Physical Sciences and Mathematics Commons^™

Continuum Charged D* Spin Alignment At √S =10.5 Gev, G. Brandenburg, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

A measurement of the spin alignment of charged D* mesons produced in continuum e⁺e^- → cc̅ events at √s = 10.5 GeV is presented. This study using 4.72 fb^-1 of CLEO II data shows that there is little evidence of any D* spin alignment.

Measurement Of The Branching Ratios For The Decays Of DS+ To Ηπ+, Η′Π+, Ηρ+, And Η′Ρ+, C. P. Jessop, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

Using a data sample with an integrated luminosity of 3.9 fb^-1 collected in e⁺e^- annihilation with the CLEO-II detector at the Cornell Electron Storage Ring, we have measured the branching ratios for the decay modes D_s⁺ → (η, η′)π⁺ and D_s⁺ → (η, η′)ρ⁺ relative to D_s⁺ → φπ⁺. These decay modes are among the most common hadronic decays of the D_s⁺, and can be related by factorization to the semileptonic decays D_s⁺ → (η, η′)ℓ⁺ν₁ . …

Hadronic Transitions Υ(2S)→Υ(1S), J. P. Alexander, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

Using a 73.6 pb^-1 data sample of Υ(2S) events collected with the CLEO II detector at the Cornell Electron Storage Ring, we have investigated the hadronic transitions between the Υ(2S) and the Υ(1S). The dipion transition Υ(2S) → Υ(1S) π⁺π^- was studied using two different analysis techniques. Selecting events in which Υ(1S) → e⁺e^-, μ⁺μ^- (‘‘exclusive’’ analysis), and using the Υ(1S) leptonic branching fractions world averages from the PDG review, we obtained Ɓ(Υ(2S) …

Protein Fragmentation Due To Slow Highly Charged Ion Impact, Christiane Ruehlicke, Dieter Schneider, Markus Schneider, Robert D. Dubois, Rod Balhorn

Physics Faculty Research & Creative Works

We present first results of experiments on the fragmentation of biomolecules using highly charged heavy ions. Fragmentation and modification of oligopeptides, such as dimerization and attachment of ionic salt components, have been observed by means of mass spectrometry. Plasmid DNA molecules were imaged with an atomic force microscope after ion irradiation and profound molecular damage was found.

Applications Of Secondary Electron Energy- And Angular-Distributions To Spacecraft Charging, Neal Nickles, R. E. Davies

All Physics Faculty Presentations

Secondary electron (SE) emission from spacecraft surfaces as a result of energetic electron bombardment is a key process in the electrical charging of spacecraft. It has been suggested that incorporating more complete knowledge of the energy- and angular-distributions of secondary electrons is necessary to fully model how SE emission and spacecraft charging are affected by re-adsorption of low energy electrons in the presence of charge-induced electrostatic fields and ambient magnetic fields in the spacecraft environment. We present data for such energy- and angular-distributions from sputtered, polycrystalline gold surfaces. The data are compared to empirical SE emission models and found to …

Shakeoff Measurement Of The L = 3 States Of Barium, Heider N. Ereifej, J. Greg Story

Physics Faculty Research & Creative Works

Isolated core excitation was used to produce low-energy continuum electrons in the l = 3 angular momentum state of barium. Data were taken over a region of energy that coincided with the energy of the 6p_3/2nf doubly excited states. Analysis of the data using multichannel quantum defect theory allowed the measurement of the widths of the 6p_3/2nf states and the energy-dependent phase of the continuum electronic wave functions due to interaction with the doubly excited states. The phase of the continuum electrons is shown to vary continuously with energy, due to the anomalously broad widths of …

Water Balloon Rupture In Low‐G, Mark M. Weislogel, S. Lichter

Mechanical and Materials Engineering Faculty Publications and Presentations

A qualitative study of the bursting of water balloons in a simulated low-gravity environment was conducted aboard NASA Lewis’s DC-9 aircraft.

The tests were performed to develop techniques to rapidly deploy large liquid drops in a microgravity environment.

