Physics Commons^™

Higher Order Corrections To H± Production, Nikolaos Kidonakis

Faculty and Research Publications

I discuss recent calculations of higher-order corrections to charged Higgs production through various partonic subprocesses. Particular attention is paid to H⁻ production in association with a top quark at the LHC.

Dynamics Of Apomyoglobin In The Α-To-Β Transition And Of Partially Unfolded Aggregated Protein, E. Fabiani, A. M. Stadler, D. Madern, M. M. Koza, M. Tehei, M. Hirai, G. Zaccai

Faculty of Science - Papers (Archive)

Changes of molecular dynamics in the α-to-β transition associated with amyloid fibril formation were explored on apo-myoglobin (ApoMb) as a model system. Circular dichroism, neutron and X-ray scattering experiments were performed as a function of temperature on the protein, at different solvent conditions. A significant change in molecular dynamics was observed at the α-to-β transition at about 55 ˚C, indicating a more resilient high temperature β structure phase. A similar effect at approximately the same temperature was observed in holo-myoglobin, associated with partial unfolding and protein aggregation. A study in a wide temperature range between 20 K and 360 K …

Theoretical Top Quark Cross Section At The Fermilab Tevatron And The Cern Lhc, Nikolaos Kidonakis, Ramona Vogt

Faculty and Research Publications

We present results for the top quark pair cross section at the Tevatron and the LHC. We use the resummed double differential cross section, employing the fully kinematics-dependent soft-anomalous-dimension matrices, to calculate the soft-gluon contributions at next-to-next-to-leading order (NNLO). We improve and update our previous estimates by refining our methods, including further subleading terms, and employing the most recent parton distribution function sets. The NNLO soft corrections significantly enhance the NLO cross section while considerably reducing the scale dependence. We provide a detailed discussion of all theoretical uncertainties in our calculation, including kinematics, scale, and parton distribution uncertainties, and clarify …

Unlv Magazine, Holly Ivy De Vore, Tony Allen, Barbara Cloud, Erin O'Donnell, Matthew K. Jacobsen, Gian Galassi, Michelle Mouton, Afsha Bawany, Shane Bevell

UNLV Magazine

No abstract provided.

Investigation Into The B(E2) Anomaly In 144Nd Using Coulomb Excitation, C. R. Fitzpatrick, V. Werner, R. F. Casten, E. Williams, H. Ai, C. W. Beausang, R. Cakirli, G. Gurdal, A. Heinz, E. A. Mccutchan, D. A. Meyer, E. Novitski, J. Qian, R. Winkler

Physics Faculty Publications

The ratio of B(E2) strengths between the lowest lying members of the ground state band in ¹⁴⁴Nd, B_4/2 = B(E2; 4⁺₁ → 2⁺₁)/B(E2; 2⁺₁ → 0⁺₁), which is used to quantify collectivity in nonmagic nuclei, has been remeasured by means of Coulomb excitation. Ambiguities in literature values for this ratio have been resolved. The results are discussed in terms of the interplay of collective and single-particle degrees of freedom, and in the context of the formation of collective structures in the A = 140 mass region, and more …

Deep Inelastic Inclusive And Diffractive Scattering At Q2 Values From 25 To 320 Gev2 With The Zeus Forward Plug Calorimeter, S. Chekanov, M. Derrick, S. Magill, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, M. Jechow, N. Pavel, P. Antonioli, G. Bari, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, F. Cindolo, M. Corradi, G. Iacobucci, A. Margotti, R. Nania, A. Polini, S. Antonelli, M. Basile, M. Bindi, L. Cifarelli, A. Contin, S. De Pasquale, G. Sartorelli, A. Zichichi, D. Bartsch

Faculty Publications

Deep inelastic scattering and its diffractive component, e p → e′ γ* p → e′ X N, have been studied at HERA with the ZEUS detector using an integrated luminosity of 52.4 pb-1. The MX method has been used to extract the diffractive contribution. A wide range in the centre-of-mass energy W (37-245 GeV), photon virtuality Q2 (20-450 GeV2) and mass MX (0.28-35 GeV) is covered. The diffractive cross section for 2 < MX < 15 GeV rises strongly with W, the rise becoming steeper as Q2 increases. The data are also presented in terms of the diffractive structure function, F2D (3), of the proton. For fixed Q2 and fixed MX, xP F2D (3) shows a strong rise as xP → 0, where xP is the fraction of the proton momentum carried by the pomeron. For Bjorken-x < 1 × 10-3, xP F2D (3) shows positive log Q2 scaling violations, while for x ≥ 5 × 10-3 negative scaling violations are observed. The diffractive structure function is compatible with being leading twist. The data show that Regge factorisation is broken. © 2008 Elsevier B.V. All rights reserved.

