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Growth of laser damage in fused silica: diameter to depth ratio

Description: Growth of laser initiated damage plays a major role in determining optics lifetime in high power laser systems. Previous measurements have established that the lateral diameter grows exponentially. Knowledge of the growth of the site in the propagation direction is also important, especially so when considering techniques designed to mitigate damage growth, where it is required to reach all the subsurface damage. In this work, we present data on both the diameter and the depth of a growing exit surface damage sites in fused silica. Measured growth rates with both 351 nm illumination and with combined 351 nm and 1054 nm illumination are discussed.
Date: October 29, 2007
Creator: Norton, M A; Adams, J J; Carr, C W; Donohue, E E; Feit, M D; Hackel, R P et al.
Partner: UNT Libraries Government Documents Department

Isoelectronic trends of line strength data in the Li and Be isoelectronic sequences

Description: The decays of the 2p J = 1/2 and J = 3/2 levels of Li-like ions and of the 2s2p {sup 1,3}P{sub 1}{sup 0} levels of Be-like ions can be used as simple-atom test beds for experimental lifetime measurements and for the development of accurate calculations of the transition rates. They have summarized and filtered the experimental data in order to obtain consistent data sets and isoelectronic trends that can be compared to theoretical predictions. The graphical presentation of line strength data enables direct comparison and evaluation of the merit of data along extended isoelectronic sequences. From this, the precision that is necessary in future meaningful experiments can be deduced.
Date: March 1, 2006
Creator: Trabert, E & Curtis, L J
Partner: UNT Libraries Government Documents Department


Description: The iButton is a 'one-wire', temperature sensor and data logger in a short metal cylinder package 17 mm in diameter and 6 mm tall. The device is designed to be attached to a surface and acquire temperature samples over time periods as short as 1 second to as long as 300 minutes. Both 8-bit and 16-bit samples are available with 8kB of memory available. Lifetime is limited to an internal battery that cannot be replaced or recharged. The RF test interest originated with the concern that the data logger could inadvertently record electrical emanations from other nearby equipment. The normal operation of the data logger does not support high speed sampling but the control interface will operate at either 15.4 kbps or 125 kbps. There were no observable effects in the operation of the module or in the data that could be attributed to the use of RF energy. They made the assumption that these devices would potentially show RF sensitivity in any of the registers and in the data memory equally, therefore gross changes in the data might show RF susceptibility. No such sensitivity was observed. Because significant power levels were used for these tests they can extrapolate downward in power to state that no RF susceptibility would occur at lower power levels given the same configurations.
Date: October 26, 2011
Creator: Kane, R J & Baluyot, E V
Partner: UNT Libraries Government Documents Department

RF Driven Multicusp H- Ion Source

Description: An rf driven multicusp source capable of generating 1-ms H{sup -} beam pulses with a repetition rate as high as 150 Hz has been developed. This source can be operated with a filament or other types of starter. There is almost no lifetime limitation and a clean plasma can be maintained for a long period of operation. It is demonstrated that rf power as high as 25 kW could be coupled inductively to the plasma via a glass-coated copper-coil antenna. The extracted H{sup -} current density achieved is about 200 mA/cm{sup 2}.
Date: June 1, 1990
Creator: Leung, K.N.; DeVries, G.J.; DiVergilio, W.F.; Hamm, R.W.; Hauck, C.A.; Kunkel, W.B. et al.
Partner: UNT Libraries Government Documents Department


Description: The last gold-gold and polarized proton-proton collision runs were performed at energies of 100 GeV/nucleon. The beam gas interactions in RHIC are very important for the beam lifetime in RHIC. In this report the lifetime predicted by pressure data differences between the beams ON and beams OFF, at the energies of 100 GeV/nucleon. are compared to the predictions for the beam gas interaction and beam lifetimes.
Date: June 2, 2002
Partner: UNT Libraries Government Documents Department

Review of Charm and Beauty Lifetimes

Description: A review of the latest experimental results on charm and beauty particle lifetimes is presented together with a brief summary of measurement methods used for beauty particle lifetime measurements. There have been significant updates to the D{sub s}{sup +}/D{sup 0}, B{sup +}/B{sub d}{sup 0} and {Lambda}{sub b}{sup 0}/B{sub d}{sup 0} lifetime ratios which have some theoretical implications. However more precise measurements are still needed before one can make conclusive statements about the theory used to calculate the particle lifetimes.
Date: February 5, 1999
Creator: Cheung, Harry W. K.
Partner: UNT Libraries Government Documents Department

