No-Core Shell Model for A = 47 and A = 49 (open access)

No-Core Shell Model for A = 47 and A = 49

We apply the no-core shell model to the nuclear structure of odd-mass nuclei straddling {sup 48}Ca. Starting with the NN interaction, that fits two-body scattering and bound state data, we evaluate the nuclear properties of A = 47 and A = 49 nuclei while preserving all the underlying symmetries. Due to model space limitations and the absence of three-body interactions, we incorporate phenomenological interaction terms determined by fits to A = 48 nuclei in a previous effort. Our modified Hamiltonian produces reasonable spectra for these odd-mass nuclei. In addition to the differences in single-particle basis states, the absence of a single-particle Hamiltonian in our no-core approach complicates comparisons with valence effective NN interactions. We focus on purely off-diagonal two-body matrix elements since they are not affected by ambiguities in the different roles for one-body potentials and we compare selected sets of fp-shell matrix elements of our initial and modified Hamiltonians in the harmonic oscillator basis with those of a recent model fp-shell interaction, the GXPF1 interaction of Honma et al. While some significant differences emerge from these comparisons, there is an overall reasonably good correlation between our off-diagonal matrix elements and those of GXPF1.
Date: November 13, 2006
Creator: Vary, J P; Negoita, A G & Stoica, S
System: The UNT Digital Library
ALE3D Simulation and Measurement of Violence in a Fast Cookoff Experiment with LX-10 (open access)

ALE3D Simulation and Measurement of Violence in a Fast Cookoff Experiment with LX-10

We performed a computational and experimental analysis of fast cookoff of LX-10 (94.7% HMX, 5.3% Viton A) confined in a 2 kbar steel tube with reinforced end caps. A Scaled-Thermal-Explosion-eXperiment (STEX) was completed in which three radiant heaters were used to heat the vessel until ignition, resulting in a moderately violent explosion after 20.4 minutes. Thermocouple measurements showed tube temperatures as high as 340 C at ignition and LX-10 surface temperatures as high as 279 C, which is near the melting point of HMX. Three micro-power radar systems were used to measure mean fragment velocities of 840 m/s. Photonics Doppler Velocimeters (PDVs) showed a rapid acceleration of fragments over 80 {micro}s. A one-dimensional ALE3D cookoff model at the vessel midplane was used to simulate the heating, thermal expansion, LX-10 decomposition composition, and closing of the gap between the HE (High Explosive) and vessel wall. Although the ALE3D simulation terminated before ignition, the model provided a good representation of heat transfer through the case and across the dynamic gap to the explosive.
Date: November 22, 2006
Creator: McClelland, M. A.; Maienschein, J. L.; Howard, W. M. & Dehaven, M. R.
System: The UNT Digital Library
FutureGen: Stepping-Stone to Sustainable Fossil-Fuel Power Generation (open access)

FutureGen: Stepping-Stone to Sustainable Fossil-Fuel Power Generation

This presentation will highlight the U.S. Department of Energy's FutureGen Initiative. The nearly $1 billion government-industry project is a stepping-stone toward future coal-fired power plants that will produce hydrogen and electricity with zero-emissions, including carbon dioxide. The 275-megawatt FutureGen plant will initiate operations around 2012 and employ advanced coal gasification technology integrated with combined cycle electricity generation, hydrogen production, and carbon capture and sequestration. The initiative is a response to a presidential directive to develop a hydrogen economy by drawing upon the best scientific research to address the issue of global climate change. The FutureGen plant will be based on cutting-edge power generation technology as well as advanced carbon capture and sequestration systems. The centerpiece of the project will be coal gasification technology that can eliminate common air pollutants such as sulfur dioxide and nitrogen oxides and convert them to useable by-products. Gasification will convert coal into a highly enriched hydrogen gas, which can be burned much more cleanly than directly burning the coal itself. Alternatively, the hydrogen can be used in a fuel cell to produce ultra-clean electricity, or fed to a refinery to help upgrade petroleum products. Carbon sequestration will also be a key feature that will set …
Date: November 1, 2006
Creator: Zitney, S. E.
System: The UNT Digital Library
Calculation of Photoneutrons from Varian Clinac Accelerators and Their Transmissions in Materials (open access)

Calculation of Photoneutrons from Varian Clinac Accelerators and Their Transmissions in Materials

