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Ab initio no core calculations of light nuclei and preludes to Hamiltonian quantum field theory
Recent advances in ab initio quantum many-body methods and growth in computer power now enable highly precise calculations of nuclear structure. The precision has attained a level sufficient to make clear statements on the nature of 3-body forces in nuclear physics. Total binding energies, spin-dependent structure effects, and electroweak properties of light nuclei play major roles in pinpointing properties of the underlying strong interaction. Eventually,we anticipate a theory bridge with immense predictive power from QCD through nuclear forces to nuclear structure and nuclear reactions. Light front Hamiltonian quantum field theory offers an attractive pathway and we outline key elements.
Date:
August 3, 2009
Creator:
Vary, J. P.; Maris, P.; Shirokov, A. M.; Honkanen, H.; li, J.; Brodsky, S. J. et al.
Object Type:
Article
System:
The UNT Digital Library
Access to Broadband Networks: The Net Neutrality Debate
This report discusses the current debate over "net neutrality." While there is no single accepted definition of "net neutrality," most agree that any such definition should include the general principles that owners of the networks that compose and provide access to the Internet should not control how consumers lawfully use that network, and they should not be able to discriminate against content provider access to that network.
Date:
August 3, 2009
Creator:
Gilroy, Angele A.
Object Type:
Report
System:
The UNT Digital Library
Air Force Next-Generation Bomber: Background and Issues for Congress
This report discusses key issues regarding funding for a next-generation bomber (NGB) program. Congress's decisions on these issues could affect Air Force capabilities and funding requirements, and the U.S. aircraft manufacturing industrial base.
Date:
August 3, 2009
Creator:
O'Rourke, Ronald
Object Type:
Report
System:
The UNT Digital Library
The Army's Future Combat System (FCS): Background and Issues for Congress
This report describes the Future Combat System (FCS) program, which was to be the Army's major research, development, and acquisition program consisting of 14 manned and unmanned systems linked by an extensive communications and information network. This report describes the proposed restructuring of the FCS program, announced by Secretary of Defense Gates in April 2009, which includes modernizing outdated equipment and re-evaluating vehicle design strategy.
Date:
August 3, 2009
Creator:
Feickert, Andrew
Object Type:
Report
System:
The UNT Digital Library
The Army's M-4 Carbine: Background and Issues for Congress
This report discusses possible replacements for the M-4 carbine, most notably the Special Operations Combat Assault Rifle (SCAR). This report also details results of studies and tests of the M-4 and feedback response from potential competitors.
Date:
August 3, 2009
Creator:
Feickert, Andrew
Object Type:
Report
System:
The UNT Digital Library
Assembly and Characterization of a Prototype Laser-Optical Firing System
The design, assembly and characterization of the latest generation of a small, ruggedized laser-optical firing system will be discussed. This work builds upon earlier results in an effort to continue the development of robust fiber-coupled laseroptical firing systems.[1][2] This newest prototype strives to improve on earlier designs, while continuing to utilize many of the environmentally proven opto-mechanical sub-assemblies.[2][3] One area of improvement involves the implementation of a second optical safing and arming component. Several additional design improvements were also incorporated to address shortcomings uncovered during environmental testing.[4][5] These tests and the subsequent failure analysis were performed at the laser sub-system level. Four identical prototypes were assembled and characterized. The performance of the units were evaluated by comparing a number of parameters including laser output energy, slope efficiency, beam divergence, spatial intensity profile, fiber injection and splitter-coupler transmission efficiency. Other factors evaluated were the ease of alignment, repeatability of the alignment process and the fabrication of the fiberoptical cables. The experimentally obtained results will be compared and contrasted to the performance of earlier prototypes.
Date:
August 3, 2009
Creator:
Morelli, Gregg L
Object Type:
Article
System:
The UNT Digital Library
A Bottom-Up Approach to SUSY Analyses
This paper proposes a new way to perform event generation and analysis in searches for new physics at the LHC. An abstract notation is used to describe the new particles on a level which better corresponds to detector resolution of LHC experiments. In this way the SUSY discovery space can be decomposed into a small number of eigenmodes each with only a few parameters, which allows to investigate the SUSY parameter space in a model-independent way. By focusing on the experimental observables for each process investigated the Bottom-Up Approach allows to systematically study the boarders of the experimental efficiencies and thus to extend the sensitivity for new physics.
Date:
August 3, 2009
Creator:
Horn, Claus
Object Type:
Article
System:
The UNT Digital Library
Burma: Economic Sanctions
This report provides background information on existing economic sanctions against Burma and possible options to expand sanctions.
