Free-electron laser generation of VUV and x-ray radiation using a conditioned beam and ion-channel focusing (open access)

Free-electron laser generation of VUV and x-ray radiation using a conditioned beam and ion-channel focusing

The use of ion-focusing and a conditioned beam greatly enhances FEL gain in the VUV and Soft X-Ray range. The equations governing FEL amplification are derived and results of a linear analysis are noted. Numerical results, including 3D effects and having an order of magnitude improvement in gain, are presented for a 30 {Angstrom} example. 3 refs., 2 figs., 1 tab.
Date: August 30, 1991
Creator: Yu, Li-Hua (Brookhaven National Lab., Upton, NY (United States)); Sessler, A. & Whittum, D.H. (Lawrence Berkeley Lab., CA (United States))
System: The UNT Digital Library
Electron--proton interactions at ISABELLE. [Possible experimental parameters, 400 GeV, cross sections, kinematics] (open access)

Electron--proton interactions at ISABELLE. [Possible experimental parameters, 400 GeV, cross sections, kinematics]

A calculation of kinematics and cross sections is done for an investigation of the physics possibilities specific to the study of weak interactions in electron-proton interactions at Isabelle at 400 GeV, with an electron/positron storage ring of 20 GeV. (JFP)
Date: August 30, 1977
Creator: Limon, P.J. & Humphrey, J.W.
System: The UNT Digital Library
Recent advances in near-term laser-fusion target design (open access)

Recent advances in near-term laser-fusion target design

Advances in near-term laser-driven fusion pellet design are described. We report the addition of angle dependent absorption and the introduction of a new formulation of the ponderomotive force. The first application of the Incomplete Cholesky-Conjugate Gradient iterative matrix solution method to the LASNEX radiation diffusion package is discussed. A brief overview of experimental results relevant to target simulation is given. We compare LASNEX calculations with recently published Soviet pellet design calculations. Finally, we discuss optimization of exploding pusher targets at 20 TW.
Date: August 30, 1977
Creator: Mead, W.C.
System: The UNT Digital Library
World Sheet Commuting beta-gamma CFT and Non-Relativistic StringTheories (open access)

World Sheet Commuting beta-gamma CFT and Non-Relativistic StringTheories

We construct a sigma model in two dimensions with Galilean symmetry in flat target space similar to the sigma model of the critical string theory with Lorentz symmetry in 10 flat spacetime dimensions. This is motivated by the works of Gomis and Ooguri[1] and Danielsson et. al.[2, 3]. Our theory is much simpler than their theory and does not assume a compact coordinate. This non-relativistic string theory has a bosonic matter {beta}{gamma} CFT with the conformal weight of {beta} as 1. It is natural to identify time as a linear combination of {gamma} and {bar {gamma}} through an explicit realization of the Galilean boost symmetry. The angle between {gamma} and {bar {gamma}} parametrizes one parameter family of selection sectors. These selection sectors are responsible for having a non-relativistic dispersion relation without a nontrivial topology in the non-relativistic setup, which is one of the major differences from the previous works[1, 2, 3]. This simple theory is the non-relativistic analogue of the critical string theory, and there are many different avenues ahead to be investigated. We mention a possible consistent generalization of this theory with different conformal weights for the {beta}{gamma} CFT. We also mention supersymmetric generalizations of these theories.
Date: August 30, 2007
Creator: Kim, Bom Soo
System: The UNT Digital Library
Overview of the National Ignition Facility (open access)

Overview of the National Ignition Facility

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory will be the world's largest and most powerful laser system for inertial confinement fusion (ICF) and experiments studying high energy density (HED) science. NIF is a 192 beam Nd-glass laser facility that will produce 1.8 MJ, 500 TW of ultraviolet light making it over fifty times more energetic than present ICF facilities. The NIF Project began in 1995 and is scheduled for completion in 2009. Ignition experiments on NIF, which will use tritium, are scheduled to begin in 2010. Tritium will arrive at the facility in individual target assemblies. The assemblies will be mounted to the Cryogenic TARget POSitioner (TARPOS), which provides the cryogenic cooling systems necessary to complete the formation of the ignition target's fuel ice layer. It also provides the positioning system that transports and holds the target at the center of the NIF chamber during a shot. After a shot, unburned tritium will be captured by the cryopumps. Upon regeneration, the cryopump effluent will be directed to the Tritium Processing System, part of NIF's. Personnel and Environmental Protection Systems. These systems also include, local contamination control systems, area and stack tritium monitoring systems, a decontamination area, and …
Date: August 30, 2007
Creator: Moses, Edward
System: The UNT Digital Library
TASI Lectures on the cosmological constant (open access)

