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Laser-Compton Scattering as a Potential Electron Beam Monitor (open access)

Laser-Compton Scattering as a Potential Electron Beam Monitor

LCS experiments were carried out at the Idaho Accelerator Center (IAC); sharp monochromatic x-ray lines were observed. These are produced using the so-called inverse Compton effect, whereby optical laser photons are collided with a relativistic electron beam. The back-scattered photons are then kinematically boosted to keV x-ray energies. We have first demonstrated these beams using a 20 MeV electron beam collided with a 100 MW, 7 ns Nd; YAG laser. We observed narrow LCS x-ray spectral peaks resulting from the interaction of the electron beam with the Nd; YAG laser second harmonic (532 nm). The LCS x-ray energy lines and energy deviations were measured as a function of the electron beam energy and enery-spread respectively. The results showed good agreement with the predicted valves. LCS could provide an exellent probe of electron beam energy, energy spread, transverse and longitudinal distribution and direction.
Date: December 14, 2002
Creator: Chouffani, K.; Wells, D.; Harmon, F.; Lancaster, G. & Jones, J.
System: The UNT Digital Library
Synthesis of (plus or minus) [5-{sup 3}H] N'-Nitrosoanatabine, a tobacco-specific nitrosamine (open access)

Synthesis of (plus or minus) [5-{sup 3}H] N'-Nitrosoanatabine, a tobacco-specific nitrosamine

Tobacco-specific N'-nitrosamines (TSNA) are a unique class of systemic organ-specific carcinogens. The TSNA are formed by N-nitrosation of nicotine and of the minor tobacco alkaloids after harvesting of tobacco and during smoking. The N-nitrosation of anatabine leads to N'-nitrosoanatabine (NAT; 1-nitroso-1,2,3,4-tetrahydro-2,3'-bipyridyl) which requires in-depth assays in laboratory animals other than the rat. Furthermore, delineation of its tissue distribution and metabolism is needed for structure:activity comparisons with other TSNA and for the assessment of potential human risk from this TSNA. We have, therefore, synthesized (+)[5-3H]NAT. 5-Bromo-3-pyridine-carboxaldehyde was condensed with ethyl carbamate prior to Diels-Alder reaction with 1,4-butadiene to give the racemic anatabine ring system. Hydrolysis followed by reduction with LiAlT4 and nitrosation, led to (+)[5-3H]NAT (60 percent yield, specific activity 266 mCi/mmol, radiochemical purity of >99 percent).
Date: June 14, 2002
Creator: Desai, Dhimant; Lin, Guoying; Morimoto, Hiromi; Williams, Philip G.; El-Bayoumy, Karam & Amin, Shantu
System: The UNT Digital Library
The Advanced Light Source: A third-generation Synchrotron Radiation Source (open access)

The Advanced Light Source: A third-generation Synchrotron Radiation Source

The Advanced Light Source (ALS) at the E.O. Lawrence Berkeley National Laboratory (Berkeley Lab) of the University of California is a ''third-generation'' synchrotron radiation source optimized for highest brightness at ultraviolet and soft x-ray photon energies. It also provides world-class performance at hard x-ray photon energies. Berkeley Lab operates the ALS for the United States Department of Energy as a national user facility that is available 24 hours/day around the year for research by scientists from industrial, academic, and government laboratories primarily from the United States but also from abroad.
Date: August 14, 2002
Creator: Robinson, Arthur L.
System: The UNT Digital Library
[3H]Azidodantrolene photoaffinity labeling, synthetic domain peptides and monoclonal antibody reactivity identify the dantrolene binding sequence on RyR1 (open access)

[3H]Azidodantrolene photoaffinity labeling, synthetic domain peptides and monoclonal antibody reactivity identify the dantrolene binding sequence on RyR1

