[en] There exists an international quest to trap neutral antimatter in the form of antihydrogen for scientific study. One method that is being developed for trapping antihydrogen employs a nested Penning trap. Such a trap serves to mix positrons and antiprotons so as to produce low energy antihydrogen atoms. Mixing is achieved when the confinement volumes of the two species overlap one another. In the work presented here, a theoretical understanding of the mixing process is developed by analyzing a mixing scheme that was recently reported [G. Gabrielse et al., Phys. Rev. Lett. 100, 113001 (2008)]. The results indicate that positron space charge or collisions among antiprotons may substantially reduce the fraction of antiprotons that have an energy suitable for antihydrogen trapping

[en] A numerical study is reported on the equilibrium properties of a surface-emitted or edge-confined non-drifting plasma. A self-consistent finite-differences evaluation of the electrostatic potential is carried out for a non-neutral plasma that follows a Boltzmann density distribution. The non-neutral plasma generates an electrostatic potential that has an extremum at the geometric center. Poisson's equation is solved for different ratios of the non-neutral plasma size to the edge Debye length. The profiles of the electrostatic potential and the plasma density are presented for different values of that ratio. A second plasma species is then introduced for two-plasma-species confinement studies, with one species confined by the space charge of the other, while each species follows a Boltzmann density distribution. An equilibrium in which a neutral region forms is found. An equilibrium is also found in which the two species have equal temperatures and charge states.

[en] Sputter-initiated resonance ionization spectroscopy (SIRIS), a highly sensitive surface analysis technique that incorporates a primary sputtering ion beam and a tunable laser system to selectively ionize sputtered neutral components, has recently been added to the array of characterization methods available at the University of North Texas (UNT). An overview of the UNT SIRIS system is given, and several of the system components and features developed at UNT are described, including optics of the primary beam and associated diagnostics, target handling, laser beam optics and diagnostics, the detector for the sputtered particles, and the fast pulse triggering scheme for time-of-flight measurements

[en] Electrostatic storage rings are used for a variety of atomic physics studies. An advantage of electrostatic storage rings is that heavy ions can be confined. An electrostatic storage ring that employs the space charge of an electron plasma for focusing is described. An additional advantage of the present concept is that slow ions, or even a stationary ion plasma, can be confined. The concept employs an artificially structured boundary, which is defined at present as one that produces a spatially periodic static field such that the spatial period and range of the field are much smaller than the dimensions of a plasma or charged-particle beam that is confined by the field. An artificially structured boundary is used to confine a non-neutral electron plasma along the storage ring. The electron plasma would be effectively unmagnetized, except near an outer boundary where the confining electromagnetic field would reside. The electron plasma produces a radially inward electric field, which focuses the ion beam. Self-consistently computed radial beam profiles are reported.

[en] Nuclear Reaction Analysis (NRA) using the ¹⁹F(p,αγ)¹⁶O resonance reaction is a powerful method of fluorine depth profiling. We have used this method to study the fluorine uptake phenomenon in mineral flint, which could potentially develop into a method of dating archeological flint artifacts. Flint samples cut with a rock saw were immersed in aqueous fluoride solutions for different times for the uptake study. The results suggest that fluorine uptake is not a simple phenomenon, but rather a combination of several simultaneous processes. Fluorine surface adsorption appears to play an important role in developing the fluorine profiles. The surface adsorption was affected by several parameters such as pH value and fluorine concentration in the solution, among others. The problem of surface charging for the insulator materials during ion bombardment is also reported

[en] The M-shell x-ray production cross sections for thorium and uranium have been measured for carbon ions with energies from 4.5 to 11.3 MeV with the charge state q increasing from 2 to 4, and oxygen ions with energies from 4.5 to 13.5 MeV with the charge state q increasing from 2 to 5. These cross sections are compared to the predictions of the first Born (PWBA+OBKN) and ECUSAR ionization theories, which were evaluated in a novel manner for the C^+q and O^+q energies and charge states of the data and converted to x-ray production cross sections with atomic parameters for a singly ionized M-shell and multiple ionization in the outer shells. Individual groups of M-shell transitions are also compared to the two ionization theories. The ECUSAR theory is shown to describe the measurements better than the first Born approximation. It is found to be in generally good agreement for all the total M-shell x-ray production and M-shell lines except for the Mγ cross sections. Reasons for the overestimation of the Mγ data are discussed. (paper)