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The superconducting solenoid magnet system for the GEM detector at the SSC (open access)

The superconducting solenoid magnet system for the GEM detector at the SSC

The design of the magnet for the GEM detector at the SSC is described. It is an 18m inner diameter, 30m long superconducting solenoid, with a magnetic field of 0.8T. The basic solenoidal field is shaped by large ferromagnetic cones, to improve detector performance in the ends of the solenoid. Because of the system`s large size and mass, field-fabrication on-site at SSC is required. The challenges in this process, together with the large stored energy of the system, 2.5 GJ, have lead to novel design choices in several areas, including the conductor. The design of the conductor, cold mass, vacuum vessel, cold mass supports, thermal shields, forward field shapers, and auxiliary systems are described.
Date: September 8, 1993
Creator: Deis, G.; Bowers, J. & Chargin, A.
System: The UNT Digital Library
Supernova explosions and hydrodynamical instabilities: From core bounce to 90 days (open access)

Supernova explosions and hydrodynamical instabilities: From core bounce to 90 days

Since the advent of SN 1987A considerable progress has been made in our understanding of supernova explosions. It is now realized that they are intrinsically multidimensional in nature due to the various hydrodynamical instabilities which take place at almost all stages of the explosion. These instabilities not only modify the observables from the supernova, but are also thought to be at the heart of the supernova mechanism itself, in a way which guarantees robust and self-regulated explosions. In this paper, we review these instabilities placing them into their appropriate context and identifying their role in the genesis of core collapse supernovas.
Date: January 8, 1993
Creator: Benz, W.; Colgate, S. A. & Herant, M.
System: The UNT Digital Library
Tests of a New Cloud Treatment in an Atmospheric General Circulation Model (open access)

Tests of a New Cloud Treatment in an Atmospheric General Circulation Model

In this study we present a new cloud treatment in an atmospheric climate model. The water (or ice) content of clouds is a introduced as a prognostic variable, subject to both advective and diffusive transport. In the first phase of the study, the cloud water does not affect the radiative properties of clouds. We then find differences in precipitation and cloud fields, but little effect on the overall climate. In the second phase the cloud water determines the reflectivity of the clouds. This causes large changes in the global circulation, largely due to enhanced reflection from high tropical cirrus clouds. As a third step, the cloud emissivity is also based on the cloud water content. This greatly enhances the outgoing terrestrial radiation and brings the model`s radiative budget quite close to the observed.
Date: December 8, 1993
Creator: Kristjansson, J. E.
System: The UNT Digital Library
Recent studies of short-range order in alloys: The Cowley theory revisited (open access)

Recent studies of short-range order in alloys: The Cowley theory revisited

We present comparisons of various statistical theories for effective pair interactions (EPI) in alloys. We then evaluate these EPI`s using the Cowley theory, the Krivoglaz-Clapp-Moss (KCM) approximation, the {gamma}-expansion method (GEM) of Tokar, Masanskii and coworkers, and the exact inverse Monte Carlo (IMC) method, introduced by Gerold and Kern. Via a series of model calculations on a hypothetical bcc alloy with a single nearest-neighbor interaction we show that the Cowley theory is successful in evaluating the EPI`s in more dilute alloys but tends to overestimate the magnitude of the nearest neighbor energy at higher concentrations, whereas the KCM expression becomes increasingly inaccurate at lower concentrations. In general, however, the approximate mean field theories are most accurate at higher concentrations and higher temperatures. Recent studies of short-range order in single crystals are discussed in which these EPI`s have been evaluated using the IMC, KCM, GEM and Cowley theories. Examples include the bcc alloy Fe{sub 0.53}Cr{sub 0.47} and the fcc alloys Cu{sub 3} Au, CU{sub 0.69}Zn{sub 0.31} and Ni{sub 0.89}BgCr{sub 0.11}. In all cases the approximate expressions do quite well, especially the GEM.
Date: February 8, 1993
Creator: Reinhard, L. & Moss, S. C.
System: The UNT Digital Library
The validation of ATSR measurements with in situ sea temperatures (open access)

The validation of ATSR measurements with in situ sea temperatures

The largest source of uncertainty in the retrieval of SST (sea-surface) temperature from space-borne infrared radiometric measurements is in the correction for the effects of the intervening atmosphere. During a research cruise of the R/V Alliance measurements of sea surface temperature, surface meteorological variables and surface infrared radiances were taken. SST fields were generated from the ATSR data using pre-launch algorithims derived by the ATSR Instrument Team (A.M. Zavody, personal communication), and the initial comparison between ATSR measurements and SST taken along the ship`s track indicate that the dual-angle atmospheric correction is accurate in mid-latitude conditions.
Date: October 8, 1993
Creator: Minnett, P. J. & Stansfield, K. L.
System: The UNT Digital Library
Design of an electromagnetic accelerator for turbulent hydrodynamic mix studies (open access)

Design of an electromagnetic accelerator for turbulent hydrodynamic mix studies

An electromagnetic accelerator in the form of a linear electric motor (LEM) has been designed to achieve controlled acceleration profiles of a carriage containing hydrodynamically unstable fluids for the investigation of the development of turbulent mix. The Rayleigh- Taylor instability is investigated by accelerating two dissimilar density fluids using the LEM to achieve a wide variety of acceleration and deceleration profiles. The acceleration profiles are achieved by independent control of rail and augmentation currents. A variety of acceleration-time profiles are possible including: (1) constant, (2) impulsive and (3) shaped. The LEM and support structure are a robust design in order to withstand high loads with deflections and to mitigate operational vibration. Vibration of the carriage during acceleration could create artifacts in the data which would interfere with the intended study of the Rayleigh-Taylor instability. The design allows clear access for diagnostic techniques such as laser induced fluorescence radiography, shadowgraphs and particle imaging velocimetry. Electromagnetic modeling codes were used to optimize the rail and augmentation coil positions within the support structure framework. Results of contemporary studies for non-arcing sliding contact of solid armatures are used for the design of the driving armature and the dynamic electromagnetic braking system. A 0. 6MJ …
Date: December 8, 1993
Creator: Susoeff, A. R.; Hawke, R. S.; Morrison, J. J.; Dimonte, G. & Remington, B. A.
System: The UNT Digital Library
Proposed first-generation WSQ bit allocation procedure (open access)