Dantrolene is a drug that suppresses intracellular Ca2+ release from sarcoplasmic reticulum in normal skeletal muscle and is used as a therapeutic agent in individuals susceptible to malignant hyperthermia. Though its precise mechanism of action has not been elucidated, we have identified the N-terminal region (amino acids 1-1400) of the skeletal muscle isoform of the ryanodine receptor (RyR1), the primary Ca2+ release channel in sarcoplasmic reticulum, as a molecular target for dantrolene using the photoaffinity analog [3H]azidodantrolene(1). Here, we demonstrate that heterologously expressed RyR1 retains its capacity to be specifically labeled with [3H]azidodantrolene,indicating that muscle specific factors are not required for this ligand-receptor interaction. Synthetic domain peptides of RyR1, previously shown to affect RyR1 function in vitro and in vivo, were exploited as potential drug binding site mimics and used in photoaffinity labeling experiments. Only DP1 and DP1-2, peptide s containing the amino acid sequence corresponding to RyR1 residues 590-609, were specifically labeled by [3H]azidodantrolene. A monoclonal anti-RyR1 antibody which recognizes RyR1 and its 1400 amino acid N-terminal fragment, recognizes DP1 and DP1-2 in both Western blots and immunoprecipitation assays, and specifically inhibits [3H]azidodantrolene photolabeling of RyR1 and its N-terminal fragment in sarcoplasmic reticulum. Our results indicate that synthetic domain …
Date: June 14, 2002
Creator: Paul-Pletzer, Kalanethee; Yamamoto, Takeshi; Bhat, Manju B.; Ma, Jianjie; Ikemoto, Noriaki; Jimenez, Leslie S. et al.
System: The UNT Digital Library
Design and simulation of a multi-beamlet injector for a highcurrent accelerator (open access)

Design and simulation of a multi-beamlet injector for a highcurrent accelerator

A multi-beamlet approach to a high current ion injector, whereby a large number of beamlets are accelerated and then merged to form a single beam, offers a number of potential advantages over a monolithic single beam injector. These advantages include a smaller transverse footprint, more control over the shaping and aiming of the beam, and more flexibility in the choice of ion sources. A potential drawback however is a larger emittance. In this paper, we seek to understand the merging of the beamlets and how it determines the emittance. When the constraints imposed by beam propagation physics and practical engineering issues are included, the design is reduced to a few free parameters. We describe the physics design of a multi-beamlet injector, and produce a design for an example set of parameters. Extensive use of 2-D and 3-D particle simulations was made in understanding the injector. Design tolerances and sensitivities are discussed in general and in relation to the example.
Date: February 14, 2002
Creator: Grote, David P.; Henestroza, Enrique & Kwan, Joe W.
System: The UNT Digital Library
CuPt-type ordering of MOCVD In{sub 0.49}Al{sub 0.51}P. (open access)

CuPt-type ordering of MOCVD In{sub 0.49}Al{sub 0.51}P.

CuPt-type ordering in In{sub 0.49}Al{sub 0.51}P is studied by TEM. The lattice-matched film was grown by MOCVD on a GaAs substrate oriented 10{sup o} off (001) towards [110], at 650 C and 25 nm/min. TEM [110] and [1{bar 1}0] cross-sections (XS) were made by wedge polishing and 2 kV Ar ion milling. In CuPt-type ordering of In{sub 0.52}Ga{sub 0.48}P, alternating In-Ga-In-Ga {l_brace}111{r_brace} planes of group III atoms produce 1/2 {bar 1}11 and 1/2 1{bar 1}1 order spots in the 110 SADP, while the [1{bar 1}0] SADP shows no order spots [1-3]. A few studies have reported this type of order in In{sub 0.49}Al{sub 0.51}P [4]. The 004 BF image of the [1{bar 1}0] XS in Fig. 1 shows uneven light/dark contrast modulation due to phase separation often observed in In{sub 0.52}Ga{sub 0.48}P. There are also light/dark layers marked ML parallel to the film growth plane; such unintentional multilayers have also been observed [5] but their origin is not understood. Order lamellae {approx}1.5 nm thick inclined at a shallow angle to the growth plane overlap the multilayer to produce Moire fringe contrast. Fig. 2 is a DF image showing the thin ordered domains in the [1{bar 1}0] XS, which are inclined …
Date: March 14, 2002
Creator: Kosel, T. H.; Hall, D. C.; Dupuis, R. D.; Heller, R. D. & Cook, R. E.
System: The UNT Digital Library
Assessing Groundwater Model Uncertainty for the Central Nevada Test Area (open access)