TASI Lectures on the cosmological constant

The energy density of the vacuum, Lambda, is at least 60 orders of magnitude smaller than several known contributions to it. Approaches to this problem are tightly constrained by data ranging from elementary observations to precision experiments. Absent overwhelming evidence to the contrary, dark energy can only be interpreted as vacuum energy, so the venerable assumption that Lambda=0 conflicts with observation. The possibility remains that Lambda is fundamentally variable, though constant over large spacetime regions. This can explain the observed value, but only in a theory satisfying a number of restrictive kinematic and dynamical conditions. String theory offers a concrete realization through its landscape of metastable vacua.
Date: August 30, 2007
Creator: Bousso, Raphael & Bousso, Raphael
System: The UNT Digital Library
Lawrence Livermore National Laboratory Workshop Characterization of Pathogenicity, Virulence and Host-Pathogen Interactions (open access)

Lawrence Livermore National Laboratory Workshop Characterization of Pathogenicity, Virulence and Host-Pathogen Interactions

The threats of bio-terrorism and newly emerging infectious diseases pose serious challenges to the national security infrastructure. Rapid detection and diagnosis of infectious disease in human populations, as well as characterizing pathogen biology, are critical for reducing the morbidity and mortality associated with such threats. One of the key challenges in managing an infectious disease outbreak, whether through natural causes or acts of overt terrorism, is detection early enough to initiate effective countermeasures. Much recent attention has been directed towards the utility of biomarkers or molecular signatures that result from the interaction of the pathogen with the host for improving our ability to diagnose and mitigate the impact of a developing infection during the time window when effective countermeasures can be instituted. Host responses may provide early signals in blood even from localized infections. Multiple innate and adaptive immune molecules, in combination with other biochemical markers, may provide disease-specific information and new targets for countermeasures. The presence of pathogen specific markers and an understanding of the molecular capabilities and adaptations of the pathogen when it interacts with its host may likewise assist in early detection and provide opportunities for targeting countermeasures. An important question that needs to be addressed is …
Date: August 30, 2006
Creator: Krishnan, A.
System: The UNT Digital Library
Mechanical and Electrical Properties of CdTe Tetrapods Studied byAtomic Force Microscopy (open access)

Mechanical and Electrical Properties of CdTe Tetrapods Studied byAtomic Force Microscopy

The mechanical and electrical properties of CdTe tetrapod-shaped nanocrystals have been studied with atomic force microscopy. Tapping mode images of tetrapods deposited on silicon wafers revealed that they contact the surface with the ends of three arms. The length of these arms was found to be 130 {+-} 10 nm. A large fraction of the tetrapods had a shortened vertical arm as a result of fracture during sample preparation. Fracture also occurs when the applied load is a few nanonewtons. Compression experiments with the AFM tip indicate that tetrapods with the shortened vertical arm deform elastically when the applied force was less than 50 nN. Above 90 nN additional fracture events occurred that further shorted the vertical arm. Loads above 130 nN produced irreversible damage to the other arms as well. Current-voltage characteristics of tetrapods deposited on gold indicated semiconducting behavior with a current gap of {approx}2 eV at low loads (<50 nN) and a narrowing to about 1 eV at loads between 60 and 110 nN. Atomic calculation of the deformation suggests that the ends of the tetrapod arms are stuck during compression so that the deformations are due to bending modes. The reduction of the current gap is …
Date: August 30, 2007
Creator: Fang, Liang; Park, Jeong Young; Cui, Yi; Alivisatos, Paul; Shcrier, Joshua; Lee, Byounghak et al.
System: The UNT Digital Library
Fabrication of Planar Laser Targets with Sub-Micrometer Thickness Uniformity (open access)

