Laboratory Studies of the Fe K-shell Emission (open access)

Laboratory Studies of the Fe K-shell Emission

An overview is given of measurements of the Fe K-shell spectrum from low-density laboratory sources. The measurements include wavelengths, electron-impact collision cross sections, innershell ionization phenomena, dielectronic recombination resonance strengths, charge exchange recombination, electron beam polarization effects, resonance excitation, and radiative cascade contributions. K-shell spectra have now also been obtained with microcalorimeters, including microcalorimeter arrays that are twins of the ASTRO-E and ASTRO-E2 missions, which illustrate typical resolving powers and spectral capabilities.
Date: December 26, 2004
Creator: Beiersdorfer, P
System: The UNT Digital Library
High Power 938nm Cladding Pumped Fiber Laser (open access)

High Power 938nm Cladding Pumped Fiber Laser

We have developed a Nd:doped cladding pumped fiber amplifier, which operates at 938nm with greater than 2W of output power. The core co-dopants were specifically chosen to enhance emission at 938nm. The fiber was liquid nitrogen cooled in order to achieve four-level laser operation on a laser transition that is normally three level at room temperature, thus permitting efficient cladding pumping of the amplifier. Wavelength selective attenuation was induced by bending the fiber around a mandrel, which permitted near complete suppression of amplified spontaneous emission at 1088nm. We are presently seeking to scale the output of this laser to 10W. We will discuss the fiber and laser design issues involved in scaling the laser to the 10W power level and present our most recent results.
Date: December 26, 2002
Creator: Dawson, J; Beach, R; Brobshoff, A; Liao, Z; Payne, S; Pennington, D et al.
System: The UNT Digital Library
PROBABILISTIC ASSESSMENT OF A CRITICALITY IN A WASTE CONTAINER AT SRS (open access)

PROBABILISTIC ASSESSMENT OF A CRITICALITY IN A WASTE CONTAINER AT SRS

Transuranic solid waste that has been generated as a result of the production of nuclear material for the United States defense program at the Savannah River Site (SRS) has been stored in more than 30,000 55-gallon drums and various size carbon steel boxes since 1953. Nearly two thirds of those containers have been processed and shipped to the Waste Isolation Pilot Plant. Among the containers assayed so far, the results indicate several drums with fissile inventories significantly higher (600-1000 grams {sup 239}Pu) than their original assigned values. While part of this discrepancy can be attributed to the past limited assay capabilities, human errors are believed to be the primary contributor. This paper summarizes an assessment of the probability of occurrence of a criticality accident during handling of the remaining transuranic waste containers at SRS.
Date: December 26, 2006
Creator: Eghbali, D
System: The UNT Digital Library
Scalar Dark Matter From Theory Space (open access)

Scalar Dark Matter From Theory Space

The scalar dark matter candidate in a prototypical theory space little Higgs model is investigated. We review all details of the model pertinent to a relic density calculation. We perform a thermal relic density calculation including couplings to the gauge and Higgs sectors of the model. We find two regions of parameter space that give acceptable dark matter abundances. The first region has a dark matter candidate with a mass {Omicron}(100 GeV), the second region has a candidate with a mass greater than {Omicron}(500 GeV). The dark matter candidate in either region is an admixture of an SU(2) triplet and an SU(2) singlet, thereby constituting a possible WIMP (weakly interacting massive particle).
Date: December 26, 2003
Creator: Birkedal-Hansen, Andreas & Wacker, Jay G.
System: The UNT Digital Library
Prediction of drug solubility in ethanol-ethyl acetate mixtures at various temperatures using the Jouyban-Acree model (open access)

Prediction of drug solubility in ethanol-ethyl acetate mixtures at various temperatures using the Jouyban-Acree model

Article on the prediction of drug solubility in ethanol-ethyl acetate mixtures at various temperatures using the Jouyban-Acree model.
Date: December 26, 2007
Creator: Jouyban, Abolghasem & Acree, William E. (William Eugene)
System: The UNT Digital Library