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Physics Faculty Research & Creative Works

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Articles 1411 - 1440 of 1762

Full-Text Articles in Physical Sciences and Mathematics

Multiple-Ionization Collision Dynamics, R. (Ronald) E. Olson, J. Ullrich, H. Schmidt-Böcking Jan 1989

Multiple-Ionization Collision Dynamics, R. (Ronald) E. Olson, J. Ullrich, H. Schmidt-Böcking

Physics Faculty Research & Creative Works

The 1.4-MeV/u U32++Ne collision system is studied in detail in order to elucidate the dynamics of multiple ionization in energetic, heavy-ion atom collisions. Differential cross sections versus recoil-ion charge state, calculated by the n-body classical-trajectory Monte Carlo method, are presented for the and cphi angle dependences of the projectile, recoil ion, and ejected electrons. The calculations show a high degree of ejected-electron asymmetry towards the projectile side of the target nucleus which strongly effects the transverse-momentum balance between the heavy particles. Experimental and calculated cross sections differential in the recoil-ion charge state and transverse momentum are found to …

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N, L Distributions For Electron-Capture From H(1s) By C⁶⁺And O8+, Ronald E. Olson, D. R. Schultz Jan 1989

N, L Distributions For Electron-Capture From H(1s) By C⁶⁺And O8+, Ronald E. Olson, D. R. Schultz

Physics Faculty Research & Creative Works

Total cross sections for electron-capture from the ground state of hydrogen by C6+(40, 50, 60, 80, 100 and 120 keV/u) and O8+(40, 50, 60, 80, 100, 120 and 140keV/u) have been calculated using the classical-trajectory Monte Carlo (CTMC) technique. We tabulate these cross sections as a function of projectile energy for (i) capture to all product states, (ii) capture to product n-levels, and (iii) capture to product n, l-levels. The results of these calculations agree with and extend previous CTMC n, ldistribution results. © 1989 IOP Publishing Ltd.

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Spin-Polarized ³He Nuclear Targets And Metastable 4he Atoms By Optical Pumping With A Tunable, Nd:Yap Laser, C. L. Bohler, Laird D. Schearer, M. Leduc, P. J. Nacher, L. Zachorowski, R. G. Milner, R. D. Mckeown, C. E. Woodward Dec 1988

Spin-Polarized ³He Nuclear Targets And Metastable 4he Atoms By Optical Pumping With A Tunable, Nd:Yap Laser, C. L. Bohler, Laird D. Schearer, M. Leduc, P. J. Nacher, L. Zachorowski, R. G. Milner, R. D. Mckeown, C. E. Woodward

Physics Faculty Research & Creative Works

Several Nd:YAP lasers were constructed which could be broadly tuned in the 1083-nm region which includes the helium 23S-23P transition, using a Lyot filter and thin, uncoated etalons within the laser cavity. 1 W of power could be extracted at 1083 nm through a 1% transmitting output coupler. This laser beam was used to optically pump metastable 4He and 3He 23S helium atoms in a weak discharge cell, spin polarizing the metastable ensemble. In a 3He cell the polarization is transferred to the nuclear spin system. A 3He target cell at 0.3 …

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Nd:Lna Laser Optical Pumping Of ⁴He: Application To Space Magnetometers, R. E. Slocum, Laird D. Schearer, P. Tin, R. Marquedant Dec 1988

Nd:Lna Laser Optical Pumping Of ⁴He: Application To Space Magnetometers, R. E. Slocum, Laird D. Schearer, P. Tin, R. Marquedant

Physics Faculty Research & Creative Works

We have observed Hanle signals and n=0, p=1 parametric resonances of 23S1 metastable helium atoms in a discharge cell by optically pumping the helium atoms with a tunable Nd:LNA laser. These resonances were used to construct a sensitive magnetometer for the measurement of very small magnetic fields. Since magnetometer sensitivity is proportional to the slope of the parametric resonance signal (signal amplitude divided by linewidth), the slopes for single-line laser pumping were compared with similar quantities obtained from conventional helium lamp pumping. Laser pumping yielded 45 times greater slopes with comparable power requirements, thus establishing the potential for …

