The development of buffer-gas trapping and magnetized beam formation has provided positron beams with significantly improved energy resolution $(\ensuremath{\Delta}E<~0.025\mathrm{eV})$ compared to those available previously. Analysis techniques have been developed take advantage the fact that is in a magnetic field $\ensuremath{\sim}0.1\mathrm{T}.$ This enabled scattering experiments at lower energies state selectivity for excitation than had possible A detailed description these presented....

We have measured the first state-resolved, absolute cross sections for positron excitation of electronic states an atom or molecule using a high resolution (Delta E approximately 25 meV FWHM) beam positrons from Penning-Malmberg trap. present low-lying levels Ar, H(2), and N(2) incident energies between threshold 30 eV. For Ar H2, comparison can be made with theoretical calculations, and, in case results resolve significant discrepancy only two available calculations.

Absolute measurements are presented for the positron-impact cross sections direct ionization and positronium formation of noble gas atoms in range energies from threshold to 90 eV. The experiment uses a cold, trap-based positron beam technique studying scattering strong magnetic field. current data show generally good, quantitative agreement with previous taken using qualitatively different method. However, significant differences both also observed. An analysis is that yields another,...

Absolute measurements are presented for the positron-impact cross sections positronium formation, direct ionization, and total ionization of diatomic molecules ${\mathrm{N}}_{2}$, CO, ${\mathrm{O}}_{2}$, in range energies from threshold to $90\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. Cross electronic excitation $a\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Pi}$ ${a}^{\ensuremath{'}}\phantom{\rule{0.2em}{0ex}}^{1}\ensuremath{\Sigma}$ state ${\mathrm{N}}_{2}$...

An evaluation of anti-rubella virus immunoglobulin G (IgG) immunoassays that report in international units per milliliter (IU/ml) was performed to determine their analytical performance and the degree correlation test results. A total 321 samples were characterized based on results from a hemagglutination inhibition assay. The 48 negative 273 positive used sensitivity specificity assays. When equivocal interpreted as reactive, ranged 98.9 99.9% 77.1 95.8%. All assays had delta values less...

The main aim of this paper is to apply modern phenomenology and accurate Monte Carlo simulation techniques obtain the same level understanding positron transport as has been achieved for electrons. To end, a reasonably complete set cross sections low energy scattering in argon used calculate coefficients positrons pure gas subject an electrostatic field. We have analyzed features these compared calculated values with those electrons gas. particular focus on influence non-conservative nature...

We demonstrate a general technique to achieve precise radial displacement of the nodal line radiofrequency (rf) field in linear Paul trap. The relies on selective adjustment load capacitance trap electrodes, achieved through addition capacitors basic resonant rf-circuit used drive Displacements up 100 micrometer with precision are measured using combination fluorescence images ion Coulomb crystals and coherent coupling such mode an optical cavity. displacements made without measurable...

We report on a novel non-invasive method to determine the normal mode frequencies of ion Coulomb crystals in traps based resonance enhanced collective coupling between electronic states ions and an optical cavity field at single photon level. Excitations modes are observed through Doppler broadening resonance. An excellent agreement with predictions zero-temperature uniformly charged liquid plasma model is found. The technique opens up for investigations heating damping cold modes, as well them.

Absolute measurements are presented for the excitation of ${\ensuremath{\nu}}_{3}$ vibrational mode in ${\mathrm{CF}}_{4}$ by positron and electron impact from 0.1 to 2 eV. To minimize systematic differences, these were made using same trap-based or beam, associated experimental apparatus, procedures. Unlike other cross sections studied date, near-threshold section is similar, both magnitude shape, positrons electrons. Comparison with an analytic Born dipole model yields good agreement,...

