Study of Abnormal Vertical Emittance Growth in ATF Extraction Line (open access)

Study of Abnormal Vertical Emittance Growth in ATF Extraction Line

Since several years, the vertical beam emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This longstanding problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experimented by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.
Date: November 4, 2011
Creator: Alabau, M.; Faus-Golfe, A.; /Valencia U., IFIC; Alabau, M.; Bambade, P.; Brossard, J. et al.
Object Type: Article
System: The UNT Digital Library
The Debt Limit: History and Recent Increases (open access)

The Debt Limit: History and Recent Increases

This report discusses how the total debt of the federal government can increase, an historical overview of debt limits, and how the current economic slowdown has led to higher deficits and thereby a series of debt limit increases, as well as legislation related to these increases.
Date: November 4, 2010
Creator: Austin, D. Andrew & Levit, Mindy R.
Object Type: Report
System: The UNT Digital Library
Searches with Mono-Leptons (open access)

Searches with Mono-Leptons

None
Date: November 4, 2013
Creator: Bai, Yang & Tait, Tim M. P.
Object Type: Article
System: The UNT Digital Library
Qatar: Background and U.S. Relations (open access)

Qatar: Background and U.S. Relations

This report presents an overview of Qatar's history and recent economic and political developments. The report discusses U.S. relations with Qatar, U.S. military cooperation and foreign assistance, political reform and elections, as well as human rights and social issues.
Date: November 4, 2014
Creator: Blanchard, Christopher M.
Object Type: Report
System: The UNT Digital Library
Energy Efficiency and Renewable Energy (EERE): Appropriations and the FY2016 Budget Request (open access)

Energy Efficiency and Renewable Energy (EERE): Appropriations and the FY2016 Budget Request

None
Date: November 4, 2015
Creator: Bracmort, Kelsi & Sissine, Fred
Object Type: Report
System: The UNT Digital Library
Evolved QCD predictions for the meson-photon transition form factors: beyond the semiclassical AdS/QCD approximation (open access)

Evolved QCD predictions for the meson-photon transition form factors: beyond the semiclassical AdS/QCD approximation

The QCD evolution of the pion distribution amplitude (DA) {phi}{sub {pi}} (x, Q{sup 2}) is computed for several commonly used models. Our analysis includes the nonperturbative form predicted by lightfront holographic QCD, thus combining the nonperturbative bound state dynamics of the pion with the perturbative ERBL evolution of the pion distribution amplitude. We calculate the meson-photon transition form factors for the {pi}{sup 0}, {eta} and {eta}' using the hard-scattering formalism. We point out that a widely-used approximation of replacing {phi} (x; (1 - x)Q) with {phi} (x;Q) in the calculations will unjustifiably reduce the predictions for the meson-photon transition form factors. It is found that the four models of the pion DA discussed give very different predictions for the Q{sup 2} dependence of the meson-photon transition form factors in the region of Q{sup 2} > 30 GeV{sup 2}. More accurate measurements of these transition form factors at the large Q{sup 2} region will be able to distinguish the four models of the pion DA. The rapid growth of the large Q{sup 2} data for the pion-photon transition form factor reported by the BABAR Collaboration is difficult to explain within the current framework of QCD. If the BABAR data for the …
Date: November 4, 2011
Creator: Brodsky, Stanley J.; /SLAC; Cao, Fu-Guang; U., /Massey U. /Beijing Normal; de Teramond, Guy F. & U., /Costa Rica
Object Type: Article
System: The UNT Digital Library
Analysis of Electromagnetic Pulse (EMP) Measurements in the National Ingition Facility's Target Bay and Chamber (open access)

Analysis of Electromagnetic Pulse (EMP) Measurements in the National Ingition Facility's Target Bay and Chamber

None
Date: November 4, 2011
Creator: Brown, C G; Clancy, T J; Eder, D C; Ferguson, W & Throop, A L
Object Type: Article
System: The UNT Digital Library
Salaries of Members of Congress: Congressional Votes, 1990-2013 (open access)

Salaries of Members of Congress: Congressional Votes, 1990-2013

The report contains information on the pay procedure of members of Congress and recent adjustments. It provides information on previous actions and votes by year, from 1990-2010.
Date: November 4, 2013
Creator: Brudnick, Ida A.
Object Type: Report
System: The UNT Digital Library
Immigration Legislation and Issues in the 113th Congress (open access)

