Analytical characterisation of a capacitively coupled plasma torch with a central tube electrode

A new type of radiofrequency capacitively coupled plasma torch is presented. The torch electrode geometry is coaxial with a tubular central electrode and one or two outer ring electrodes. The argon plasma is generated at 275 W radiofrequency power and 27.12 MHz and it has a very good stability and a low gas consumption of 0.4 l min(-1). The nebulized sample is introduced through the tubular electrode into the core of the annular shaped plasma thus achieving a better atomisation and a lower background. The limits of detection for 20 elements are in the range of ng ml(-1) and the dynamic range between 2.5 and 3.5. The best results are obtained with the torch with two outer ring electrodes.     

Characteristics of Λ andK 0 particles produced in central nucleus nucleus collisions at a 4.5 GeV/c momentum per incident nucleon

Data on Λ's andK ⁰'s, produced in central nucleus-nucleus collisions (C?C, C?Ne, O?Ne, C?Cu, C?Zr, C?Pb, O?Pb) at a 4.5 GeV/c momentum per incident nucleon obtained in the streamer chamber spectrometer SKM-200, are presented. Multiplicities, transverse momenta, rapidities and other characteristics are considered and compared with those for inelastic He?Li interactions. The polarization of Λ's was found to be consistent with zero. The upper limit of \(\bar \Lambda /\Lambda \) production ratio was estimated to be ≤10^?2 with a 90% confidence level. The results are compared with data of other experiments and some model calculations.     

A scaling test in π− p semi-inclusive reactions

The scaling properties of the semi-inclusive reactions π^?p → π^?+(n?1) charged + neutrals at 7.5 and 21 GeV/c are analysed. The distributions of the h-functions on the x-variable for π^? particles indicate the presence of a limited scaling. The choosing of a certain value for the reduced charged multiplicity $\text{n}\text{〈n〉}$ is pointed out.     

Interaction potential between two 16O nuclei derived from the Skyrme interaction

The energy functional for the Skyrme density-dependent force is used to calculate the interaction potential between two ¹⁶O nuclei. A two-centre harmonic oscillator potential is employed to construct the density and kinetic energy density of the ground state of the combined system and of the separated nuclei. The antisymmetrization effects are investigated. The relative motion of the nuclei is taken approximately into account and the energy dependence of the potential derived from the Skyrme force is presented.     

Analytical performance of an r.f. capacitively coupled plasma for atomic emission with tip-ring electrode geometry

A low to medium power radiofrequency capacitively coupled plasma is characterized as spectral source for atomic emission. The signal to background ratio and the limits of detection were determined for 19 elements as a function of the plasma torch geometry and the observation point.     

Charged and neutral particle multiplicity in π−p and π−n interactions at 40 GeV/c

Data on the multiplicity of charged particles and π⁰ mesons in π^?p and π^?n interactions are presented and compared to various models. The average π⁰ multiplicity tends to increase with increasing number of charged particles.     

Structural characterization of amorphous and nanostructured bismuth silicate xerogels

Bismuth silicate xBi₂O₃·(1 − x)SiO₂ xerogels, 0 ≤ x ≤ 0.5, doped with gadolinium have been synthesized by sol–gel method. The study aims to evidence by X-ray diffraction (XRD), electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) the structural changes in amorphous Bi₂O₃–SiO₂ xerogels, function of Bi₂O₃ content and heat treatment. As was proved by XRD, nanostructured samples were obtained after 30 min heat treatment at 400 °C of the as-prepared samples with x > 0, in the mainly amorphous matrices nanocrystals of Bi_5.6Si_0.5O_9.4 phase being developed. The dimension of the nanocrystallites are function of the bismuth content, and vary from few nanometers to 25 nm for samples with x = 0.14 and x = 0.5 respectively. The local order around silicon, reflected by 29Si MAS NMR spectra, is less dependent on both composition and thermal history of the samples, showing that an amorphous silicon rich phase is present in all samples. The changes in the local order around Gd³⁺ ions, as reflected by the EPR spectra dependence on composition and especially on the heat treatment, support the assumption that a part of these paramagnetic ions is incorporated in the bismuth rich phase.     

Results from the kaonic hydrogen X-ray measurement at DAFNE and outlook to future experiments

The $\overline{K}N$ system at rest plays a key role for the understanding of strong interaction of hadrons with strangeness involved. The experiment SIDDHARTA used X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. It was the first experiment on kaonic He3 and deuterium ever, kaonic hydrogen was measured with improved precision resulting in $\epsilon_{1s} = -283 \pm 36 \mbox{(stat)} \pm 6 \mbox{(syst)}$ eV and $\Gamma_{1s} = 541 \pm 89 \mbox{(stat)} \pm 22 \mbox{(syst)}$ eV. Additionally a scheme for an improved future experiment on kaonic deuterium is introduced in this contribution.