Low-Field Hopping Among Randomly-Distributed Sites With Uncorrelated Energetic Disorder, Paul Ernest Parris

Physics Faculty Research & Creative Works

The low-field mobility μ of a small concentration of charge carriers hopping among a random distribution of transport sites is studied, as a function of the mean interparticle spacing ρ and the temperature T, for model systems having different site-energy distribution functions. For a uniform density of states our calculations show that the mobility obeys empirical scaling laws similar to those found in the theory of variable-range hopping. For a binary distribution of site energies we observe a crossover as a function of site density between trap-limited conduction and trap-mediated conduction. For a Gaussian density of states our results confirm …

Optimal Atmospheric Compensation For Anisoplanatism In Adaptive-Optical Systems, Matthew R. Whiteley

Theses and Dissertations

Anisoplanatism in adaptive optics (AO) systems is a performance-degrading effect that arises whenever light from the wave-front sensor beacon and light from the object of interest sample different volumes of optical turbulence. This effect occurs if there is either a spatial separation between the object and the beacon, or a spatial separation between the wave-front sensor and phase-compensation aperture, or if both types of separation are present in the AO system. Anisoplanatism results in an increased value of the aperture-averaged residual phase variance after AO compensation, which causes an exponential decrease in system performance. This dissertation offers a theoretical framework …

Emissivity Measurements And Modeling Of Silicon Related Materials And Structures, Sufian Abedrabbo

Dissertations

The objective of this dissertation is to investigate the major issues concerning applications of pyrometry for applications in rapid thermal processing (RTP) of silicon related materials. The research highlights of this work are:

Establishment of spectral ernissometry as a novel, reliable and reproducible technique for:

Determination of wavelength and temperature dependent reflectivity, transmissivity, emissivity and temperature, simultaneously, of silicon related materials and structures. The emissometer operates in the wavelength range of 1-20mm and temperature range of 300-1200K. The analysis of the influence of morphological effects on the radiative properties by measurement of (a) front-smooth incidence versus backside-rough incidence of singleside …

Observation Of High Momentum Η′ Production In B Decays, T. E. Browder, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

We report the first observation of B→ η′X transitions with high momentum η′ mesons. We observe 39.0 ± 11.6 B decay events with 2.0 < Pη′ < 2.7 GeV/c, the high momentum region where background from b → c processes is suppressed. We discuss the physical interpretation of the signal, including the possibility that it is due to b → sg* transitions. Given that interpretation, we find Ɓ(B →η′X_s) = [6.2 ± 1.6(stat) ± 1.3(syst) _-1.5^+0.0(bkg)] X 10^-4 for 2.0 < Pη′ < 2.7 GeV/c.

Putative Light Scalar Nonet, Joseph Schechter, Deirdre Black, Amir H. Fariborz, Francesco Sannino

Physics - All Scholarship

We investigate the "family" relationship of a possible scalar nonet composed of the a_0(980), the f_0(980) and the \sigma and \kappa type states found in recent treatments of \pi\pi and \pi K scattering. We work in the effective Lagrangian framework, starting from terms which yield "ideal mixing" according to Okubo's original formulation. It is noted that there is another solution corresponding to dual ideal mixing which agrees with Jaffe's picture of scalars as qq\bar q \bar q states rather than as q\bar q states. At the Lagrangian level there is no difference in the formulation of the two cases (other …

Search For Selectron And Squark Production In E+P Collisions At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

We have searched for the production of a selectron and a squark in e+p collisions at a center-of-mass energy of 300 GeV using the ZEUS detector at HERA. The selectron and squark are sought in the direct decay into the lightest neutralino in the framework of supersymmetric extensions to the Standard Model which conserve R-parity. No evidence for the production of supersymmetric particles has been found in a data sample corresponding to 46.6 pb-1 of integrated luminosity. We express upper limits on the product of the cross section times the decay branching ratios as excluded regions in the parameter space …

The Tubular Phase Of Self-Avoiding Anisotropic Crystalline Membranes, Mark Bowick, Alex Travesset