Spatially Resolved Optical Absorption Spectrometry And Single Crystal Diffraction On Metamict Materials, Alison Savage, Oliver Tschauner, Sergey Tkachev

Undergraduate Research Opportunities Program (UROP)

A major goal in developing storage medium for radioactive waste is the identification of chemically suitable and durable material for storage in repositories (Lumpkin 2006). Radiation damage induces enhanced chemical diffusion and structural breakdown of the host materials, which can lead to contamination of the surrounding environment. During this project four different naturally occurring materials which are common carriers of thorium and uranium were examined : gadolinite, perrierite, allanite, and pyrochlore of which the first three are silicates and pyrochlore being an oxide. Their spectra and absorptions bands were examined to identify prominent features due to radiation damage. The goal …

The Applications Of The Tracer Particle Method To Multi-Dimensional Supernova Simulations, Ching-Tsai Lee

Doctoral Dissertations

A new tracer particle implementation has been developed for the 2D supernova code ”CHIMERA”. 2D supernova simulations have been performed for a wide range of progenitors, between 10 and 25 solar mass. In the case of the Heger12 model, we have obtained a successful explosion. Analysis of the tracer particle data generated by supernova simulations reveals the aspherical geometry of the ejecta. Using the hydrodynamic trajectories provided by the tracer particles, we have performed the nucleosynthesis calculations in the post processing approximation, including the effects of neutrino captures, to understand the nucleosynthesis consequences of these models.

High-Efficiency Resonant Rf Spin Rotator With Broad Phase Space Acceptance For Pulsed Polarized Cold Neutron Beams, P.-N. Seo, L. Barron-Palos, J. D. Bowman, T. E. Chupp, C. Crawford, M. Dabaghyan, M. Dawkins, S. J. Freedman, T. Gentile, M. T. Gericke, R. C. Gillis, G. L. Greene, F. W. Hersman, Gordon L. Jones, M. Kandes, S. Lamoreaux, B. Lauss, M. B. Leuschner, R. Mahurin, M. Mason, J. Mei, G. S. Mitchell, H. Nann, S. A. Page, S. I. Penttila, W. D. Ramsay, A. Salas Bacci, S. Santra, M. Sharma, T. B. Smith, W. M. Snow, W. S. Wilburn, H. Zhu

Articles

High precision fundamental neutron physics experiments have been proposed for the intense pulsed spallation neutron beams at JSNS, LANSCE, and SNS to test the standard model and search for new physics. Certain systematic effects in some of these experiments have to be controlled at the few ppb level. The NPDGamma experiment, a search for the small parity-violating gamma-ray asymmetry A(gamma) in polarized cold neutron capture on parahydrogen, is one example. For the NPDGamma experiment we developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5 cm x 9.5 cm pulsed cold neutron beam with high efficiency …

3he Spin-Dependent Cross Sections And Sum Rules, K. Slifer, M. Amarian, L. Auerbach, T. Averett, J. Berthot, P. Bertin, B. Bertozzi, K. Mccormick, F. Sabatié, L. Todor

Physics Faculty Publications

We present a measurement of the spin-dependent cross sections for the ^3→He(→e,e′)X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1≤Q²≤0.9  GeV². The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body Faddeev calculation in the quasielastic region.

Higgs Production Via B Bbar -> H In Hadron Colliders, Nikolaos Kidonakis

Faculty and Research Publications

I present NNNLO collinear and soft gluon corrections for Higgs production via the process b bbar -> H. I show that the collinear corrections dominate and contribute large enhancements to the cross section at both the Tevatron and the LHC.

Status Of Eikonal Two-Loop Calculations With Massive Quarks, Nikolaos Kidonakis, Philip Stephens

Faculty and Research Publications

We present results for two-loop diagrams with massive quarks in the eikonal approximation. Explicit expressions are given for the UV poles in dimensional regularization of several of the required integrals.

