N = 2 string amplitudes (open access)

N = 2 string amplitudes

In physics, solvable models have played very important roles. Understanding a simple model in detail teaches us a lot about more complicated models in generic situations. Five years ago, C. Vafa and I found that the closed N = 2 string theory, that is a string theory with the N = 2 local supersymmetry on the worldsheet, is classically equivalent to the self-dual Einstein gravity in four spacetime dimensions. Thus this string theory is solvable at the classical level. More recently, we have examined the N = 2 string partition function for spacial compactifications, and computed it to all order in the string perturbation expansion. The fact that such computation is possible at all suggests that the N = 2 string theory is solvable even quantum mechanically.
Date: August 1, 1995
Creator: Ooguri, H.
System: The UNT Digital Library
2 {times} 2 TeV {mu}{sup +}{mu}{sup {minus}} collider: Lattice and accelerator-detector interface study (open access)

2 {times} 2 TeV {mu}{sup +}{mu}{sup {minus}} collider: Lattice and accelerator-detector interface study

The design for a high-luminosity {mu}{sup +}{mu}{sup {minus}} superconducting storage ring is presented based on first-pass calculations. Special attention is paid to two Iowa interaction regions (IR) whose optics are literally interlaced with the collider detectors. Various sources of backgrounds in IR are explored via realistic Monte Carlo simulations. An improved design of the collider lattice in the neighborhood of the interaction points (EP) is determined by the need to reduce significantly background levels in the detectors.
Date: May 1, 1995
Creator: Gelfand, N. M. & Mokhov, N. V.
System: The UNT Digital Library
A 3-D numerical study of pinhole diffraction to predict the accuracy of EUV point diffraction interferometry (open access)

A 3-D numerical study of pinhole diffraction to predict the accuracy of EUV point diffraction interferometry

A 3-D electromagnetic field simulation is used to model the propagation of extreme ultraviolet (EUV), 13-nm, light through sub-1500 {Angstrom} dia pinholes in a highly absorptive medium. Deviations of the diffracted wavefront phase from an ideal sphere are studied within 0.1 numerical aperture, to predict the accuracy of EUV point diffraction interferometersused in at-wavelength testing of nearly diffraction-limited EUV optical systems. Aberration magnitudes are studied for various 3-D pinhole models, including cylindrical and conical pinhole bores.
Date: December 1, 1995
Creator: Goldberg, K.A.; Tejnil, E. & Bokor, J.
System: The UNT Digital Library
3-D Seismic Imaging of Complex Geologies (open access)

3-D Seismic Imaging of Complex Geologies

We present three codes for the Intel Paragon that address the problem of three-dimensional seismic imaging of complex geologies. The first code models acoustic wave propagation and can be used to generate data sets to calibrate and validate seismic imaging codes. This code reported the fastest timings for acoustic wave propagation codes at a recent SEG (Society of Exploration Geophysicists) meeting. The second code implements a Kirchhoff method for pre-stack depth migration. Development of this code is almost complete, and preliminary results are presented. The third code implements a wave equation approach to seismic migration and is a Paragon implementation of a code from the ARCO Seismic Benchmark Suite.
Date: February 1, 1995
Creator: Womble, David E.; Dosanjh, Sudip S.; VanDyke, John P.; Oldfield, Ron A. & Greenberg, David S.
System: The UNT Digital Library
10 CFR 830.120 Criterion 10, Independent Assessment: We`re here to help you! (open access)

10 CFR 830.120 Criterion 10, Independent Assessment: We`re here to help you!

Each organization performing activities in the DOE Weapons Complex is required to have an pendent assessment function. This is consistent from DOE Order 5700.6C, Quality Assurance to 10 CFR 830-120, sometimes referred to as the Price-Anderson rule. DOE Order 5700.6C, Criterion 10 Independent Assessment requires, `` Planned and periodic independent assessments shall be conducted to measure item quality and process effectiveness and to promote improvement. The organization performing independent assessments shall have sufficient authority and freedom from the line organization to carry out its responsibilities. Persons conducting independent assessments shall be technically qualified and knowledgeable in the areas assessed.`` 10 CFR 830.120, (c) Quality assurance criteria -- (3) Assessment -- (ii) Independent Assessment requires,``Independent assessments shall be planned and conducted to measure item and service quality, to measure the adequacy of work performance, and to promote improvement. The group performing independent assessments shall have sufficient authority and freedom from the line to carry out its responsibilities. Persons conducting independent assessments shall be technically qualified and knowledgeable in the areas assessed.``
Date: July 1, 1995
Creator: Farrell, R.E.
System: The UNT Digital Library
A 30-T pulsed magnet suitable for neutron scattering experiments (open access)