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Magnetism And Superconductivity In (Er₀.₁₆Ho₀.₈₄)Rh₄B₄, Oran Allan Pringle, Herbert A. Mook, Steven E. Lambert, M. Brian Maple Nov 1988

Magnetism And Superconductivity In (Er₀.₁₆Ho₀.₈₄)Rh₄B₄, Oran Allan Pringle, Herbert A. Mook, Steven E. Lambert, M. Brian Maple

Physics Faculty Research & Creative Works

The superconducting and ferromagnetic phase boundaries in the (Er1-xHox)Rh4B4 mixed ternary alloy system meet in a multicritical point at xcr ≈ 0.9. For xcr, the compounds first become superconducting as the temperature is lowered, and then lose superconductivity in a transition to ferromagnetism. The coexistence of superconductivity and ferromagnetism for alloys near the erbium-rich end of the phase diagram is well established. It has also been suggested that ferromagnetism and superconductivity coexist in alloys with x just below xcr. We have carried out neutron-diffraction, ac magnetic susceptibility, and heat-capacity …

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Resonant Transfer And Excitation In Li-Like F Colliding With H₂, Michael Schulz, Reinhold S. Schuch, Sheldon Datz, Edson L B Justiniano, Philip D. Miller, Harald Schone Nov 1988

Resonant Transfer And Excitation In Li-Like F Colliding With H₂, Michael Schulz, Reinhold S. Schuch, Sheldon Datz, Edson L B Justiniano, Philip D. Miller, Harald Schone

Physics Faculty Research & Creative Works

We have measured coincidences between x rays and projectiles that have captured one electron in F6+ + H2 collisions at projectile energies between 15 and 33 MeV. The cross sections for capture and simultaneous x-ray emission as a function of projectile energy show clear structures. Indications of an unexpectedly high population of high-n states predominantly formed by resonant transfer and excitation (RTE) were found. Above the Kln (n>1) RTE resonance energies another maximum was observed.

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Excitation Of The Lowest Autoionizing Levels In Lithiumlike Ions By Electron Impact, Rajesh C. Srivastava, Don H. Madison Nov 1988

Excitation Of The Lowest Autoionizing Levels In Lithiumlike Ions By Electron Impact, Rajesh C. Srivastava, Don H. Madison

Physics Faculty Research & Creative Works

We present theoretical, differential, and total cross sections for electron impact excitation of the lowest autoionizing levels of various lithiumlike ions (viz., Be+, B2+, C3+, O5+, and Ne7+). For these ions, the autoionizing level of interest results from excitation of an inner-shell electron. A distorted-wave Born approximation (with exchange) is used for the calculation. The present results are compared with previous theoretical calculations and it is concluded that the Coulomb-Born approach is unreliable, particularly near threshold.

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A Neutron Diffraction And Mössbauer Spectral Study Of The Structure And Magnetic Properties Of The Y₂Fe₁₄₋ₓsiₓb Solid Solutions, Gaya Kanishka Marasinghe, Oran Allan Pringle, Gary J. Long, William B. Yelon, Fernande Grandjean Nov 1988

A Neutron Diffraction And Mössbauer Spectral Study Of The Structure And Magnetic Properties Of The Y₂Fe₁₄₋ₓsiₓb Solid Solutions, Gaya Kanishka Marasinghe, Oran Allan Pringle, Gary J. Long, William B. Yelon, Fernande Grandjean

Physics Faculty Research & Creative Works

A neutron diffraction and Mössbauer spectral study of Y2Fe14-xSixB shows that silicon preferentially occupies the 4c, and to a lesser extent, the 8j1 sites in Y2Fe14-xSixB. The trend in the site occupancy is the same as in Nd2Fe14-xSixB. The Curie temperature of Y2Fe14-xSixB increases with increasing silicon content. Neutron diffraction data show that the increase in Curie temperature is accompanied by a contraction of the unit cell. Wigner-Seitz cell calculations, using the Y2Fe …

