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LHC Signals from Warped Extra Dimensions (open access)

LHC Signals from Warped Extra Dimensions

We study production of Kaluza-Klein gluons (KKG) at the Large Hadron Collider (LHC) in the framework of a warped extra dimension with the Standard Model (SM) fields propagating in the bulk. We show that the detection of KK gluon is challenging since its production is suppressed by small couplings to the proton's constituents. Moreover, the KK gluon decaysmostly to top pairs due to an enhanced coupling and hence is broad. Nevertheless, we demonstrate that for MKKG<~;; 4 TeV, 100 fb-1 of data at the LHC can provide discovery of the KK gluon. We utilize a sizeable left-right polarization asymmetry from the KK gluon resonance to maximize the signal significance, and we explore the novel feature of extremely highly energetic"top-jets." We briefly discuss how the detection of electroweak gauge KK states (Z/W) faces a similar challenge since their leptonic decays ("golden" modes) are suppressed. Our analysis suggests that other frameworks, for example little Higgs, which rely on UV completion via strong dynamics might face similar challenges, namely (1) Suppressed production rates for the new particles (such as Z'), due to their"lightfermion-phobic" nature, and (2) Difficulties in detection since the new particles are broad and decay predominantly to third generation quarks and …
Date: December 6, 2006
Creator: Agashe, K.; Belyaev, A.; Krupovnickas, T.; Perez, G. & Virzi, J.
System: The UNT Digital Library
EMC Diagnosis and Corrective Actions for Silicon Strip Tracker Detectors (open access)

EMC Diagnosis and Corrective Actions for Silicon Strip Tracker Detectors

The tracker sub-system is one of the five sub-detectors of the Compact Muon Solenoid (CMS) experiment under construction at CERN for the Large Hadron Collider (LHC) accelerator. The tracker subdetector is designed to reconstruct tracks of charged sub-atomic particles generated after collisions. The tracker system processes analogue signals from 10 million channels distributed across 14000 silicon micro-strip detectors. It is designed to process signals of a few nA and digitize them at 40 MHz. The overall sub-detector is embedded in a high particle radiation environment and a magnetic field of 4 Tesla. The evaluation of the electromagnetic immunity of the system is very important to optimize the performance of the tracker sub-detector and the whole CMS experiment. This paper presents the EMC diagnosis of the CMS silicon tracker sub-detector. Immunity tests were performed using the final prototype of the Silicon Tracker End-Caps (TEC) system to estimate the sensitivity of the system to conducted noise, evaluate the weakest areas of the system and take corrective actions before the integration of the overall detector. This paper shows the results of one of those tests, that is the measurement and analysis of the immunity to CM external conducted noise perturbations.
Date: June 6, 2006
Creator: Arteche, F. & Rivetta, C.
System: The UNT Digital Library
EMC Phenomena in HEP Detectors: Prevention and Cost Savings (open access)

EMC Phenomena in HEP Detectors: Prevention and Cost Savings

This paper addresses electromagnetic compatibility (EMC) studies applied to high-energy physics (HEP) detectors. They are focused on the quantification of the front-end electronic (FEE) sensitivity to conductive noise coupled through the input/output cables. Immunity tests performed on FEE prototypes of both the CMS hadron calorimeter and the CMS silicon tracker are presented. These tests characterize the sensitivity of the FEE to common and differential mode noise coupled through the power cables and the slow control network. Immunity tests allow evaluating the weakest areas of the system to take corrective actions before the integration of the overall detector, saving time and important costs.
Date: June 6, 2006
Creator: Arteche, F.; /Imperial Coll., London /CERN & Rivetta, C.
System: The UNT Digital Library
Black Hole Entropy, Marginal Stability and Mirror Symmetry (open access)

