; Velasco, A.A.; Taylor, S.R. & Randall, G.E.
Partner: UNT Libraries Government Documents Department

Reaction theories for N* excitations in {pi}N and {gamma}N reactions

Description: The importance of developing reaction theories for investigating N* physics is illustrated in an analysis of pion photoproduction on the nucleon. It is shown that the {gamma}N {leftrightarrow} {Delta} transition amplitudes predicted by the constituent quark model are in agreement with the values extracted from the {gamma}N {r_arrow} {pi}N data only when the contributions from the reaction mechanisms calculated using a dynamical approach are taken into account in the analysis.
Date: December 31, 1996
Creator: Lee, T. S. H.
Partner: UNT Libraries Government Documents Department

KN scattering in the nonrelativistic quark model

Description: KN scattering is of interest as a probe of nuclear structure and, more fundamentally, as a laboratory for the study of nonresonant hadron-hadron interactions. KN is a I theoretically attractive channel because of its simplicity, having only S = 1/2, no one pion exchange contributions and no valence q{anti q} annihilation. It may therefore be useful for the study of short-ranged quark forces analogous to the NN repulsive core. Since there are two isospin states, comparison of two closely related amplitudes is possible. This contribution reviews the experimental status of S-wave KN scattering and related theoretical studies based on quark-gluon dynamics. The experimental low-energy S-wave phase shift is well established for I = 1, but is not yet well determined for I = 0. The ratio of I = 0 to I = 1 scattering lengths is an interesting number theoretically, and may discriminate between different scattering mechanisms. A measurement of these scattering lengths at DAPHNE would be a useful contribution to low energy hadron physics.
Date: December 31, 1995
Creator: Barnes, F.E.
Partner: UNT Libraries Government Documents Department

Theoretical aspects of light meson spectroscopy

Description: In this pedagogical review the authors discuss the theoretical understanding of light hadron spectroscopy in terms of QCD and the quark model. They begin with a summary of the known and surmised properties of QCD and confinement. Following this they review the nonrelativistic quark potential model for q{anti q} mesons and discuss the quarkonium spectrum and methods for identifying q{anti q} states. Finally, they review theoretical expectations for non-q{anti q} states (glueballs, hybrids and multiquark systems) and the status of experimental candidates for these states.
Date: December 31, 1995
Creator: Barnes, T.
Partner: UNT Libraries Government Documents Department

The high energy behavior of the forward scattering parameters - an amplitude analysis update

Description: Utilizing the most recent experimental data, we reanalyze high energy pp and pp data, using the asymptotic amplitude analysis, under the assumption that we have reached {open_quotes}asymptopia{close_quotes}. This analysis gives strong evidence for a log (s/s{sub 0}) dependence at current energies and not log{sup 2} (s/s{sub 0}), and also demonstrates that odderons are not necessary to explain the experimental data.
Date: December 1995
Creator: Block, M. M.; Margolis, B. & White, A. R.
Partner: UNT Libraries Government Documents Department

Experiment to measure total cross sections, differential cross sections and polarization effects in pp elastic scattering at RHIC

Description: The author is describing an experiment to study proton-proton (pp) elastic scattering experiment at the Relativistic Heavy Ion Collider (RHIC). Using both polarized and unpolarized beams, the experiment will study pp elastic scattering from {radical}s = 60 GeV to {radical}s = 500 GeV in two kinematical regions .In the Coulomb Nuclear Interference (CNI) region, 0.0005 < {vert_bar}t{vert_bar} < 0.12 (GeV/c){sup 2}, we will measure and study the s dependence of the total and elastic cross sections, {sigma}{sub tot} and {sigma}{sub el}; the ratio of the real to the imaginary part of the forward elastic scattering amplitude, {rho}; and the nuclear slope parameter of the pp elastic scattering, b. In the medium {vert_bar}t{vert_bar}, {vert_bar}t{vert_bar} {le} 1.5 (GeV/c){sup 2}, we plan to study the evolution of the dip structure with s, as observed at ISR in the differential elastic cross section, d{sigma}{sub el}/dt, and the s and {vert_bar}t{vert_bar} dependence of b. With the polarized beams the following can be measured: the difference in the total cross sections as function of initial transverse spin stated {Delta}{sigma}{sub T}, the analyzing power, A{sub N}, and the transverse spin correlation parameter A{sub NN}. The behavior of the analyzing power A{sub N} at RHIC energies in the dip region of d{sigma}{sub el}/dt, where a pronounced structure was found at fixed-target experiments will be studied.
Date: December 31, 1995
Creator: Guryn, W.
Partner: UNT Libraries Government Documents Department

Fast Particle Destabilization of Toroidicity Induced Alfven Eigenmodes in National Spherical Torus Experiment

Description: Toroidicity induced Alfven Eigenmode (TAE) stability in National Spherical Torus Experiment (NSTX) is analyzed using the improved NOVA-K code, which includes finite orbit width and Larmor radius effects and is able to predicts the saturation amplitude for the mode using the quasilinear theory. Broad spectrum of unstable global TAEs with different toroidal mode numbers is predicted. Due to the strong poloidal field and the presence of the magnetic well in NSTX better particle confinement in the presence of TAEs in comparison with tokamaks is illustrated making use of the ORBIT code.
Date: December 10, 1999
Creator: Cheng, C.Z.; Fu, G.Y.; Gorelenkova, M.V.; Gorelenkov, N.N.; White, R. & Kaye, S.
Partner: UNT Libraries Government Documents Department