Enhanced Mixing Of Intrinsic States In Deformed Hf Nuclei, E. A. Mccutchan, R. F. Casten, V. Werner, E. Williams, R. Winkler, A. Wolf, Z. Berant, G. Gurdal, J. Qian, H. Ai, L. Amon, C. W. Beausang, D. S. Brenner, R. Cakirli, R. J. Casperson, C. R. Fitzpatrick, D Franks, A. B. Garnsworthy, A. Heinz, R. Luttke, A. F. Mertz, Y. Oktem, N. Pietralla, P. H. Regan, B. Shoraka, J. R. Terry, N. J. Thompson

Physics Faculty Publications

Excited low-spin, nonyrast states in ^170,172,174Hf were populated in β + /∈decay and studied through off-beam γ-ray spectroscopy. New coincidence data allowed for a substantial revision of the level schemes of Hf^170,172 and a confirmation of the level scheme of ¹⁷⁴Hf. The Hf isotopes represent a unique situation in which a crossing of collective intrinsic excitations occurs, enhancing significantly the effects of mixing. Using branching ratios from excited 2⁺ states, this mixing is followed and studied. The resulting mixing matrix elements are found to be ∼30 keV—an …

Nuclear Energy, Steve Kraft

Native American Forum on Nuclear Issues

Abstract:

-Why Nuclear Energy?

-The lesson of the last 20 years in U.S. electricity policy:

– Diversified fuel and technology portfolio is essential

– All fuels and technologies (nuclear, coal, natural gas, renewables, efficiency) have a legitimate role

-The challenge for the future:

– Preserving/restoring diversified portfolio

– Ensuring resource adequacy, particularly in competitive markets

-Expanded use of nuclear energy is part of the answer

– Integrated used fuel management supports nuclear competitiveness

Three- And Four-Jet Final States In Photoproduction At Hera, S. Chekanov, M. Derrick, S. Magill, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, M. Jechow, N. Pavel, A. G. Yagües Molina, S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, G. Sartorelli, A. Zichichi

Faculty Publications

Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121 pb -1. The results are presented for jets with transverse energy E Tjet > 6 GeV and pseudorapidity | η jet | < 2.4, in the kinematic region given by the virtuality of the photon Q 2 < 1 GeV 2 and the inelasticity 0.2 ≤ y ≤ 0.85 and in two mass regions defined as 25 ≤ M n j < 50 GeV and M n j ≥ 50 GeV, where M n j is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O (α α s2) perturbative QCD calculation. © 2007 Elsevier B.V. All rights reserved.

Measurement Of Conversion Coefficients In Normal And Triaxial Strongly Deformed Bands In 167Lu, G. Gurdal, C. W. Beausang, D. S. Brenner, H. Ai, R. F. Casten, B. Crider, A. Heinz, E. Williams, D. J. Hartley, M. P. Carpenter, A. A. Hecht, R.V. F. Janssens, T.` Lauritsen, C. J. Lister, R. Raabe, D. Seweryniak, S. Zhu, J. X. Saladin

Physics Faculty Publications

Internal conversion coefficients have been measured for transitions in both normal deformed and triaxial strongly deformed bands in ¹⁶⁷Lu using the Gammasphere and ICE Ball spectrometers. The results for all in-band transitions are consistent with E2 multipolarity. Upper limits are determined for the internal conversion coefficients for linking transitions between TSD Band 2 and TSD Band 1, the n_w = 1 and n_w = 0 wobbling bands, respectively.

Evaluation Of Cs/Sr Waste Form For Long Term Storage And Disposal, Gary Cerefice

Waste Forms Campaign (TRP)

The goal of this project is to examine the potential long term performance of the proposed aluminosilicate waste/storage form for the isolation and eventual direct disposal of the cesium and strontium separated from recycled nuclear fuel. In the first phase of this work, researchers will investigate the sintering procedure to prepare the drum-like aluminosilicate waste/storage form from the as-received aluminosilicate powder, and then examine the basic physical properties, phase structure and microstructure of the sintered aluminosilicate with /without mixing solution with several ppm Cs/Sr. In the second phase, researchers will evaluate the interaction of the proposed waste form with structural …

Studies Of Low-Lying States In 94zr Excited With The Inelastic Neutron Scattering Reaction, Esmat Elhami

University of Kentucky Doctoral Dissertations

The aim of nuclear structure studies is to observe and describe the structures and associated symmetries in nuclei, which in turn help us in understanding the nature of nucleon-nucleon interactions in a nucleus as a many-body quantum system. The protons and neutrons as constituents of a nucleus and their interactions are responsible for nuclear properties. The evolution of nuclear structure as a function of valence nucleon number, i.e., the number of nucleons beyond a magic number, can be inferred from the experimental level scheme and transition rates. In particular, the studies of low-lying, low-spin excited states in stable nuclei provide …