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Temperature And Supersaturation Dependent Nucleation Rates Of Water By Molecular Cluster Model Calculations, Sung-Ho Suck Salk, Chen K. Lutrus, Donald E. Hagen Oct 1988

Temperature And Supersaturation Dependent Nucleation Rates Of Water By Molecular Cluster Model Calculations, Sung-Ho Suck Salk, Chen K. Lutrus, Donald E. Hagen

Physics Faculty Research & Creative Works

Using a microphysical approach to nucleation, we present an extensive study of water nucleation rates for wide ranges of both temperature and supersaturation ratio. Based on the fundamental molecular properties of clusters instead of bulk properties, the microphysical approach is demonstrated to predict good agreement with measured nucleation rates over this broad range of conditions. Predicted critical sizes for nucleation are found to be relatively small, and are in the molecular cluster size regime rather than in a size regime that should be characterized by bulk values. Estimated sticking coefficient values cover the range of ~0.9 to ~0.2 for the …

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High-Pressure Neutron-Scattering Studies Of Graphite And Stage-Two Graphite-Sbcl₅, B. Alzyam, Clive H. Perry, C. Zahopoulos, Oran Allan Pringle, Robert M. Nicklow Jul 1988

High-Pressure Neutron-Scattering Studies Of Graphite And Stage-Two Graphite-Sbcl₅, B. Alzyam, Clive H. Perry, C. Zahopoulos, Oran Allan Pringle, Robert M. Nicklow

Physics Faculty Research & Creative Works

The longitudinal-acoustic (LA) phonons propagating along the c axis in highly oriented pyrolytic graphite (HOPG) were investigated as a function of pressure up to 20 kbar using inelastic-neutron-scattering techniques. The phonon frequencies varied as (P,q)=A(P)sin[c(P)q/2], where A(P) and c(P) indicate the pressure dependences of the zone-center LO frequency of B1g1 symmetry and of the c-axis lattice spacing, respectively. From the measurements, the mode Grüneisen parameter for the LA branch was estimated to be 1.5 x 10-2 kbar-1 (independent of q); the elastic constant C33 for HOPG was found to be 3.40 x 1011 dyn/cm …

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Some Issues Of Thermodynamic Consistency In Binary Nucleation Theory, Gerald Wilemski Apr 1988

Some Issues Of Thermodynamic Consistency In Binary Nucleation Theory, Gerald Wilemski

Physics Faculty Research & Creative Works

The "generalized" Kelvin equations used to determine the critical nucleus composition in some binary nucleation theories are shown to be thermodynamically inconsistent. Also, the surface tension calculated by the method of Flageollet-Daniel, Gamier, and Mirabel [J. Chem. Phys. 78, 2600 (1983)] is shown to be thermodynamically consistent with respect to the dynamic surface tension, contrary to the recent assertion of Spiegel, Zahoransky, and Wittig.

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The Role Of Dephasing In Some Recent Theories Of Quantum Localization, Paul Ernest Parris, Philip W. Phillips Mar 1988

The Role Of Dephasing In Some Recent Theories Of Quantum Localization, Paul Ernest Parris, Philip W. Phillips

Physics Faculty Research & Creative Works

We consider the transport of electrons or excitons through a random environment in the presence of constant site off-diagonal dephasing processes. It is shown that dephasing of this form will always defeat Anderson localization at long times. Some recent theories of quantum localization which depend upon such dephasing processes are, therefore, seen to be inconsistent.

