Results 1 - 10 of 20008
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[en] Fermionic Molecular Dynamics (FMD) is a many-body approach that uses Gaussian wave-packets localized in phase-space as single-particle states. The wave-packet basis is very flexible and includes harmonic oscillator and localized cluster states. The width of the wave-packets is a variational parameter which helps to describe extended nuclear halos. The intrinsic many-body basis states are projected on parity, angular momentum and linear momentum. The Hamiltonian is finally diagonalized in a set of many-body states. In this talk I present calculations for the Neon isotopes 17-22Ne. The calculated charge radii describe very well recent experimental results from the COLLAPS collaboration. The calculations show that 17Ne (18Ne) can be considered as 15O (16O) plus two protons in either s2 or d2 configurations. In 17Ne we find an extended s2-component with about 40% contribution explaining the very large charge radius. In 18Ne the s2-component is only 15% corresponding to a smaller radius. In 19,20Ne again very large charge radii are observed which are due to the admixture of 3He and 4He cluster configurations into the ground states.
[en] Complete text of publication follows. The ATOMKI ECRIS Laboratory celebrated the 20th anniversary of the project starting-up in 1992. Ion beams themselves are being delivered since 1996. The facility is used for low energy atomic physics research, plasma investigations and for applications. There is continuous necessity to increase the quality of the produced ion beams and plasmas in order to satisfy the diversified requirements. For example high intensity, highly charged neon ion beams with very low kinetic energy (several hundred eV/nucleon) are necessary to measure some aspect of the nowadays very intensively studied physics of nano-capillaries (guiding of highly charged ions through nanocapillaries). We were motivated to measure the intensity of a fully-stripped neon ion beam (at first time in Hungary) which is impossible with natural neon due to the (always) present molecular hydrogen ions (same charge - to- mass ratio). In order to overcome this difficulty it was decided to use isotopically enriched (99.95 %) 22Ne gas. The ECR ion source operated in standard mode. The plasma was tuned for the required charge state by changing parameters like the microwave power (klystron amplified), the biased electrode (voltage and position) and the neon-gas flow. The extraction voltage was 10 kV and the analysed beam was measured by a Faraday cup. The size of the beam was defined by (10 mm x 30 mm) slits. At first the charge state distribution (CSD) of the extracted ion beam was recorded using natural neon gas when the source was tuned for 20Ne8+ in order to get a benchmark for comparison. The natural neon gas abundances of 20Ne and 22Ne are 90.48 % and 9.25 %, respectively. By measuring the CSD of both isotopes in one setting we were able to observe (likely for the first time) the so-called isotopic anomaly, well known for nitrogen and oxygen, see figure 1. The CSD for the heavier isotope is shifted to higher charges at the cost of higher losses (output) for low charge states of the lighter isotope. Then the working gas was changed to the isotopically enriched 22Ne gas; the source was optimized to maximise the 22Ne8+ ion current. The analysed beam current (22Ne8+) increased by a factor of 1.3 compared to the 20Ne8+ current. The main goal was to produce fully-stripped neon beam, which was easily reached when the source was optimised for the 20Ne9+ production. Result: 20 electrical nA (i.e. 2 particle nA) of 22Ne10+ current appeared in the spectra. This value was then further increased up to 43 nA by tuning the plasma directly to 22Ne10+ and by mixing helium gas into the neon.
[en] This paper applies the multiple ellipsoid model to the 16Ne (20Ne, 28Ne, 34Ne)-Na2 collision systems, and calculates integral cross sections for rotational excitation at the incident energy of 190 meV. It can be seen that the accuracy of the integral cross sections can be improved by increasing the number of equipotential ellipsoid surfaces. Moreover, by analysing the differences of these integral cross sections, it obtains the change rules of the integral cross sections with the increase of rotational angular quantum number J', and with the change of the mass of isotope substitution neon atom. Finally, the contribution of different regions of the potential to inelastic cross sections for 20Ne-Na2 collision system is investigated at relative incident energy of 190 meV. (general)
[en] High-precision mass and charge radius measurements on 17-22Ne, including the proton-halo candidate 17Ne, have been performed with Penning trap mass spectrometry and collinear laser spectroscopy. The 17Ne mass uncertainty is improved by factor 50, and the charge radii of 17-19Ne are determined for the first time. The fermionic molecular dynamics model explains the pronounced changes in the ground-state structure. It attributes the large charge radius of 17Ne to an extended proton configuration with an s2 component of about 40%. In 18Ne the smaller radius is due to a significantly smaller s2 component. The radii increase again for 19-22Ne due to cluster admixtures