Physics - All Scholarship

We analyze the tubular phase of self-avoiding anisotropic crystalline membranes. A careful analysis using renormalization group arguments together with symmetry requirements motivates the simplest form of the large-distance free energy describing fluctuations of tubular configurations. The non-self-avoiding limit of the model is shown to be exactly solvable. For the full self-avoiding model we compute the critical exponents using an epsilon-expansion about the upper critical embedding dimension for general internal dimension D and embedding dimension d. We then exhibit various methods for reliably extrapolating to the physical point (D=2,d=3). Our most accurate estimates are nu=0.62 for the Flory exponent and zeta=0.80 …

Mid- And Low-Latitude Prompt-Penetration Ionospheric Zonalplasma Drifts, Bela G. Fejer, L. Scherliess

Bela G. Fejer

We have used ion drift observations from the DE-2 satellite to determine the latitudinal variation and the temporal evolution of mid- and low-latitude prompt penetration zonal plasma drifts driven by magnetospheric electric fields. Our results indicate that sudden increases in convection lead to predominantly westward perturbation drifts which decrease equartorwards and have largest amplitudes in the dusk-midnight sector. The diurnal perturbation drift patterns shift to later local times with increasing storm time and decay to new quasi-equilibrium values in about 2 hours, as the ring current readjusts to the new polar cap potential. The daily and latitudinal variations and temporal …

Measured Stark Widths And Shifts Of Several Niii Sectral Lines: Temperature Dependence, Stevan Djenize, Vladimir Milosavljevic

Articles

Stark parameters (width and shift) of four doubly ionized nitrogen spectral lines, that belong to 3s-3p and 3p-3d transitions (lower multiplets), have been measured in a linear pulsed, low pressure, arc discharge in the nitrogen-oxygen and helium-nitrogen-oxygen plasmas in a (30 000 - 54 000) K electron temperature and a (0.75 10²³ - 2.8 10²³) electron density ranges. The measured values have been compared to the existing experimental and calculated data.

Method And Apparatus For Generating And Accelerating Ultrashort Electron Pulses, Donald P. Umstadter, Joon-Koo Kim, Evan Dodd

Donald Umstadter Publications

The invention provides a novel laser-plasma-based source of relativistic electrons; and a method to use laser-driven plasma waves as the basis for the source of electrons. The technique involves a combination of laser beams, which are focused in a plasma. One beam creates a wakefield plasma wave and the other beam alters the trajectory of background electrons, such that they become trapped in the plasma wave and are then accelerated to relativistic velocities, preferably in a distance less than a millimeter. In another embodiment, the second beam removes electrons from atomic ions previously generated by the first beam thereby providing …

Micromagnetics Of Ultrathin Films With Perpendicular Magnetic Anisotropy , Ralph Skomski, H.-P. Oepen, J. Kirschner

Ralph Skomski Publications

Magnetization processes in ultra-thin transition-metal films with perpendicular magnetic anisotropy are investigated. By model calculations it is shown that nucleation in ideal films is incoherent and therefore bulk-like, whereas the truly ultra-thin limit of coherent nucleation is restricted to film patches of small cross-section areas. In ideal mono-layers, the nonzero film thickness leads to bulk-like nucleation if the lateral dimensions of the film exceed about 1 mm. This means that monolayer patches having sub-micrometer diameters cannot be regarded as ultra-thin in a micro-magnetic sense. On the other hand, the critical single-domain diameter of ultra-thin films is larger by one order …

Investigation Of The 10b(Γ,P) Reaction Using Tagged Photons, L J. De Bever, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

The reaction 10B(γ,p) has been studied using tagged photons of mean energies Eγ=57.6 and 72.9 MeV. Angular distributions and derived single-particle momentum distributions for protons leading to the ground state of 9Be and higher excited states are compared to various calculations made using model parameters constrained by 10B(e,e′p)9Be and 9Be(p,p′)9Be measurements. The effects of varying final-state interactions (including channel couplings) and meson exchange currents are considered. A sizable discrepancy between direct-knockout calculations and the experimental results is observed. If meson exchange currents are included in an approximate fashion, a good description of the 10B(γ,p0)9Be data is found.