Separation Of Technetium From Uranium And Waste Form Synthesis, Kenneth Czerwinski

Waste Forms Campaign (TRP)

In this project, systematic investigations on the Tc-Zr binary metal system will be evaluated for the first time. The synthesis of metallic Tc as well as its alloys with Zr will be evaluated. In order to provide valuable data to AFC R&D, the thermodynamic equilibrium phases, as well as their performance under repository conditions, will be examined.

The research objectives of this project are as follows:

• Evaluate anion exchange methods for achieving the separation of Tc from U.

• Synthesize metallic Tc from the separated product.

• Synthesize and characterize Tc alloys.

• Investigate Tc-corrosion and Tc-leaching of binary …

Evaluation Of Cs/Sr Waste Form For Long Term Storage And Disposal, Gary Cerefice, Longzhou Ma

Waste Forms Campaign (TRP)

To facilitate long-term storage, the disposal containers will need to be able to survive for the entire storage interval. The first aspect of the project will explore the potential interaction of the aluminosilicate waste form with the storage canister materials to determine if there is any corrosion or chemical interaction concerns for the storage of the materials. At the end of the storage interval, most of the cesium (¹³⁷Cs) in the waste form will have decayed to its daughter, barium (¹³⁷Ba). While this decay provides a significant reduction in the decay heat generated by the waste …

Reactor Physics Studies For The Afci Reactor-Accelerator Coupling Experiments Project, Denis Beller

Transmutation Sciences Physics (TRP)

The specific research objective of this three-year project was to design and conduct accelerator driven experiments, to help demonstrate the ability to design, compute, and conduct ADS experiments and to predict and measure source importance, coupling efficiency, sub-critical reactor kinetics and source-driven transients. In addition, databases were created for both steady state and transient ADS experiments for the nuclear community to develop and test new computational codes and methods. The importance of a driving neutron source in various regions of different subcritical assemblies was mapped. Experiments were conducted and compared to calculations with radiation transport and thermal hydraulics codes such …

Combined Radiation Detection Methods For Assay Of Higher Actinides In Separation Processes, Denis Beller, Charlotta Sanders, Warnick Kernan

Safeguards Campaign (TRP)

In the MPAC project, faculty and students are investigating the potential to use combined neutron and gamma-ray detector systems to measure quantities and isotopic constituents contained during separations and intermediate storage. This will require knowledge of the nuclear and decay characteristics of materials during processing, the development of conceptual designs of monitoring systems, radiation transport studies to develop an understanding of operational regimes, and experiments to confirm performance. In addition, both passive and active concepts will be investigated, including collaborations with the Idaho Accelerator Center at Idaho State University (ISU) to use electron linear accelerators for producing photoneutrons in situ, …

Implementation Of Uncertainty Propagation In Triton/Keno, Charlotta Sanders, Denis Beller

Reactor Campaign (TRP)

Monte Carlo methods are beginning to be used for three dimensional fuel depletion analyses to compute various quantities of interest, including isotopic compositions of used nuclear fuel. The TRITON control module, available in the SCALE 5.1 code system, can perform three-dimensional (3-D) depletion calculations using either the KENO V.a or KENO-VI Monte Carlo transport codes, as well as the two-dimensional (2-D) NEWT discrete ordinates code. To overcome problems such as spatially nonuniform neutron flux and non-uniform statistical uncertainties in computed reaction rates and to improve the fidelity of calculations using Monte Carlo methods, uncertainty propagation is needed for depletion calculations.

Monaco/Mavric Evaluation For Facility Shielding And Dose Rate Analysis, Charlotta Sanders, Denis Beller

Reactor Campaign (TRP)

The dimensions and the large amount of shielding required for Global Nuclear Energy Partnership (GNEP) facilities, advanced radiation shielding, and dose computation techniques are beyond today’s capabilities and will certainly be required. With the Generation IV Nuclear Energy System Initiative, it will become increasingly important to be able to accurately model advanced Boiling Water Reactor and Pressurized Water Reactor facilities, and to calculate dose rates at all locations within a containment (e.g., resulting from radiations from the reactor as well as the from the primary coolant loop) and adjoining structures (e.g., from the spent fuel pool).