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Effects Of Transport Coherence On The Mutual Annihilation Of Excitons, Demet Gulen, Vasudev M. Kenkre, Robert S. Knox, Paul Ernest Parris Feb 1988

Effects Of Transport Coherence On The Mutual Annihilation Of Excitons, Demet Gulen, Vasudev M. Kenkre, Robert S. Knox, Paul Ernest Parris

Physics Faculty Research & Creative Works

We report results of a theoretical investigation into the mutual annihilation of tight-binding excitons. The results are in apparent contradiction with intuitive expectations and provide corrections to expressions given by one of the present authors (V.M.K.) in an earlier analysis. A part of that analysis was based on a mapping of the dynamics of two mobile, mutually annihilating excitons onto the dynamics of a single exciton migrating in the presence of a fixed trap. We find that while this equivalence is valid for incoherent, randomly walking particles in an ordered system, it does not hold for an arbitrary degree of …

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Dynamics Of Antimatter-Atom Collisions, Ronald E. Olson, Timothy James Gay Jan 1988

Dynamics Of Antimatter-Atom Collisions, Ronald E. Olson, Timothy James Gay

Physics Faculty Research & Creative Works

Classical-trajectory Monte Carlo calculations have been used to study ionizing collisions between charged particles (p,p»,e+,e-) and He atoms at an incident velocity of 2.83 a.u. While differences in the total single-ionization cross sections for these projectiles are small, our calculations reveal large effects at all angles in the ionized electron spectra and provide qualitative evidence for a Barkas effect in p and p» collisions. Experimental data agree well with our fully classical calculations, including cross sections involving ejected electrons of long wavelength. © 1988 The American Physical Society.

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Contribution Of Excited Hydrogen Atoms To Charge-Exchange Excitation Of Impurities In Fusion Plasmas, R. C. Isler, Ronald E. Olson Jan 1988

Contribution Of Excited Hydrogen Atoms To Charge-Exchange Excitation Of Impurities In Fusion Plasmas, R. C. Isler, Ronald E. Olson

Physics Faculty Research & Creative Works

Cross sections are calculated for charge transfer into excited states of C5+ and O7+ from collisions of C6+ and O8+ with hydrogen atoms in the n=2 and 3 levels. Effective emission cross sections that account for cascading is then derived for spectral lines emitted when the product ions decay. These are compared to the emission cross sections calculated for excitation by ground-state hydrogen. It is shown that in some circumstances the contribution from excited hydrogen atoms must be taken into account when visible lines are used to determine the oxygen or carbon density from charge-exchange spectroscopy …

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A Study Of Vapor Phase Self-Initiated Thermal Polymerization Of Styrene With An Expansion Chamber, John L. Schmitt Jan 1988

A Study Of Vapor Phase Self-Initiated Thermal Polymerization Of Styrene With An Expansion Chamber, John L. Schmitt

Physics Faculty Research & Creative Works

Studies of the self-initiated polymerization of styrene have been performed in the uniform environment of an expansion cloud chamber, using nucleation of liquid monomer drops for detection. These studies are the first of this kind in an expansion chamber and, although preliminary and designed to explore feasibility, have yielded many interesting results. The occurrence of the self-initiated nonterminated gas phase processes, previously observed in a diffusion cloud chamber, has now been confirmed in an expansion chamber. At 15 °C the initiation rate is measured to be 2 to 6 radicals cm-3 s-1 and the propagation constant is approximately 6X10-21 cm3 …

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Projectile-Charge Dependence Of Ejected-Electron Spectra, V. D. Irby, Timothy James Gay, Jimmie Garwin Edwards, Edward Boyd Hale, M. L. Mckenzie, Ronald E. Olson Jan 1988

Projectile-Charge Dependence Of Ejected-Electron Spectra, V. D. Irby, Timothy James Gay, Jimmie Garwin Edwards, Edward Boyd Hale, M. L. Mckenzie, Ronald E. Olson

Physics Faculty Research & Creative Works

We have studied H++He and He++3+He ionizing collisions at intermediate energies (60 to 120 keV/amu) and have observed a significant shift in the velocity position of the maxima in forward-ejected electron spectra when changing projectiles from protons to particles. In ionizing collisions, a large portion of the ejected electrons are stranded near the transitory equiforce, or saddle point, position between the target ion and receding projectile. The shift in the electron spectra maxima to smaller velocities, due to changing projectiles from protons to particles, is consistent with the shift in the saddle-point velocity when the projectile …

