212 research outputs found
Isomer triggering via nuclear excitation by electron capture
Triggering of long-lived nuclear isomeric states via coupling to the atomic
shells in the process of nuclear excitation by electron capture (NEEC) is
studied. NEEC occurring in highly-charged ions can excite the isomeric state to
a triggering level that subsequently decays to the ground state. We present
total cross sections for NEEC isomer triggering considering experimentally
confirmed low-lying triggering levels and reaction rates based on realistic
experimental parameters in ion storage rings. A comparison with other isomer
triggering mechanisms shows that, among these, NEEC is the most efficient.Comment: minor changes - updated to the final version; 4 pages, 1 figur
Parity nonconservation in electron recombination of multiply charged ions
We discuss a parity nonconserving asymmetry in the cross section of KLL
dielectronic recombination of polarized electrons on the hydrogen-like ions
with . This effect is strongly enhanced because of the
near-degeneracy of doubly-excited states of opposite parity in He-like
ions. For ions with the asymmetry is of the order of . For
a level crossing takes place, leading to the PNC asymmetry of
, which is times greater than the basic strength of
the weak interaction in atoms.Comment: 11 pages, 5 figures; v.2: sign errors in Eqs.(29-32,38) corrected,
figs.4,5 and related discussion change
Isotope shift in the dielectronic recombination of three-electron ^{A}Nd^{57+}
Isotope shifts in dielectronic recombination spectra were studied for Li-like
^{A}Nd^{57+} ions with A=142 and A=150. From the displacement of resonance
positions energy shifts \delta E^{142,150}(2s-2p_1/2)= 40.2(3)(6) meV
(stat)(sys)) and \delta E^{142,150}(2s-2p_3/2) = 42.3(12)(20) meV of 2s-2p_j
transitions were deduced. An evaluation of these values within a full QED
treatment yields a change in the mean-square charge radius of ^{142,150}\delta
= -1.36(1)(3) fm^2. The approach is conceptually new and combines the
advantage of a simple atomic structure with high sensitivity to nuclear size.Comment: 10 pages, 3 figures, accepted for publication in Physical Review
Letter
Molecular dynamics study of accelerated ion-induced shock waves in biological media
We present a molecular dynamics study of the effects of carbon- and iron-ion induced shock waves in DNA duplexes in liquid water. We use the CHARMM force field implemented within the MBN Explorer simulation package to optimize and equilibrate DNA duplexes in liquid water boxes of different sizes and shapes. The translational and vibrational degrees of freedom of water molecules are excited according to the energy deposited by the ions and the subsequent shock waves in liquid water are simulated. The pressure waves generated are studied and compared with an analytical hydrodynamics model which serves as a benchmark for evaluating the suitability of the simulation boxes. The energy deposition in the DNA backbone bonds is also monitored as an estimation of biological damage, something which is not possible with the analytical model
Consensus on measurement properties and feasibility of performance tests for the exercise and sport sciences: a Delphi study
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