A 30-T pulsed magnet suitable for neutron scattering experiments

We describe a conceptual design for a 30-T vertical-field split-pair magnet suitable for neutron scattering studies. While the magnet is primarily intended for diffraction and spectroscopic studies using a pulsed neutron source, it might also have application for relaxational studies,at steady-state sources. The magnet will have a 5-cm bore for sample environment equipment, a 1-cm gap for the neutrons to illuminate the sample and through which to observe the scattering. It will run with a repetition frequency of 2 Hz, and a pulse length of 3 ms. We discuss scientific and engineering considerations that led to this specification and describe the designs of both magnet and power supply.
Date: July 1, 1995
Creator: Robinson, R. A.; Boenig, H. J.; Eyssa, Y. M. & Schneider-Muntau, H. J.
System: The UNT Digital Library
A 100 ps gated x-ray spectrometer (open access)

A 100 ps gated x-ray spectrometer

Material opacities are of interest in many fields. We have developed a Bragg reflection spectrometer that is gated for imaging samples in a laser heated environment for opacity measurement. A micro-channel plate is coated with a photocathode material and a fast pulse is launched across it. Electrons are converted to photons in a phosphor and recorded on film. Optical gate pulse widths of 100 ps are achieved. Some optical pulse width and sensitivity enhancements are noted at launch and termination. Events of interest are 200 ps long. The framing window is approximately 250 ps in length. Timing jitter is a problem. The instrument timing networks have been examined, and the source of jitter is still unknown. Timing to 50 ps resolution is desired. Close in proximity to the laser-driven event leads to complications in shielding from hard x-rays, hot electrons and shock-driven damage. High Z materials provide shielding from hard x-rays. Magnets screen out hot electrons produced by laser-matter interactions Filters provide energy fiducials. PCD`s provide high resolution timing measurements. Data is recorded on film in a specially designed film pack. The instrument is designed to be used in the NOVA Laser Facility at Lawrence Livermore National Laboratory.
Date: September 1, 1995
Creator: Walsh, Peter J.; Blake, Richard L.; Caldwell, Stephen; Hockaday, Mary; Chrien, Robert E. & Smith, Clayton R.
System: The UNT Digital Library
1995 Department of Energy Records Management Conference (open access)

1995 Department of Energy Records Management Conference

The Department of Energy (DOE) Records Management Group (RMG) provides a forum for DOE and its contractor personnel to review and discuss subjects, issues, and concerns of common interest. This forum will include the exchange of information, and interpretation of requirements, and a dialog to aid in cost-effective management of the DOE Records Management program. Issues addressed by the RMG may result in recommendations for DOE-wide initiatives. Proposed DOE-wide initiatives shall be, provided in writing by the RMG Steering Committee to the DOE Records Management Committee and to DOE`s Office of ERM Policy, Records, and Reports Management for appropriate action. The membership of the RMG is composed of personnel engaged in Records Management from DOE Headquarters, Field sites, contractors, and other organizations, as appropriate. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.
Date: July 1, 1995
Creator: unknown
System: The UNT Digital Library
1995 International Sherwood Fusion Theory Conference (open access)

1995 International Sherwood Fusion Theory Conference

This book is a guide to the 1995 International Sherwood Fusion Theory Conference. It consists largely of abstracts of the oral and poster presentations that were to be made, and gives some general information about the conference and its schedule.
Date: July 1, 1995
Creator: unknown
System: The UNT Digital Library
1995 verification flow testing of the HDR reservoir at Fenton Hill, New Mexico (open access)

