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Low Mode Control of Cryogenic ICF Fuel Layers Using Infrared Heating (open access)

Low Mode Control of Cryogenic ICF Fuel Layers Using Infrared Heating

Infrared heating has been demonstrated as an effective technique to smooth solid hydrogen layers inside transparent cryogenic inertial confinement fusion capsules. Control of the first two Legendre modes of the fuel thickness perturbations using two infrared beams injected into a hohlraum was predicted by modeling and experimentally demonstrated. In the current work, we use coupled ray tracing and heat transfer simulations to explore a wider range of control of long scale length asymmetries. We demonstrate several scenarios to control the first four Legendre modes in the fuel layer using four beams. With such a system, it appears possible to smooth both short and long scale length fuel thickness variations in transparent indirect drive inertial confinement fusion targets.
Date: July 6, 2005
Creator: London, R. A.; Kozioziemski, B. J.; Marinak, M. M.; Kerbel, G. D. & Bittner, D. N.
System: The UNT Digital Library
Search for B- -> Ds+(*)- Phi (open access)

Search for B- -> Ds+(*)- Phi

We report on searches for B{sup -} {yields} D{sub S}{sup -}{phi} and B{sup -} {yields} D*{sub S}{sup -}{phi}. In the context of the Standard Model the branching fractions for these decays are expected to be highly suppressed, since they proceed through annihilation of the b and {bar u} quarks in the B{sup -} meson. Our results are based on 234 million {Upsilon}(42) {yields} B{bar B} decays collected with the BABAR detector at SLAC. We find no evidence for these decays, and we set 90% confidence level upper limits on the branching fractions {Beta}(B{sup -} {yields} D{sub S}{sup -}{phi}) < 1.8 x 10{sup -6}; {Beta}(B{sup -} {yields} D*{sub S}{sup -}{phi}) < 1.1 x 10{sup -5}. These results are consistent with Standard Model expectations.
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Measurement of the $B^+\rightarrow p \bar{p} K^{+}$ Branching Fraction and Study of the Decay Dynamics (open access)

Measurement of the $B^+\rightarrow p \bar{p} K^{+}$ Branching Fraction and Study of the Decay Dynamics

With a sample of 232 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector, we study the decay B{sup +} {yields} p{bar p}K{sup +} excluding charmonium decays to p{bar p}. We measure a branching fraction {Beta}(B{sup +} {yields} p{bar p}K{sup +}) = (6.7 {+-} 0.5 {+-} 0.4) x 10{sup -6}. An enhancement at low p{bar p} mass is observed and the Dalitz plot asymmetry suggests dominance of the penguin amplitude in this B decay. We search for a pentaquark candidate {Theta}*{sup ++} decaying into pK{sup +} in the mass range 1.43 to 2.00 GeV/c{sup 2} and set limits on {Beta}(B{sup +} {yields} {Theta}*{sup ++} {bar p}) x {Beta}({Theta}*{sup ++} {yields} pK{sup +}) at the 10{sup -7} level.
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Measurement of CP Asymmetries for the Decays B^+/- --> D^0_CP K*^+/- (open access)

Measurement of CP Asymmetries for the Decays B^+/- --> D^0_CP K*^+/-

Using a sample of 232 million {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II B Factory in 1999-2004, they study B{sup -} {yields} K{sup 0}K*(892){sup -} decays where K*{sup -} {yields} K{sub S}{sup 0} {pi}{sup -} and D{sup 0} {yields} K{sup -}{pi}{sup +}, K{sup -}{pi}{sup +}{pi}{sup 0}, K{sup -}{pi}{sup +}{pi}{sup +}{pi}{sup -} (non-CP final states); K{sup +}K{sup -}, {pi}{sup +}{pi}{sup -} (CP+ eigenstates); K{sub S}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}{phi} and K{sub S}{sup 0}{omega} (CP- eigenstates). They measure four observables that are sensitive to the angle {gamma} of the CKM unitarity triangle; the partial-rate charge asymmetries A{sub CP{+-}} and the ratios of the B-decay branching fraction in CP{+-} and non-CP decays R{sub CP{+-}}: A{sub CP+} = -0.08 {+-} 0.19 (stat.) {+-} 0.08 (syst.); A{sub CP-} = -0.26 {+-} 0.40 (stat.) {+-} 0.12 (syst.); R{sub CP+} = 1.96 {+-} 0.40 (stat.) {+-} 0.11 (syst.); R{sub CP-} = 0.65 {+-} 0.26 (stat.) {+-} 0.08 (syst.).
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Radiation Safety Aspects of the Linac Coherent Light Source Project At SLAC (open access)

