Resource Type

Analysis of TPV Network Losses (a Presentation) (open access)

Analysis of TPV Network Losses (a Presentation)

This talk focuses on the theoretical analysis of electrical losses associated with electrically networking large numbers of TPV cells to produce high power TPV power generators.
Date: December 8, 2004
Creator: DePoy, DM; Dashiell, MW; Rahner, DD; Danielson, LR; Oppenlander, JE; Vell, JL et al.
System: The UNT Digital Library
The photon polarization in b -> X gamma in the standard model (open access)

The photon polarization in b -> X gamma in the standard model

The standard model prediction for the {bar B}{sup 0} {yields} X{sub s,d}{gamma} decay amplitude with a right-handed photon is believed to be tiny, suppressed by m{sub s,d}/m{sub b}, compared to the amplitude with a left-handed photon. We show that this suppression is fictitious: in inclusive decays, the ratio of these two amplitudes is only suppressed by g{sub s}/(4{pi}), and in exclusive decays by {Lambda}{sub QCD}/m{sub b}. The suppression is not stronger in {bar B}{sup 0} {yields} X{sub d}{gamma} decays than it is in {bar B}{sup 0} {yields} X{sub s}{gamma}. We estimate that the time dependent CP asymmetries in B {yields} K*{gamma}, {rho}{gamma}, K{sub S}{pi}{sup 0}{gamma}, and {pi}{sup +}{pi}{sup -} {gamma} are of order 0.1 and that they have significant uncertainties.
Date: December 8, 2004
Creator: Grinstein, Benjamin; Grossman, Yuval; Ligeti, Zoltan & Pirjol, Dan
System: The UNT Digital Library
New ion-guide for the production of beams of neutron-rich nucleibetween Z = 20 - 28 (open access)

New ion-guide for the production of beams of neutron-rich nucleibetween Z = 20 - 28

It has been shown for the first time that quasi- and deep-inelastic reactions can be successfully incorporated into the conventional Ion-Guide Isotope Separator On-Line (IGISOL) technique. This is of particular interest for characterizing the decay properties of refractory elements and is applied to neutron rich nuclei between Z = 20-28. As a first step of this project, the kinematics of quasi- and deep-inelastic reactions, such as {sup 197}Au({sup 65}Cu,X)Y, were studied. Based on these studies, a specialized IGISOL target chamber was designed and built. This chamber was tested in on- and off-line conditions at the Jyvaskyla IGISOL facility. Yields of radioactive, projectile-like species such as {sup 62,63}Co are about 0.8 ions/s/pnA corresponding to a total IGISOL efficiency of about 0.06%.
Date: December 8, 2004
Creator: Perajarvi, Kari; Cerny, Joe; Hakala, Jani; Huikari, Jussi; Jokinen, Ari; Karvonen, Pasi et al.
System: The UNT Digital Library
Fourier transform infrared spectroscopy studies of water-polymer interactions in chemically amplified photoresists (open access)

Fourier transform infrared spectroscopy studies of water-polymer interactions in chemically amplified photoresists

Fourier-Transform Infrared (FTIR) absorption spectroscopy is implemented to measure the infrared spectrum of water absorbed by the Poly(t-butoxycarbonylstyrene) (tBOC) and the ketal-protected Poly(hydroxystyrene) (KRS-XE) polymer photoresists. The shape and intensity of the OH stretching band of the water spectrum is monitored in a variety of humidity conditions in order to obtain information on the hydrogen-bonding interactions between the water and the polymer chains. The band is deconvoluted into four sub-bands, which represent four types of water molecules in different environments. Because of the hydrophilicity of the polymers studied, a large portion of the sorbed water molecules is believed to be strongly bound to the polar sites of the polymer. The ratios of each type of water are found to be dependent on the humidity conditions to which the sample was exposed. At higher humidities, there is an increase in the fraction of free and weakly-bound water molecules. These findings are used to explain the humidity dependence of the deprotection reaction rates, since certain types of water may slow transport of reactive species within the polymer network.
Date: December 8, 2004
Creator: McDonough, Laurie A.; Chikan, Viktor; Kim, Zee Hwan; Leone, Stephen R. & Hinsberg, William D.
System: The UNT Digital Library
Evidence for neutrino mass: A decade of discovery (open access)