Black Hole Entropy, Marginal Stability and Mirror Symmetry

We consider the superconformal quantum mechanics associated to BPS black holes in type IIB Calabi-Yau compactifications. This quantum mechanics describes the dynamics of D-branes in the near-horizon attractor geometry of the black hole. In many cases, the black hole entropy can be found by counting the number of chiral primaries in this quantum mechanics. Both the attractor mechanism and notions of marginal stability play important roles in generating the large number of microstates required to explain this entropy. We compute the microscopic entropy explicitly in a few different cases, where the theory reduces to quantum mechanics on the moduli space of special Lagrangians. Under certain assumptions, the problem may be solved by implementing mirror symmetry as three T-dualities: this is essentially the mirror of a calculation by Gaiotto, Strominger and Yin. In some simple cases, the calculation may be done in greater generality without resorting to conjectures about mirror symmetry. For example, the K3 x T{sub 2} case may be studied precisely using the Fourier-Mukai transform.
Date: October 6, 2006
Creator: Aspinwall, Paul S.; Maloney, Alexander & Simons, Aaron
System: The UNT Digital Library
Durability of Advanced Electrocatalysts for PEM Fuel Cells (open access)

Durability of Advanced Electrocatalysts for PEM Fuel Cells

None
Date: December 6, 2006
Creator: Atanassova, Paolina
System: The UNT Digital Library
Observation of CP violation in B^0 to eta' K^0 (open access)

Observation of CP violation in B^0 to eta' K^0

The authors present measurements of the time-dependent CP-violation parameters S and C in B{sup 0} {yields} K{sup 0} decays. The data sample corresponds to 384 million B{bar B} pairs produced by e{sup +}e{sup -} annihilation at the {Upsilon}(4S). The results are S = 0.58 {+-} 0.10 {+-} 0.03, and C = -0.16 {+-} 0.07 {+-} 0.03. They observe mixing-induced CP violation with a significance of 5.5 standard deviations in this b {yields} s penguin dominated mode.
Date: October 6, 2006
Creator: Aubert, B.
System: The UNT Digital Library
Measurement of Branching Fractions and CP-ViolatingCharge Asymmetries for B Meson Decays to D(*)D(*), and Implications for the CKMAngle gamma (open access)

Measurement of Branching Fractions and CP-ViolatingCharge Asymmetries for B Meson Decays to D(*)D(*), and Implications for the CKMAngle gamma

In summary, the authors have measured branching fractions, upper limits, and charge asymmetries for all B meson decays to D{sup (*)} {bar D}{sup (*)}.
Date: July 6, 2006
Creator: Aubert, B.; Barate, R.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y. et al.
System: The UNT Digital Library
Measurement of the Branching Fractions of the Decays \bar{B}^0 to Lambda_c^+ \bar{p} and B^- to Lambda_c^+ \bar{p} pi^- (open access)

Measurement of the Branching Fractions of the Decays \bar{B}^0 to Lambda_c^+ \bar{p} and B^- to Lambda_c^+ \bar{p} pi^-

The authors present studies of two-body and three-body charmed baryonic B decays in a sample of 232 million B{bar B} pairs collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. The branching fractions of the decays {bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p} and B{sup -} {yields} {Lambda}{sub c}{sup +} {bar p}{pi}{sup -} are measured to be (2.15 {+-} 0.36 {+-} 0.13 {+-} 0.56) x 10{sup -5} and (3.53 {+-} 0.18 {+-} 0.31 {+-} 0.92) x 10{sup -4}, respectively. The uncertainties quoted are statistical, systematic, and from the {Lambda}{sub c}{sup +} {yields} pK{sup -} {pi}{sup +} branching fraction. They observe a baryon-antibaryon threshold enhancement in the {Lambda}{sub c}{sup +}{bar p} invariant mass spectrum of the three-body mode and measure the ratio of the branching fractions to be {Beta}(B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -})/{Beta}({bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}) = 16.4 {+-} 2.9 {+-} 1.4. These results are preliminary.
Date: December 6, 2006
Creator: Aubert, B.; Barate, R.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y. et al.
System: The UNT Digital Library
Search for b to u transitions in B- to [K+pi-pi0]_D K- (open access)