Radiation Safety Aspects of the Linac Coherent Light Source Project At SLAC

The Linac Coherent Light Source (LCLS) is a Self-Amplified Spontaneous Emission based Free Electron Laser (FEL) that is being designed and built at the Stanford Linear Accelerator Center (SLAC) by a multilaboratory collaboration. This facility will provide ultra-short pulses of coherent x-ray radiation with the fundamental harmonic energy tunable over the energy range of 0.82 to 8.2 keV. One-third of the existing SLAC LINAC will compress and accelerate the electron beam to energies ranging from 4.5 GeV to 14.35 GeV. The beam will then be transported through a 130-meter long undulator, emit FEL and spontaneous radiation. After passing through the undulator, the electron beam is bent to the main electron dump. The LCLS will have two experiment halls as well as x-ray optics and infrastructure necessary to make use of the FEL for research and development in a variety of scientific fields. The facility design will incorporate features that would make it possible to expand in future such that up to 6 independent undulators can be used. While some of the radiation protection issues for the LCLS are similar to those encountered at both high-energy electron linacs and synchrotron radiation facilities, LCLS poses new challenges as well. Some of these …
Date: July 6, 2005
Creator: Rokni, S.H.; Fasso, A.; Mao, S.; Vincke, H. & /LCLS, /SLAC
System: The UNT Digital Library
Externally Dispersed Interferometry for Planetary Studies (open access)

Externally Dispersed Interferometry for Planetary Studies

We describe a plan to study the radial velocity of low mass stars and brown dwarfs using a combination of interferometry and multichannel dispersive spectroscopy, Externally Dispersed Interferometry (EDI). The EDI technology allows implementation of precision velocimetry and spectroscopy on existing moderate-resolution echelle or linear grating spectrograph over their full and simultaneous bandwidth. We intend to add EDI to the new Cornell TripleSpec infrared simultaneous JHK-band spectrograph at the Palomar Observatory 200'' telescope for a science-demonstration program that will allow a unique Doppler-search for planets orbiting low mass faint M, L and T type stars. The throughput advantage of EDI with a moderate resolution spectrograph is critical to achieving the requisite sensitivity for the low luminosity late L and T dwarfs.
Date: July 6, 2005
Creator: Erskine, D. J.; Edelstein, J.; Harbeck, D. & Lloyd, J.
System: The UNT Digital Library
Measurement of Time-Dependent CP Asymmetries and the CP-Odd Fraction in the Decay B0->D*+D*- (open access)

Measurement of Time-Dependent CP Asymmetries and the CP-Odd Fraction in the Decay B0->D*+D*-

We present an updated measurement of time-dependent CP asymmetries and the CP-odd fraction in the decay B{sup 0} D*{sup +}D*{sup -} using 232 x 10{sup 6} B{bar B} pairs collected by the BABAR detector at the PEP-II B factory. We determine the CP-odd fraction to be 0.125 {+-} 0.044(stat) {+-} 0.007(syst). The time-dependent CP asymmetry parameters C{sub +} and S{sub +} are determined to be 0.06 {+-} 0.17(stat) {+-} 0.03(syst) and -0.75 {+-} 0.25(stat) {+-} 0.03(syst), respectively. The Standard Model predicts these parameters to be 0 and -sin2{beta}, respectively, in the absence of penguin amplitude contributions.
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Bootstrapping Multi-Parton Loop Amplitudes in QCD (open access)