Assessing Groundwater Model Uncertainty for the Central Nevada Test Area

The purpose of this study is to quantify the flow and transport model uncertainty for the Central Nevada Test Area (CNTA). Six parameters were identified as uncertain, including the specified head boundary conditions used in the flow model, the spatial distribution of the underlying welded tuff unit, effective porosity, sorption coefficients, matrix diffusion coefficient, and the geochemical release function which describes nuclear glass dissolution. The parameter uncertainty was described by assigning prior statistical distributions for each of these parameters. Standard Monte Carlo techniques were used to sample from the parameter distributions to determine the full prediction uncertainty. Additional analysis is performed to determine the most cost-beneficial characterization activities. The maximum radius of the tritium and strontium-90 contaminant boundary was used as the output metric for evaluation of prediction uncertainty. The results indicate that combining all of the uncertainty in the parameters listed above propagates to a prediction uncertainty in the maximum radius of the contaminant boundary of 234 to 308 m and 234 to 302 m, for tritium and strontium-90, respectively. Although the uncertainty in the input parameters is large, the prediction uncertainty in the contaminant boundary is relatively small. The relatively small prediction uncertainty is primarily due to the …
Date: June 14, 2002
Creator: Pohll, Greg; Pohlmann, Karl; Hassan, Ahmed; Chapman, Jenny & Mihevc, Todd
System: The UNT Digital Library
A Comparison of Methods Used to Evaluate Intakes of Transuranics Influenced by Chelation Therapy (open access)

A Comparison of Methods Used to Evaluate Intakes of Transuranics Influenced by Chelation Therapy

A comparison of methods is used to evaluate the intake of transuranics influenced by chelation therapy. The purpose of this paper is to introduce the mechanistic method by using it to validate Hall's method and Jech's method. This is accomplished by using the mechanistic method to generate a known set of data suitable for benchmarking all three methods.
Date: May 14, 2002
Creator: La Bone, T.
System: The UNT Digital Library
Study of the radiation damage of Nd-Fe-B permanent magnets. (open access)

Study of the radiation damage of Nd-Fe-B permanent magnets.

Nd-Fe-B permanent magnets are highly desirable for use in the insertion devices of synchrotron radiation sources due to their high remanence, or residual magnetic induction, and intrinsic coercivity. However, the radiation environment within high-energy electron storage rings necessitates the determination of the degree of radiation sensitivity as well as the mechanisms of radiation-induced demagnetization. A 0.5% change in the residual induction due to radiation damage cannot be tolerated in these devices. Sample Nd-Fe-B permanent magnets were irradiated at the Advanced Photon Source (APS) with bending magnet x-rays up to an absorbed dose of approximately 280 Mrad (1 Mrad = 10 kGy). Sample magnets were also irradiated with 60 Co {gamma}-rays up to an absorbed dose of 700 Mrad at the National Institute of Standards and Technology's (NIST) standard gamma irradiation facility. Changes in the residual induction were found to be within the experimental uncertainties for both the x-ray and {gamma}-ray irradiations. Sample Nd-Fe-B permanent magnets were then irradiated at Oak Ridge National Laboratory's (ORNL) Californium User Facility for Neutron Science with fast neutrons up to a total fast fluence of 1.61 x 10{sup 14} n/cm{sup 2} and with thermal neutrons up to a total thermal fluence of 2.94 x 10{sup …
Date: February 14, 2002
Creator: Job, P. K.; Alderman, J. M.; Martin, R. C. & Simmons, C. M.
System: The UNT Digital Library
The low-energy undulator test line : a SASE FEL operating from 660 to 130 nm. (open access)

The low-energy undulator test line : a SASE FEL operating from 660 to 130 nm.

