37 Matching Results

Search Results

Inadvertent RDA: New Catalogers' Errors in AACR2

Description: This article discusses Resource Description and Access (RDA) and new catalogers' errors in Anglo-American Cataloguing Rules, 2nd ed. (AACR2).
Date: August 17, 2012
Creator: Harden, Jean, 1948-
Partner: UNT Libraries

A Compact Ring Design with Tunable Momentum Compaction

Description: A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and predamping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.
Date: May 17, 2012
Creator: Sun, Y.
Partner: UNT Libraries Government Documents Department

Angular Scaling In Jets

Description: We introduce a jet shape observable defined for an ensemble of jets in terms of two-particle angular correlations and a resolution parameter R. This quantity is infrared and collinear safe and can be interpreted as a scaling exponent for the angular distribution of mass inside the jet. For small R it is close to the value 2 as a consequence of the approximately scale invariant QCD dynamics. For large R it is sensitive to non-perturbative effects. We describe the use of this correlation function for tests of QCD, for studying underlying event and pile-up effects, and for tuning Monte Carlo event generators.
Date: February 17, 2012
Creator: Jankowiak, Martin & Larkoski, Andrew J.
Partner: UNT Libraries Government Documents Department

A New Green's Function for the Wake Potential Calculation of the SLAC S-band Constant Gradient Accelerating Section

Description: The behavior of the longitudinal wake fields excited by a very short bunch in the SLAC S-band constant gradient accelerating structures has been studied. Wake potential calculations were performed for a bunch length of 10 microns using the author's code to obtain a numerical solution of Maxwell's equations in the time domain. We have calculated six accelerating sections in the series (60-ft) to find the stationary solution. While analyzing the computational results we have found a new formula for the Green's function. Wake potentials, which are calculated using this Green's function are in amazingly good agreement with numerical results over a wide range of bunch lengths. The Green's function simplifies the wake potential calculations and can be easily incorporated into the tracking codes. This is very useful for beam dynamics studies of the linear accelerators of LCLS and FACET.
Date: February 17, 2012
Creator: Novokhatski, A,
Partner: UNT Libraries Government Documents Department

Fermi-LAT and Suzaku Observations of the Radio Galaxy Centaurus B

Description: CentaurusB is a nearby radio galaxy positioned in the Southern hemisphere close to the Galactic plane. Here we present a detailed analysis of about 43 months accumulation of Fermi-LAT data and of newly acquired Suzaku X-ray data for Centaurus B. The source is detected at GeV photon energies, although we cannot completely exclude the possibility that it is an artifact due to incorrect modeling of the bright Galactic diffuse emission in the region. The LAT image provides a weak hint of a spatial extension of the {gamma} rays along the radio lobes, which is consistent with the lack of source variability in the GeV range. We note that the extension cannot be established statistically due to the low number of the photons. Surprisingly, we do not detect any diffuse emission of the lobes at X-ray frequencies, with the provided upper limit only marginally consistent with the previously claimed ASCA flux. The broad-band modeling shows that the observed {gamma}-ray flux of the source may be produced within the lobes, if the diffuse non-thermal X-ray emission component is not significantly below the derived Suzaku upper limit. This association would imply that efficient in-situ acceleration of the ultrarelativistic particles is occurring and that the lobes are dominated by the pressure from the relativistic particles. However, if the diffuse X-ray emission is much below the Suzaku upper limits, the observed {gamma}-ray flux is not likely to be produced within the lobes, but instead within the unresolved core of Centaurus B. In this case, the extended lobes could be dominated by the pressure of the magnetic field.
Date: August 17, 2012
Creator: Katsuta, Junichiro; Tanaka, Y. T.; Stawarz, L.; O'Sullivan, S. P.; Cheung, C. C.; Kataoka, J. et al.
Partner: UNT Libraries Government Documents Department

Limits on Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

Description: We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to {gamma}{gamma} should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.
Date: August 17, 2012
Creator: Ajello, M.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R. et al.
Partner: UNT Libraries Government Documents Department