The MAVRIC sequence is …

Dissolution, Reactor, And Environmental Behavior Of Zro2-Mgo Inert Fuel Matrix, Kenneth Czerwinski

Fuels Campaign (TRP)

This project will examine inert fuels containing ZrO₂ and MgO as the inert matrix. Ceramics with this inert matrix, Ce, U and eventually Pu will be synthesized and examined. While the Advanced Fuel Cycle Initiative focus is on inert fuels with Pu as the fissile component, this task will perform initial laboratory experiments with Ce and U. The initial work with Ce will be performed early in the project with results used as a basis for U studies. Reactor physics calculations will be used to examine suitable quantities of burnable poisons from the candidate elements Gd, Er, or Hf. …

Impact Of The Synthesis Process On Structure Properties For Afci Fuel Candidates, Kenneth Czerwinski

Fuels Campaign (TRP)

The research objectives are:

• To explore a low-temperature fluoride route to synthesize actinide nitrides. • To characterize actinide nitrides structurally and thermally.

• To use high resolution TEM techniques to explore the microstructure of the radioactive samples.

Solution-Based Synthesis Of Nitride Fuels, Kenneth Czerwinski, Tyler A. Sullens

Fuels Campaign (TRP)

One of the original synthetic routes devised for the synthesis of U (III)N involved the entire reaction taking place in liquid ammonia. Several experimental reactions were conducted in an attempt to synthesize the UI₃(NH₃)_x and U(NH₂)₃(NH₃)_x precursors of U(III) N. Each attempt involved cleaning of the uranium metal to remove the oxide coating of the metal reagent with 3 washes of concentrated nitric acid, each followed by a rinse with liquid ammonia. Success of this cleaning procedure was varied, with a majority of cleaned metal oxidizing rapidly once …

University Of Nevada, Las Vegas Transmutation Research Program Annual Progress Report Academic Year 2007-2008, Anthony Hechanova, Rebecca Paulson

Transmutation Research Program Reports (TRP)

It is my pleasure to present the UNLV Transmutation Research Program’s seventh annual report that highlights the academic year 2007-2008. Supporting this document are the many technical reports and theses that have been generated over the past seven years.

In the seventh year of our program, we continued to see growth in the Radiochemistry Ph.D. program with a total of 20 students in the fourth year of the program (we anticipated twelve in the program proposal). Since our inception, the program has sponsored to their conclusion 48 M.S. and 6 Ph.D. degrees. The program supported 53 graduate students, 11 undergraduates, …

Light Vector Mesons In The Nuclear Medium, M. H. Wood, M. J. Amaryan, H. Bagdasaryan, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, G. Gavalian, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, K. V. Klimenko, S. E. Kuhn, J. Lachniet, M. R. Niroula, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, J. Zhang, Clas Collaboration

Physics Faculty Publications

The light vector mesons (ρ,ω, and ϕ) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the ρ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to e+e−. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The ρ-meson mass spectrum was extracted after the ω and ϕ signals were removed in a nearly model-independent way. Comparisons …

Ratios Of 15N/12C And 4He/12C Inclusive Electroproduction Cross Sections In The Nucleon Resonance Region, P. E. Bosted, R. Fersch, G. Adams, M. Amaryan, S. Anefalos, M. Anghinolfi, G. Asryan, H. Avakian, H. Badasaryan, N. Baillie, M. Bektasoglu, S. Bültmann, S. L. Careccia, G. E. Dodge, K. V. Dharmawardane, T. A. Forest, G. Gavalian, N. Guler, C. E. Hyde-Wright, N. Kalantarians, A. Klein, S. E. Kuhn, J. Lachniet, R. A. Niyazov, L. M. Qin, F. Sabatié, S. Tkachenko, L. B. Weinstein, J. Zhang, Clas Collaboration

Physics Faculty Publications

The (W,Q²) dependence of the ratio of inclusive electron scattering cross sections for ¹⁵N/¹²C was determined in the kinematic ranges 0.8 < W < 2 GeV and 0.2 < Q² < 1 GeV² using 2.285 GeV electrons and the CLAS detector at Jefferson Lab. The ratios exhibit only slight resonance structure, in agreement with a simple phenomenological model and an extrapolation of deep-inelastic scattering ratios to low Q². Ratios of ⁴He/¹²C using 1.6 to 2.5 GeV electrons were measured with very high statistical precision and were used to correct for He in the N and C targets. …