None
Date: August 14, 2002
Creator: Biedron, S. G.; Borland, M.; Den Hartog, P.; Dejus, R.; Erdmann, M.; Huang, Z. et al.
System: The UNT Digital Library
Labs21 Environmental Performance Criteria: Toward 'LEED (trademark) for Labs' (open access)

Labs21 Environmental Performance Criteria: Toward 'LEED (trademark) for Labs'

Laboratory facilities present a unique challenge for energy efficient and sustainable design, with their inherent complexity of systems, health and safety requirements, long-term flexibility and adaptability needs, energy use intensity, and environmental impacts. The typical laboratory is about three to five times as energy intensive as a typical office building and costs about three times as much per unit area. In order to help laboratory stakeholders assess the environmental performance of their laboratories, the Labs21 program, sponsored by the US Environmental Protection Agency and the US Department of Energy, is developing the Environmental Performance Criteria (EPC), a point-based rating system that builds on the LEED(TM) rating system. Currently, LEED(TM) is the primary tool used to rate the sustainability of commercial buildings. However, it lacks some attributes essential to encouraging the application of sustainable design principles to laboratory buildings. Accordingly, the EPC has additions and modifications to the prerequisites and credits in each of the six sections of LEED(TM). It is being developed in a consensus-based approach by a diverse group of architects, engineers, consulting experts, health & safety personnel and facilities personnel. This report describes the EPC version 2.0, highlighting the underlying technical issues, and describes implications for the development …
Date: October 14, 2002
Creator: Mathew, Paul; Sartor, Dale; Lintner, William & Wirdzek, Phil
System: The UNT Digital Library
Present and future electroweak precision measurements and the indirect determination of the mass of the Higgs boson (open access)

Present and future electroweak precision measurements and the indirect determination of the mass of the Higgs boson

We discuss the experimental and theoretical uncertainties on precision electroweak observables and their relationship to the indirect constraints on the Higgs boson mass, MH, in the Standard Model (SM). The critical experimental measurements (M{sub W}, sin{sup 2}{theta}{sub eff}, m{sub t},...) are evaluated in terms of their present uncertainties and their prospects for improved precision at future colliders, and their contribution to the constraints on MH. In addition, the current uncertainties of the theoretical predictions for M{sub W} and sin{sup 2} {theta}{sub eff} due to missing higher order corrections are estimated and expectations and necessary theoretical improvements for future colliders are explored. The constraints from rare B decays are also discussed. Analysis of the present experimental and theoretical precisions yield a current upper bound on M{sub H} of {approx} 200 GeV. Including anticipated improvements corresponding to the prospective situation at future colliders (Tevatron Run II, LHC, LC/GigaZ), we find a relative precision of about 25% to 8% (or better) is achievable in the indirect determination of M{sub H}.
Date: February 14, 2002
Creator: al., U. Baur et
System: The UNT Digital Library
Feasibility of natural circulation heat transport in the ENHS. (open access)

Feasibility of natural circulation heat transport in the ENHS.

An analysis has been carried out of natural circulation thermal hydraulics in both the primary and intermediate circuits of the Encapsulated Nuclear Heat Source (ENHS). It is established that natural circulation enhanced by gas injection into the primary coolant above the core, or the intermediate coolant above the heat exchange zone, is effective in transporting the nominal core power to the steam generators without the attainment of excessive system temperatures. Uncertainties in thermophysical properties and wall friction have a relatively small effect upon the calculated best estimate primary and intermediate coolant system temperature rises.
Date: February 14, 2002
Creator: Sienicki, J. J.
System: The UNT Digital Library
The nuclear liquid-vapor phase transition: Equilibrium between phases or free decay in vacuum? (open access)

The nuclear liquid-vapor phase transition: Equilibrium between phases or free decay in vacuum?