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Charge- And Angle-Correlated Inelasticities In Collisions Of Bare Fast Carbon Ions With Neon, R. Schuch, H. Schöne, P. D. Miller, H. F. Krause, P. F. Dittner, S. Datz, Ronald E. Olson Jan 1988

Charge- And Angle-Correlated Inelasticities In Collisions Of Bare Fast Carbon Ions With Neon, R. Schuch, H. Schöne, P. D. Miller, H. F. Krause, P. F. Dittner, S. Datz, Ronald E. Olson

Physics Faculty Research & Creative Works

We have studied the detailed energy balance in collisions of 10-MeV C6+ ions with Ne. In these collisions, the Ne is multiply ionized and the C ion may emerge as either C6+ or C5+. Projectile energy loss and scattering angle for a given carbon-ion charge state were determined in a high-resolution magnetic spectrograph and were measured in coincidence with the formation of a given Ne recoil-ion charge state. The amount of energy transferred to the continuum electrons exceeds, by far, the sum of the values of the ionization potentials. © 1988 The American Physical Society.

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Argon Metastable-Cadmium Dihalide Energy Transfer Collisions In A Flowing Afterglow, Christopher L. Bohler, Laird D. Schearer Jan 1988

Argon Metastable-Cadmium Dihalide Energy Transfer Collisions In A Flowing Afterglow, Christopher L. Bohler, Laird D. Schearer

Physics Faculty Research & Creative Works

The energy dependence of dissociating collisions between argon metastable atoms and cadmium dihalide molecules have been studied in a flowing afterglow apparatus. The fluorescence spectra obtained in the range of 3000-7600 Å which result from the Ar(3P2) + CdX2 interactions indicate a dominant dissociative excitation production mechanism. The emission spectra are used to narrow the uncertainty in the currently accepted values for the dissociation energy of the CdX2 molecules. The Wigner spin rule (conservation of total electronic spin) was verified for these processes as shown by the dominance of final state triplet production as compared to the virtual absence of …

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Electron Loss From Helium Atoms By Collisions With Fully Stripped Ions, A. E. Wetmore, Ronald E. Olson Jan 1988

Electron Loss From Helium Atoms By Collisions With Fully Stripped Ions, A. E. Wetmore, Ronald E. Olson

Physics Faculty Research & Creative Works

Electron-loss cross sections have been calculated for fully stripped ions with charge states +1 to +100 colliding with helium atoms in the energy range 100 1000 kev/amu. The classical-trajectory Monte Carlo method was used along with a model of the helium atom with two active electrons. The reactions studied were single and double ionization, single- and double-electron capture, and electron capture plus ionization. Cross sections for the single-electron-removal reactions agree well with experimental data. Double-electron-removal cross sections are in qualitative agreement with experimental results. The n-level distributions following electron capture show that the electron-capture plus ionization and double electron-capture processes …

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Aerosol Evolution And Metamorphosis During And After Haze (Fog) Formation Over The Bay Of Naples, Josef Podzimek, H. Andriambeloma, A. De Maio, M. Ianniruberto, R. Montmory, E. Sansone, G. Spezie, G. Stowell Jan 1988

Aerosol Evolution And Metamorphosis During And After Haze (Fog) Formation Over The Bay Of Naples, Josef Podzimek, H. Andriambeloma, A. De Maio, M. Ianniruberto, R. Montmory, E. Sansone, G. Spezie, G. Stowell

Physics Faculty Research & Creative Works

No abstract provided.