Bootstrapping Multi-Parton Loop Amplitudes in QCD

The authors present a new method for computing complete one-loop amplitudes, including their rational parts, in non-supersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a unitarity-factorization bootstrap approach previously applied by the authors to the one-loop amplitudes required for next-to-leading order QCD corrections to the processes e{sup +}e{sup -} {yields} Z, {gamma}* {yields} 4 jets and pp {yields} W + 2 jets. We illustrate the method by reproducing the one-loop color-ordered five-gluon helicity amplitudes in QCD that interfere with the tree amplitude, namely A{sub 5;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}) and A{sub 5;1}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup +}). Then we describe the construction of the six- and seven-gluon amplitudes with two adjacent negative-helicity gluons, A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}) and A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), which uses the previously-computed logarithmic parts of the amplitudes as input. They present a compact expression for the six-gluon amplitude. No loop integrals are required to obtain the rational parts.
Date: July 6, 2005
Creator: Bern, Zvi; Dixon, Lance J. & Kosower, David A.
System: The UNT Digital Library
Fast Detector Simulation Using Lelaps, Detector Descriptions in GODL (open access)

Fast Detector Simulation Using Lelaps, Detector Descriptions in GODL

Lelaps is a fast detector simulation program which reads StdHep generator files and produces SIO or LCIO output files. It swims particles through detectors taking into account magnetic fields, multiple scattering and dE/dx energy loss. It simulates parameterized showers in EM and hadronic calorimeters and supports gamma conversions and decays. In addition to three built-in detector configurations, detector descriptions can also be read from files in the new GODL file format.
Date: July 6, 2005
Creator: Langeveld, Willy
System: The UNT Digital Library
Measurement of the Partial Branching Fraction for Inclusive Charmless Semileptonic B Decays and Extraction of |Vub| (open access)

Measurement of the Partial Branching Fraction for Inclusive Charmless Semileptonic B Decays and Extraction of |Vub|

Charmless semileptonic decays, {bar B} {yields} X{sub u}{ell}{bar {nu}}, are studied in a sample of 232 million B{bar B} decays recorded with the BABAR detector, in events where the decay of the second B meson is fully reconstructed. Inclusive charmless decays are selected in kinematic regions where the dominant background from semileptonic B decays to charm is reduced by requirements on the hadronic mass M{sub X} and the momentum transfer q{sup 2}. The partial branching fraction for {bar B} {yields} X{sub u}{ell}{bar {nu}} decays for M{sub X} < 1.7 GeV/c{sup 2} and q{sup 2} > 8 GeV{sup 2}/c{sup 4} is measured to be {Delta}{Beta}({bar b} {yields} X{sub u}{ell}{bar {nu}}) = (0.87 {+-} 0.09{sub stat} {+-} 0.09{sub sys} {+-} 0.01{sub th}) x 10{sup -3}. The CKM matrix element|V{sub ub}| is determined by using theoretical calculations of phase space acceptances. Theoretical uncertainties in this extrapolation are reduced by using the inclusive b {yields} s{gamma} photon spectrum and moments of the b {yields} c{ell}{bar {nu}} lepton energy and hadronic invariant mass.
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Measurement of Pressure Dependent Fluorescence Yield of Air: Calibration Factor for UHECR Detectors (open access)

Measurement of Pressure Dependent Fluorescence Yield of Air: Calibration Factor for UHECR Detectors