Immigration Legislation and Issues in the 113th Congress

Immigration reform was an active legislative issue in the first session of the 113th Congress. The Senate passed the Border Security, Economic Opportunity, and Immigration Modernization Act (S. 744), a comprehensive immigration reform bill that includes provisions on border security, interior enforcement, employment eligibility verification and worksite enforcement, legalization of unauthorized aliens, immigrant visas, nonimmigrant visas, and humanitarian admissions. For its part, the House took a different approach to immigration reform. Rather than considering a single comprehensive bill, the House acted on a set of immigration bills that address border security, interior enforcement, employment eligibility verification and worksite enforcement, and nonimmigrant and immigrant visas. House committees reported or ordered to be reported the following immigration bills: Border Security Results Act of 2013 (H.R. 1417); Strengthen and Fortify Enforcement (SAFE) Act (H.R. 2278); Legal Workforce Act (H.R. 1772); Agricultural Guestworker (AG) Act (H.R. 1773); and Supplying Knowledge-based Immigrants and Lifting Levels of STEM Visas (SKILLS Visa) Act (H.R. 2131). This report discusses these and other immigration-related issues that received legislative action or have been of significant congressional interest in the 113th Congress.
Date: November 4, 2014
Creator: Bruno, Andorra; Bjelopera, Jerome P.; Garcia, Michael John; Kandel, William A.; Lee, Margaret Mikyung; Siskin, Alison et al.
Object Type: Report
System: The UNT Digital Library
Correlation between structure and electrical transport in ion-irradiated graphene grown on Cu foils (open access)

Correlation between structure and electrical transport in ion-irradiated graphene grown on Cu foils

Graphene grown by chemical vapor deposition and supported on SiO2 and sapphire substrates was studied following controlled introduction of defects induced by 35 keV carbon ion irradiation. Changes in Raman spectra following fluences ranging from 1012 cm-2 to 1015 cm-2 indicate that the structure of graphene evolves from a highly-ordered layer, to a patchwork of disordered domains, to an essentially amorphous film. These structural changes result in a dramatic decrease in the Hall mobility by orders of magnitude while, remarkably, the Hall concentration remains almost unchanged, suggesting that the Fermi level is pinned at a hole concentration near 1x1013 cm-2. A model for scattering by resonant scatterers is in good agreement with mobility measurements up to an ion fluence of 1x1014 cm-2.
Date: November 4, 2010
Creator: Buchowicz, G.; Stone, P. R.; Robinson, J. T.; Cress, C. D.; Beeman, J. W. & Dubon, O. D.
Object Type: Article
System: The UNT Digital Library
Fishery, Aquaculture, and Marine Mammal Issues in the 112th Congress (open access)

Fishery, Aquaculture, and Marine Mammal Issues in the 112th Congress

This report provides the information related to the fishery, aquaculture, and marine mammal issues in the 112th Congress
Date: November 4, 2011
Creator: Buck, Eugene H. & Upton, Harold F.
Object Type: Report
System: The UNT Digital Library

Stakeholder Meeting on Long-term Revision Issues

A presentation discussing the Lead and Copper Rule (LCR) and how the EPA is in the process of developing revisions to the rule.
Date: November 4, 2010
Creator: Burneson, Eric.
Object Type: Presentation
System: The UNT Digital Library
Copper Prototype Measurements of the HOM, LOM And SOM Couplers for the ILC Crab Cavity (open access)

Copper Prototype Measurements of the HOM, LOM And SOM Couplers for the ILC Crab Cavity

The ILC Crab Cavity is positioned close to the IP and delivered luminosity is very sensitive to the wakefields induced in it by the beam. A set of couplers were designed to couple to and damp the spurious modes of the crab cavity. As the crab cavity operates using a dipole mode, it has different damping requirements from an accelerating cavity. A separate coupler is required for the monopole modes below the operating frequency of 3.9 GHz (known as the LOMs), the opposite polarization of the operating mode (the SOM), and the modes above the operating frequency (the HOMs). Prototypes of each of these couplers have been manufactured out of copper and measured attached to an aluminum nine cell prototype of the cavity and their external Q factors were measured. The results were found to agree well with numerical simulations.
Date: November 4, 2011
Creator: Burt, G.; Ambattu, P.K.; Dexter, A.C.; U., /Lancaster; Bellantoni, L.; /Fermilab et al.
Object Type: Article
System: The UNT Digital Library
Asymmetric Ferromagnet-Superconductor-Ferromagnet Switch (open access)

Asymmetric Ferromagnet-Superconductor-Ferromagnet Switch

In layered ferromagnet-superconductor-ferromagnet F{sub 1} /S/F{sub 2} structures, the critical temperature T{sub c} of the superconductors depends on the magnetic orientation of the ferromagnetic layers F{sub 1} and F{sub 2} relative to each other. So far, the experimentally observed magnitude of change in T{sub c} for structures utilizing weak ferromagnets has been 2 orders of magnitude smaller than is expected from calculations. We theoretically show that such a discrepancy can result from the asymmetry of F/S boundaries, and we test this possibility by performing experiments on structures where F{sub 1} and F{sub 2} are independently varied. Our experimental results indicate that asymmetric boundaries are not the source of the discrepancy. If boundary asymmetry is causing the suppressed magnitude of T{sub c} changes, it may only be possible to detect in structures with thinner ferromagnetic layers.
Date: November 4, 2011
Creator: Cadden-Zimansky, P.; Bazaliy, Ya. B.; Litvak, L. M.; Jiang, J. S.; Pearson, J.; Gu, J. Y. et al.
Object Type: Article
System: The UNT Digital Library
Progress report:: NTOF-extracted C rhoR for gas symcap shots (open access)