Fermi-LAT Observation of Supernova Remnant S147

Description: We present an analysis of gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region around SNR S147 (G180.0-1.7). A spatially extended gamma-ray source detected in an energy range of 0.2-10 GeV is found to coincide with SNR S147. We confirm its spatial extension at >5{sigma} confidence level. The gamma-ray flux is (3.8 {+-} 0.6) x 10{sup -8} photons cm{sup -2} s{sup -1}, corresponding to a luminosity of 1.3 x 10{sup 34} (d/1.3 kpc){sup 2} erg s{sup -1} in this energy range. The gamma-ray emission exhibits a possible spatial correlation with prominent H{alpha} filaments of S147. There is no indication that the gamma-ray emission comes from the associated pulsar PSR J0538+2817. The gamma-ray spectrum integrated over the remnant is likely dominated by the decay of neutral {pi} mesons produced through the proton-proton collisions in the filaments. Reacceleration of pre-existing CRs and subsequent adiabatic compression in the filaments is sufficient to provide the required energy density of high-energy protons.
Date: August 17, 2012
Creator: Katsuta, J.; Uchiyama, Y.; Tanaka, T.; Tajima, H.; Bechtol, K.; Funk, S. et al.
Partner: UNT Libraries Government Documents Department

Systematic Improvement of QCD Parton Showers

Description: In this contribution, we will give a brief overview of the progress that has been achieved in the field of combining matrix elements and parton showers. We exemplify this by focusing on the case of electron-positron collisions and by reporting on recent developments as accomplished within the SHERPA event generation framework.
Date: May 17, 2012
Creator: Winter, Jan; Hoeche, Stefan; Hoeth, Hendrik; Krauss, Frank; Schonherr, Marek; Zapp, Korinna et al.
Partner: UNT Libraries Government Documents Department

New Insights into the EMC Effect

Description: Deep-inelastic scattering cross section ratios plotted as a function of the Bjorken scaling variable, xB, show an unexpected structure indicating that partonic structure in nuclei is different than in free nucleons. This phenomenon is commonly referred to as the EMC effect. Recent Jefferson Lab experimental data showed that the slope of the EMC effect in the 0.3 < xB > 0.7 region scales as the local nuclear density rather than the average nuclear density. This result lead to the comparison of xB>1 short-range correlation plateaus, also a local density effect, to the magnitude of the EMC effect slopes and a clear linear relation was found. In this talk, I will discuss the EMC effect and the short-range correlation plateaus and what this phenomenological relationship between the two implies.
Date: August 17, 2012
Creator: Higinbotham, Douglas
Partner: UNT Libraries Government Documents Department

2012 DEFECTS IN SEMICONDUCTORS GORDON RESEARCH CONFERENCE, AUGUST 12-17, 2012

Description: The meeting shall strive to develop and further the fundamental understanding of defects and their roles in the structural, electronic, optical, and magnetic properties of bulk, thin film, and nanoscale semiconductors and device structures. Point and extended defects will be addressed in a broad range of electronic materials of particular current interest, including wide bandgap semiconductors, metal-oxides, carbon-based semiconductors (e.g., diamond, graphene, etc.), organic semiconductors, photovoltaic/solar cell materials, and others of similar interest. This interest includes novel defect detection/imaging techniques and advanced defect computational methods.
Date: August 17, 2012
Creator: GLASER, EVAN
Partner: UNT Libraries Government Documents Department

2012 WATER & AQUEOUS SOLUTIONS GORDON RESEARCH CONFERENCE (GRC) AND GORDON RESEARCH SEMINAR (GRS), AUG 10-17, 2012

Description: Understanding the fundamental principles governing the structure and dynamics of water - and particularly how water mediates chemical interactions and processes - continues to pose formidable challenges and yield abundant surprises. The focus of this Gordon Research Conference is on identifying key questions, describing emerging understandings, and unveiling surprising discoveries related to water and aqueous solutions. The talks and posters at this meeting will describe studies of water and its interactions with objects such as interfaces, channels, electrons, oils, ions, and proteins; probed using optical, electrical, and particle experiments, and described using classical, quantum, and multi-scale theories.
Date: August 17, 2012
Creator: Dor Ben-Amotz, PI
Partner: UNT Libraries Government Documents Department

Electronic Structure and Oxidation State Changes in the Mn (4) Ca Cluster of Photosystem II