In a test experiment at the Final Focus Test Beam of the Stanford Linear Accelerator Center, the fluorescence yield of 28.5 GeV electrons in air and nitrogen was measured. The measured photon yields between 300 and 400 nm at 1 atm and 29 C are Y(760 Torr){sup air} = 4.42 {+-} 0.73 and Y(760 Torr){sup N{sub 2}} = 29.2 {+-} 4.8 photons per electron per meter. Assuming that the fluorescence yield is proportional to the energy deposition of a charged particle traveling through air, good agreement with measurements at lower particle energies is observed.
Date: July 6, 2005
Creator: Belz, J. W.; Burt, G. W.; Cao, Z.; Chang, F. Y.; Chen, C. C.; Chen, C. W. et al.
System: The UNT Digital Library
High Resolution Absorption Spectroscopy using Externally Dispersed Interferometry (open access)

High Resolution Absorption Spectroscopy using Externally Dispersed Interferometry

We describe the use of Externally Dispersed Interferometry (EDI) for high-resolution absorption spectroscopy. By adding a small fixed-delay interferometer to a dispersive spectrograph, a precise fiducial grid in wavelength is created over the entire spectrograph bandwidth. The fiducial grid interacts with narrow spectral features in the input spectrum to create a moire pattern. EDI uses the moire pattern to obtain new information about the spectra that is otherwise unavailable, thereby improving spectrograph performance. We describe the theory and practice of EDI instruments and demonstrate improvements in the spectral resolution of conventional spectrographs by a factor of 2 to 6. The improvement of spectral resolution offered by EDI can benefit space instruments by reducing spectrograph size or increasing instantaneous bandwidth.
Date: July 6, 2005
Creator: Edelstein, J & Erskine, D J
System: The UNT Digital Library
A Link between Meiotic Prophase Progression and CrossoverControl (open access)

A Link between Meiotic Prophase Progression and CrossoverControl

During meiosis, most organisms ensure that homologous chromosomes undergo at least one exchange of DNA, or crossover, to link chromosomes together and accomplish proper segregation. How each chromosome receives a minimum of one crossover is unknown. During early meiosis in Caenorhabditis elegans and many other species, chromosomes adopt a polarized organization within the nucleus, which normally disappears upon completion of homolog synapsis. Mutations that impair synapsis even between a single pair of chromosomes in C. elegans delay this nuclear reorganization. We quantified this delay by developing a classification scheme for discrete stages of meiosis. Immunofluorescence localization of RAD-51 protein revealed that delayed meiotic cells also contained persistent recombination intermediates. Through genetic analysis, we found that this cytological delay in meiotic progression requires double-strand breaks and the function of the crossover-promoting heteroduplex HIM-14 (Msh4) and MSH-5. Failure of X chromosome synapsis also resulted in impaired crossover control on autosomes, which may result from greater numbers and persistence of recombination intermediates in the delayed nuclei. We conclude that maturation of recombination events on chromosomes promotes meiotic progression, and is coupled to the regulation of crossover number and placement. Our results have broad implications for the interpretation of meiotic mutants, as we have …
Date: July 6, 2005
Creator: Carlton, Peter M.; Farruggio, Alfonso P. & Dernburg, Abby F.
System: The UNT Digital Library
A Precision Measurement of the Lambda_c Baryon Mass (open access)

A Precision Measurement of the Lambda_c Baryon Mass

The {Lambda}{sub c}{sup +} baryon mass is measured using {Lambda}{sub c}{sup +} {yields} {Lambda}K{sub S}{sup 0}K{sup +} and {Lambda}{sub c}{sup +} {yields} {Sigma}{sup 0}K{sub S}{sup 0}K{sup +} decays reconstructed in 232 fb{sup -1} of data collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring. The {Lambda}{sub c}{sup +} mass is measured to be 2286.46 {+-} 0.14 MeV/c{sup 2}. The dominant systematic uncertainties arise from the amount of material in the tracking volume and from the magnetic field strength.
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Observation of a Broad Structure in the $\pi^+\pi^-J/\psi$ Mass Spectrum around 4.26~GeV/$c^2$ (open access)

Observation of a Broad Structure in the $\pi^+\pi^-J/\psi$ Mass Spectrum around 4.26~GeV/$c^2$

