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Acceleration of polarized proton beams (open access)

Acceleration of polarized proton beams

The acceleration of polarized beams in circular accelerators is complicated by the numerous depolarizing spin resonances. Using a partial Siberian snake and a rf dipole that ensure stable adiabatic spin motion during acceleration has made it possible to accelerate polarized protons to 25 GeV at the Brookhaven AGS. Full Siberian snakes are being developed for RHIC to make the acceleration of polarized protons to 250 GeV possible. A similar scheme is being studied for the 800 GeV HERA proton accelerator.
Date: December 31, 1998
Creator: Roser, T.
System: The UNT Digital Library
Accomplishments of the American-Polish Program for Elimination of Low Emissions in Krakow (open access)

Accomplishments of the American-Polish Program for Elimination of Low Emissions in Krakow

Since 1990 the US Department of Energy (DOE) has been involved in a program aimed at reducing air pollution caused by small, coal-fired sources in Poland. The activity is focused on the city of Cracow, Poland with the intention that results will be applicable and extendable to the entire region. The effort under this program has been focused into 5 main areas of interest as follows: (1) energy conservation and extension of central station district heating; (2) replacement of coal- and coke-fired boilers with natural gas-fired boilers; (3) replacement of coal-fired home stoves with electric heating appliances; (4) reduction of emissions from stoker-fired boiler houses; and (5) reduction of emissions from coal-fired home heating stoves.
Date: December 31, 1998
Creator: Butcher, T. A. & Pierce, B.
System: The UNT Digital Library
Adapting perspectives to facilitate knowledge assimilation (open access)

Adapting perspectives to facilitate knowledge assimilation

The notion of perspective when supported in knowledge representation can allow the representation of multiple and varying points of view, some of which may even be inconsistent with one another. In an object-based knowledge representation methodology created and used by the authors, a perspective is defined by consolidating a number of objects and a number of those objects` associated attributes and methods into a view. This view can help partition a knowledge domain into separate portions. A separate portion represents an individual`s view of the knowledge domain. Representation of multiple and varying perspectives may add to the existing knowledge as well as reveal paths to additional knowledge. A simple example is presented where perspectives are used to represent game playing strategies and levels of expertise in those strategies. Players` perspectives are adapted and changed to provide additional knowledge and insight into further game playing strategies. Results show improvement in the playing of the games. Additionally, a more complex problem for applying these techniques is introduced.
Date: December 31, 1998
Creator: Kelsey, R.L. & Webster, R.B.
System: The UNT Digital Library
Adaptive feedforward of estimated ripple improves the closed loop system performance significantly (open access)

Adaptive feedforward of estimated ripple improves the closed loop system performance significantly

The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of Acceleration Production of Tritium (APT) accelerator. This paper addresses the problem of LLRF control system for LEDA. The authors propose an estimator of the ripple and its time derivative and a control law which is based on PID control and adaptive feedforward of estimated ripple. The control law reduces the effect of the deterministic cathode ripple that is due to high voltage power supply and achieves tracking of desired set points.
Date: December 31, 1998
Creator: Kwon, S.; Regan, A.; Wang, Y. M. & Rohlev, T.
System: The UNT Digital Library
An adaptive simulation model for analysis of nuclear material shipping operations (open access)

An adaptive simulation model for analysis of nuclear material shipping operations

Los Alamos has developed an advanced simulation environment designed specifically for nuclear materials operations. This process-level simulation package, the Process Modeling System (ProMoS), is based on high-fidelity material balance criteria and contains intrinsic mechanisms for waste and recycle flows, contaminant estimation and tracking, and material-constrained operations. Recent development efforts have focused on coupling complex personnel interactions, personnel exposure calculations, and stochastic process-personnel performance criteria to the material-balance simulation. This combination of capabilities allows for more realistic simulation of nuclear material handling operations where complex personnel interactions are required. They have used ProMoS to assess fissile material shipping performance characteristics at the Los Alamos National Laboratory plutonium facility (TA-55). Nuclear material shipping operations are ubiquitous in the DOE complex and require the largest suite of varied personnel interacting in a well-timed manner to accomplish the task. They have developed a baseline simulation of the present operations and have estimated the operational impacts and requirement of the pit production mission at TA-55 as a result of the SSM-PEIS. Potential bottlenecks have been explored and mechanisms for increasing operational efficiency are identified.
Date: December 31, 1998
Creator: Boerigter, S.T.; Sena, D.J. & Fasel, J.H.
System: The UNT Digital Library
Advanced buck converter power supply ABCPS for APT (open access)