Monte Carlo calculations of the giant-dipole-resonance photoneutrons (GRN) around the Varian Clinac 2100C/2300C medical accelerator heads (10-20 MV modes) were made using the coupled EGS4-MORSE code. The actual head materials and geometries were simulated in great detail using the Combinatorial Geometry facility of MORSE. The neutron production (i.e., sites and yields) was calculated with EGS4 and, then, the neutron transport in the accelerator head was done with MORSE. Both the evaporation and direct neutron components of the GRN were considered by incorporating the EVAP4 code and an empirical algorithm, respectively, into MORSE. With the calculated neutron spectra around the head as source terms, MCNP4a was used to estimate the corresponding dose equivalent transmission (considering both the neutron attenuation and the build-up of captured gamma rays) in several different types of concrete. The calculated results of the absolute neutron fluence and spectra around the heads, as well as the transmission curves, are presented and discussed.
Date: November 13, 2006
Creator: Liu, J. C.; Kase, K. R.; Mao, X. S.; Nelson, W. R.; Kleck, J. H. & Johnson, S.
System: The UNT Digital Library
Synthesis and Stability of a Nanoparticle-Infiltrated Solid OxideFuel Cell Electrode (open access)

Synthesis and Stability of a Nanoparticle-Infiltrated Solid OxideFuel Cell Electrode

Nanoparticulate catalysts infiltrated into SOFC (Solid OxideFUel Cell) electrodes can significantly enhance the cell performance, butthe stability of these electrodes has been an open issue. An infiltrationprocedure is reported that leads to a stable scandia-stablized zirconia(SSZ) cathode electrode performance.
Date: November 20, 2006
Creator: Sholklapper, Tal Z.; Radmilovic, Velimir; Jacobson, Craig P.; Visco, Steven J. & De Jonghe, Lutgard C.
System: The UNT Digital Library
Long Term Electrochemical Behavior of Creviced and Non-Creviced Alloy 22 in CaCl2 + Ca(NO3)2 Brines at 155?C (open access)

Long Term Electrochemical Behavior of Creviced and Non-Creviced Alloy 22 in CaCl2 + Ca(NO3)2 Brines at 155?C

Alloy 22 is a nickel base alloy highly resistant to all forms of corrosion. In very aggressive conditions (e.g. hot concentrated chloride containing brines) Alloy 22 could suffer localized attack, namely pitting and crevice corrosion. Chloride ion is known to be the most detrimental aggressive agent for Alloy 22 and is able to promote crevice corrosion when tight crevices exist in hot chloride containing solutions of different concentrations. Nitrate ion is an effective inhibitor of chloride induced crevice corrosion when present in a high enough [NO{sub 3}{sup -}]/[Cl{sup -}] ratio. The occurrence of localized corrosion in a given environment is governed by the values of the critical potential (E{sub crit}) for crevice corrosion and the corrosion potential (E{sub corr}) that the alloy may establish in the studied environment. If E{sub corr} is equal or higher than E{sub crit}, localized corrosion may be expected. This paper discusses the evolution of E{sub corr} and corrosion rate (CR) of Alloy 22 specimens in 18 m CaCl{sub 2} + 9 m Ca(NO{sub 3}){sub 2} and 18 m CaCl{sub 2} + 0.9 m Ca(NO{sub 3}){sub 2} brines at 155 C. Two types of specimens were used, polished as-welded (ASW) creviced and non-creviced specimens and as-welded …
Date: November 8, 2006
Creator: Rodriguez, M. A.; Stuart, M. L. & Rebak, R. B.
System: The UNT Digital Library
Coherent Control of Optically Generated and Detected Picosecond Surface Acoustic Phonons (open access)

Coherent Control of Optically Generated and Detected Picosecond Surface Acoustic Phonons

Coherent control of elementary optical excitations is a key issue in ultrafast materials science. Manipulation of electronic and vibronic excitations in solids as well as chemical and biological systems on ultrafast time scales has attracted a great deal of attention recently. In semiconductors, coherent control of vibronic excitations has been demonstrated for bulk acoustic and optical phonons generated in superlattice structures. The bandwidth of these approaches is typically fully utilized by employing a 1-D geometry where the laser spot size is much larger than the superlattice repeat length. In this presentation we demonstrate coherent control of optically generated picosecond surface acoustic waves using sub-optical wavelength absorption gratings. The generation and detection characteristics of two material systems are investigated (aluminum absorption gratings on Si and GaAs substrates).
Date: November 1, 2006
Creator: Hurley, David H.
System: The UNT Digital Library
Crevice Repassivation Potentials for Alloy 22 in Simulated Concentrated Ground Waters (open access)