Proposed first-generation WSQ bit allocation procedure

The Wavelet/Scalar Quantization (WSQ) gray-scale fingerprint image compression algorithm involves a symmetric wavelet transform (SWT) image decomposition followed by uniform scalar quantization of each subband. The algorithm is adaptive insofar as the bin widths for the scalar quantizers are image-specific and are included in the compressed image format. Since the decoder requires only the actual bin width values -- but not the method by which they were computed -- the standard allows for future refinements of the WSQ algorithm by improving the method used to select the scalar quantizer bin widths. This report proposes a bit allocation procedure for use with the first-generation WSQ encoder. In previous work a specific formula is provided for the relative sizes of the scalar quantizer bin widths in terms of the variances of the SWT subbands. An explicit specification for the constant of proportionality, q, that determines the absolute bin widths was not given. The actual compression ratio produced by the WSQ algorithm will generally vary from image to image depending on the amount of coding gain obtained by the run-length and Huffman coding, stages of the algorithm, but testing performed by the FBI established that WSQ compression produces archival quality images at compression …
Date: September 8, 1993
Creator: Bradley, J. N. & Brislawn, C. M.
System: The UNT Digital Library
Transmission Electron Microscopy Study of Thick Copper-304 Stainless Steel Multilayers (open access)

Transmission Electron Microscopy Study of Thick Copper-304 Stainless Steel Multilayers

Thick (10 to 25 {mu}m), free-standing, equal layer thickness, Copper(Cu)-304 Stainless Steel(SS) multilayer foils, having periods of 1 to 100 nm, synthesized by magnetron sputter deposition, were examined by plan view and cross-sectional transmission electron microscopy. Multilayer growth morphology, individual layer structure and crystallographic phase orientation relationships were characterized in this study. Electron Energy Loss filtered imaging of a 20 nm period multilayer cross-section was also performed and showed that nickel had diffused into the Cu layers from the SS during synthesis. X-ray powder diffraction scans were performed and analyzed. A pure deposit of 304SS was synthesized and had a metastable BCC structure. Multilayer samples having periods of 20 nm were found to have a coherent layered Cu(FCC)SS(FCC) structure. At larger periods (50 & 100 nm) a bimodal Cu(FCC)-SS(FCC & BCC) structure was formed. These observations show that the 304SS will grow with a metastable BCC structure when sputter deposited. When layered with Cu(FCC) the 304SS has its equilibrium FCC structure at layer thicknesses up to 10nm as a result of epitaxy with the copper. At larger SS layer thicknesses the SS appears to locally transform to the metastable BCC structure during synthesis, refining the grain structure of the depositing …
Date: June 8, 1993
Creator: Wall, M. A.; Barbee, T. W., Jr. & Weihs, T.
System: The UNT Digital Library
Calculated cross sections for production and destruction of some long-lived nuclides of importance in fusion energy applications (open access)

Calculated cross sections for production and destruction of some long-lived nuclides of importance in fusion energy applications

Knowledge of the production and destruction of long-lived species via neutrons, photons, and charged-particles is required in many fusion energy applications, such as reactor first-wall and blanket design, radioactive waste management, etc. Here we describe our calculational results for the production, via the (n,2n) reaction, of the following long-lived species: {sup 150}Eu(t{sub 1/2} = 36 y), {sup 152}Eu(t{sub 1/2} = 13 y), and {sup 192m2}Ir(t{sub 1/2} = 241 y). Some comments on calculations that we`ve made for destruction reactions of these species are also included.
Date: July 8, 1993
Creator: Gardner, M. A. & Gardner, D. G.
System: The UNT Digital Library
Plans for building the largest thin solenoid ever (open access)

Plans for building the largest thin solenoid ever

The superconducting solenoid magnet for the GEM detector poses unusual fabrication and handling challenges because of its extraordinary size. It will be more than 30% larger in diameter than the largest existing particle detector coils. Each of the two coil elements that compose the air-core solenoid, will be about 19 meters in diameter and 15 meters long. Major components weighing as much as 1500 Mg must be transported and manipulated at the Interaction Region 5 (IR5) fabrication site of the SSC Laboratory as the magnets are fabricated. Because of their large size, the magnets will be fabricated, assembled and tested at special purpose facilities at the IR5 site. The site-use plan must accommodate the fabrication of other detector components and the assembly of large flux shaping iron structures in a timely manner to allow subsequent testing and detector assembly. Each cold mass will be composed of twelve 45-Mg coil windings that are joined prior to assembly into the 19-m diam annular cryostat.
Date: September 8, 1993
Creator: Heim, J.; Bowers, J. & Deis, G.
System: The UNT Digital Library
A Theoretical Study of Nitrososilane and Six Isomers of SiH3NO (open access)

A Theoretical Study of Nitrososilane and Six Isomers of SiH3NO

Article on a theoretical study of nitrososilane and six isomers of SiH2NO.
Date: January 8, 1993
Creator: Marshall, Paul
System: The UNT Digital Library