Advanced buck converter power supply ABCPS for APT

The United States Department of Energy (DOE) is planning to fabricate an Accelerator for the Production of Tritium (APT) at their Savannah River Site, to provide Tritium for national defense. The 1700 million electron volt (MeV) proton beam accelerator will be powered by radio frequency (RF) klystrons. A direct current (DC) power supply is required for each of the approximately two hundred and fifty 1-megawatt (MW) continuous wave klystrons in the RF power system. The requirements are that the power supply meet output performance specifications, provide fault protection for the klystron, have high efficiency, high reliability, good maintainability, and be readily manufacturable. As the power supplies are one of the largest cost elements in the accelerator, a technology review was made to determine the most economical approach to satisfy the requirements. A switch-mode power supply employing a buck-regulator was identified as being potentially the lowest cost approach. As the switch represents a certain development risk, a small-scale prototype has been constructed for evaluation, and has resulted in the decision to fabricate a full-scale prototype power supply. A description of the hardware will be presented.
Date: December 31, 1998
Creator: Street, R.; Overett, T. & Bowles, E.
System: The UNT Digital Library
Aeroelastic behavior of twist-coupled HAWT blades (open access)

Aeroelastic behavior of twist-coupled HAWT blades

As the technology for horizontal axis wind turbines (HAWT) development matures, more novel techniques are required for the capture of additional amounts of energy, alleviation of loads and control of the rotor. One such technique employs the use of an adaptive blade that could sense the wind velocity or rotational speed in some fashion and accordingly modify its aerodynamic configuration to meet a desired objective. This could be achieved in either an active or passive manner, although the passive approach is much more attractive due to its simplicity and economy. As an example, a blade design might employ coupling between bending and/or extension, and twisting so that, as it bends and extends due to the action of the aerodynamic and inertial loads, it also twists modifying the aerodynamic performance in some way. These performance modifications also have associated aeroelastic effects, including effects on aeroelastic instability. To address the scope and magnitude of these effects a tool has been developed for investigating classical flutter and divergence of HAWT blades. As a starting point, an adaptive version of the uniform Combined Experiment Blade will be investigated. Flutter and divergence airspeeds will be reported as a function of the strength of the coupling …
Date: December 31, 1998
Creator: Lobitz, D. W. & Veers, P. S.
System: The UNT Digital Library
Aging and PBX 9502 (open access)

Aging and PBX 9502

Components made from PBX 9502, an insensitive high explosive formulated with triaminotrinitrobenzene (TATB) and Kel-F 800 binder, have been in service for nearly two decades. Since that time, samples have been destructively evaluated to determine if potential changes that might affect safety, reliability, or performance have occurred in the high explosive with time. Data from routine, historical testing is reported elsewhere. This paper focuses on specific tests conducted to evaluate the effects of natural aging on handling sensitivity (through the small-scale tests of Human Electrostatic Discharge, friction, and Drop Weight Impact), compressive strength, and thermal ignition. Also reported are the effects of a radiation environment on TATB. Small-scale sensitivity tests show no differences between aged and unaged material. Observed differences in compressive strength behavior are attributed to conditions of original material rather than aging effects. Thermal ignition by flame and laser methods showed no changes between aged and unaged material. Extreme levels of radiation are shown to have only minimal effects in explosive response tests. PBX 9502 is concluded, once again, to be a very stable material, aging gracefully.
Date: December 31, 1998
Creator: Skidmore, C. B.; Idar, D. J.; Buntain, G. A.; Son, S. F. & Sander, R. K.
System: The UNT Digital Library
Aging phenomenon in metallic plutonium (open access)