Evidence for neutrino mass: A decade of discovery

Neutrino mass and mixing are amongst the major discoveries of recent years. From the observation of flavor change in solar and atmospheric neutrino experiments to the measurements of neutrino mixing with terrestrial neutrinos, recent experiments have provided consistent and compelling evidence for the mixing of massive neutrinos. The discoveries at Super-Kamiokande, SNO, and KamLAND have solved the long-standing solar neutrino problem and demand that we make the first significant revision of the Standard Model in decades. Searches for neutrinoless double-beta decay probe the particle nature of neutrinos and continue to place limits on the effective mass of the neutrino. Possible signs of neutrinoless double-beta decay will stimulate neutrino mass searches in the next decade and beyond. I review the recent discoveries in neutrino physics and the current evidence for massive neutrinos.
Date: December 8, 2004
Creator: Heeger, Karsten M.
System: The UNT Digital Library
Selection of the InGaAs/InP as the Single TPV Diode Material System for NR Research and Development (open access)

Selection of the InGaAs/InP as the Single TPV Diode Material System for NR Research and Development

Advanced Concepts has focused on developing two material systems (InGaAs/InP and InGaAsSb/GaSb) over the past several years. This work summarizes a scientific evaluation of both material systems to determine which material has the greatest potential for high-efficiency (27%) and power density (0.8W/cm{sup 2}) TPV energy conversion. Lockheed Martin, KAPL Inc. and Bechtel Bettis have issued a joint recommendation to focus all diode development efforts in the future on InGaAs/InP TPV diodes, based on it's potential to acquire the required performance.
Date: December 8, 2004
Creator: Dashiell, M
System: The UNT Digital Library
Formation of GEMS from shock-accelerated crystalline dust in Superbubbles (open access)

Formation of GEMS from shock-accelerated crystalline dust in Superbubbles

Interplanetary dust particles (IDPs) contain enigmatic sub-micron components called GEMS (Glass with Embedded Metal and Sulfides). The compositions and structures of GEMS indicate that they have been processed by exposure to ionizing radiation but details of the actual irradiation environment(s) have remained elusive. Here we propose a mechanism and astrophysical site for GEMS formation that explains for the first time the following key properties of GEMS; they are stoichiometrically enriched in oxygen and systematically depleted in S, Mg, Ca and Fe (relative to solar abundances), most have normal (solar) oxygen isotopic compositions, they exhibit a strikingly narrow size distribution (0.1-0.5 {micro}m diameter), and some of them contain ''relict'' crystals within their silicate glass matrices. We show that the compositions, size distribution, and survival of relict crystals are inconsistent with amorphization by particles accelerated by diffusive shock acceleration. Instead, we propose that GEMS are formed from crystalline grains that condense in stellar outflows from massive stars in OB associations, are accelerated in encounters with frequent supernova shocks inside the associated superbubble, and are implanted with atoms from the hot gas in the SB interior. We thus reverse the usual roles of target and projectile. Rather than being bombarded at rest by …
Date: December 8, 2004
Creator: Westphal, A & Bradley, J P
System: The UNT Digital Library
Helical rays in two-dimensional resonant wave conversion (open access)

Helical rays in two-dimensional resonant wave conversion

The process of resonant wave conversion (often called linear mode conversion) has traditionally been analyzed with a spatially one-dimensional slab model, for which the rays propagate in a two-dimensional phase space. However, it has recently been shown [E.R. Tracy and A.N. Kaufman, Phys. Rev. Lett. 91, 130402 (2003)] that multidimensional rays have a helical structure for conversion in two or more spatial dimensions (if their dispersion matrix is generic). In that case, a one-dimensional model is inadequate; a correct analysis requires two spatial dimensions and, thus, four-dimensional phase space. In this paper we show that a cold plasma model will exhibit ray helicity in conversion regions where the density and magnetic field gradients are significantly non-parallel. For illustration, we examine a model of the poloidal plane of a deuterium-tritium tokamak plasma, and identify such a region. In this region, characterized by a six-sector topology, rays in the sector for incident and reflected magnetosonic waves exhibit significant helicity. We introduce a ''symmetric-wedge'' model, to develop a detailed analytic and numerical study of helical rays in this sector.
Date: December 8, 2004
Creator: Kaufman, Allan N.; Tracy, Eugene R. & Brizard, Alain J.
System: The UNT Digital Library