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Single-Electron Removal Processes In Collisions Of Positrons And Protons With Helium At Intermediate Velocities, D. R. Schultz, Ronald E. Olson Jan 1988

Single-Electron Removal Processes In Collisions Of Positrons And Protons With Helium At Intermediate Velocities, D. R. Schultz, Ronald E. Olson

Physics Faculty Research & Creative Works

Total cross sections for single ionization and charge transfer have been calculated using the classical-trajectory Monte Carlo (CTMC) technique for collisions of both positrons and protons with helium. Analysis of the classical trajectories has helped to explain the differences in the collision mechanisms responsible for the observed relative magnitudes of the positron and proton electron-removal cross sections. In the intermediate collision velocity range (1.5 a.u.

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Ion-Ion Recombination In Mixtures Of Methane And Sulphur Hexafluoride, M. C. Cornell, Ian M. Littlewood Dec 1987

Ion-Ion Recombination In Mixtures Of Methane And Sulphur Hexafluoride, M. C. Cornell, Ian M. Littlewood

Physics Faculty Research & Creative Works

The authors have measured the recombination rate for positive and negative ions in Sulphur hexafluoride and in mixtures of methane and Sulphur hexafluoride in an electron beam sustained discharge. Measurements were made as a function of gas composition, gas pressure in the range 100 to 600 Torr, and reduced electric field strength in the range 12 to 150 Td. When plotted as a function of an effective ion temperature, defined by the drift velocities of the ions in the applied electric field, the rates in each of the gas mixtures follow the same Teff-1.6 power law. From comparisons with theories …

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Dynamics Of Multiply Charged Ion-Atom Collisions: U³²⁺+Ne, Ronald E. Olson, J. Ullrich, H. Schmidt-Bocking Dec 1987

Dynamics Of Multiply Charged Ion-Atom Collisions: U³²⁺+Ne, Ronald E. Olson, J. Ullrich, H. Schmidt-Bocking

Physics Faculty Research & Creative Works

Measurements and calculations are presented for the mean recoil-ion energies of Nei+ produced in 1.4 MeV u-1 (0.33 GeV) collisions of U32+ with Ne. Recoil-ion charge states i=1-8 have been observed; the mean recoil energies are low and do not exceed 1 eV until i>6. Calculations employing a newly developed n-body classical trajectory Monte Carlo method are found to yield results in qualitative agreement with the recoil-ion experiment. Calculations also are presented for the ionisation and charge exchange cross sections, the projectile energy loss and the ejected-electron energy and angular spectra. The importance of fast ejected electrons …

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Angular-Differential Studies Of Excitation In Quasi-One-Electron Collisions At "High" Energy, E. Redd, Timothy Gay, D. M. Blankenship, John T. Park, Jerry Peacher, Denver G. Seely Oct 1987

Angular-Differential Studies Of Excitation In Quasi-One-Electron Collisions At "High" Energy, E. Redd, Timothy Gay, D. M. Blankenship, John T. Park, Jerry Peacher, Denver G. Seely

Physics Faculty Research & Creative Works

Qualitative differences have been observed between two types of "quasi-one-electron" collision systems. We have studied valence-electron excitation at "high" energy (relative collision velocities up to 0.5 a.u.) in the Mg++He and Na++H collision systems, and find that while Mg++He collisions are dominated by "direct" excitation, the Na++H collisions exhibit significant "molecular" excitation, even at the highest velocities. This behavior can be understood in terms of the molecular structure of the respective collision complexes, and the energy separation between the ground and first excited states of the valence electron.

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Site-Diagonal T-Matrix Expansion For Anisotropic Transport And Percolation On Bond-Disordered Lattices, Paul Ernest Parris Oct 1987

Site-Diagonal T-Matrix Expansion For Anisotropic Transport And Percolation On Bond-Disordered Lattices, Paul Ernest Parris

Physics Faculty Research & Creative Works

A study is made of the dynamical behavior of an electron or exciton undergoing anisotropic hopping on a d-dimensional bond-disordered lattice. Starting with a master equation for the site probabilities, an exact equation of motion is obtained for the probability currents that flow along the bonds connecting nearest-neighbor sites. Unlike the original master equation, the equation of motion which couples the microscopic currents contains the randomly distributed hopping rates in a form which is strictly site diagonal. The simplification that results leads to a new and exact expansion for the diffusion tensor in powers of an appropriately defined single-bond t …