Description: Oxygen-evolving complex (Mn{sub 4}Ca cluster) of Photosystem II cycles through five intermediate states (S{sub i}-states, i = 0-4) before a molecule of dioxygen is released. During the S-state transitions, electrons are extracted from the OEC, either from Mn or alternatively from a Mn ligand. The oxidation state of Mn is widely accepted as Mn{sub 4}(III{sub 2},IV{sub 2}) and Mn{sub 4}(III,IV{sub 3}) for S{sub 1} and S{sub 2} states, while it is still controversial for the S{sub 0} and S{sub 3} states. We used resonant inelastic X-ray scattering (RIXS) to study the electronic structure of Mn{sub 4}Ca complex in the OEC. The RIXS data yield two-dimensional plots that provide a significant advantage by obtaining both K-edge pre-edge and L-edge-like spectra (metal spin state) simultaneously. We have collected data from PSII samples in the each of the S-states and compared them with data from various inorganic Mn complexes. The spectral changes in the Mn 1s2p{sub 3/2} RIXS spectra between the S-states were compared to those of the oxides of Mn and coordination complexes. The results indicate strong covalency for the electronic configuration in the OEC, and we conclude that the electron is transferred from a strongly delocalized orbital, compared to those in Mn oxides or coordination complexes. The magnitude for the S{sub 0} to S{sub 1}, and S{sub 1} to S{sub 2} transitions is twice as large as that during the S{sub 2} to S{sub 3} transition, indicating that the electron for this transition is extracted from a highly delocalized orbital with little change in charge density at the Mn atoms.
Date: August 17, 2012
Creator: Yano, J.; Pushkar, Y.; Messinger, J.; Bergmann, U.; Glatzel, P.; Yachandra, V.K. et al.
Partner: UNT Libraries Government Documents Department

Photoconductivity and Non-Exponential Relaxation at Insulating LaAlO3/SrTiO3 Interfaces

Description: LaAlO{sub 3} is grown on SrO terminated (100) SrTiO{sub 3}, and (110) SrTiO{sub 3}, producing insulating heterointerfaces without light. Photocurrent spectroscopy at low temperatures reveals a broad distribution of interface states between 2 eV and 2.7 eV at both interfaces, with a higher density in the (110) case concomitant with relatively shallow traps. The photocurrent relaxation can be well fitted by a stretched exponential form, confirming energetically distributed electron traps. Photo-carrier lifetimes are larger than a few hundred seconds for optical excitation approaching the SrTiO{sub 3} band-gap energy, providing the opportunity to study transient light-induced properties at low temperatures.
Date: August 17, 2012
Creator: Kim, Minu; Bell, C.; Hikita, Y.; Kozuka, Y.; Kim, B.G. & Hwang, H.Y.
Partner: UNT Libraries Government Documents Department

Search for Lepton-Number Violating Processes in B+ to h- l+ l+ Decays

Description: We have searched for the lepton-number violating processes B{sup +} {yields} h{sup -}{ell}{sup +}{ell}{sup +} with h{sup -} = K{sup -}/{pi}{sup -} and {ell}{sup +} = e{sup +}/{mu}{sup +}, using a sample of 471 {+-} 3 million B{bar B} events collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. We find no evidence for these decays and place 90% confidence level upper limits on their branching fractions B (B{sup +} {yields} {pi}{sup -}e{sup +}e{sup +}) < 2.3 x 10{sup -8}, {Beta}(B{sup +} {yields} K{sup -}e{sup +}e{sup +}) < 3.0 x 10{sup -8}, {Beta}(B{sup +} {yields} {pi}{sup -}{mu}{sup +}{mu}{sup +}) < 10.7 x 10{sup -8}, and {Beta}(B{sup +} {yields} K{sup -}{mu}{sup +}{mu}{sup +}) < 6.7 x 10{sup -8}.
Date: May 17, 2012
Creator: Lees, J.P.
Partner: UNT Libraries Government Documents Department

Multi-unit Operations in Non-Nuclear Systems: Lessons Learned for Small Modular Reactors

Description: The nuclear-power community has reached the stage of proposing advanced reactor designs to support power generation for decades to come. Small modular reactors (SMRs) are one approach to meet these energy needs. While the power output of individual reactor modules is relatively small, they can be grouped to produce reactor sites with different outputs. Also, they can be designed to generate hydrogen, or to process heat. Many characteristics of SMRs are quite different from those of current plants and may be operated quite differently. One difference is that multiple units may be operated by a single crew (or a single operator) from one control room. The U.S. Nuclear Regulatory Commission (NRC) is examining the human factors engineering (HFE) aspects of SMRs to support licensing reviews. While we reviewed information on SMR designs to obtain information, the designs are not completed and all of the design and operational information is not yet available. Nor is there information on multi-unit operations as envisioned for SMRs available in operating experience. Thus, to gain a better understanding of multi-unit operations we sought the lesson learned from non-nuclear systems that have experience in multi-unit operations, specifically refineries, unmanned aerial vehicles and tele-intensive care units. In this paper we report the lessons learned from these systems and the implications for SMRs.
Date: January 17, 2012
Creator: M., OHara J.; Higgins, J. & DAgostino, A.
Partner: UNT Libraries Government Documents Department