Date:
August 3, 2009
Creator:
Niksch, Larry A. & Weiss, Martin A.
Object Type:
Report
System:
The UNT Digital Library
Conceptual Design of the Drive Beam for a PWFA-LC
Plasma Wake-Field Acceleration (PWFA) has demonstrated acceleration gradients above 50 GeV/m. Simulations have shown drive/witness bunch configurations that yield small energy spreads in the accelerated witness bunch and high energy transfer efficiency from the drive bunch to the witness bunch, ranging from 30% for a Gaussian drive bunch to 95% for bunch with triangular shaped longitudinal profile. These results open the opportunity for a linear collider that could be compact, efficient and more cost effective than the present microwave technologies. A concept of a PWFA-based Linear Collider (PWFA-LC) has been developed by the PWFA collaboration. Here we will describe the conceptual design and optimization of the drive beam, which includes the drive beam linac and distribution system. We apply experience of the CLIC drive beam design and demonstration in the CLIC Test Facility (CTF3) to this study. We discuss parameter optimization of the drive beam linac structure and evaluate the drive linac efficiency in terms of the drive beam distribution scheme and the klystron/modulator requirements.
Date:
August 3, 2009
Creator:
Pei, S.; Hogan, M. J.; Raubenheimer, T. O.; Seryi, A.; Braun, H. H.; Corsini, R. et al.
Object Type:
Article
System:
The UNT Digital Library
Connecting Reionization to the Local Universe
We present results of combined N-body and three-dimensional reionization calculations to determine the relationship between reionization history and local environment in a volume 1 Gpc h{sup -1} across and a resolution of about 1 Mpc. We resolve the formation of about 2 x 10{sup 6} halos of mass greater than {approx} 10{sup 12} M{sub {circle_dot}} at z = 0, allowing us to determine the relationship between halo mass and reionization epoch for galaxies and clusters. For our fiducial reionization model, in which reionization begins at z {approx} 15 and ends by z {approx} 6, we find a strong bias for cluster-size halos to be in the regions which reionized first, at redshifts 10 < z < 15. Consequently, material in clusters was reionized within relatively small regions, on the order of a few Mpc, implying that all clusters in our calculation were reionized by their own progenitors. Milky Way mass halos were on average reionized later and by larger regions, with a distribution most similar to the global one, indicating that low mass halos are nearly uncorrelated with reionization when only their mass is taken as a prior. On average, we find that most halos with mass less than 10{sup …
Date:
August 3, 2009
Creator:
Alvarez, Marcelo A.; Busha, Michael; Abel, Tom; Wechsler, Risa H. & /KIPAC, Menlo Park
Object Type:
Article
System:
The UNT Digital Library
Constraining the Scatter in the Mass-Richness Relation of maxBCG Clusters With Weak Lensing and X-ray Data
We measure the logarithmic scatter in mass at fixed richness for clusters in the maxBCG cluster catalog, an optically selected cluster sample drawn from SDSS imaging data. Our measurement is achieved by demanding consistency between available weak lensing and X-ray measurements of the maxBCG clusters, and the X-ray luminosity-mass relation inferred from the 400d X-ray cluster survey, a flux limited X-ray cluster survey. We find {sigma}{sub lnM|N{sub 200}} = 0.45{sub -0.18}{sup +0.20} (95%CL) at N{sub 200} {approx} 40, where N{sub 200} is the number of red sequence galaxies in a cluster. As a byproduct of our analysis, we also obtain a constraint on the correlation coefficient between lnL{sub X} and lnM at fixed richness, which is best expressed as a lower limit, r{sub L,M|N} {ge} 0.85 (95% CL). This is the first observational constraint placed on a correlation coefficient involving two different cluster mass tracers. We use our results to produce a state of the art estimate of the halo mass function at z = 0.23 - the median redshift of the maxBCG cluster sample - and find that it is consistent with the WMAP5 cosmology. Both the mass function data and its covariance matrix are presented.
Date:
August 3, 2009
Creator:
Rozo, Eduardo; U., /Ohio State; Rykoff, Eli S.; /UC, Santa Barbara; Evrard, August; U., /Michigan et al.