Search for b to u transitions in B- to [K+pi-pi0]_D K-

The authors search for decays of a B meson into a neutral D meson and a kaon, with the D meson decaying into K{sup +}{pi}{sup -}{pi}{sup 0}. This final state can be reached through the b {yields} c transition B{sup -} {yields} D{sup 0}K{sup -} followed by the doubly Cabibbo-suppressed D{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0}, or the b {yields} u transition B{sup -} {yields} {bar D}{sup 0}K{sup -} followed by the Cabibbo-favored {bar D}{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0}. The interference of these two amplitudes is sensitive to the angle {gamma} of the unitarity triangle. They present preliminated results based on 226 x 10{sup 6} e{sup +}e{sup -} {yields} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at SLAC.
Date: December 6, 2006
Creator: Aubert, B.; Barate, R.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y. et al.
System: The UNT Digital Library
Measurement of the Ratio BR(B+ to X e nu) / BR(B0 to X e nu) (open access)

Measurement of the Ratio BR(B+ to X e nu) / BR(B0 to X e nu)

The authors report measurements of the inclusive electron momentum spectra in decays of charged and neutral B mesons, and of the ratio of semileptonic branching fractions {Beta}(B{sup +} {yields} Xe{nu}) and {Beta}(B{sup 0} {yields} Xe{nu}). These were performed on a sample of 231 million B{bar B} events recorded with the BABAR detector at the {Upsilon}(4S) resonance. Events are selected by fully reconstructing a hadronic decay of one B meson and identifying an electron among the decay products of the recoiling {bar B} meson. They obtain {Beta}(B{sup +} {yields} Xe{nu})/{Beta}(B{sup 0} {yields} Xe{nu}) = 1.084 {+-} 0.041{sub (stat)} {+-} 0.025{sub (syst)}.
Date: December 6, 2006
Creator: Aubert, B.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Designing PV Incentive Programs to Promote Performance: A Reviewof Current Practice in the U.S. (open access)

Designing PV Incentive Programs to Promote Performance: A Reviewof Current Practice in the U.S.

In the U.S., the increasing financial support for customer-sited photovoltaic (PV) systems provided through publicly-funded incentive programs has heightened concerns about the long-term performance of these systems. Given the barriers that customers face to ensuring that their PV systems perform well, and the responsibility that PV incentive programs bear to ensure that public funds are prudently spent, these programs should, and often do, play a critical role in addressing PV system performance. To provide a point of reference for assessing the current state of the art, and to inform program design efforts going forward, we examine the approaches to encouraging PV system performance used by 32 prominent PV incentive programs in the U.S. We identify eight general strategies or groups of related strategies that these programs have used to address factors that affect performance, and describe key implementation details. Based on this review, we then offer recommendations for how PV incentive programs can be effectively designed to mitigate potential performance issues.
Date: October 6, 2006
Creator: Barbose, Galen; Wiser, Ryan & Bolinger, Mark
System: The UNT Digital Library
From Non-Hermitian Effective Operators to Large-Scale No-Core Shell Model Calculations for Light Nuclei (open access)

From Non-Hermitian Effective Operators to Large-Scale No-Core Shell Model Calculations for Light Nuclei

No-core shell model (NCSM) calculations using ab initio effective interactions are very successful in reproducing experimental nuclear spectra. The main theoretical approach is the use of effective operators, which include correlations left out by the truncation of the model space to a numerically tractable size. We review recent applications of the effective operator approach, within a NCSM framework, to the renormalization of the nucleon-nucleon interaction, as well as scalar and tensor operators.
Date: March 6, 2006
Creator: Barrett, B R; Stetcu, I; Navratil, P & Vary, J P
System: The UNT Digital Library
Mitigation of Laser Damage Growth in Fused Silica NIF Optics with a Galvanometer Scanned Carbon Dioxide Laser (open access)

Mitigation of Laser Damage Growth in Fused Silica NIF Optics with a Galvanometer Scanned Carbon Dioxide Laser