11th National Conference on Science, Policy, and the Environment: Our Changing Oceans

Description: On January 19-21, 2011, The National Council for Science and the Environment (NCSE) successfully convened its 11th National Conference on Science, Policy and the Environment: Our Changing Oceans in Washington, DC at the Ronald Reagan Building and International Trade Center. Over 1,247 participants attended the conference, representing federal, state and local governments, university and colleges across the US, civil society organizations, the business community, and international entities. In addition, the conference was webcast to an audience across several states. The conference provided a forum to examine the profound changes our ocean will undergo over the next 25-50 years and share various perspectives on the new research, tools, and policy initiatives to protect and sustain our ocean. Conference highlights and recommendations are available to the public on NCSE's conference website, www.OurChangingOceans.org.
Date: April 17, 2012
Creator: Saundry, Peter
Partner: UNT Libraries Government Documents Department

Single Phase Melt Processed Powellite (Ba,Ca) MoO{sub 4} For The Immobilization Of Mo-Rich Nuclear Waste

Description: Crystalline and glass composite materials are currently being investigated for the immobilization of combined High Level Waste (HLW) streams resulting from potential commercial fuel reprocessing scenarios. Several of these potential waste streams contain elevated levels of transition metal elements such as molybdenum (Mo). Molybdenum has limited solubility in typical silicate glasses used for nuclear waste immobilization. Under certain chemical and controlled cooling conditions, a powellite (Ba,Ca)MoO{sub 4} crystalline structure can be formed by reaction with alkaline earth elements. In this study, single phase BaMoO{sub 4} and CaMoO{sub 4} were formed from carbonate and oxide precursors demonstrating the viability of Mo incorporation into glass, crystalline or glass composite materials by a melt and crystallization process. X-ray diffraction, photoluminescence, and Raman spectroscopy indicated a long range ordered crystalline structure. In-situ electron irradiation studies indicated that both CaMoO{sub 4} and BaMoO{sub 4} powellite phases exhibit radiation stability up to 1000 years at anticipated doses with a crystalline to amorphous transition observed after 1 X 10{sup 13} Gy. Aqueous durability determined from product consistency tests (PCT) showed low normalized release rates for Ba, Ca, and Mo (<0.05 g/m{sup 2}).
Date: September 17, 2012
Creator: Brinkman, Kyle; Marra, James; Fox, Kevin; Reppert, Jason; Crum, Jarrod & Tang, Ming
Partner: UNT Libraries Government Documents Department

Integrating The Non-Electrical Worker Into The Electrical Safety Program

Description: The intent of this paper is to demonstrate an electrical safety program that incorporates all workers into the program, not just the electrical workers. It is largely in response to a paper presented at the 2012 ESW by Lanny Floyd entitled "Facilitating Application of Electrical Safety Best Practices to "Other" Workers" which requested all attendees to review their electrical safety program to assure that non-electrical workers were protected as well as electrical workers. The referenced paper indicated that roughly 50% of electrical incidents involve workers whose primary function is not electrical in nature. It also encouraged all to "address electrical safety for all workers and not just workers whose job responsibilities involve working on or near energized electrical circuits." In this paper, a program which includes specific briefings to non-electrical workers as well as to workers who may need to perform their normal activities in proximity to energized electrical conductors is presented. The program uses a targeted approach to specific areas such as welding, excavating, rigging, chart reading, switching, cord and plug equipment and several other general areas to point out hazards that may exist and how to avoid them. NFPA 70E-2004 was incorporated into the program several years ago and with it the need to include the "other" workers became apparent. The site experience over the years supports the assertion that about half of the electrical incidents involve non-electrical workers and this prompted us to develop specific briefings to enhance the knowledge of the non-electrical worker regarding safe electrical practices. The promotion of "May is Electrical Safety Month" and the development of informative presentations which are delivered to the general site population as well as electrical workers have greatly improved the hazards awareness status of the general worker on site.
Date: August 17, 2012
Creator: Mills, T. David & McAlhaney, John H.
Partner: UNT Libraries Government Documents Department