Fabrication of Planar Laser Targets with Sub-Micrometer Thickness Uniformity

None
Date: August 30, 2005
Creator: Bono, M.; Castro, C.; Griffith, L.; Hibbard, R.; Kass, J. & Satcher, J.
System: The UNT Digital Library
Frequency-Domain Multiplexed Readout for Superconducting Gamma-Ray Detectors (open access)

Frequency-Domain Multiplexed Readout for Superconducting Gamma-Ray Detectors

We are developing a frequency-multiplexed readout for arrays of high-resolution Gamma detectors based on superconducting transition edge sensors (TESs). Each sensor is part of an LCR resonant circuit and is biased at an identifying carrier frequency. Several carrier signals are added and amplified with a single SQUID preamplifier at 4 K. Gamma absorption modulates the amplitude of the carrier, and demodulation at room temperature retrieves the initial temperature evolution of the sensor. This multiplexing system has originally been developed to read out large arrays of bolometers for cosmic microwave background studies. To accommodate the faster Gamma-ray signals, its demodulator bandwidth is being extended to 20 kHz to allow reading out up to eight TESs with a detector bandwidth of 10 kHz. Here we characterize the system noise performance and show how this multiplexing scheme can be adapted to read out arrays of superconducting Gamma-ray detectors.
Date: August 30, 2006
Creator: Dreyer, Jonathan G.; Arnold, Kam; Lanting, Trevor M.; Dobbs, Matt A.; Friedrich, Stephan; Lee, Adrian T. et al.
System: The UNT Digital Library
SELECTIVITY IN ZEOLITE OCCLUSION OF OLEFINS (open access)

SELECTIVITY IN ZEOLITE OCCLUSION OF OLEFINS

Selective occlusions of straight-chain paraffins in the presence of branched-chain hydrocarbons by naturally occurring zeolites of suitable dimension was reported as early as 1944 by Barrer and Ibbitson. More recently the capacity of synthetic zeolites or molecular sieves to absorb exclusively the straight-chain hydrocarbons from complex hydrocarbon mixtures has found extensive application in the petroleum industry. Under the conditions developed for most sieving operations any normal olefins present are occluded along with the normal paraffins. A supplemental separation technique must be employed to obtain n-paraffins free of olefins.
Date: August 30, 1966
Creator: Fenselau, Catherine & Calvin, Melvin
System: The UNT Digital Library
XRM2005 Conference Summary (open access)

XRM2005 Conference Summary

X-ray microscopy is at a state of rapid development. The presentations at the Conference covered the latest developments in the field.
Date: August 30, 2005
Creator: Kirz, Janos
System: The UNT Digital Library
Three Frontiers in the Thermodynamics of Protein Solutions (open access)

Three Frontiers in the Thermodynamics of Protein Solutions

Three examples illustrate the versatility and usefulness of biothermodynamics. The first example concerns calculation of a phase diagram for aqueous lysozyme with a new potential of mean force that takes the Hofmeister effect into account; such calculations may be useful for design of a separation process where addition of a salt to an aqueous protein mixture precipitates a target protein. The second example concerns thermodynamic studies to elucidate the effect of an organic cosolvent on the mechanism of crystallizing aqueous insulin. The final example concerns a thermodynamic contribution to mitigating the AIDS epidemic; it indicates how isothermal-titration-calorimetry studies are helpful for choosing an optimum inhibitor that is effective not only for the wild-type HIV protease but also for at least some of its mutants.
Date: August 30, 2006
Creator: Prausnitz, John & Hagar, Loddie
System: The UNT Digital Library
Integration of Nevada Test Site (NTS) Work Control Programs and Incorporating Integrated Safety Management (ISM) into Activity Level Work Planning and Control (open access)

Integration of Nevada Test Site (NTS) Work Control Programs and Incorporating Integrated Safety Management (ISM) into Activity Level Work Planning and Control