Object Type:
Article
System:
The UNT Digital Library
Cosmological Constraints from the SDSS maxBCG Cluster Catalog
We use the abundance and weak lensing mass measurements of the SDSS maxBCG cluster catalog to simultaneously constrain cosmology and the richness-mass relation of the clusters. Assuming a flat {Lambda}CDM cosmology, we find {sigma}{sub 8}({Omega}{sub m}/0.25){sup 0.41} = 0.832 {+-} 0.033 after marginalization over all systematics. In common with previous studies, our error budget is dominated by systematic uncertainties, the primary two being the absolute mass scale of the weak lensing masses of the maxBCG clusters, and uncertainty in the scatter of the richness-mass relation. Our constraints are fully consistent with the WMAP five-year data, and in a joint analysis we find {sigma}{sub 8} = 0.807 {+-} 0.020 and {Omega}{sub m} = 0.265 {+-} 0.016, an improvement of nearly a factor of two relative to WMAP5 alone. Our results are also in excellent agreement with and comparable in precision to the latest cosmological constraints from X-ray cluster abundances. The remarkable consistency among these results demonstrates that cluster abundance constraints are not only tight but also robust, and highlight the power of optically-selected cluster samples to produce precision constraints on cosmological parameters.
Date:
August 3, 2009
Creator:
Rozo, Eduardo; Wechsler, Risa H.; Rykoff, Eli S.; Annis, James T.; Becker, Matthew R.; Evrard, August E. et al.
Object Type:
Report
System:
The UNT Digital Library
Damping Effect Studies for X-band Normal Conducting High Gradient Standing Wave Structures
The Multi-TeV colliders should have the capability to accelerate low emittance beam with high rf efficiency, X-band normal conducting high gradient accelerating structure is one of the promising candidate. However, the long range transverse wake field which can cause beam emittance dilution is one of the critical issues. We examined effectiveness of dipole mode damping in three kinds of X-band, {pi}-mode standing wave structures at 11.424GHz with no detuning considered. They represent three damping schemes: damping with cylindrical iris slot, damping with choke cavity and damping with waveguide coupler. We try to reduce external Q factor below 20 in the first two dipole bands, which usually have very high (R{sub T}/Q){sub T}. The effect of damping on the acceleration mode is also discussed.
Date:
August 3, 2009
Creator:
Pei, S.; Li, Z.; Tantawi, S. G.; Dolgashev, V. A. & Wang, J.
Object Type:
Article
System:
The UNT Digital Library
A Domino Theory of Flavor
We argue that the fermion masses and mixings are organized in a specific pattern. The approximately equal hierarchies between successive generations, the sizes of the mixing angles, the heaviness of just the top quark, and the approximate down-lepton equality can all be accommodated by many flavor models but can appear ad hoc. We present a simple, predictive mechanism to explain these patterns. All generations are treated democratically and the flavor symmetries are broken collectively by only two allowed couplings in flavor-space, a vector and matrix, with arbitrary {Omicron}(1) entries. Repeated use of these flavor symmetry breaking spurions radiatively generates the Yukawa couplings with a natural hierarchy. We demonstrate this idea with two models in a split supersymmetric grand unified framework, with minimal additional particle content at the unification scale. Although flavor is generated at the GUT scale, there are several potentially testable predictions. In our minimal model the usual prediction of exact b-{tau} unification is replaced by the SU(5) breaking relation m{sub {tau}}/m{sub b} = 3/2, in better agreement with observations. Other SU(5) breaking effects in the fermion masses can easily arise directly from the flavor model itself. The symmetry breaking that triggers the generation of flavor necessarily gives rise …
Date:
August 3, 2009
Creator:
Graham, Peter W. & Rajendran, Surjeet
Object Type:
Article
System:
The UNT Digital Library
Duration of Continuing Resolutions in Recent Years
This report provides information about the Duration of Continuing Resolutions in Recent Years. continuing appropriation acts have been an integral component of the annual appropriations process for decades
Date:
August 3, 2009
Creator:
Keith, Robert
Object Type:
Report
System:
The UNT Digital Library
Empirical Assessment of Shareholder Incentive Mechanisms Designs under Aggressive Savings Goals: Case Study of a Kansas"Super-Utility"