B physics at the Tevatron Collider

Description: Precision B-physics results from the CDF and DO Collaborations based on data collected during the Tevatron 1992-96 run are presented. In particular we discuss the measurement of B hadron lifetimes, and B{sup 0} - {anti B}{sup 0} mixing results obtained using time- evolution analyses. Perspectives for the next Tevatron run, starting in 1999, are also reported.
Date: May 1, 1997
Creator: De Troconiz, J. F.
Partner: UNT Libraries Government Documents Department

Limitations of the Arrhenius Methododolgy

Description: The Arrhenius methodology has been utilized for many years to NOV 171998 predict polymer lifetimes in various applications. Unfortunately, there are numerous potential limitations associated with this methodology, o ST I many of which can lead to non-Arrhenius behavior. This paper will review several of these limitations, including a brief mention of diffusion-limited oxidation (DLO) effects and a more extensive discussion of the implication of changes in the effective Arrhenius activation energy E. or in the dominant reactions as the temperature changes. Changes in Ea or in the dominant reactions with temperature can happen for any material, making extrapolations beyond the experimental temperature range problematic. Unfortunately, when mechanistic changes occur, they invariably result in a reduction in effective Arrhenius activation energy, leading to lower than expected material lifetimes. Thus it is critically important to derive methods for testing the Arrhenius extrapolation assumption. One approach that we have developed involves ultrasensitive oxygen consumption measurements. Results from the application of this approach will be reviewed.
Date: October 27, 1998
Creator: Celina, M.; Clough, R.L. & Gillen, K.T.
Partner: UNT Libraries Government Documents Department

Residual gas pressure profile in the recycler ring

Description: We simulate the pressure profile of residual gases from basic principles using detailed beam pipe geometry and the relevant physical parameters. These profiles are compared with the actual ion gauge measurements and is being used to predict the vacuum contribution to the Recycler Ring beam lifetime.
Date: May 27, 2003
Creator: Gounder, Krish; Marriner, John & Mishra, Shekhar
Partner: UNT Libraries Government Documents Department

Quantifying the Thermal Fatigue of CPV Modules

Description: A method is presented to quantify thermal fatigue in the CPV die-attach from meteorological data. A comparative; study between cities demonstrates a significant difference in the accumulated damage. These differences are most; sensitive to the number of larger (&#916;T) thermal cycles experienced for a location. High frequency data (<1/min) may; be required to most accurately employ this method.
Date: February 1, 2011
Creator: Bosco, N. & Kurtz, S.
Partner: UNT Libraries Government Documents Department

Strong Circularly Polarized Luminescence from Highly Emissive Terbium Complexes in Aqueous Solution

Description: Two luminescent terbium(III) complexes have been prepared from chiral ligands containing 2-hydroxyisophthalamide (IAM) antenna chromophores and their non-polarized and circularly-polarized luminescence properties have been studied. These tetradentate ligands, which form 2:1 ligand/Tb{sup III} complexes, utilize diaminocyclohexane (cyLI) and diphenylethylenediamine (dpenLI) backbones, which we reasoned would impart conformational rigidity and result in Tb{sup III} complexes that display both large luminescence quantum yield ({phi}) values and strong circularly polarized luminescence (CPL) activities. Both Tb{sup III} complexes are highly emissive, with {phi} values of 0.32 (dpenLI-Tb) and 0.60 (cyLI-Tb). Luminescence lifetime measurements in H{sub 2}O and D{sub 2}O indicate that while cyLI-Tb exists as a single species in solution, dpenLI-Tb exists as two species: a monohydrate complex with one H{sub 2}O molecule directly bound to the Tb{sup III} ion and a complex with no water molecules in the inner coordination sphere. Both cyLI-Tb and dpenLI-Tb display increased CPL activity compared to previously reported Tb{sup III} complexes made with chiral IAM ligands. The CPL measurements also provide additional confirmation of the presence of a single emissive species in solution in the case of cyLI-Tb, and multiple emissive species in the case of dpenLI-Tb.
Date: March 15, 2010
Creator: Samuel, Amanda; Lunkley, Jamie; Muller, Gilles & Raymond, Kenneth
Partner: UNT Libraries Government Documents Department