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Measurement Of The Condensation Coefficient Of Water In The Umr Cloud Simulation Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, A. R. Hopkins, Max B. Trueblood, M. W. Alcorn Jun 1987

Measurement Of The Condensation Coefficient Of Water In The Umr Cloud Simulation Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, A. R. Hopkins, Max B. Trueblood, M. W. Alcorn

Physics Faculty Research & Creative Works

Measurements of the condensation coefficient of water under conditions closely approximating those in natural atmospheric cloud have been made in the cooled-wall UMR cloud simulation chamber. Current measurements disclose a value of condensation coefficient near unity at the outset of the experiment, generally decreasing to lower values (~ .01) as the experiment progresses. The significance of the magnitude of condensation coefficient in atmospheric cloud is briefly discussed.

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University Of Missouri--Rolla Cloud Simulation Facility: Proto Ii Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, Alfred Raymond Hopkins, Max B. Trueblood, Max W. Alcorn, William L. Walker May 1987

University Of Missouri--Rolla Cloud Simulation Facility: Proto Ii Chamber, Daniel R. White, James L. Kassner, John C. Carstens, Donald E. Hagen, John L. Schmitt, Darryl J. Alofs, Alfred Raymond Hopkins, Max B. Trueblood, Max W. Alcorn, William L. Walker

Physics Faculty Research & Creative Works

The Graduate Center for Cloud Physics Research at UMR has developed a cloud simulation facility to study phenomena occurring in terrestrial clouds and fogs. The facility consists of a pair of precision cooled-wall expansion chambers along with extensive supporting equipment. The smaller of these chambers, described in this article, is fully operational, and is capable of simulating a broad range of in-cloud thermodynamic conditions. It is currently being used to study water drop growth and evaporation for drops nucleated (activated) on well-characterized aerosol particles. Measurements have been made not only for continuous expansions (simulated updraft) but also for cyclic conditions, …

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Separated Resonances In Simultaneous Capture And Excitation Of S¹⁵⁺ In H₂ Observed By K-X-Ray K-X-Ray Coincidences, Michael Schulz, Edson L B Justiniano, Reinhold S. Schuch, Paul H. Mokler, S. Reusch Apr 1987

Separated Resonances In Simultaneous Capture And Excitation Of S¹⁵⁺ In H₂ Observed By K-X-Ray K-X-Ray Coincidences, Michael Schulz, Edson L B Justiniano, Reinhold S. Schuch, Paul H. Mokler, S. Reusch

Physics Faculty Research & Creative Works

We have measured cross sections for the correlated emission of two K x rays following the collision of hydrogenlike sulfur ions with H2 in the energy range between 70 and 160 MeV. The observation of the two correlated x rays is interpreted as a resonant capture of a target electron accompanied by simultaneous excitation of the projectile in the collision (RTE). By our distinguishing between Kα and Kβ lines, contributions from KLL and KLn (n≥M) resonances could be determined independently.

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Transport Anisotropy And Percolation In The Two-Dimensional Random-Hopping Model, Kalyan P. Kundu, Paul Ernest Parris, Philip W. Phillips Mar 1987

Transport Anisotropy And Percolation In The Two-Dimensional Random-Hopping Model, Kalyan P. Kundu, Paul Ernest Parris, Philip W. Phillips

Physics Faculty Research & Creative Works

We consider hopping transport on an anisotropic two-dimensional square lattice. The displacements parallel to one axis are governed by uniform, nearest-neighbor hopping rates c, while the displacements parallel to the other axis are governed by static but spatially fluctuating rates wn. Adapting a new class of generating functions recently introduced for the random-trapping problem, we are able to obtain expressions for the mean-square displacement in the fluctuating direction through an exact decoupling of the effects due to displacements in the uniform direction. The resulting expressions for the low-frequency diffusion coefficient D(ε) are exact in the limits c →0 …

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