1995 verification flow testing of the HDR reservoir at Fenton Hill, New Mexico

Recent flow testing of the Fenton Hill HDR reservoir has demonstrated that engineered geothermal systems can be shut-in for extended periods of d= with apparently no adverse effects. However, when this particular reservoir at Venton Hill was shut-in for 2 years in a pressurized condition, natural convection within the open-jointed reservoir region appears to have leveled out the preexisting temperature gradient so that the gradient has now approached a condition more typical of liquid-dominated hydrothermal reservoirs which air invariably almost isothermal due to natural convection. As a result of the sudden flow impedance reduction that led to an almost 50% increase in Production flow new the end of the Second Phase of the LTFR in May 1993, we were uncertain as to the state of the reservoir after being shut-in for 2 years. The flow performance observed during the current testing was found to be intermediate between that at-the end of the Second Phase of the LTFT and that following, the subsequent sudden flow increase, implying that whatever caused the sudden reduction in impedance in the first place is probably somehow associated with the cooldown of the reservoir near the injection interval, since temperature recovery at the surfaces of the …
Date: January 1, 1995
Creator: Brown, D.
System: The UNT Digital Library
21st Century Advanced Hydropower Turbine System (open access)

21st Century Advanced Hydropower Turbine System

While hydropower turbine manufacturers have incrementally improved turbine technology to increase efficiency, the basic design concepts haven`t changed for decades. These late 19th and early 20th century designs did not consider environmental effects, since little was known about environmental effects of hydropower at the time. The U.S. Department of Energy (DOE) and the hydropower industry recognize that hydropower plants have an effect on the environment and there is a great need to bring turbine designs into the 21st century. DOE has issued a request for proposals (RFP) that requested proposers to discard conventional thinking, search out innovative solutions, and to visualize innovative turbines designed from a new perspective. This perspective would look at the {open_quotes}turbine system{close_quotes} (intake to tailrace) which will balance environmental, technical, and economic considerations. This paper describes the DOE Advanced Hydropower Turbine System Program.
Date: November 1, 1995
Creator: Brookshier, P. A.; Flynn, J. V. & Loose, R. R.
System: The UNT Digital Library
A 2D smart pixel detector for time-resolved protein crystallography (open access)

A 2D smart pixel detector for time-resolved protein crystallography

A smart pixel detector is being developed for Time Resolved Crystallography for biological and material science applications. Using the Pixel detector presented here, the Laue method will enable the study of the evolution of structural changes that occur within the protein as a function of time. The x-ray pixellated detector is assembled to the integrated circuit through a bump bonding process. Within a pixel size of 150 x 150 {mu}m{sup 2}, a low noise preamplifier-shaper, a discriminator, a 3 bit counter and the readout logic are integrated. The readout, based on the Column Architecture principle, will accept hit rates above 5x10{sup 8}/cm{sup 2}/s with a maximum hit rate per pixel of 1 MHz. This detector will allow time resolved Laue crystallography to be performed in a frameless operation mode, without dead time. Target specifications, architecture, and preliminary results on the 8 x 8 front-end prototype and column readout are presented.
Date: October 1, 1995
Creator: Beuville, E.; Cork, C. & Earnest, T.
System: The UNT Digital Library
Above and beyond basic public participation (open access)

Above and beyond basic public participation

This paper evolved out of a discussion about public participation as it is currently being brought to the fore-front of clean-up activities at hazardous waste sites. There exists much official and unofficial documentation pertaining to the need for public involvement. The purposes for public involvement efforts in Environmental Restoration are: to enable substantive input to the clean-up process; methods for establishing formal, and now informal, mechanisms for public input and awareness of on-going facility activities; and the opening of better channels for communication and conflict resolution between the public and the facility. This presentation will briefly outline the regulatory approach for public outreach because many of these terms are used with such frequency, their meanings tend to get forgotten or misconstrued. Then, the authors will critique the most common methods for conducting public involvement as attempted through advisory boards and public meetings. For illustrative purposes, they will be referring to the site they are most familiar with, which is Los Alamos National Laboratory (LANL).
Date: July 1, 1995
Creator: Mathai, L. P.; Lefkoff, M. S. & Kelly, E. J.
System: The UNT Digital Library
Absolute calibration of TFTR helium proportional counters (open access)