Achieving significant reductions in retail electric sales is becoming a priority for policymakers in many states and is echoed at the federal level with the introduction of legislation to establish a national energy efficiency resource standard. Yet, as the National Action Plan on Energy Efficiency (NAPEE) pointed out, many utilities continue to shy away from seriously expanding their energy efficiency program offerings because they claim there is insufficient profit motivation, or even a financial disincentive, when compared to supply-side investments. In response to an information request from the Kansas Corporation Commission staff, we conducted a financial analysis to assess the utility business case in Kansas for pursuing more aggressive energy efficiency that complies with recent state legislation. Kansas' utilities are vertically integrated and don't face retail competition. With historically low retail rates and modest experience with energy efficiency, the achievement of rapid and substantial sales reductions from energy efficiency will require a viable utility business model. Using a conglomerate of the three largest utilities in Kansas, we quantitatively illustrate the tradeoff between ratepayer and shareholder interests when a 1percent reduction in incremental sales is achieved through energy efficiency both with and without the impact of future carbon regulation. We then …
Date:
August 3, 2009
Creator:
Cappers, Peter & Goldman, Charles
Object Type:
Article
System:
The UNT Digital Library
Federal Contracting: Application of OMB Guidance Can Improve Use of Award Fee Contracts
Testimony issued by the Government Accountability Office with an abstract that begins "From fiscal year 2004 through fiscal year 2008, agencies spent over $300 billion on contracts which include award fees. While many agencies use award fee contracts, over 95 percent of the government's spending using this contract type in fiscal year 2008 occurred at five: the departments of Defense (DOD), Energy (DOE), Health and Human Services (HHS), and Homeland Security (DHS) and the National Aeronautics and Space Administration (NASA). In December 2007, the Office of Management and Budget's (OMB) Office of Federal Procurement Policy issued guidance to chief acquisition officers and procurement executives across the government that echoed several recommendations we made in 2005 on the use of award fees and emphasized positive practices to be implemented by all agencies. GAO's statement today is based on our May 29, 2009, report, Federal Contracting: Guidance on Award Fees Has Led to Better Practices But is Not Consistently Applied (GAO-09-630). Like the report, this statement addresses how agencies are implementing OMB's guidance. Specifically, we (1) identified the actions agencies have taken to revise or develop policies and guidance to reflect OMB guidance on using award fees, (2) determined the extent to …
Date:
August 3, 2009
Creator:
United States. Government Accountability Office.
Object Type:
Text
System:
The UNT Digital Library
FLASH Beam-off RF Measurements and Analyses
None
Date:
August 3, 2009
Creator:
Pei, S.; Adolphsen, C.; Carwardine, J. & Walker, N. J.
Object Type:
Article
System:
The UNT Digital Library
Follow-On Biologics: Intellectual Property and Innovation Issues
This report reviews doctrinal and policy issues pertaining to follow-on biologics. The report first introduces the application of federal food and drug legislation to follow-on biologics. It next turns to the patent implications of marketing follow-on biologics. Following this review of substantive law, the remainder of the report introduces innovation policy issues pertaining to follow-on biologics.
Date:
August 3, 2009
Creator:
Schacht, Wendy H. & Thomas, John R.
Object Type:
Report
System:
The UNT Digital Library
A Fusing Switch for Fault Suppression in the SNS High Voltage Converter Modulators
The High Voltage Converter Modulators (HVCMs) at the Spallation Neutron Source (SNS) have operated in excess of a combined 250,000 hours. Performance and reliability improvements to the HVCM are ongoing to increase modulator availability as accelerator system demands increase. There is a relatively large amount of energy storage in the HVCMs, {approx}180 kJ. This energy has the potential to dump into unsuppressed faults, cause damage, and increase the time to repair. The 'fusing switch' concept involves isolation of this stored energy from the location of the most common faults. This paper introduces this concept and its application to the HVCMs.
Date:
August 3, 2009
Creator:
Kemp, Mark A.; Burkhart, Craig; Nguyen, Minh N. & Anderson, David E.