Abstract Metastable levels of highly charged ions that can only decay via forbidden transitions have a significant effect on the properties high temperature plasmas. For example, 3d $$^{10}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mn>10</mml:mn> </mml:mmultiscripts> </mml:math> $$_{J=0}$$ <mml:mrow> <mml:mi>J</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> - $$^9$$ <mml:mn>9</mml:mn> 4 s $$(\frac{5}{2},\frac{1}{2})_{J=3}$$...

Transport properties of positron swarms in water vapour under the influence electric and magnetic fields are investigated using a Monte Carlo simulation technique multi-term theory for solving Boltzmann equation. Special attention is paid to correct treatment non-conservative nature positronium (Ps) formation its explicit implicit influences on various transport properties. Many interesting atypical phenomena induced by these identified discussed. Calculated positrons compared with those...

Nearly steady-state electron plasmas are trapped in a toroidal magnetic field for the first time. We report results from new plasma experiment, Lawrence Non-neutral Torus II, which densities on order of ${10}^{7}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}3}$ 270\ifmmode^\circ\else\textdegree\fi{} arc (670 G field) by application trapping potentials to segments conducting shell. The total charge inferred measurements frequency $m=1$ diocotron mode is observed decay 3 s time scale, scale...

A detailed description and theoretical analysis of experiments achieving coherent coupling between an ion Coulomb crystal optical cavity field are presented. The various methods used to measure the rate large crystals in a linear quadrupole radiofrequency trap single mode moderately high-finesse described detail. Theoretical models based on semiclassical approach applied assessment experimental results [P. F. Herskind et al., Nature Phys. 5, 494 (2009)] complementary new measurements....

We present an investigation of the coherent coupling various transverse field modes optical cavity to ion Coulomb crystals. The obtained experimental results, which include demonstration identical collective rates for different a ions in same large crystal, are excellent agreement with theoretical predictions. results furthermore suggest that crystals future may serve as near-ideal media high-fidelity multimode quantum information processing and communication purposes, including generation...

Motivated by an increasing number of applications, new techniques in the analysis electron transport have been developed over past 30 years or so, but similar methods had yet to be applied positrons. Recently, in-depth look at positron pure argon gas has performed using a recently established comprehensive set cross sections and well-established Monte Carlo simulations. The key novelty as compared is effect positronium formation which changes particles strong energy dependence. This coupled...

We demonstrate a spatial-imaging thermometry technique for ions in one-dimensional Coulomb crystal by relating their imaged spatial extent along the linear radiofrequency ion trap axis to normal modes of vibration coupled oscillators harmonic potential. also use thermal spread “bright” case two-species mixed chain measure center-of-mass resonance frequency entire and infer molecular composition co-trapped “dark” ions. These non-destructive techniques create new possibilities better...

Electron plasmas with densities of 5×106 cm−3 are trapped in the Lawrence Non-neutral Torus II (LNT II) for times exceeding 1 s. LNT is a high aspect ratio (R0/a≳10) partially toroidal trap (270° arc, B0=670 G). The m=1 diocotron mode launched and detected using isolated segments fully sectored conducting boundary its frequency used to determine total charge as function time. observed confinement time (≈3 s) approaches theoretical limit (≈6 set by magnetic pumping transport mechanism Crooks...

The recent detection of a neutron star merger by the LIGO collaboration has renewed interest in laboratory studies r-process elements. Accurate modeling and interpretation electromagnetic transients following mergers requires computationally expensive calculations both structure opacity all trans-iron To date, necessary atomic data to benchmark codes are incomplete or, some cases, absent entirely. Within available studies, literature on Au i ii provides reports emission lines level...

ABSTRACT Three automated assays (Abbott AxSYM, Bayer ADVIA Centaur, and bioMerieux VIDAS) used for the detection of rubella virus-specific immunoglobulin M were evaluated. A total 57 samples from individuals with evidence infection virus to estimate sensitivity, 220 blood donors attending an antenatal clinic who had no recent specificity. Seroconversion panels comprising additional 31 four determine clinical sensitivity. Samples containing potentially cross-reacting substances also tested....