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Physics Faculty Publications and Presentations

Particles (Nuclear physics)

Articles 1 - 9 of 9

Full-Text Articles in Physics

On The Production Of The Positive Antihydrogen Ion H̄+ Via Radiative Attachment, Chris M. Keating, M. Charlton, Jack C. Straton Jan 2014

On The Production Of The Positive Antihydrogen Ion H̄+ Via Radiative Attachment, Chris M. Keating, M. Charlton, Jack C. Straton

Physics Faculty Publications and Presentations

We provide an estimate of the cross section for the radiative attachment of a second positron into the state of the ion using Ohmura and Ohmura's (1960 Phys. Rev. 118 154) effective range theory and the principle of detailed balance. The ion can potentially be created using interactions of positrons with trapped antihydrogen, and our analysis includes a discussion in which estimates of production rates are given. Motivations to produce include its potential use as an intermediary to cool antihydrogen to ultra-cold (sub-mK) temperatures for a variety of studies, including spectroscopy and probing the gravitational interaction of the anti-atom.


Selective Growth Of Single-Crystalline Zno Nanowires On Doped Silicon, Rolf Könenkamp, Robert Campbell Word, M. Dosmailov, J. Meiss, Athavan Nadarajah Jan 2007

Selective Growth Of Single-Crystalline Zno Nanowires On Doped Silicon, Rolf Könenkamp, Robert Campbell Word, M. Dosmailov, J. Meiss, Athavan Nadarajah

Physics Faculty Publications and Presentations

We report the growth of single-crystalline ZnO nanowires on n- and p-type Si wafers by electrodeposition. On strongly doped n-type Si high-quality nanowires can be grown under similar conditions as used for metallic substrates. For low electron concentrations occurring in weakly n-type or in p-type wafers, nanowire growth is inhibited. This difference allows selective growth in strongly n-type areas. The inhibited growth on weakly n-type and p-type wafers can be improved by applying stronger cathodic electrode potentials or by illuminating the growth area. The wires on n-Si show efficient electroluminescence covering the visible and extending into the ultraviolet spectral range.


Vertical Nanowire Light-Emitting Diode, Rolf Könenkamp, Robert Campbell Word, C. Schlegel Dec 2004

Vertical Nanowire Light-Emitting Diode, Rolf Könenkamp, Robert Campbell Word, C. Schlegel

Physics Faculty Publications and Presentations

We report room-temperature, white-color electroluminescence in vertically oriented ZnO nanowires. Excitonic luminescence around 380 nm is observed as a shoulder on a broader defect-related band covering all of the visible range and centered at 620 nm. The ZnO nanowires are grown in a low-temperature process on SnO2-coated glass substrates, employing a technique that is suitable for large-area applications. The nanowires are robustly encapsulated in a thin polystyrene film deposited from high-molecular-weight solutions. Electron injection occurs through the transparent SnO2 layer, while hole injection is mediated by a p-doped polymer and an evaporated Au contact. Stable device operation ...


Addendum: "Bethe Stopping-Power Theory For Heavy-Target Atoms", P.T. Leung Sep 1999

Addendum: "Bethe Stopping-Power Theory For Heavy-Target Atoms", P.T. Leung

Physics Faculty Publications and Presentations

Our previous result on the correction of the Bethe stopping power theory for heavy target elements is amended, with the application of a more consistent version of the semirelativistic Bethe sum rule worked out recently [Phys. Rev. A 57, 4994 (1998)]. This correction is found to be significant for high-Z target atoms and relatively high-energy incident particles.


Fock-Tani Hamiltonian For Reactions Involving Two-Electron Atoms, Jack C. Straton Jun 1991

Fock-Tani Hamiltonian For Reactions Involving Two-Electron Atoms, Jack C. Straton

Physics Faculty Publications and Presentations

The Fock-Tani Hamiltonian is found for scattering processes involving up to two ions and two electrons. Possible bound-state species include one or two electrons bound on an ion fixed at the origin, and a one-electron projectile atom. A diagrammatic technique is illustrated that simplifies the algebra of the transformation. Coulomb- or plane-wave states are automatically generated by the same asymptotic Hamiltonian for all arrangement channels.


First-Order Amplitude For General State-To-State Transitions In Hydrogen By Projectile Impact, Jack C. Straton Feb 1991

First-Order Amplitude For General State-To-State Transitions In Hydrogen By Projectile Impact, Jack C. Straton

Physics Faculty Publications and Presentations

The closed analytic form for bound-state transitions due to projectile impact is found in the intermediate representation. The coordinate integral is obtained by evaluating the remaining two integrals in the general multicenter integral derived previously [J.C. Straton, Phys. Rev. A 41, 71 (1990)]. Evaluating the remaining time integral depends upon relating a sum of modified Bessel functions of the second kind KN+1/2(z) to a simple polynomial in 1/z. The results of Van Den Bos and De Heer [Physica 34, 333 (1967)] are shown to be missing a phase factor of (-i)(l′+l)


Recoil Distributions In Particle Transfer, James H. Mcguire, Jack C. Straton, W. J. Axmann, T. Ishihara, E. Horsdal Sep 1989

Recoil Distributions In Particle Transfer, James H. Mcguire, Jack C. Straton, W. J. Axmann, T. Ishihara, E. Horsdal

Physics Faculty Publications and Presentations

Classical Thomas peaks in various fast second-order particle transfer processes are quantum mechanically broadened by energy nonconservation in the intermediate states of collision. This quantum broadening is considered in observable velocity distributions of recoil particles.


Energy Losses Of Solar Neutrinos And The Oscillation Hypothesis, P.T. Leung, S. Boedo, M. L. Rustgi Jun 1984

Energy Losses Of Solar Neutrinos And The Oscillation Hypothesis, P.T. Leung, S. Boedo, M. L. Rustgi

Physics Faculty Publications and Presentations

A formula for the stopping power of neutrinos interacting via the standard weak-interaction model, but incorporating the possibility of neutrino oscillations among the three flavors, is derived. The results are applied to study the solar-neutrino anomaly and it is found that the anomaly cannot be accounted for by many orders of magnitude from consideration of the energy losses of the neutrinos interacting with the solar matter, even if the oscillation hypothesis is found to be valid.


General Formula For The Inelastic Scattering Of Relativistic Spin-½ Particles By Heavy Atoms, P.T. Leung, M. L. Rustgi, S. A. Long Jun 1984

General Formula For The Inelastic Scattering Of Relativistic Spin-½ Particles By Heavy Atoms, P.T. Leung, M. L. Rustgi, S. A. Long

Physics Faculty Publications and Presentations

A general differential-cross-section formula for the inelastic scattering of relativistic spin-½ particles by heavy atoms is derived in the Born approximation and the structure and polarization of the incident particle is incorporated. The results reduce to those of Fano (1963) and of Turner et al. (1973) in well-known limiting cases.