Absolute calibration of TFTR helium proportional counters

The TFTR helium proportional counters are located in the central five (5) channels of the TFTR multichannel neutron collimator. These detectors were absolutely calibrated using a 14 MeV neutron generator positioned at the horizontal midplane of the TFTR vacuum vessel. The neutron generator position was scanned in centimeter steps to determine the collimator aperture width to 14 MeV neutrons and the absolute sensitivity of each channel. Neutron profiles were measured for TFTR plasmas with time resolution between 5 msec and 50 msec depending upon count rates. The He detectors were used to measure the burnup of 1 MeV tritons in deuterium plasmas, the transport of tritium in trace tritium experiments, and the residual tritium levels in plasmas following 50:50 DT experiments.
Date: June 1, 1995
Creator: Strachan, J.D.; Diesso, M.; Jassby, D.; Johnson, L.; McCauley, S.; Munsat, T. et al.
System: The UNT Digital Library
Absolute calibration of TFTR neutron detectors for D-T plasma operation (open access)

Absolute calibration of TFTR neutron detectors for D-T plasma operation

The two most sensitive TFTR fission-chamber detectors were absolutely calibrated in situ by a D-T neutron generator ({approximately}5 {times} 10{sup 7} n/s) rotated once around the torus in each direction, with data taken at about 45 positions. The combined uncertainty for determining fusion neutron rates, including the uncertainty in the total neutron generator output ({plus_minus}9%), counting statistics, the effect of coil coolant, detector stability, cross-calibration to the current mode or log Campbell mode and to other fission chambers, and plasma position variation, is about {plus_minus}13%. The NE-451 (ZnS) scintillators and {sup 4}He proportional counters that view the plasma in up to 10 collimated sightlines were calibrated by scanning. the neutron generator radially and toroidally in the horizontal midplane across the flight tubes of 7 cm diameter. Spatial integration of the detector responses using the calibrated signal per unit chord-integrated neutron emission gives the global neutron source strength with an overall uncertainty of {plus_minus}14% for the scintillators and {plus_minus}15% for the {sup 4}He counters.
Date: March 1, 1995
Creator: Jassby, D. L.; Johnson, L. C.; Roquemore, A. L.; Strachan, J. D.; Johnson, D. W.; Medley, S. S. et al.
System: The UNT Digital Library
Abstract and research accomplishments of University Coal Research Projects (open access)

Abstract and research accomplishments of University Coal Research Projects

The Principal Investigators of the grants supported by the University Coal Research Program were requested to submit abstracts and highlight accomplishments of their respective projects in time for distribution at a conference on June 13--14, 1995 at Tennessee State University in Nashville, Tennessee. This book is a compilation of the material received in response to that request. For convenience, the 70 grants reported in this book are stored into eight technical areas, Coal Science, Coal Surface Science, Reaction Chemistry, Advanced Process Concepts, Engineering Fundamentals and Thermodynamics, Environmental Science, high Temperature Phenomena, and Special topics. Indexes are provided for locating projects by subject, principal investigators, and contracting organizations. Each extended abstract describes project objectives, work accomplished, significance to the Fossil Energy Program, and plans for the next year.
Date: June 1, 1995
Creator: unknown
System: The UNT Digital Library
He abundance variations in the solar wind: Observations from Ulysses (open access)