Description: A DC wire has been installed in RHIC to explore the long-range beam-beam effect, and test its compensation. We report on experiments that measure the effect of the wire's electro-magnetic field on the beam's lifetime and tune distribution, and accompanying simulations.
Date: June 25, 2007
Partner: UNT Libraries Government Documents Department

Measurement of the $\Lambda_b^0$ lifetime in the exclusive decay $\Lambda_b^0 \to J/\psi \Lambda^0$ in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV

Description: We measure the {Lambda}{sub b}{sup 0} lifetime in the fully reconstructed decay {Lambda}{sub b}{sup 0} {yields} J/{psi} {Lambda}{sup 0} using 10.4 fb{sup -1} of p{bar p} collisions collected with the D0 detector at {radical}s = 1.96 TeV. The lifetime of the topologically similar decay channel B{sup 0} {yields} J/{psi} K{sub S}{sup 0} is also measured. We obtain {tau} ({Lambda}{sub b}{sup 0}) = 1.303 {+-} 0.075 (stat.) {+-} 0.035 (syst.) ps and {tau} (B{sup 0}) = 1.508 {+-} 0.025 (stat.) {+-} 0.043 (syst.) ps. Using these measurements, we determine the lifetime ratio of {tau} ({Lambda}{sub b}{sup 0})/{tau} (B{sup 0}) = 0.864 {+-} 0.052 (stat.) {+-} 0.033 (syst.).
Date: April 1, 2012
Creator: Abazov, Victor Mukhamedovich & al., et
Partner: UNT Libraries Government Documents Department

Of Microenvironments and Mammary Stem Cells

Description: In most adult tissues there reside pools of stem and progenitor cells inside specialized microenvironments referred to as niches. The niche protects the stem cells from inappropriate expansion and directs their critical functions. Thus guided, stem cells are able to maintain tissue homeostasis throughout the ebb and flow of metabolic and physical demands encountered over a lifetime. Indeed, a pool of stem cells maintains mammary gland structure throughout development, and responds to the physiological demands associated with pregnancy. This review discusses how stem cells were identified in both human and mouse mammary glands; each requiring different techniques that were determined by differing biological needs and ethical constraints. These studies together create a robust portrait of mammary gland biology and identify the location of the stem cell niche, elucidate a developmental hierarchy, and suggest how the niche might be manipulated for therapeutic benefit.
Date: June 1, 2007
Creator: LaBarge, Mark A; Petersen, Ole W & Bissell, Mina J
Partner: UNT Libraries Government Documents Department

REACTIVITY LIFETIME 5091.4-5806.1 EFPH. CORE I, SEED 1. Test Results T- 612118-B

Description: The Shippingport Atomic Power Station was operated for 715 EFPH from Ang. 11 to Oct. 7, 1959, in order to determine the performance characteristics reliability, stability, and lifetime variation of the core during rated power operation for an extended period of time. The plant was operated at successively lower power levels of 60, 43, and 17 Mwe to extend the Core I, Seed 1 lifetime. Logs and tables are included which present the events and all recorded data in this period. (D.L.C.)
Date: August 1, 1960
Partner: UNT Libraries Government Documents Department

Terahertz metamaterials

Description: In this paper we present our recent developments in terahertz (THz) metamaterials and devices. Planar THz metamaterials and their complementary structures fabricated on suitable substrates have shown electric resonant response, which causes the band-pass or band-stop property in THz transmission and reflection. The operational frequency can be further tuned up to 20% upon photoexcitation of an integrated semiconductor region in the splitring resonators as the metamaterial elements. On the other hand, the use of semiconductors as metamaterial substrates enables dynamical control of metamaterial resonances through photoexcitation, and reducing the substrate carrier lifetime further enables an ultrafast switching recovery. The metamaterial resonances can also be actively controlled by application of a voltage bias when they are fabricated on semiconductor substrates with appropriate doping concentration and thickness. Using this electrically driven approach, THz modulation depth up to 80% and modulation speed of 2 MHz at room temperature have been demonstrated, which suggests practical THz applications.
Date: January 1, 2009
Creator: Chen, Hou-tong; Taylor, Antoineete J; Azad, Abul K & O' Hara, John F
Partner: UNT Libraries Government Documents Department