Object Type:
Article
System:
The UNT Digital Library
Galaxy Mergers and Dark Matter Halo Mergers in LCDM: Mass, Redshift, and Mass-Ratio Dependence
We employ a high-resolution LCDM N-body simulation to present merger rate predictions for dark matter halos and investigate how common merger-related observables for galaxies - such as close pair counts, starburst counts, and the morphologically disturbed fraction - likely scale with luminosity, stellar mass, merger mass ratio, and redshift from z = 0 to z = 4. We provide a simple 'universal' fitting formula that describes our derived merger rates for dark matter halos a function of dark halo mass, merger mass ratio, and redshift, and go on to predict galaxy merger rates using number density-matching to associate halos with galaxies. For example, we find that the instantaneous merger rate of m/M > 0.3 mass ratio events into typical L {approx}> fL{sub *} galaxies follows the simple relation dN/dt {approx_equal} 0.03(1+f)Gyr{sup -1} (1+z){sup 2.1}. Despite the rapid increase in merger rate with redshift, only a small fraction of > 0.4L{sub *} high-redshift galaxies ({approx} 3% at z = 2) should have experienced a major merger (m/M > 0.3) in the very recent past (t < 100 Myr). This suggests that short-lived, merger-induced bursts of star formation should not contribute significantly to the global star formation rate at early times, in …
Date:
August 3, 2009
Creator:
Stewart, Kyle R.; Bullock, James S.; Barton, Elizabeth J.; /UC, Irvine; Wechsler, Risa H. & /KIPAC, Menlo Park /SLAC
Object Type:
Article
System:
The UNT Digital Library
Gas-Rich Mergers in LCDM: Disk Survivability and the Baryonic Assembly of Galaxies
We use N-body simulations and observationally-normalized relations between dark matter halo mass, stellar mass, and cold gas mass to derive robust expectations about the baryonic content of major mergers out to redshift z {approx} 2. First, we find that the majority of major mergers (m/M > 0.3) experienced by Milky Way size dark matter halos should have been gas-rich, and that gas-rich mergers are increasingly common at high redshift. Though the frequency of major mergers into galaxy halos in our simulations greatly exceeds the observed late-type galaxy fraction, the frequency of gas-poor major mergers is consistent with the observed fraction of bulge-dominated galaxies across the halo mass range M{sub DM} {approx} 10{sup 11} - 10{sup 13} M{sub {circle_dot}}. These results lend support to the conjecture that mergers with high baryonic gas fractions play an important role in building and/or preserving disk galaxies in the universe. Secondly, we find that there is a transition mass below which a galaxy's past major mergers were primarily gas-rich and above which they were gas poor. The associated stellar mass scale corresponds closely to that marking the observed bimodal division between blue, star-forming, disk-dominated systems and red, bulge-dominated systems with old populations. Finally, we find …
Date:
August 3, 2009
Creator:
Stewart, Kyle R.; Bullock, James S.; /UC, Irvine; Wechsler, Risa H.; /KIPAC, Menlo Park /SLAC; Maller, Ariyeh H. et al.
Object Type:
Article
System:
The UNT Digital Library
Historic Habitat Opportunities and Food-Web Linkages of Juvenile Salmon in the Columbia River Estuary and Their Implications for Managing River Flows and Restoring Estuarine Habitat, Physical Sciences Component, Progress Report.
Long-term changes and fluctuations in river flow, water properties, tides, and sediment transport in the Columbia River and its estuary have had a profound effect on Columbia River salmonids and their habitat. Understanding the river-flow, temperature, tidal, and sediment-supply regimes of the Lower Columbia River (LCR) and how they interact with habitat is, therefore, critical to development of system management and restoration strategies. It is also useful to separate management and climate impacts on hydrologic properties and habitat. This contract, part of a larger project led by the National Oceanic and Atmospheric Administration (NOAA), consists of three work elements, one with five tasks. The first work element relates to reconstruction of historic conditions in a broad sense. The second and third elements consist, respectively, of participation in project-wide integration efforts, and reporting. This report focuses on the five tasks within the historic reconstruction work element. It in part satisfies the reporting requirement, and it forms the basis for our participation in the project integration effort. The first task consists of several topics related to historic changes in river stage and tide. Within this task, the chart datum levels of 14 historic bathymetric surveys completed before definition of Columbia River Datum …
Date:
August 3, 2009
Creator:
Jay, David A.
Object Type:
Report
System:
The UNT Digital Library
The Impact of Inhomogeneous Reionization on the Satellite Galaxy Population of the Milky Way
We use the publicly available subhalo catalogs from the via Lactea simulation along with a Gpc-scale N-body simulation to understand the impact of inhomogeneous reionization on the satellite galaxy population of the Milky Way. The large-volume simulation is combined with a model for reionization that allows us to predict the distribution of reionization times for Milky Way mass halos. Motivated by this distribution, we identify candidate satellite galaxies in the simulation by requiring that any subhalo must grow above a specified mass threshold before it is reionized; after this time the photoionizing background will suppress both the formation of stars and the accretion of gas. We show that varying the reionization time over the range expected for Milky Way mass halos can change the number of satellite galaxies by roughly two orders of magnitude. This conclusion is in contradiction with a number of studies in the literature, and we conclude that this is a result of inconsistent application of the results of Gnedin (2000); subtle changes in the assumptions about how reionization affects star formation in small galaxies can lead to large changes in the effect of changing the reionization time on the number of satellites. We compare our satellite …
Date:
August 3, 2009
Creator:
Busha, Michael T.; Alvarez, Marcelo A.; Wechsler, Risa H.; Abel, Tom; Strigari, Louis E. & /KIPAC, Menlo Park
Object Type:
Article
System:
The UNT Digital Library