Aging phenomenon in metallic plutonium

Today, as with weapons science issues, the monitoring of plutonium aging becomes an important issue for surveillance. The reasons for this are many-fold. First, and perhaps most important, plutonium is radioactive, primarily through the process of alpha decay. This process has many consequences. One pragmatic one is that the alpha particles ejected near the surface can be used with an ionization gauge-type detector to assess the presence of fine plutonium particulates, allowing plutonium handlers and facilities to detect the presence of contamination in virtual real time. But this alpha decay has other consequences for weapon integrity which are not well known. The same surface alpha particles which allow it`s detection, can also cause a variety of problems with materials which may be found in contact with plutonium over extended time periods. However, when this alpha emission occurs within the bulk of the plutonium metal, it is essentially trapped. Within the metal atom lattice, it acquires valence electrons and becomes a helium atom. At the same time that these helium atoms accumulate within the lattice, atomic displacements and damage to the plutonium lattice occurs due to collisions with the energetic uranium and alpha particles. At the current time, the authors have …
Date: December 31, 1998
Creator: Stevens, M.F. & Martz, J.C.
System: The UNT Digital Library
Amplitude path corrections for regional phases in China (open access)

Amplitude path corrections for regional phases in China

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.
System: The UNT Digital Library
[Analysis of Trace Elements in Limestone for Archeological Functions] (open access)

[Analysis of Trace Elements in Limestone for Archeological Functions]

Numerous quarries in the Lutetian limestone formations of the Paris Basin provided stone for the building and the decoration of monuments from antiquity to the present. To determine the origin of stone used for masonry and sculptures in these monuments, a team of geologists and archaeologists has investigated 300 quarries and collected 2,300 samples. Petrographic and paleontologic examination of thin sections allows geologists to distinguish Lutetian limestones from Jurassic and Cretaceous limestones. Geologists also seek to formulate hypotheses regarding the origin of Lutetian limestones used for building and sculpture in the Paris region. In the search for the sources of building and sculptural stone, the analytical methods of geologists are limited because often several quarries produce the same lithofacies. A new tool is now available, however, to attack questions of provenance raised by art historians. Because limestones from different sources have distinctive patterns of trace-element concentrations, compositional analysis by neutron activation allows one to compare building or sculptural stone from one monument with stone from quarries or other monuments. This analytical method subjects a powdered limestone sample to standard neutron activation analysis procedures at Brookhaven National Laboratory. With the help of computer programs, the compositional fingerprints of Lutetian limestones can …
Date: December 31, 1998
Creator: Blanc, A.; Holmes, L. & Harbottle, G.
System: The UNT Digital Library
Analysis of vibration and pressure pulsation in positive displacement drilling motors (open access)

Analysis of vibration and pressure pulsation in positive displacement drilling motors

Three, Moineau principle, positive displacement (drilling) motors were tested on a dynamometer using water, air/mist, and foam. In conjunction with a traditional motor performance test, data were collected at 5000 samples per second using an adapted seismic data acquisition system. Shaft speed, torque, pressure, and three-axis vibration data were processed using Seismic Analysis Code (SAC) to obtain energy density spectrums (EDSs). Cascade plots were generated by plotting the EDSs against shaft speed. The cascade plots revealed that pressure pulses and motor vibrations are closely related to the eccentric rotation of the rotor in the power section. Excessive no-load vibrations were not observed in the small motors and test apparatus used; increasing torque usually decreases the amplitude of vibrations observed. Motor vibration amplitudes were as a rule not increased when compressible fluids were substituted for water.
Date: December 31, 1998
Creator: Hamlin, D. B. & Dreesen, D. S.
System: The UNT Digital Library
Application of molten salt oxidation for the minimization and recovery of plutonium-238 contaminated wastes (open access)

Application of molten salt oxidation for the minimization and recovery of plutonium-238 contaminated wastes