The authors study initial-state radiation events, e{sup +}e{sup -} {yields} {gamma}{sub ISR} {pi}{sup +}{pi}{sup -} J/{psi}, with data collected with the BABAR detector. They observe an accumulation of events near 4.26 GeV/c{sup 2} in the invariant-mass spectrum of {pi}{sup +}{pi}{sup -} J/{psi}. Fits of the mass spectrum indicate that a broad resonance with a mass of about 4.26 GeV/c{sup 2} is required to describe the observed structure. The presence of additional narrow resonances cannot be excluded. The fitted width of the broad resonance is 50 to 90 MeV/c{sup 2}, depending on the fit hypothesis.
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Measurements of the Rare Decays B -> Kl+l- and B ->K*l+l- (open access)

Measurements of the Rare Decays B -> Kl+l- and B ->K*l+l-

The authors present measurements of the flavor-changing neutral current decays B {yields} K{ell}{sup +}{ell}{sup -} and B {yields} K*{ell}{sup +}{ell}{sup -}, where {ell}{sup +}{ell}{sup -} is either an e{sup +}e{sup -} or {mu}{sup +}{mu}{sup -} pair. The data sample comprises 229 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring.
Date: July 6, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Cavity Alignment Using Beam Induced Higher Order Modes Signals in the TTF Linac (open access)

Cavity Alignment Using Beam Induced Higher Order Modes Signals in the TTF Linac

Each nine cell superconducting (SC) accelerator cavity in the TESLA Test Facility (TTF) at DESY [1] has two higher order mode (HOM) couplers that efficiently remove the HOM power [2]. They can also provide useful diagnostic signals. The most interesting modes are in the first 2 cavity dipole passbands. They are easy to identify and their amplitude depends linearly on the beam offset from the cavity axis making them excellent beam position monitors (BPM). By steering the beam through an eight-cavity cryomodule, we can use the HOM signals to estimate internal residual alignment errors and minimize wakefield related beam emittance growth. We built and tested a time-domain based waveform recorder system that captures information from each mode in these two bands on each beam pulse. In this paper we present a preliminary experimental study of the single-bunch generated HOM signals at the TTF linac including estimates of cavity alignment precision and HOM BPM resolution.
Date: July 6, 2005
Creator: Ross, M.; Frisch, J.; Hacker, K. E.; Jones, R. M.; McCormick, D.; O'Connell, C. et al.
System: The UNT Digital Library
Extraction of short-lived zirconium and hafnium isotopes usingcrown ethers: A model system for the study of rutherfordium (open access)

Extraction of short-lived zirconium and hafnium isotopes usingcrown ethers: A model system for the study of rutherfordium

The extraction of zirconium and hafnium from hydrochloric acid media was studied using the crown ethers dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DC18C6) and dicyclohexano-24-crown-8 (DC24C8) as extractants. The goal was to find an extraction system that exhibits a high selectivity between the members of group 4 of the periodic table and is suitable for the study of rutherfordium. It was found that Zr and Hf are both extracted using DB18C6, DC18C6 and DC24C8. The extraction yield increases with increasing acid concentration and increasing concentration of crown ether. The extracted species most likely consists of an ion-association complex formed between a Zr or Hf chloro complex and a hydronium crown ether complex. Conditions can be found for each extractant that provide for the separation of Zr from Hf. This selective separation between Zr and Hf makes the extraction with crown ethers from HCl well suited to study the extraction behavior of Rf and compare it to the behavior of Zr and Hf. These extraction systems can be used to determine whether the extraction behavior of Rf is similar to Zr, similar to Hf or follows the trend established by the lighter homologs. The extraction kinetics are fast enough for the study of the …
Date: July 6, 2005
Creator: Sudowe, Ralf; Calvert, Michael G.; Dullmann, Christoph E.; Farina, Lindsy M.; Folden, Charles M., III; Gregorich, Kenneth E. et al.
System: The UNT Digital Library