Coronal Mass Ejections, Magnetic Clouds, And Relativistic Magnetospheric Electron Events: Istp, D. N. Baker, T. I. Pulkkinen, X. Li, S. G. Kanekal, J. B. Blake, R. S. Selesnick, M. G. Henderson, G. D. Reeves, Harlan E. Spence, G. Rostoker

Physics & Astronomy

The role of high-speed solar wind streams in driving relativistic electron acceleration within the Earth's magnetosphere during solar activity minimum conditions has been well documented. The rising phase of the new solar activity cycle (cycle 23) commenced in 1996, and there have recently been a number of coronal mass ejections (CMEs) and related “magnetic clouds” at 1 AU. As these CME/cloud systems interact with the Earth's magnetosphere, some events produce substantial enhancements in the magnetospheric energetic particle population while others do not. This paper compares and contrasts relativistic electron signatures observed by the POLAR, SAMPEX, Highly Elliptical Orbit, and geostationary …

Parity Nonconservation In Neutron Resonances In 232th,, Sharon L. Stephenson, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Y-F Yen, V W. Yuan

Physics and Astronomy Faculty Publications

Parity nonconservation (PNC) was measured for 24 p-wave resonances from 8 to 300 eV in ²³²Th by measuring the helicity dependence of the total neutron cross section for epithermal neutrons with an improved experimental system. Ten resonances show statistically significant parity violation. For these ten resonances the analyzing powers are all positive, thus confirming the previously observed sign correlation. The data are fit to the sum of two terms, a constant asymmetry and a fluctuating asymmetry. With this ansatz the root-mean-square PNC matrix element M=1.12 meV, which corresponds to a weak spreading widthΓ_w=4.7×10^-7 eV. For the …

Neutron Resonance Spectroscopy Of 106pd, And 108pd From 20–2000 Ev, Bret E. Crawford, J D. Bowman, P P J. Delheij, T Haseyama, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, V W. Yuan

Physics and Astronomy Faculty Publications

Parity nonconserving asymmetries have been measured in p-wave resonances of ¹⁰⁶Pd and ¹⁰⁸Pd. The data analysis requires knowledge of the neutron resonance parameters. Transmission and capture γ-ray yields were measured for E_n=20–2000 eV with the time-of-flight method at the Los Alamos Neutron Science Center (LANSCE). A total of 28 resonances in ¹⁰⁶Pd and 32 resonances in ¹⁰⁸Pd were studied. The resonance parameters for ¹⁰⁶Pd are new for all except one resonance. In ¹⁰⁸Pd six new resonances were observed and the precision improved for many of the resonance parameters. A Bayesian analysis was …

Nature Of Resonant Photoemission In Gd, Shubhra R. Mishra, Thomas K. Cummins, George Daniel Waddill, W. J. Gammon, Gerrit V. Van Der Laan, Kyle W. Goodman, James G. Tobin

Physics Faculty Research & Creative Works

The phenomenon of resonant photoemission happens when, in addition to a direct photoemission channel, a second indirect channel opens up as the absorption threshold of a core level is crossed. A massive increase in emission cross section can occur, but the nature of the process remains clouded. Using novel magnetic linear dichroism in photoelectron spectroscopy experiments and theoretical calculations, we can now clearly demonstrate that temporal matching of the processes as well as energy matching is a requirement for true "resonant photoemission.".

Ultrafast Phenomena: A Laboratory Experiment For Undergraduates, Thomas D. Donnelly, Carl Grossman

All HMC Faculty Publications and Research

We present a set of experiments that introduce students to ultrafast science. We discuss the relationship between the description of an ultrashort laser pulse in the frequency domain and the time domain. Using experimental results we demonstrate that this relationship is constrained by the lower limit of the Heisenberg uncertainty principle. Students carrying out the experiments will become familiar with ultrafast techniques, such as autocorrelation and laser cavity design, as well as various other concepts such as dispersion, Fourier transformation, interference, and nonlinear optics.