Progress report:: NTOF-extracted C rhoR for gas symcap shots

None
Date: November 4, 2013
Creator: Caggiano, J
Object Type: Article
System: The UNT Digital Library
Critical Magnetic Field Determination of Superconducting Materials (open access)

Critical Magnetic Field Determination of Superconducting Materials

Superconducting RF technology is becoming more and more important. With some recent cavity test results showing close to or even higher than the critical magnetic field of 170-180 mT that had been considered a limit, it is very important to develop a way to correctly measure the critical magnetic field (H{sup RF}{sub c}) of superconductors in the RF regime. Using a 11.4 GHz, 50-MW, <1 {mu}s, pulsed power source and a TE013-like mode copper cavity, we have been measuring critical magnetic fields of superconductors for accelerator cavity applications. This device can eliminate both thermal and field emission effects due to a short pulse and no electric field at the sample surface. A model of the system is presented in this paper along with a discussion of preliminary experimental data.
Date: November 4, 2011
Creator: Canabal, A.; Tajima, T.; Alamos, /Los; Dolgashev, V.A.; Tantawi, S.G.; /SLAC et al.
Object Type: Article
System: The UNT Digital Library
Conceptual Design of Minor Actinides Burner With an Accelerator-Driven Subcritical System. (open access)

Conceptual Design of Minor Actinides Burner With an Accelerator-Driven Subcritical System.

In the environmental impact study of the Yucca Mountain nuclear waste repository, the limit of spent nuclear fuel (SNF) for disposal is assessed at 70,000 metric tons of heavy metal (MTHM), among which 63,000 MTHM are the projected SNF discharge from U.S. commercial nuclear power plants though 2011. Within the 70,000 MTHM of SNF in storage, approximately 115 tons would be minor actinides (MAs) and 585 tons would be plutonium. This study describes the conceptual design of an accelerator-driven subcritical (ADS) system intended to utilize (burn) the 115 tons of MAs. The ADS system consists of a subcritical fission blanket where the MAs fuel will be burned, a spallation neutron source to drive the fission blanket, and a radiation shield to reduce the radiation dose to an acceptable level. The spallation neutrons are generated from the interaction of a 1 GeV proton beam with a lead-bismuth eutectic (LBE) or liquid lead target. In this concept, the fission blanket consists of a liquid mobile fuel and the fuel carrier can be LBE, liquid lead, or molten salt. The actinide fuel materials are dissolved, mixed, or suspended in the liquid fuel carrier. Therefore, fresh fuel can be fed into the fission blanket …
Date: November 4, 2011
Creator: Cao, Y. & Gohar, Y. (Nuclear Engineering Division)
Object Type: Report
System: The UNT Digital Library
Bispectral Speckle Imaging Algorithm Performance on Specific Simulated Scenarios (open access)

Bispectral Speckle Imaging Algorithm Performance on Specific Simulated Scenarios

None
Date: November 4, 2013
Creator: Carrano, C J
Object Type: Report
System: The UNT Digital Library
Quarkonium Spectroscopy And Search for New States at BaBar (open access)

Quarkonium Spectroscopy And Search for New States at BaBar

The BaBar experiment at the PEP-II B-factory gives excellent opportunities for the quarkonium spectroscopy. Investigation of the properties of new states like the X(3872), Y(3940) and Y(4260) are performed aiming to understand their nature. Recent BaBar results will be presented in this paper. At the B-factories charmonium and charmonium-like states are copiously produced via several mechanisms: in B decay (color suppressed b {yields} c transition), double charmonium production (e{sup +}e{sup -} {yields} c{bar c} + c{bar c}), two photons production ({gamma}*{gamma}* {yields} c{bar c}, where the c{bar c} state has positive C-parity) and in initial state radiation (ISR) when the e{sup {+-}} in its initial state emits a photon lowering the effective center of mass energy of the e{sup +}e{sup -} interaction (e{sup +}e{sup -} {yields} {gamma}{sub ISR} + c{bar c}, where the charmonium state has the quantum numbers J{sup PC} = 1{sup -2}). Many new states have been recently discovered at the B-factories, BaBar and Belle, above the D{bar D} threshold in the charmonium energy region. While some of them appear to be consistent with conventional c{sub c} states others do not fit with any expectation. Several interpretations for these states have been proposed: for some of them the …
Date: November 4, 2011
Creator: Cibinetto, G.
Object Type: Article
System: The UNT Digital Library
The Design of the Positron Source for the International Linear Collider (open access)