Observation of Secondary Plasma Waves in Laser-Plasma Interaction Experiments

Description: An experiment is described where the two products of the Langmuir Decay Instability (LDI) of a primary electron plasma wave have been observed and identified without any ambiguity. Primary Langmuir waves are driven by Stimulated Raman Scattering (SRS) of an incident laser which provides well-defined electron plasma waves. Thomson scattering of a short wavelength probe beam yields measurements of the amplitude of the waves resolved in time, space, wavelength and wavevector, that allow identification of the probed waves.
Date: December 8, 1999
Creator: Depierreux, S.; Labaune, C.; Baldis, H.A.; Fuchs, J. & Michard, A.
Partner: UNT Libraries Government Documents Department

Over-the-road tests of nuclear materials package response to normal environments

Description: In support of the development of American National Standards Institute standards for the transport of radioactive materials, Sandia has a program to characterize the normal transport environment. This program includes both analytical modeling of package and trailer responses, and over-the-road tests to measure those responses. This paper presents the results of a series of over-the-road tests performed using Chem-Nuclear equipment in the Barnwell, SC, area. The test events included a variety of road types such as rough concrete, shock events such as railroad grade crossings, and driver responses such as sharp turns. The response of the package and trailer to these events was measured with accelerometers at various locations to determine the inertial loads. Either load cells or strain gages were used to measure tiedown response. These accelerations and loads were measured on systems with flexible and ``rigid`` tiedowns. The results indicated that while significant accelerations occur on the trailer bed, these do not translate into equivalent loads in either the package or the tiedown system. This indicates that trailer-bed response should not be used in determining the load factor for fatigue calculations of the package components or in determining design loads for tiedowns.
Date: December 1, 1991
Creator: Gwinn, K.W.; Glass, R.E. & Edwards, K.R.
Partner: UNT Libraries Government Documents Department

Techniques in meson spectroscopy

Description: This report contains lectures on the following topics: the quark model and beyond using quantum chromodynamics; analysis of formation reactions; energy dependence of the partial wave amplitudes; where the data for the t-matrix analysis comes from; and coupled channel analysis of isoscalar mesons.
Date: December 31, 1991
Creator: Longacre, R. S.
Partner: UNT Libraries Government Documents Department

Hadron dynamics in high-energy pion-nucleus scattering

Description: It is argued that pion-nucleus scattering at high energy (above 300 MeV) is likely to be easier to interpret than it has been at lower energies where the {Delta}{sub 33} resonance dominates. We establish this by examining the relative importance of various dynamic ingredients of scattering theory for high-energy pions and comparing different versions of the theory: a ``model-exact`` microscopic optical model and an eikonal approximation. For nuclei as heavy as Ca, the eikonal theory is an excellent approximation to the full theory for the angular distribution out to the position of the second minimum in the cross section. The prospects for using high-energy pions to examine modifications of nucleons and baryon resonances in nuclei, nuclear structure, exchange currents, short-range correlations, and to characterize pion propagation are discussed.
Date: December 31, 1992
Creator: Johnson, M. B.
Partner: UNT Libraries Government Documents Department

Ringwaldmania reconsidered

Description: The exciting possibility that anomalous baryon and lepton number violation might be observable at the next generation of supercolliders is suggested by an instanton calculation due to Ringwald and Espinoa. Here, the current controversial status of these claims is discussed, and progress on several fronts is described.
Date: December 31, 1991
Creator: Mattis, M. P.
Partner: UNT Libraries Government Documents Department

Narrow structure in {Lambda}d scattering near the {Sigma} threshold ({sub {Sigma}}{sup 3}He states)

Description: A separable-potential, Faddeev-type calculation of {Lambda}-deuteron scattering near the threshold for {Sigma} production is shown to produce structure (a resonance peak) in the cross section which lies below the {Sigma} threshold for two different YN ({Lambda}N-{Sigma}N coupled-channel) potential models. In one case the {Sigma}NN eigenvalue corresponds to a pole which lies below threshold (bound) and in the second case the poles lies above the threshold.
Date: December 31, 1991
Creator: Gibson, B. F. & Afnan, I. R.
Partner: UNT Libraries Government Documents Department

The E2/M1 mixing ratio in the excitation of the {Delta} from polarized photo-reactions

Description: In constituent quark models, a tensor interaction, mixing quark spins with their relative motion, is introduced to reproduce the observed baryon spectrum. This has a consequence completely analogous to the nuclear tensor force between the n and p in deuterium. A D state component is mixed into what would otherwise be a purely S-wave object. The D-wave component breaks spherical symmetry, resulting in a non-vanishing matrix element for the nucleon and a static quadrupole moment and deformation for its first excited state, the {Delta} resonance, at {approximately}325 MeV. The magnitude and sign of this D-state component are quite sensitive to the internal structure of the proton and have been of great interest in recent years. The intrinsic deformation of the spin 1/2 nucleon cannot be observed directly; it must be inferred from transition amplitudes such as N {yields} {Delta}. In a spherical bag model, the {Delta} is viewed as a pure quark-spin-flip transition proceeding only through M1 excitation. If there are D-state admixtures in the ground state of the nucleon and/or {Delta}, quadrupole excitation, in addition to spin-flip M1, is also allowed. The problem is to evaluate the relative magnitude of this E2 excitation in the presence of the dominant M1 transition. A variety of models predict this mixing ratio to be quite small, anywhere from {minus}0.9% to {minus}6%, so that a high degree of precision is demanded of experiment.
Date: December 1, 1993
Creator: Collaboration, The LEGS
Partner: UNT Libraries Government Documents Department

Resonant and non-resonant magnetic scattering

Description: The tunability and the polarization of synchrotron radiation open upon new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and thy fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.
Date: December 31, 1991
Creator: McWhan, D. B.; Hastings, J. B.; Kao, C. C. & Siddons, D. P.
Partner: UNT Libraries Government Documents Department