Self-Calibrating Method For Measuring Local Multiphotonionization Yields As A Function Of Absolute Intensity, Cornelis J. Uiterwaal, B. Witzel, H. Schröder, K.-L. Kompa

C.J.G.J. Uiterwaal Publications

We present a self-calibrating method for measuring local multiphoton-ionization yields as a function of absolute intensity. In contrast to the method recently described by Walker et al. [Phys. Rev. A 57, R701 (1998)], our method does not require any assumption on the intensity distribution inside a laser focus, nor does it use any mathematical procedure such as deconvolution that would be based on such an assumption. In this sense, our method is self-calibrating. The proposed method immediately gives ion yields as a function of absolute intensity. Furthermore, it allows the intensity distribution inside the focal volume to be measured with …

Angle-Resolved Studies Of Inner Shell Excitations For Argon, Krypton And Xenon Using Third Generation Synchrotron Sources, Ahmad H. Farhat

Dissertations

This dissertation, which is in the area of atomic physics, concentrates on the study of the interaction between VUV-soft X-ray radiation and atoms in the gas phase. The main area of interest is the study of Auger decay in atoms utilizing the process known as the resonance Auger effect, where an inner shell electron is excited to an unfilled orbital followed by the ejection of an Auger electron. The measurements in this thesis were performed by using the high resolution Atomic, Molecular and Optical Physics undulator beam line, which utilizes a spherical grating monochromator at the Advanced Light Source at …

Improved Measurement Of The Pseudoscalar Decay Constant FDS, M. Chada, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

We present a new determination of f_Ds using 5 million e⁺e^- → cc̅ events obtained with the CLEO II detector. Our value is derived from our new measured ratio Γ(D_s⁺ → μ⁺ν)/Γ(D_s⁺ → φ π ⁺) = 0.173±0.023 ±0.035. Using Ɓ(D_s⁺ → φ π ⁺) = (3.6±0.9)%, we extract f_Ds = (280±19±28±34) MeV. We compare this result with various model calculations.

Ultrafast Phenomena: A Laboratory Experiment For Undergraduates, T. D. Donnelly, Carl H. Grossman

Physics & Astronomy Faculty Works

We present a set of experiments that introduce students to ultrafast science. We discuss the relationship between the description of an ultrashort laser pulse in the frequency domain and the time domain. Using experimental results we demonstrate that this relationship is constrained by the lower limit of the Heisenberg uncertainty principle. Students carrying out the experiments will become familiar with ultrafast techniques, such as autocorrelation and laser cavity design, as well as various other concepts such as dispersion, Fourier transformation, interference, and nonlinear optics. (C) 1998 American Association of Physics Teachers.

Parity Nonconservation In Neutron Resonances In 238u, Bret E. Crawford, J D. Bowman, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, Sharon L. Stephenson, Y-F Yen, V W. Yuan

Physics and Astronomy Faculty Publications

Parity nonconservation (PNC) was studied for 24 p-wave neutron resonances in ²³⁸U from 10 to 300 eV by measuring the helicity dependence of the total neutron cross section with an improved experimental apparatus. Six resonances show statistically significant (greater than 2.9σ) parity violation. An analysis treating the PNC matrix elements as random variables yields a root-mean-square PNC matrix element M=0.67_-0.16^+0.24 meV. The corresponding weak spreading width Γ_w=(1.35_-0.64^+0.97)×10^-7 eV.

Electric Potential In The Classical Hall Effect: An Unusual Boundary-Value Problem, Matthew J. Moelter, James Evans, Greg Elliot, Martin Jackson

Physics

The classical Hall effect presents a surprisingly unusual and challenging problem in electrostatics, with boundary conditions that are not of Dirichlet, Neumann, or of mixed Dirichlet and Neumann type. These unusual boundary conditions create several difficulties not normally encountered in standard problems, and ultimately lead to expansion of the electric potential in a nonorthogonal basis set. We derive the boundary conditions for the potential in a rectangular geometry, construct a solution for the potential, and discuss the relation between this problem and problems of the standard mixed type. We also address a commonly encountered misconception about the current distribution.