Economic operation of the National Ignition Facility at the Lawrence Livermore National Laboratory depends on controlling growth of laser damage in the large, high cost optics exposed to UV light at 351 nm. Mitigation of the growth of damage sites on fused silica surfaces greater than several hundred microns in diameter has been previously reported by us using galvanometer scanning of a tightly focused 10.6 {micro}m CO{sub 2} laser spot over an area encompassing the laser damage. Further investigation revealed that fused silica vapor re-deposited on the surface as ''debris'' led to laser damage at unexpectedly low fluences when exposed to multiple laser shots at 351 nm. Additionally, laser power and spatial mode fluctuations in the mitigation laser led to poor repeatability of the process. We also found that the shape of the mitigation pit could produce downstream intensification that could damage other NIF optics. Modifications were made to both the laser system and the mitigation process in order to address these issues. Debris was completely eliminated by these changes, but repeatability and downstream intensification issues still persist.
Date: April 6, 2006
Creator: Bass, I L; Draggoo, V; Guss, G M; Hackel, R P & Norton, M A
System: The UNT Digital Library
Grazing-Incidence Spectrometer for Soft X-Ray and Extreme Ultraviolet Spectroscopy on the National Spherical Torus Experiment (open access)

Grazing-Incidence Spectrometer for Soft X-Ray and Extreme Ultraviolet Spectroscopy on the National Spherical Torus Experiment

None
Date: April 6, 2006
Creator: Beiersdorfer, P.; Bitter, M.; Roquemore, L.; Lepson, J. K. & Gu, M.
System: The UNT Digital Library
Harmonic Number Jump in a Ring With Cavities Distributed Everywhere. (open access)

Harmonic Number Jump in a Ring With Cavities Distributed Everywhere.

One of the primary motivations for using fixed field alternating gradient accelerators (FFAGs) is their ability to accelerate rapidly, since the magnetic fields do not need to be varied. However, one must then face the difficulty that the time of flight in an FFAG depends strongly on the particle energy. Traditionally, this is dealt with by varying the RF frequency. The rate at which one can vary the RF frequency is limited, and a cavity and power source which have a rapidly varying RF frequency are costly. One solution to this is harmonic number jump acceleration, where the RF frequency is fixed. The RF frequency is chosen so that each turn has an integer number of RF periods, but that integer number is different on each turn. When accelerating rapidly, a large number of cavities is often required. This paper will show that in general, the time of flight can only be an integer number of RF periods for all turns at one position in the ring. It will then compute how well one can do when cavities are distributed everywhere in the ring. The paper will show some examples, and will discuss possible applications for this technique.
Date: November 6, 2006
Creator: Berg, J. S.
System: The UNT Digital Library
METHODS FOR ADDRESSING THE PROBLEM OF THE DEPENDENCE OF THE TIME OF FLIGHT ON TRANSVERSE AMPLITUTE IN LINEAR NON-SCALING FFAGs (open access)

METHODS FOR ADDRESSING THE PROBLEM OF THE DEPENDENCE OF THE TIME OF FLIGHT ON TRANSVERSE AMPLITUTE IN LINEAR NON-SCALING FFAGs

Because the time of flight in a linear non-scaling FFAG depends on the transverse amplitude, motion in the longitudinal plane will be different for different transverse particle amplitudes. This effect, if not considered, will lead the failure of a substantial portion of the beam to be accelerated. I will first briefly review this effect. Then I will outline some techniques for addressing the problems created by the effect. In particular, I will discuss partially correcting the chromaticity and increasing the energy gain per cell. I will discuss potential problems with another technique, namely the introduction of higher harmonic cavities.
Date: November 6, 2006
Creator: Berg, J. S.
System: The UNT Digital Library
Working Group 1 Summary for the 2006 Ffag Workshop at Kurri. (open access)

Working Group 1 Summary for the 2006 Ffag Workshop at Kurri.