Anomalous Flavor U(1)_X for Everything

Description: We present an ambitious model of flavor, based on an anomalous U(1)_X gauge symmetry with one flavon, only two right-handed neutrinos and only two mass scales: M_{grav} and m_{3/2}. In particular, there are no new scales introduced for right-handed neutrino masses. The X-charges of the matter fields are such that R-parity is conserved exactly, higher-dimensional operators are sufficiently suppressed to guarantee a proton lifetime in agreement with experiment, and the phenomenology is viable for quarks, charged leptons, as well as neutrinos. In our model one of the three light neutrinos automatically is massless. The price we have to pay for this very successful model are highly fractional X-charges which can likely be improved with less restrictive phenomenological ansatze for mass matrices.
Date: December 1, 2003
Creator: Dreiner, Herbi K.; Murayama, Hitoshi & Thormeier, Marc
Partner: UNT Libraries Government Documents Department

Impacts of Water Quality on Residential Water Heating Equipment

Description: Water heating is a ubiquitous energy use in all residential housing, accounting for 17.7% of residential energy use (EIA 2012). Today, there are many efficient water heating options available for every fuel type, from electric and gas to more unconventional fuel types like propane, solar, and fuel oil. Which water heating option is the best choice for a given household will depend on a number of factors, including average daily hot water use (total gallons per day), hot water draw patterns (close together or spread out), the hot water distribution system (compact or distributed), installation constraints (such as space, electrical service, or venting accommodations) and fuel-type availability and cost. While in general more efficient water heaters are more expensive than conventional water heating technologies, the savings in energy use and, thus, utility bills can recoup the additional upfront investment and make an efficient water heater a good investment over time in most situations, although the specific payback period for a given installation will vary widely. However, the expected lifetime of a water heater in a given installation can dramatically influence the cost effectiveness and savings potential of a water heater and should be considered, along with water use characteristics, fuel availability and cost, and specific home characteristics when selecting the optimum water heating equipment for a particular installation. This report provides recommendations for selecting and maintaining water heating equipment based on local water quality characteristics.
Date: November 1, 2013
Creator: Widder, Sarah H. & Baechler, Michael C.
Partner: UNT Libraries Government Documents Department

Lifetime of the 1s2s 3S1 metastable level in He-like S14+ measured with an electron beam ion trap

Description: A precision measurement of the lifetime of the lowest exited level of the He-like S{sup 14+} ion carried out at the Livermore EBIT-II electron beam ion trap yielded a value of (703 {+-} 4) ns. Our method extends the range of lifetime measurements accessible with electron beam ion traps into the nanosecond region and improves the accuracy of currently available data for this level by an order of magnitude.
Date: March 16, 2006
Creator: L?pez-Urrutia, J C; Beiersdorfer, P & Widmann, K
Partner: UNT Libraries Government Documents Department

Damage detection using frequency domain ARX models and extreme value statistics

Description: Structural health monitoring (SHM) is fast becoming a field of great importance as engineers seek for new ways to ensure the safety of structures throughout their designed lifetime. Current methods for analyzing the dynamic response of structures often use standard frequency response functions to model linear system input/output relationships. However, these functions do not account for the nonlinear response of a system, which damage often introduces. In this study, an auto-regressive model with exogenous inputs (ARX) in the frequency domain is used to extract damage sensitive features, explicitly considering the nonlinear effect in the frequency domain. Furthermore, because of the non-Gaussian nature of the extracted features, extreme value statistics (EVS) is employed to develop a robust damage classifier. The applicability of the ARX model combined with EVS to nonlinear damage detection is demonstrated using vibration data obtained from a laboratory experiment of a three-story building model.
Date: January 1, 2002
Creator: Fasel, T. R. (Timothy R.); Sohn, H. (Hoon) & Farrar, C. R. (Charles R.)
Partner: UNT Libraries Government Documents Department