This paper presents the technical and economic feasibility of molten salt oxidation technology as a volume reduction and recovery process for {sup 238}Pu contaminated waste. Combustible low-level waste material contaminated with {sup 238}Pu residue is destroyed by oxidation in a 900 C molten salt reaction vessel. The combustible waste is destroyed creating carbon dioxide and steam and a small amount of ash and insoluble {sup 2328}Pu in the spent salt. The valuable {sup 238}Pu is recycled using aqueous recovery techniques. Experimental test results for this technology indicate a plutonium recovery efficiency of 99%. Molten salt oxidation stabilizes the waste converting it to a non-combustible waste. Thus installation and use of molten salt oxidation technology will substantially reduce the volume of {sup 238}Pu contaminated waste. Cost-effectiveness evaluations of molten salt oxidation indicate a significant cost savings when compared to the present plans to package, or re-package, certify and transport these wastes to the Waste Isolation Pilot Plant for permanent disposal. Clear and distinct cost advantages exist for MSO when the monetary value of the recovered {sup 238}Pu is considered.
Date: December 31, 1998
Creator: Wishau, R.; Ramsey, K.B. & Montoya, A.
System: The UNT Digital Library
Application of X-ray K-edge densitometry in D and D operations (open access)

Application of X-ray K-edge densitometry in D and D operations

K-edge densitometry is a nondestructive assay technique which provides accurate measurement of heavy metal contamination in pipes, containers, and other items encountered in D and D operations. A prototype mobile K-edge instrument has been built and demonstrated in several applications. Results from measurements of uranium in pipes and spent reactor fuel plates, and quantification of mercury and lead in waste drums are presented. In this report the authors briefly describe the theory behind K-edge densitometry. They follow that with a description of the prototype system they have developed, and a presentation of results from demonstrations of this system. They conclude with a discussion of the potential for application of K-edge analysis in D and D operations.
Date: December 31, 1998
Creator: Jensen, T.; Aljundi, T. & Gray, J.N.
System: The UNT Digital Library
Applications of dielectric barrier discharges (open access)

Applications of dielectric barrier discharges

Dielectric barrier discharges (DBDs) in oxygen and air are well established for the production of large quantities of ozone and are more recently being applied to a wider range of plasmachemical processes. Here, the application of DBDs for ozone synthesis, the non-thermal oxidation of volatile organic compounds (VOCs) in air, the generation of incoherent (V)UV radiation and surface processing (etching, ashing) is presented. The main plasmaphysical features of sinusoidally-driven DBDs (transient, filamented, non-thermal plasmas at atmospheric pressure) are described, and a simple plasmachemical reaction pathway for ozone synthesis are give. Experimental results on the degradation of VOCs (2-propanol, trichloroethylene, carbon tetrachloride), as well as byproduct formation is presented for stand-alone DBD treatment, as well as for simultaneous (V)UV illumination of the discharge. Illumination of the discharge with (V)UV can change the plasmachemistry by enhanced formation of certain species of radicals--and thereby change byproduct formation--but also can change the discharge physics, known as the Joshi effect. As an example for generation of excited dimers and exiplexes for the production of incoherent UV light, experimental results on a XeBr* excimer UV light source are presented. Effects of the total and partial pressure of a Xe/Br{sub 2} system, the gap spacing and the …
Date: December 31, 1998
Creator: Falkenstein, Z.
System: The UNT Digital Library
Applications of inventory difference tool at Los Alamos Plutonium Facility (open access)

Applications of inventory difference tool at Los Alamos Plutonium Facility

A prototype computer program reads the inventory entries directly from the Microsoft Access database. Based on historical data, the program then displays temporal trends and constructs a library of rules that encapsulate the system behavior. The analysis of inventory data is illustrated using a combination of realistic and simulated facility examples. Potential payoffs of this methodology include a reduction in time and resources needed to perform statistical tests and a broad applicability to DOE needs such as treaty verification.
Date: December 31, 1998
Creator: Hench, K.W.; Longmire, V.; Yarbro, T.F. & Zardecki, A.
System: The UNT Digital Library
The ARM eddy correlation system for monitoring surface fluxes (open access)