Crevice Repassivation Potentials for Alloy 22 in Simulated Concentrated Ground Waters

The resistance of Alloy 22 (N06022) to localized corrosion, mainly crevice corrosion, has been extensively investigated in the last few years. However, the behavior of Alloy 22 in concentrated aqueous solutions that may simulate concentrated ground waters was not fully understood. Systematic electrochemical tests using cyclic potentiodynamic polarization as well as the Tsujikawa-Hisamatsu electrochemical method were performed to determine the crevice corrosion susceptibility of Alloy 22 in simulated concentrated water (SCW), simulated acidified water (SAW) and basic saturated water (BSW). Results show that Alloy 22 is immune to crevice corrosion in SCW and SAW but may suffer crevice corrosion initiation in BSW. Results also show that in a naturally aerated environment, the corrosion potential would never reach the critical potential for crevice corrosion initiation.
Date: November 8, 2006
Creator: Rebak, R B; Evans, K J & Ilevbare, G O
System: The UNT Digital Library
New results on X(3872) from CDF (open access)

New results on X(3872) from CDF

In 2003 the X(3872) particle was discovered by the Belle collaboration. Despite results collected since then, the nature of the state still remains unclear. In this contribution we report on new results on properties of the X(3872) state using data collected with CDF II detector at the Fermilab Tevatron. The dipion mass spectrum and angular distributions are used to determine the J{sup PC} quantum numbers of the state.
Date: November 1, 2006
Creator: Kreps, M.
System: The UNT Digital Library
Spin Echo and Interference in Synchrotrons (open access)

Spin Echo and Interference in Synchrotrons

Spin dynamics in crossing a single depolarization resonance is a well-studied subject. One well-known example is that of Froissart and Stora in 1960. More is needed to complete the understanding, particularly of the transient effects, when crossing a single resonance, but question arises what happens if we cross two resonances or cross a single resonance twice. When a resonance is crossed twice, the particle's spin dynamics encounters two additional phenomena. First, the two crossings will interfere with each other, leading to an interference effect. Second, there will be a spin echo effect. We discuss these two effects in this report. Two proposals to test these effects experimentally are made at the end.
Date: November 30, 2006
Creator: Chao, Alex
System: The UNT Digital Library
Magnetocentrifugal Winds in 3D: Nonaxisymmetric Steady State (open access)

Magnetocentrifugal Winds in 3D: Nonaxisymmetric Steady State

Outflows can be loaded and accelerated to high speeds along rapidly rotating, open magnetic field lines by centrifugal forces. Whether such magnetocentrifugally driven winds are stable is a longstanding theoretical problem. As a step towards addressing this problem, we perform the first large-scale 3D MHD simulations that extend to a distance {approx} 10{sup 2} times beyond the launching region, starting from steady 2D (axisymmetric) solutions. In an attempt to drive the wind unstable, we increase the mass loading on one half of the launching surface by a factor of {radical}10, and reduce it by the same factor on the other half. The evolution of the perturbed wind is followed numerically. We find no evidence for any rapidly growing instability that could disrupt the wind during the launching and initial phase of propagation, even when the magnetic field of the magnetocentrifugal wind is toroidally dominated all the way to the launching surface. The strongly perturbed wind settles into a new steady state, with a highly asymmetric mass distribution. The distribution of magnetic field strength is, in contrast, much more symmetric. We discuss possible reasons for the apparent stability, including stabilization by an axial poloidal magnetic field, which is required to bend …
Date: November 28, 2006
Creator: Anderson, Jeffrey M.; Li, Zhi-Yun; /Virginia U., Astron. Dept.; Krasnopolsky, Ruben; /Toronto U., Astron. Dept.; Blandford, Roger D. et al.
System: The UNT Digital Library
Impedancemetric NOx Sensing Using Yttria-Stabilized Zirconia (YSZ) Electrolyte and YSZ/Cr2O3 Composite Electrodes (open access)

Impedancemetric NOx Sensing Using Yttria-Stabilized Zirconia (YSZ) Electrolyte and YSZ/Cr2O3 Composite Electrodes