The Design of the Positron Source for the International Linear Collider

The high luminosity requirements and the option of a polarized positron beam present a great challenge for the positron source of a future linear collider. This paper provides a comprehensive overview of the latest proposed design for the baseline positron source of the International Linear Collider (ILC). We report on recent progress and results concerning the main components of the source: including the undulator, capture optics, and target.
Date: November 4, 2011
Creator: Clarke, J. A.; Malyshev, O. B.; Scott, D. J.; Bailey, I. R.; Dainton, J. B.; Hock, K. M. et al.
Object Type: Article
System: The UNT Digital Library
The one-loop six-dimensional hexagon integral with three massive corners (open access)

The one-loop six-dimensional hexagon integral with three massive corners

We compute the six-dimensional hexagon integral with three non-adjacent external masses analytically. After a simple rescaling, it is given by a function of six dual conformally invariant cross-ratios. The result can be expressed as a sum of 24 terms involving only one basic function, which is a simple linear combination of logarithms, dilogarithms, and trilogarithms of uniform degree three transcendentality. Our method uses differential equations to determine the symbol of the function, and an algorithm to reconstruct the latter from its symbol. It is known that six-dimensional hexagon integrals are closely related to scattering amplitudes in N = 4 super Yang-Mills theory, and we therefore expect our result to be helpful for understanding the structure of scattering amplitudes in this theory, in particular at two loops.
Date: November 4, 2011
Creator: Del Duca, Vittorio; Dixon, Lance J.; Drummond, James M.; Duhr, Claude; Henn, Johannes M. & Smirnov, Vladimir A.
Object Type: Article
System: The UNT Digital Library
Scattering Amplitudes: The Most Perfect Microscopic Structures in the Universe (open access)

Scattering Amplitudes: The Most Perfect Microscopic Structures in the Universe

This article gives an overview of many of the recent developments in understanding the structure of relativistic scattering amplitudes in gauge theories ranging from QCD to N = 4 super-Yang-Mills theory, as well as (super)gravity. I also provide a pedagogical introduction to some of the basic tools used to organize and illuminate the color and kinematic structure of amplitudes. This article is an invited review introducing a special issue of Journal of Physics A devoted to 'Scattering Amplitudes in Gauge Theories'.
Date: November 4, 2011
Creator: Dixon, Lance J. & /SLAC, /CERN
Object Type: Article
System: The UNT Digital Library
Status of High Power Tests of Normal Conducting Single-Cell Structures (open access)

Status of High Power Tests of Normal Conducting Single-Cell Structures

We report the results of ongoing high power tests of single-cell standing wave structures. These tests are part of an experimental and theoretical study of rf breakdown in normal conducting structures at 11.4 GHz. The goal of this study is to determine the maximum gradient possibilities for normal-conducting rf powered particle beam accelerators. The test setup consists of reusable mode launchers and short test structures powered by SLACs XL-4 klystron. The mode launchers and structures were manufactured at SLAC and KEK and tested at the SLAC klystron test laboratory.
Date: November 4, 2011
Creator: Dolgashev, V. A.; Tantawi, S. G.; Higashi, Y. & Higo, T.
Object Type: Article
System: The UNT Digital Library
Observations and Modeling of Debris and Shrapnel Impacts on Optics and Diagnostics at the National Ignition Facility (open access)

Observations and Modeling of Debris and Shrapnel Impacts on Optics and Diagnostics at the National Ignition Facility

A wide range of targets with laser energies spanning two orders of magnitude have been shot at the National Ignition Facility (NIF). The National Ignition Campaign (NIC) targets are cryogenic with Si supports and cooling rings attached to an Al thermo-mechanical package (TMP) with a thin (30 micron) Au hohlraum inside. Particular attention is placed on the low-energy shots where the TMP is not completely vaporized. In addition to NIC targets, a range of other targets has also been fielded on NIF. For all targets, simulations play a critical role in determining if the risks associated with debris and shrapnel are acceptable. In a number of cases, experiments were redesigned, based on simulations, to reduce risks or to obtain data. The majority of these simulations were done using the ALE-AMR code, which provides efficient late-time (100-1000X the pulse duration) 3D calculations of complex NIF targets.
Date: November 4, 2011
Creator: Eder, D.; Bailey, D.; Chamgers, F.; Darnell, I.; Nicola, P. D.; Dixit, S. et al.
Object Type: Article
System: The UNT Digital Library