He abundance variations in the solar wind: Observations from Ulysses

The Ulysses mission is providing the first opportunity to observe variations in solar wind plasma parameters at heliographic latitudes far removed from the ecliptic plane. We present an overview of the solar wind speed and the variability in helium abundance, [He] data on [He] in six high latitude coronal mass ejections (CMEs), and a superposed epoch analysis of [He] variations at the seven heliospheric current sheet (HCS) crossings made during the rapid-latitude-scan portion of the mission. The differences in the variability of the solar wind speed and [He] in high latitude and equatorial regions are quite striking. Solar wind speed is generally low but highly variable near the solar equator, while at higher latitudes the average speed is quite high with little variability. [He] can vary over nearly two decades at low solar latitudes, while at high latitudes it varies only slightly. In contrast to the high [He] that is commonly associated with CMEs observed in the ecliptic, none of the six high-speed CMEs encountered at high southern heliographic latitudes showed any significant variation in helium content. A superposed epoch analysis of the [He] during all seven HCS crossings made as Ulysses passed from the southern to northern solar hemisphere …
Date: September 1, 1995
Creator: Barraclough, Bruce L.; Gosling, John T.; Phillips, John L.; McComas, David J.; Feldman, William C. & Goldstein, Bruce E.
System: The UNT Digital Library
Accelerated degradation studies of MEH-PPV (open access)

Accelerated degradation studies of MEH-PPV

MEH-PPV, which normally has a reddish color, is well known to show photobleaching problems. The photobleaching can be greatly accelerated by exposure to laser light while in air. For example, shining 457 mn light of relatively low intensity (0.06 W/cm{sup 2}) on the MEH-PPV causes the photoluminescence to decrease by a factor of two within a few seconds of exposure, and to show a nearly complete bleaching of the material within 30 minutes. The degradation rate is strongly influenced by laser power, sample thickness, oxygen exposure during preparation and spinning, as well as the oxygen environment during the measurement. The photobleach is indicative of one class of degradation mechanisms limiting the usefulness of PPV based polymers in electroluminescent devices. MEH-PPV which was spin coated in a nitrogen environment and measured in vacuum showed no measurable photo-chemical degradation for measuring times of up to several hours. A dramatic decrease in PL intensity was observed, however, in the presence of oxygen, as well as in samples spin coated in air, but measured in vacuum. We present data on the PL of MEH-PPV, as a function of oxygen concentration.
Date: July 1, 1995
Creator: Radousky, H. B.; Madden, A. D.; Pakbaz, K.; Hagler, T. W.; Lee, H. W. H.; Lorenzana, H. E. et al.
System: The UNT Digital Library
An accelerated remedial strategy developed for J-Field, Aberdeen Proving Ground, Maryland (open access)

An accelerated remedial strategy developed for J-Field, Aberdeen Proving Ground, Maryland

For an installation with many disposal sites and multiple contaminant sources, successful remediation at minimum cost can be complicated by insufficient geologic and hydrogeologic information, incomplete records of historical disposal activities, and uncertainty about the effectiveness of different investigative methods. To reduce these uncertainties and to increase the probability of successful remediation at minimum cost, a ``Phased and pilot`` accelerated remedial strategy has been developed for the J-Field area of Aberdeen Proving Ground, Maryland. The strategy includes four phases. First, the most contaminated site is selected as a pilot for detailed investigation. Second, the most contaminated areas within the pilot site are chosen as a pilot source area for interim action study, and a remedial action is developed to remove the primary contaminant sources. The subsequent sitewide investigation uses the effective tools developed in the first phase. Third, a cleanup operation is initiated in the pilot source area, while a sitewide feasibility study is developed by taking advantage of lessons learned in the interim action. Fourth, a sitewide cleanup operation proceeds.
Date: June 1, 1995
Creator: Yuen, C. R.; Martino, L.; Patton, T. & Wrobel, J.
System: The UNT Digital Library
Accelerating polarized beams at the AGS (open access)