An impedancemetric method for NO{sub x} sensing using an yttria-stabilized zirconia (YSZ) based electrochemical cell is described. The sensor cell consists of a planar YSZ electrolyte and two identical YSZ/Cr{sub 2}O{sub 3} composite electrodes exposed to the test gas. The sensor response to a sinusoidal ac signal applied between the two electrodes is measured via two parameters calculated from the complex impedance, the modulus |Z| and phase angle {Theta}. While either of these parameters can be correlated to the NO{sub x} concentration in the test gas, {Theta} was found to provide a more robust metric than |Z|. At frequencies below approximately 100 Hz, {Theta} is sensitive to both the NO{sub x} and O{sub 2} concentrations. At higher frequencies, {Theta} is predominantly affected by the O{sub 2} concentration. A dual frequency measurement is demonstrated to compensate for changes in the O{sub 2} background between 2 and 18.9%. Excellent sensor performance is obtained for NO{sub x} concentrations in the range of 8-50 ppm in background. An equivalent circuit model was used to extract fitting parameters from the impedance spectra for a preliminary analysis of NO{sub x} sensing mechanisms.
Date: November 1, 2006
Creator: Martin, L P; Woo, L Y & Glass, R S
System: The UNT Digital Library
POSTCLOSURE GROUNDWATER REMEDIATION AND MONITORING AT THE SANITARY LANDFILL, SAVANNAH RIVER SITE TRANSITIONING TO MONITORED NATURAL ATTENUATION (open access)

POSTCLOSURE GROUNDWATER REMEDIATION AND MONITORING AT THE SANITARY LANDFILL, SAVANNAH RIVER SITE TRANSITIONING TO MONITORED NATURAL ATTENUATION

Resource Conservation and Recovery Act (RCRA) requirements for hazardous waste facilities include 30 years of post-closure monitoring. The use of an objective-based monitoring strategy allows for a significant reduction in the amount of groundwater monitoring required, as the groundwater remediation transitions from an active biosparging system to monitored natural attenuation. The lifecycle of groundwater activities at the landfill has progressed from detection monitoring and plume characterization, to active groundwater remediation, and now to monitored natural attenuation and postclosure monitoring. Thus, the objectives of the groundwater monitoring have changed accordingly. Characterization monitoring evaluated what biogeochemical natural attenuation processes were occurring and determined that elevated levels of radium were naturally occurring. Process monitoring of the biosparging system required comprehensive sampling network up- and down-gradient of the horizontal wells to verify its effectiveness. Currently, the scope of monitoring and reporting can be significantly reduced as the objective is to demonstrate that the alternate concentration limits (ACL) are being met at the point of compliance wells and the maximum contaminant level (MCL) is being met at the surface water point of exposure. The proposed reduction is estimated to save about $2M over the course of the remaining 25 years of postclosure monitoring.
Date: November 17, 2006
Creator: Ross, J; Walt Kubilius, W; Thomas Kmetz, T; D Noffsinger, D & Karen M Adams, K
System: The UNT Digital Library
The effect of pulse duration on laser-induced damage by 1053-nm light in potassium dihydrogen phosphate crystals (open access)

The effect of pulse duration on laser-induced damage by 1053-nm light in potassium dihydrogen phosphate crystals

Laser induced damage in potassium dihydrogen phosphate (KDP) has previously been shown to depend significantly on pulse duration for 351-nm Gaussian pulses. In this work we studied the properties of damage initiated by 1053-nm temporally Gaussian pulses with 10ns and 3ns FWHM durations. Our results indicate that the number of damage sites induced by 1053-nm light scales with pulse duration ({tau}) as ({tau}{sub 1}/{tau}{sub 2}){sup 0.17} in contrast to the previously reported results for 351-nm light as ({tau}{sub 1}/{tau}{sub 2}){sup 0.35}. This indicates that damage site formation is significantly less probable at longer wavelengths for a given fluence.
Date: November 27, 2006
Creator: Cross, D A; Braunstein, M R & Carr, C W
System: The UNT Digital Library
Beam diagnostics, collimation, injection/extraction, targetry, accidents and commissioning: Working group C&G summary report (open access)

Beam diagnostics, collimation, injection/extraction, targetry, accidents and commissioning: Working group C&G summary report

The performance of accelerators with high beam power or high stored beam energy is strongly dependent on the way the beam is handled, how beam parameters are measured and how the machine is commissioned. Two corresponding working groups have been organized for the Workshop: group C ''Beam diagnostics, collimation, injection/extraction and targetry'' and group G ''Commissioning strategies and procedures''. It has been realized that the issues to be discussed in these groups are interlaced with the participants involved and interested in the above topics, with an extremely important subject of beam-induced accidents as additional topic. Therefore, we have decided to combine the group sessions as well as this summary report. Status, performance and outstanding issues of each the topic are described in the sections below, with additional observations and proposals by the joint group at the end.
Date: November 1, 2006
Creator: Mokhov, N. V.; Hasegawa, K.; Henderson, S.; Schmidt, R.; Tomizawa, M. & Wittenburg, K.
System: The UNT Digital Library
IN SITU URANIUM STABILIZATION BY MICROBIAL METABOLITES (open access)