This session will examine a method developed by Federal and Contractor personnel at the Nevada Site Office (NSO) to improve the planning and execution of work activities utilizing an Activity Level Work Control process in response to Defense Nuclear Facilities Safety Board (DNFSB) Recommendation 2004-1, Oversight of Complex, High-Hazard Nuclear Operations. The process was initially developed during Fiscal Year (FY) 2007, and implementation is commencing during the fourth quarter of FY 2008. This process will significantly enhance the flexibility and the appropriate rigor in the performance of work activities.
Date: August 30, 2008
Creator: Breen, Mike Kinney and Kevin
System: The UNT Digital Library
Rayleigh-Taylor Shock Waves (open access)

Rayleigh-Taylor Shock Waves

Beginning from a state of hydrostatic equilibrium, in which a heavy gas rests atop a light gas in a constant gravitational field, Rayleigh-Taylor instability at the interface will launch a shock wave into the upper fluid. The rising bubbles of lighter fluid act like pistons, compressing the heavier fluid ahead of the fronts and generating shocklets. These shocklets coalesce in multidimensional fashion into a strong normal shock, which increases in strength as it propagates upwards. Large-eddy simulations demonstrate that the shock Mach number increases faster in three dimensions than it does in two dimensions. The generation of shocks via Rayleigh-Taylor instability could have profound implications for astrophysical flows.
Date: August 30, 2007
Creator: Olson, B J & Cook, A W
System: The UNT Digital Library
IRRADIATION OF 3- SUBSTITUTED-2-PHENYLOXAZIRIDINES (open access)

IRRADIATION OF 3- SUBSTITUTED-2-PHENYLOXAZIRIDINES

It was noted previously that 3-(p-dimethylamino)-2-phenyloxaziridine (I) and 3-(p-dimethylamino)-2-(m-nitrophenyl)oxaziridine were photosensitive. Further study on the irradiation (in a variety of solvents under nitrogen) of (I), 2,3-diphenyloxaziridine (II), and 3-(p-nitrophenyl)-2-phenyloxaziridine (III) indicates the major photoreaction to be cleavage to the aldehyde and an intermediate which forms aniline and azobenzene. There is also formed in the photolysis varying amounts of the corresponding anilide. A table provided gives the yields in three different solvents.
Date: August 30, 1967
Creator: Splitter, Janet S. & Calvin, Melvin.
System: The UNT Digital Library
Commercial bacterial colony counter for semiautomatic track counting (open access)

Commercial bacterial colony counter for semiautomatic track counting

Bacterial colony counters have not been widely used for track counting. However, they do provide an economical alternative to sophisticated optical analyzers for applications that require reproducible track density measurements for large numbers of samples. Simple measurements of size characteristics can be made when there is little need for high resolutions. Such systems are particularly well suited for neutron and alpha dosimetry work, particularly if electrochemical etching or some other track enhancement method has been used. 5 refs., 3 figs.
Date: August 30, 1983
Creator: Griffith, R.V.; McMahon, T.A. & Espinosa, G.
System: The UNT Digital Library
Status of tandem-mirror confinement (open access)

Status of tandem-mirror confinement

Recent end-stopping experiments in TMX-Upgrade show strong plugging of the central cell by lower-density plugs, requiring both electron-cyclotron heating (ECRH) and 47/sup 0/ neutral-beam injection, consistent with the thermal-barrier concept. These experiments have low density (n < 10/sup 12/ cm/sup -3/) due to inefficient ECRH power coupling. Hot-ion and hot-electron buildup are consistent with Fokker-Planck calculations. No ion-cyclotron activity is observed in the plugs; occasional electron-cyclotron activity is observed. With plugging, axial lifetimes (tau/sub parallel/ > 40 ms) are larger than radial (tau/sub perpendicular/ = 5 to 10 ms) due to observed non-ambipolar ion transport. Recent tandem-mirror theoretical activities are also surveyed.
Date: August 30, 1983
Creator: Baldwin, D.E.
System: The UNT Digital Library
Magnetic reconnection simulation using the 2. 5D em (electromagnetic) direct implicit code AVANTI (open access)

Magnetic reconnection simulation using the 2. 5D em (electromagnetic) direct implicit code AVANTI