Recent analyses of multifragmentation in terms of Fisher's model and the related construction of a phase diagram brings forth the problem of the true existence of the vapor phase and the meaning of its associated pressure. Our analysis shows that a thermal emission picture is equivalent to a Fisher-like equilibrium description which avoids the problem of the vapor and explains the recently observed Boltzmann-like distribution of the emission times. In this picture a simple Fermi gas thermometric relation is naturally justified. Low energy compound nucleus emission of intermediate mass fragments is shown to scale according to Fisher's formula and can be simultaneously fit with the much higher energy ISiS multifragmentation data.
Date: November 14, 2002
Creator: Phair, L.; Moretto, L. G.; Elliott, J. B. & Wozniak, G. J.
System: The UNT Digital Library
Engineering properties of superhard films with ion energy and post-deposition processing (open access)

Engineering properties of superhard films with ion energy and post-deposition processing

Recent developments in plasma synthesis of hard materials using energetic ions are described. Metal Plasma Immersion Ion Implantation and Deposition (MePIIID) has been used to prepare several hard films: from diamondlike carbon (DLC) to carbides, from nitrides to oxides. The energy of the depositing species is controlled to maximize adhesion as well as to change the physical and chemical properties of the films. Adhesion is promoted by the creation of a graded interface between the film and the substrate. The energy of the depositing ions is also used to modify and control the intrinsic stresses and the microstructure of the films. The deposition is carried out at room temperature, which is important for temperature sensitive substrates. A correlation between intrinsic stresses and the energetics of the deposition is presented for the case of DLC films, and means to reduce stress levels are discussed.
Date: October 14, 2002
Creator: Monteiro, Othon R. & Delplancke-Ogletree, Mari-Paule
System: The UNT Digital Library
Status of the CDF II experiment (open access)

Status of the CDF II experiment

The status of the CDF II experiment is described. Since operations start-up for run II data taking in March 2001, the CDF detector has been commissioned using about 20 pb{sup -1} of data provided by the Tevatron (utilized about 4-8). Most detector components are ready for physics quality data. The goal is to present the first physics results by summer-fall 2002.
Date: August 14, 2002
Creator: Rolli, S.
System: The UNT Digital Library
Indium nitride: A narrow gap semiconductor (open access)

Indium nitride: A narrow gap semiconductor

The optical properties of wurtzite InN grown on sapphire substrates by molecular-beam epitaxy have been characterized by optical absorption, photoluminescence, and photomodulated reflectance techniques. All these three characterization techniques show an energy gap for InN between 0.7 and 0.8 eV, much lower than the commonly accepted value of 1.9 eV. The photoluminescence peak energy is found to be sensitive to the free electron concentration of the sample. The peak energy exhibits a very weak hydrostatic pressure dependence and a small, anomalous blueshift with increasing temperature. The bandgap energies of In-rich InGaN alloys were found to be consistent with the narrow gap of InN. The bandgap bowing parameter was determined to be 1.43 eV in InGaN.
Date: August 14, 2002
Creator: Wu, J.; Walukiewicz, W.; Yu, K. M.; Ager, J. W., III; Haller, E. E.; Lu, Hai et al.
System: The UNT Digital Library
Low and medium velocity cavity development for the RIA driver LINAC. (open access)

Low and medium velocity cavity development for the RIA driver LINAC.

None
Date: January 14, 2002
Creator: Shepard, K.W. & Kedzie, M.
System: The UNT Digital Library
Tracking of three variants of transition-free lattices for a proton driver (open access)

Tracking of three variants of transition-free lattices for a proton driver

Transition-free lattices are favored as possible realization of proton drivers. Several variants have been proposed, some of which have considerably different behavior. One of the main quantities used to characterize this behavior is the short term dynamic aperture (DA). In this note we study three different variants of such lattices, and show that the differences in DA among the lattices essentially disappear as soon as magnet multipole errors are included in the simulation. The tracking results can be understood in terms of the normal form based amplitude dependent tune shift and resonance strength coefficients.
Date: October 14, 2002
Creator: Johnstone, Bela Erdelyi and Carol
System: The UNT Digital Library
Graphite Materials Testing in the ATR for Lifetime Management of Magnox Reactors (open access)