This paper summarizes the workshop presentations at the 2006 FFAG Workshop at KURRI related to FFAG use for muons. The particular topics covered were harmonic number jump acceleration, ionization cooling, PRISM and muon phase rotation, tracking and error analysis, and our understanding of scaling and non-scaling FFAGs.
Date: November 6, 2006
Creator: Berg, J. S.
System: The UNT Digital Library
Seismic Waves in Rocks with Fluids and Fractures (open access)

Seismic Waves in Rocks with Fluids and Fractures

Seismic wave propagation through the earth is often strongly affected by the presence of fractures. When these fractures are filled with fluids (oil, gas, water, CO{sub 2}, etc.), the type and state of the fluid (liquid or gas) can make a large difference in the response of the seismic waves. This paper will summarize some early work of the author on methods of deconstructing the effects of fractures, and any fluids within these fractures, on seismic wave propagation as observed in reflection seismic data. Methods to be explored here include Thomsen's anisotropy parameters for wave moveout (since fractures often induce elastic anisotropy), and some very convenient fracture parameters introduced by Sayers and Kachanov that permit a relatively simple deconstruction of the elastic behavior in terms of fracture parameters (whenever this is appropriate).
Date: February 6, 2006
Creator: Berger, E. L.
System: The UNT Digital Library
The Age of Human Cerebral Cortex Neurons (open access)

The Age of Human Cerebral Cortex Neurons

The traditional static view of the adult mammalian brain has been challenged by the realization of continuous generation of neurons from stem cells. Based mainly on studies in experimental animals, adult neurogenesis may contribute to recovery after brain insults and decreased neurogenesis has been implicated in the pathogenesis of neurological and psychiatric diseases in man. The extent of neurogenesis in the adult human brain has, however, been difficult to establish. We have taken advantage of the integration of {sup 14}C, generated by nuclear bomb tests during the Cold War, in DNA to establish the age of neurons in the major areas of the human cerebral cortex. Together with the analysis of the cortex from patients who received BrdU, which integrates in the DNA of dividing cells, our results demonstrate that whereas non-neuronal cells turn over, neurons in the human cerebral cortex are not generated postnatally at detectable levels, but are as old as the individual.
Date: April 6, 2006
Creator: Bhardwaj, R. D.; Curtis, M. A.; Spalding, K. L.; Buchholz, B. A.; Fink, D.; Bjork-Eriksson, T. et al.
System: The UNT Digital Library
Monte Carlo Particle Transport Capability for Inertial Confinement Fusion Applications (open access)

Monte Carlo Particle Transport Capability for Inertial Confinement Fusion Applications

A time-dependent massively-parallel Monte Carlo particle transport calculational module (ParticleMC) for inertial confinement fusion (ICF) applications is described. The ParticleMC package is designed with the long-term goal of transporting neutrons, charged particles, and gamma rays created during the simulation of ICF targets and surrounding materials, although currently the package treats neutrons and gamma rays. Neutrons created during thermonuclear burn provide a source of neutrons to the ParticleMC package. Other user-defined sources of particles are also available. The module is used within the context of a hydrodynamics client code, and the particle tracking is performed on the same computational mesh as used in the broader simulation. The module uses domain-decomposition and the MPI message passing interface to achieve parallel scaling for large numbers of computational cells. The Doppler effects of bulk hydrodynamic motion and the thermal effects due to the high temperatures encountered in ICF plasmas are directly included in the simulation. Numerical results for a three-dimensional benchmark test problem are presented in 3D XYZ geometry as a verification of the basic transport capability. In the full paper, additional numerical results including a prototype ICF simulation will be presented.
Date: November 6, 2006
Creator: Brantley, P. S. & Stuart, L. M.
System: The UNT Digital Library
Simulating Effects of Non-Isothermal Flow on Reactive Transport of Radionuclides Originating from an Underground Nuclear Test (open access)

Simulating Effects of Non-Isothermal Flow on Reactive Transport of Radionuclides Originating from an Underground Nuclear Test