IN SITU URANIUM STABILIZATION BY MICROBIAL METABOLITES

Soil contaminated with U was the focus of this study in order to develop in-situ, U bio-immobilization technology. We have demonstrated microbial production of a metal chelating biopolymer, pyomelanin, in U contaminated soil from the Tims Branch area of the Department of Energy (DOE) Savannah River Site (SRS) as a result of tyrosine amendments. Bacterial densities of pyomelanin producers were >106 cells/g wet soil. Pyomelanin demonstrated U chelating and mineral binding capacities at pH 4 and 7. In laboratory studies, in the presence of goethite or illite, pyomelanin enhanced U sequestration by these minerals. Tyrosine amended soils in field tests demonstrated increased U sequestration capacity following pyomelanin production up to 13 months after tyrosine treatments.
Date: November 29, 2006
Creator: Turick, C; Anna Knox, A; Chad L Leverette,C & Yianne Kritzas, Y
System: The UNT Digital Library
Dissimilar behavior of technetium and rhenium in borosilicatewaste glass as determined by X-ray absorption spectroscopy (open access)

Dissimilar behavior of technetium and rhenium in borosilicatewaste glass as determined by X-ray absorption spectroscopy

Technetium-99 is an abundant, long-lived (t1/2 = 213,000 yr)fission product that creates challenges for the safe, long-term disposalof nuclear waste. While 99Tc receives attention largely due to its highenvironmental mobility, it also causes problems during its incorporationinto nuclear waste glass due to the volatility of Tc(VII) compounds. Thisvolatility decreases the amount of 99Tc stabilized in the waste glass andcauses contamination of the waste glass melter and off-gas system. Theapproach to decrease the volatility of 99Tc that has received the mostattention is reduction of the volatile Tc(VII) species to less volatileTc(IV) species in the glass melt. On engineering scale experiments,rhenium is often used as a non-radioactive surrogate for 99Tc to avoidthe radioactive contamination problems caused by volatile 99Tc compounds.However, Re(VII) is more stable towards reduction than Tc(VII), so morereducing conditions would be required in the glass melt to produceRe(IV). To better understand the redox behavior of Tc and Re in nuclearwaste glass, a series of glasses were prepared under different redoxconditions. The speciation of Tc and Re in the resulting glasses wasdetermined by X-ray absorption fine structure spectroscopy. Surprisingly,Re and Tc do not behave similarly in the glass melt. Although Tc(0),Tc(IV), and Tc(VII) were observed in these samples, only Re(0) andRe(VII) …
Date: November 9, 2006
Creator: Lukens, Wayne W.; McKeown, David A.; Buechele, Andrew C.; Muller,Isabelle S.; Shuh, David K. & Pegg, Ian L.
System: The UNT Digital Library
TRANSITION TEMPERATURE IN QCD WITH PHYSICAL LIGHT AND STRANGE QUARK MASSES. (open access)

TRANSITION TEMPERATURE IN QCD WITH PHYSICAL LIGHT AND STRANGE QUARK MASSES.

We present results from a calculation of the transition temperature in QCD with two light (up, down) and one heavier (strange) quark mass as well as for QCD with three degenerate quark masses. Furthermore, we discuss first results from an ongoing calculation of the QCD equation of state with almost realistic light and strange quark masses.
Date: November 14, 2006
Creator: KARSCH, F.
System: The UNT Digital Library
Electronic Desorption of gas from metals (open access)

Electronic Desorption of gas from metals

During heavy ion operation in several particle accelerators world-wide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion induced gas desorption scales with the electronic energy loss (dE{sub e}/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.
Date: November 2, 2006
Creator: Molvik, A W; Kollmus, H; Mahner, E; Covo, M K; Bender, M; Bieniosek, F M et al.
System: The UNT Digital Library
Swift Detects a Remarkable Gamma-Ray Burst, GRB 060614, That Introduces a New Classification Scheme (open access)

Swift Detects a Remarkable Gamma-Ray Burst, GRB 060614, That Introduces a New Classification Scheme