The ARM eddy correlation system for monitoring surface fluxes

The Atmospheric Radiation Measurement (ARM) Program was established by the Department of Energy as part of the US Global Climate Change Research Program to improve methods of determining radiative transfer and cloud processes in large-scale models. The ARM observational facility in the Southern Great Plains (SGP) of the US uses various types of instrument systems to make continuous measurements of the state of the atmosphere, cloud properties, radiative transfer, and other forms of energy transfer. Most of the instrument systems for these continuous observations come from commercial sources; many are adaptations of systems that have been used previously, mostly in short-term field campaigns. Eddy correlation systems (ECORs) are used to measure the air-surface exchange rates of heat, moisture, and momentum at eight locations in the overall area (350 km by 400 km) of the SGP site. At most locations, measurements are made at a height of about three meters above the ground over tilled agricultural land. At 14 other locations, air-surface exchange is measured above grasslands with an energy balance Bowen ratio system.
Date: December 31, 1998
Creator: Hart, R.L.; Cook, D.R. & Wesely, M.L.
System: The UNT Digital Library
Array design and expression evaluation in POOMA II (open access)

Array design and expression evaluation in POOMA II

POOMA is a templated C++ class library for use in the development of large-scale scientific simulations on serial and parallel computers. POOMA II is a new design and implementation of POOMA intended to add richer capabilities and greater flexibility to the framework. The new design employs a generic Array class that acts as an interface to, or view on, a wide variety of data representation objects referred to as engines. This design separates the interface and the representation of multidimensional arrays. The separation is achieved using compile-time techniques rather than virtual functions, and thus code efficiency is maintained. POOMA II uses PETE, the Portable Expression Template Engine, to efficiently represent complex mathematical expressions involving arrays and other objects. The representation of expressions is kept separate from expression evaluation, allowing the use of multiple evaluator mechanisms that can support nested where-block constructs, hardware-specific optimizations and different run-time environments.
Date: December 31, 1998
Creator: Karmesin, S.; Crotinger, J.; Cummings, J.; Haney, S.; Humphrey, W.; Reynders, J. et al.
System: The UNT Digital Library
Artificial neural network simulation of battery performance (open access)

Artificial neural network simulation of battery performance

Although they appear deceptively simple, batteries embody a complex set of interacting physical and chemical processes. While the discrete engineering characteristics of a battery such as the physical dimensions of the individual components, are relatively straightforward to define explicitly, their myriad chemical and physical processes, including interactions, are much more difficult to accurately represent. Within this category are the diffusive and solubility characteristics of individual species, reaction kinetics and mechanisms of primary chemical species as well as intermediates, and growth and morphology characteristics of reaction products as influenced by environmental and operational use profiles. For this reason, development of analytical models that can consistently predict the performance of a battery has only been partially successful, even though significant resources have been applied to this problem. As an alternative approach, the authors have begun development of a non-phenomenological model for battery systems based on artificial neural networks. Both recurrent and non-recurrent forms of these networks have been successfully used to develop accurate representations of battery behavior. The connectionist normalized linear spline (CMLS) network has been implemented with a self-organizing layer to model a battery system with the generalized radial basis function net. Concurrently, efforts are under way to use the feedforward …
Date: December 31, 1998
Creator: O`Gorman, C. C.; Ingersoll, D.; Jungst, R. G. & Paez, T. L.
System: The UNT Digital Library
Assessment of capital requirements for alternative fuels infrastructure under the PNGV program (open access)

Assessment of capital requirements for alternative fuels infrastructure under the PNGV program

This paper presents an assessment of the capital requirements of using six different fuels in the vehicles with tripled fuel economy (3X vehicles) that the Partnership for a new Generation of Vehicles is currently investigating. The six fuels include two petroleum-based fuels (reformulated gasoline and low-sulfur diesel) and four alternative fuels (methanol, ethanol, dimethyl ether, and hydrogen). This study develops estimates of cumulative capital needs for establishing fuels production and distribution infrastructure to accommodate 3X vehicle fuel needs. Two levels of fuel volume-70,000 barrels per day and 1.6 million barrels per day-were established for meeting 3X-vehicle fuel demand. As expected, infrastructure capital needs for the high fuel demand level are much higher than for the low fuel demand level. Between fuel production infrastructure and distribution infrastructure, capital needs for the former far exceed those for the latter. Among the four alternative fuels, hydrogen bears the largest capital needs for production and distribution infrastructure.
Date: December 31, 1998
Creator: Stork, K.; Singh, M.; Wang, M. & Vyas, A.
System: The UNT Digital Library
Asymmetry in inclusive {pi}{sup {+-}}, p production at 22 GeV, BNL E925 (open access)