Temperature can significantly affect radionuclide transport behavior. In simulation of radionuclide transport originating from an underground nuclear test, temperature effects from residual test heat include non-isothermal groundwater flow behavior (e.g. convection cells), increased dissolution rates of melt glass containing refractory radionuclides, changes in water chemistry, and, in turn, changes in radionuclide sorption behavior. The low-yield (0.75 kiloton) Cambric underground nuclear test situated in alluvium below the water table offers unique perspectives on radionuclide transport in groundwater. The Cambric test was followed by extensive post-test characterization of the radionuclide source term and a 16-year pumping-induced radionuclide migration experiment that captured more mobile radionuclides in groundwater. Discharge of pumped groundwater caused inadvertent recirculation of radionuclides through a 220-m thick vadose zone to the water table and below, including partial re-capture in the pumping well. Non-isothermal flow simulations indicate test-related heat persists at Cambric for about 10 years and induces limited thermal convection of groundwater. The test heat has relatively little impact on mobilizing radionuclides compared to subsequent pumping effects. However, our reactive transport models indicate test-related heat can raise melt glass dissolution rates up to 10{sup 4} faster than at ambient temperatures depending on pH and species activities. Non-isothermal flow simulations indicate …
Date: March 6, 2006
Creator: Carle, S. F.; Zavarin, M.; Shumaker, D. E.; Tompson, A. B.; Maxwell, R. M. & Pawloski, G. A.
System: The UNT Digital Library
Erythroblastic Islands: Specialized Mircoenvironmental Niches forErythropoiesis (open access)

Erythroblastic Islands: Specialized Mircoenvironmental Niches forErythropoiesis

This review focuses on current understanding of molecular mechanisms operating within erythroblastic islands including cell-cell adhesion, regulatory feedback, and central macrophage function. RECENT FINDINGS: Erythroblasts express a variety of adhesion molecules and recently two interactions have been identified that appear to be critical for island integrity. Erythroblast macrophage protein, expressed on erythroblasts and macrophages, mediates cell-cell attachments via homophilic binding. Erythroblast intercellular adhesion molecule-4 links erythroblasts to macrophages through interaction with macrophage alphav integrin. In intercellular adhesion molecule-4 knockout mice, erythroblastic islands are markedly reduced, whereas the erythroblast macrophage protein null phenotype is severely anemic and embryonic lethal. Retinoblastoma tumor suppressor (Rb) protein stimulates macrophage differentiation by counteracting inhibition of Id2 on PU.1, a transcription factor that is a crucial regulator of macrophage differentiation. Rb-deficient macrophages do not bind Rb null erythroblasts and the Rb null phenotype is anemic and embryonic lethal. Lastly, extruded nuclei rapidly expose phosphatidylserine on their surface, providing a recognition signal similar to apoptotic cells. SUMMARY: Although understanding of molecular mechanisms operating within islands is at an early stage, tantalizing evidence suggests that erythroblastic islands are specialized niches where intercellular interactions in concert with cytokines play critical roles in regulating erythropoiesis.
Date: January 6, 2006
Creator: Chasis, Joel Anne
System: The UNT Digital Library
Current and Potential Distribution in a Divertor with Torioidally-Asymmetric Biasing of the Divertor Plate (open access)

Current and Potential Distribution in a Divertor with Torioidally-Asymmetric Biasing of the Divertor Plate

Toroidally-asymmetric biasing of the divertor plate may increase convective cross-field transport in SOL and thereby reduce the divertor heat load. Experiments performed with the MAST spherical tokamak generally agree with a simple theory of non-axisymmetric biasing. However, some of the experimental results have not yet received a theoretical explanation. In particular, existing theory seems to overestimate the asymmetry between the positive and the negative biasing. Also lacking a theoretical explanation is experimentally observed increase of the average floating potential in the main SOL in the presence of biasing. In this paper we attempt to solve these problems by accounting for the closing of the currents (driven by the biasing) in a strong-shear region near the X-point. We come up with the picture which, at least qualitatively, agrees with these experimental results.
Date: June 6, 2006
Creator: Cohen, R. H.; Ryutov, D. D.; Counsell, G. F. & Helander, P.
System: The UNT Digital Library
The SuperMacho Project: Wide-field, Time-domain Survey of the Large Magellanic Cloud (open access)

The SuperMacho Project: Wide-field, Time-domain Survey of the Large Magellanic Cloud

The MACHO Project sought evidence for Massive Compact Halo Objects (MACHO) by surveying for the gravitational effort of the objects on light, microlensing.
Date: July 6, 2006
Creator: Cook, K.; Huber, M.; Nikolaev, S.; Olsen, K.; Rest, A.; Smith, R. et al.
System: The UNT Digital Library