Accelerating polarized beams at the AGS

The acceleration of polarized beams in circular accelerators is complicated by the presence of numerous depolarizing resonances. During acceleration, a depolarizing resonance is crossed whenever the spin precession frequency equals the frequency with which spin-perturbing magnetic fields are encountered. There are two main types of depolarizing resonances corresponding to the possible sources of such fields: imperfection resonances, which are driven by magnet errors and misalignments, and intrinsic resonances, driven by the focusing fields. The resonance conditions are usually expressed in terms of the spin tune {nu}{sub s}, which is defined as the number of spin precessions per revolution. For an ideal planar accelerator, where orbiting particles experience only the vertical guide field, the spin tune is equal to G{gamma}, where G = 1.7928 is the anomalous magnetic moment of the proton and {gamma} is the relativistic Lorentz factor. The resonance condition for imperfection depolarizing resonances arise when {nu}{sub s} = G{gamma} = n, where n is an integer. Imperfection resonances are therefore separated by only 523 MeV energy steps. The condition for intrinsic resonances is {nu}{sub s} = G{gamma} = kP {+-} {nu}{sub y}, where k is an integer, {nu}{sub y} is the vertical betatron tune and P is the …
Date: December 1, 1995
Creator: Roser, T.
System: The UNT Digital Library
Accelerating RCRA corrective action: The principles of the DOE approach (open access)

Accelerating RCRA corrective action: The principles of the DOE approach

The US Department of Energy (DOE) is involved in the remediation of environmental contamination at many of its facilities under the Resource Conservation and Recovery Act (RCRA). RCRA`s corrective action provisions were established by the Hazardous and Solid Waste Amendments of 1984 (HSWA). In response to the HSWA mandate, EPA established a program for the conduct of RCRA corrective action that was similar to that established under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). In addition, EPA developed and implemented its ``stabilization`` initiative as a means of quickly addressing immediate risks posed by releases until long term solutions can be applied. To improve the efficiency of environmental restoration at its facilities, DOE is developing guidance and training programs on accelerated environmental restoration under RCRA. A RCRA guidance document, entitled ``Accelerating RCRA Corrective Action at DOE Facilities,`` is currently being developed by DOE`s Office of Environmental Policy and Assistance. The new guidance document will outline a decision-making process for determining if acceleration is appropriate for individual facilities, for identifying, evaluating, and selecting options for program acceleration, and for implementing selected acceleration options. The document will also discuss management and planning strategies that provide a firm foundation for accelerating RCRA …
Date: March 1, 1995
Creator: Kimmell, T. A.; Green, D. R.; Ranek, N. L. & Coalgate, J. L.
System: The UNT Digital Library
Accelerator complex for a radioactive ion beam facility at ATLAS (open access)

Accelerator complex for a radioactive ion beam facility at ATLAS

Since the superconducting heavy ion linac ATLAS is an ideal post-accelerator for radioactive beams, plans are being developed for expansion of the facility with the addition of a driver accelerator, a production target/ion source combination, and a low q/m pre-accelerator for radioactive ions. A working group including staff from the ANL Physics Division and current ATLAS users are preparing a radioactive beam facility proposal. The present paper reviews the specifications of the accelerators required for the facility.
Date: June 1, 1995
Creator: Nolen, J.A.
System: The UNT Digital Library
Accelerator operation management using objects (open access)

Accelerator operation management using objects

Conflicts over control of shared devices or resources in an accelerator control system, and problems that can occur due to applications performing conflicting operations, are usually resolved by accelerator operators. For these conflicts to be detected by the control system, a model of accelerator operation must be available to the system. The authors present a design for an operation management system addressing the issues of operations management using the language of Object-Oriented Design (OOD). A possible implementation using commercially available software tools is also presented.
Date: April 1, 1995
Creator: Nishimura, H.; Timossi, C. & Valdez, M.
System: The UNT Digital Library
Accelerator requirements for fast-neutron interrogation of luggage and cargo (open access)

Accelerator requirements for fast-neutron interrogation of luggage and cargo

Several different fast-neutron based techniques are being studied for the detection of contraband substances in luggage and cargo containers. The present work discusses the accelerator requirements for fast-neutron transmission spectroscopy (FNTS), pulsed fast-neutron analysis (PFNA), and 14-MeV neutron interrogation. These requirements are based on the results of Monte-Carlo simulations of neutron or gamma detection rates. Accelerator requirements are driven by count-rate considerations, spatial resolution and acceptable uncertainties in elemental compositions. The authors have limited their analyses to luggage inspection with FNTS and to cargo inspection with PFNA or 14-MeV neutron interrogation.
Date: May 1, 1995
Creator: Micklich, B.J.; Fink, C.L. & Yule, T.J.
System: The UNT Digital Library