Gamma ray bursts (GRBs) are known to come in two duration classes, separated at {approx}2 s. Long bursts originate from star forming regions in galaxies, have accompanying supernovae (SNe) when near enough to observe and are likely caused by massive-star collapsars. Recent observations show that short bursts originate in regions within their host galaxies with lower star formation rates, consistent with binary neutron star (NS) or NS - black hole (BH) mergers. Moreover, although their hosts are predominantly nearby galaxies, no SNe have been so far associated with short GRBs. We report here on the bright, nearby GRB 060614 that does not fit in either class. Its {approx}102 s duration groups it with long GRBs, while its temporal lag and peak luminosity fall entirely within the short GRB subclass. Moreover, very deep optical observations exclude an accompanying supernova, similar to short GRBs. This combination of a long duration event without accompanying SN poses a challenge to both a collapsar and merging NS interpretation and opens the door on a new GRB classification scheme that straddles both long and short bursts.
Date: November 28, 2006
Creator: Gehrels, Neil; Norris, J.P.; Mangano, V.; Barthelmy, S.D.; Burrows, D.N.; Granot, J. et al.
System: The UNT Digital Library
Conductivity of carbon nanotube polymer composites (open access)

Conductivity of carbon nanotube polymer composites

Dissipative Particle Dynamics (DPD) simulations were used to investigate methods of controlling the assembly of percolating networks of carbon nanotubes (CNTs) in thin films of block copolymer melts. For suitably chosen polymers the CNTs were found to spontaneously self-assemble into topologically interesting patterns. The mesoscale morphology was projected onto a finite-element grid and the electrical conductivity of the films computed. The conductivity displayed non-monotonic behavior as a function of relative polymer fractions in the melt. Results are compared and contrasted with CNT dispersion in small-molecule fluids and mixtures.
Date: November 20, 2006
Creator: Wescott, J. T.; Kung, P. & Maiti, A.
System: The UNT Digital Library
Methodology for Analyzing the Technical Potential for Energy Performance in the U.S. Commercial Buildings Sector with Detailed Energy Modeling: Preprint (open access)

Methodology for Analyzing the Technical Potential for Energy Performance in the U.S. Commercial Buildings Sector with Detailed Energy Modeling: Preprint

This paper summarizes a methodology for developing quantitative answers to the question, ''How low can energy use go within the commercial buildings sector''? The basic process is to take each building in the 1999 CBECS public use data files and create a baseline building energy model for it as if it were being built new in 2005 with code-minimum energy performance.
Date: November 1, 2006
Creator: Griffith, B. & Crawley, D.
System: The UNT Digital Library
Construction Safety Forecast for ITER (open access)

Construction Safety Forecast for ITER

The International Thermonuclear Experimental Reactor (ITER) project is poised to begin its construction activity. This paper gives an estimate of construction safety as if the experiment was being built in the United States. This estimate of construction injuries and potential fatalities serves as a useful forecast of what can be expected for construction of such a major facility in any country. These data should be considered by the ITER International Team as it plans for safety during the construction phase. Based on average U.S. construction rates, ITER may expect a lost workday case rate of < 4.0 and a fatality count of 0.5 to 0.9 persons per year.
Date: November 1, 2006
Creator: Cadwallader, Lee Charles
System: The UNT Digital Library
Observation of an Excited Charm Baryon Omega^*_C Decaying to Omega^0_C Gamma (open access)

Observation of an Excited Charm Baryon Omega^*_C Decaying to Omega^0_C Gamma

The authors report the first observation of an excited singly-charmed baryon {Omega}*{sub c} (css) in the radiative decay {Omega}{sub c}{sup 0}{gamma}, where the {Omega}{sub c}{sup 0} baryon is reconstructed in the decays to the final states {Omega}{sup -}{pi}{sup +}, {Omega}{sup -} {pi}{sup +}{pi}{sup 0}, {Omega}{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup +}, and {Xi}{sup -} K{sup -} {pi}{sup +}{pi}{sup +}. This analysis is performed using a dataset of 230.7 fb{sup -1} collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The mass difference between the {Omega}*{sub c} and the {Omega}{sub c}{sup 0} baryons is measured to be 70.8 {+-} 1.0(stat) {+-} 1.1(syst) MeV/c{sup 2}. They also measure the ratio of inclusive production cross sections of {Omega}*{sub c} and {Omega}{sub c}{sup 0} in e{sup +}e{sup -} annihilation.
Date: November 15, 2006
Creator: Aubert, B.
System: The UNT Digital Library