Collisionless reconnection of magnetic field lines depends upon electron inertia effects and details of the electron and ion distribution functions, thus requiring a kinetic description of both. Though traditional explicit PIC techniques provide this description in principle, they are severely limited in parameters by time step constraints. This parameter regime has been expanded by using the recently constructed 2.5 D electromagnetic code AVANTI in this work. The code runs stably with arbitrarily large {Delta}t and is quite robust with respect to large fluctuations occurring due to small numbers of particles per cell. We have found several qualitatively new features. The reconnection process is found to occur in distinct stages: early spontaneous reconnection fed by the free energy of an initial anisotropy in the electron component, coalescence of the resulting small-scale filaments of electron current, accompanied by electron jetting, and oscillatory flow of electrons through the magnetic X-point, superposed on continuing nonlinear growth of ion-mediated reconnection. The time evolution of stage is strongly dependent on M{sub i}/m{sub e}. 12 refs., 6 figs.
Date: August 30, 1988
Creator: Hewett, D. W.; Francis, G. E. & Max, C. E.
System: The UNT Digital Library
Time-resolved suprathermal x-rays (open access)

Time-resolved suprathermal x-rays

Temporally resolved x-ray spectra in the range of 1 to 20 keV have been obtained from gold disk targets irradiated by 1.06 ..mu..m laser pulses from the Argus facility. The x-ray streak camera used for the measurement has been calibrated for streak speed and dynamic range by using an air-gap Fabry-Perot etalon, and the instrument response has been calibrated using a multi-range monoenergetic x-ray source. The experimental results indicate that we are able to observe the ''hot'' x-ray temperature evolve in time and that the experimentally observed values can be qualitatively predicted by LASNEX code computations when the inhibited transport model is used.
Date: August 30, 1978
Creator: Lee, P.H.Y. & Rosen, M.D.
System: The UNT Digital Library
Gyrokinetic and global fluid simulations of tokamak microturbulence and transport (open access)

Gyrokinetic and global fluid simulations of tokamak microturbulence and transport

Results are presented from the first systematic nonlinear kinetic simulation study of the swings and parameter dependences of toroidal ion-temperature-gradient (ITG) turbulence and transport, and from the first such study that includes sheared toroidal flows. Key results include the observation of clear gyroBohm scaling of the turbulent transport and of a surprisingly weak dependence of the transport on toroidal flow shear. Based on the simulation results, a parameterization of the transport is given that includes the dependence on all of the relevant physical parameters. The transition from local to nonlocal transport as a function of the profile scale length has been investigated using two-dimensional global fluid simulations of dissipative drift-wave turbulence. Local gyroBohm scaling is observed, except at very short profile scale lengths.
Date: August 30, 1994
Creator: Dimits, A. M.; Byers, J. A.; Williams, T. J.; Cohen, B. I.; Xu, W. Q.; Cohen, R. H. et al.
System: The UNT Digital Library
Restoring locality with faster-than-light velocities (open access)

Restoring locality with faster-than-light velocities

The idea of ``locality`` is a deep rooted concept. It does not have to be abandoned even if ``loophole free`` EPR experiments are performed and confirm the predictions of quantum theory. To satisfy locality, one can imagine that influences at a distance are exerted via mechanisms involving an ether and effects propagating in that ether a velocity V > c. Such model of physical phenomena is not Lorentz invariant but, with V large enough, the model can be made to reproduce the results of all experiments where quantum mechanics and Lorentz invariance have been verified.
Date: August 30, 1993
Creator: Eberhard, P. H.
System: The UNT Digital Library
A 10 kHz Short-Stroke Rotary Fast Tool Servo (open access)

A 10 kHz Short-Stroke Rotary Fast Tool Servo

None
Date: August 30, 2004
Creator: Montesanti, R C & Trumper, D L
System: The UNT Digital Library
Large-scale search for dark-matter axions (open access)

Large-scale search for dark-matter axions

We review the status of two ongoing large-scale searches for axions which may constitute the dark matter of our Milky Way halo. The experiments are based on the microwave cavity technique proposed by Sikivie, and marks a ''second-generation'' to the original experiments performed by the Rochester-Brookhaven-Fermilab collaboration, and the University of Florida group.
Date: August 30, 2000
Creator: Kinion, D. & van Bibber, K.
System: The UNT Digital Library