Asymmetry in inclusive {pi}{sup {+-}}, p production at 22 GeV, BNL E925

Preliminary results from Experiment E925 on inclusive pion asymmetries from a 22 GeV/c polarized proton beam on a carbon target show significant asymmetries for {pi}{sup {+-}} production similar to those observed earlier at the ZGS and Fermilab with beams of 12 and 200 GeV respectively. This experiment demonstrates the viability of using the analyzing power in inclusive pion production for high energy beam polarimetry at RHIC. Inclusive proton asymmetries are consistent with zero.
Date: December 31, 1998
Creator: Makdisi, Y.; Allgower, C. & Bai, M.
System: The UNT Digital Library
Base Distance Optimization for SQUID Gradiometers (open access)

Base Distance Optimization for SQUID Gradiometers

The measurement of magnetic fields generated by weak nearby biomagnetic sources is affected by ambient noise generated by distant sources both internal and external to the subject under study. External ambient noise results from sources with numerous origins, many of which are unpredictable in nature. Internal noise sources are biomagnetic in nature and result from muscle activity (such as the heart, eye blinks, respiration, etc.), pulsation associated with blood flow, surgical implants, etc. Any magnetic noise will interfere with measurements of magnetic sources of interest, such as magnetoencephalography (MEG), in various ways. One of the most effective methods of reducing the magnetic noise measured by the SQUID sensor is to use properly designed superconducting gradiometers. Here, the authors optimized the baseline length of SQUID-based symmetric axial gradiometers using computer simulation. The signal-to-noise ratio (SNR) was used as the optimization criteria. They found that in most cases the optimal baseline is not equal to the depth of the primary source, rather it has a more complex dependence on the gradiometer balance and the ambient magnetic noise. They studied both first and second order gradiometers in simulated shielded environments and only second order gradiometers in a simulated unshielded environment. The noise source …
Date: December 31, 1998
Creator: Garachtchenko, Alexander; Matlashov, Andrei & Kraus, Robert
System: The UNT Digital Library
Basis for low beam loss in the high-current APT linac (open access)

Basis for low beam loss in the high-current APT linac

The present evidence that the APT proton linac design will meet its goal of low beam loss operation. The conclusion has three main bases: (1) extrapolation from the understanding of the performance of the 800-MeV LANSCE proton linac at Los Alamos, (2) the theoretical understanding of the dominant halo-forming mechanism in the APT accelerator from physics models and multiparticle simulations, and (3) the conservative approach and key principles underlying the design of the APT linac, which are aimed at minimizing beam halo and providing large apertures to reduce beam loss to a very low value.
Date: December 31, 1998
Creator: Wangler, T. P.; Gray, E. R.; Krawczyk, F. L.; Kurennoy, S. S.; Lawrence, G. P.; Ryne, R. D. et al.
System: The UNT Digital Library
Beam dynamics design of the 211 MeV APT normal conducting linac (open access)

Beam dynamics design of the 211 MeV APT normal conducting linac

This paper describes the normal conducting linac design that is part of the Accelerator for Production of Tritium (APT) project. The new version of PARMILA designed this linac. This linac accepts the beam from the 6.7 MeV radio frequency quadrupole without a separate matching section. At about 10 MeV, it has a smooth transition in the length of period from 8{beta}{lambda} to 9{beta}{lambda} in quadrupole focusing lattice. This adjustment of the period was needed to provide sufficient space for the quadrupole focusing magnets and beam diagnostic equipment. The linac consists of the coupled cavity drift tube linac up to 97 MeV and coupled cavity linac above 97 MeV.
Date: December 31, 1998
Creator: Young, L. M.; Billen, J. H.; Takeda, H. & Wood, R. L.
System: The UNT Digital Library