Graphite Materials Testing in the ATR for Lifetime Management of Magnox Reactors

A major feature of the Magnox gas cooled reactor design is the graphite core, which acts as the moderator but also provides the physical structure for fuel, control rods, instrumentation and coolant gas channels. The lifetime of a graphite core is dependent upon two principal aging processes: irradiation damage and radiolytic oxidation. Irradiation damage from fast neutrons creates lattice defects leading to changes in physical and mechanical properties and the accumulation of stresses. Radiolytic oxidation is caused by the reaction of oxidizing species from the carbon dioxide coolant gas with the graphite, these species being produced by gamma radiation. Radiolytic oxidation reduces the density and hence the moderating capability of the graphite, but also reduces strength affecting the integrity of core components. In order to manage continued operation over the planned lifetimes of their power stations, BNFL needed to extend their database of the effects of these two phenomena on the ir graphite cores through an irradiation experiment. This paper will discuss the background, purpose, and the processes taken and planned (i.e. post irradiation examination) to ensure meaningful data on the graphite core material is obtained from the irradiation experiment.
Date: March 14, 2002
Creator: Grover, S.B. (INEEL) & Metcalfe, M.P. (BNFL, United Kingdom)
System: The UNT Digital Library
Passive correction of the persistent current effect in Nb3Sn accelerator magnets (open access)

Passive correction of the persistent current effect in Nb3Sn accelerator magnets

Superconducting accelerator magnets must provide a uniform field during operation. However, the field quality significantly deteriorates due to persistent currents induced in superconducting filaments. This effect is especially large for the Nb{sub 3}Sn conductor being implemented in the next generation of accelerator magnets. A simple and inexpensive method of passive correction of the persistent current effect was developed and experimentally verified. This paper describes numerical simulations of the passive correctors and reports the test results.
Date: October 14, 2002
Creator: al., Vadim V. Kashikhin et
System: The UNT Digital Library
Photoinduced changes of reflectivity in single crystals of YBa2Cu3O6.5 (Ortho II) (open access)

Photoinduced changes of reflectivity in single crystals of YBa2Cu3O6.5 (Ortho II)

We report measurements of the photoinduced change in reflectivity of an untwinned single crystal of YBa2Cu3O6.5 in the ortho II structure. The decay rate of the transient change in reflectivity is found to decrease rapidly with decreasing temperature and, below Tc, with decreasing laser intensity. We interpret the decay as a process of thermalization of antinodal quasiparticles, with a rate determined by inelastic scattering of quasiparticle pairs.
Date: March 14, 2002
Creator: Segre, Gino P.; Gedik, Nuh; Orenstein, Joseph; Bonn, Doug A.; Liang, Ruixing & Hardy, Walter N.
System: The UNT Digital Library
Analytic semi-classical quantization of a QCD string with light quarks (open access)

Analytic semi-classical quantization of a QCD string with light quarks

We perform an analytic semi-classical quantization of the straight QCD string with one end fixed and a massless quark on the other, in the limits of orbital and radial dominant motion. Our results well approximate those of the exact numerical semi-classical quantization as well as our exact numerical canonical quantization.
Date: August 14, 2002
Creator: al., Theodore J. Allen et
System: The UNT Digital Library
Elevated stratified layers observed during VTMX. (open access)

Elevated stratified layers observed during VTMX.

A suite of instrumentation including a minisodar, a low-frequency, single-axis sodar, a wind profiling radar and a tethersonde was used during the Vertical Transport and Mixing field study in Salt Lake City, UT, USA, to study the evolution and dynamics of stratified layers that commonly develop during nighttime. The month-long field study provided ten nights with good conditions for tethersonde flights. The real-time sodar display was used to place the tethersonde within and near the stratified layers and to make multiple transects, while atmospheric temperature, moisture, wind speed and wind direction were measured. Not surprisingly, the existence of layers with enhanced acoustic scattering correlated well with regions of potential temperature inversions; however, because wind speeds were invariably low, the Richardson number was rarely less than 0.25. The possible role of moisture in the dynamics of elevated stable layer is discussed.
Date: March 14, 2002
Creator: Coulter, R. L.; Pekour, M. S. & Martin, T. J.
System: The UNT Digital Library