INVESTIGADORES
RIVAROLA Roberto Daniel
artículos
Título:
Using channeling properties for studying the impact parameter dependence of electron capture by 20-MeV/u uranium ions in a silicon crystal
Autor/es:
E. TESTA, P. N. ABUFAGER, F. BOSCH, A. BRÄUNING-DEMIAN, H. BRÄUNING, M. CHEVALLIER, C. COHEN, D. DAUVERGNE, A. GUMBERIDZE, A. L´HOIR, R. KIRSCH, C. KOZHUHAROV, D. LIESEN, P. H. MOKLER, J. C. POIZAT, C. RAY, R. D. RIVAROLA Y OTROS
Revista:
PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS
Editorial:
Americal Physical Society
Referencias:
Lugar: New York; Año: 2007 vol. 76 p. 629011 - 6290111
ISSN:
1050-2947
Resumen:
The impact-parameter dependence of electron capture by 20-MeV/u U91+ ions has been studied by means of
channeling in a 11-m-thick silicon crystal. Such ions are far from their equilibrium charge state in matter, and
channeling offers a unique opportunity to study electron capture in conditions going from the extreme case of
a single capture event for the best channeled ions to the case of multiple charge exchange events leading to
charge state equilibrium for unchanneled ions. For each incident ion, the charge states at emergence, energy
loss, electron emission-, and x-ray yields are measured. The correlations between these quantities are studied.
The data are reproduced by simulations based on the ion flux distribution. We show that the mechanical
electron capture dominates at impact parameters smaller than 0.5 Å, whereas radiative electron capture is the
only process occurring beyond. Specific features associated with highly charged heavy ions at intermediate
velocities are discussed, in particular the ionization following capture into highly excited states and the local
electron density enhancement due to the electron gas polarization. The measured impact-parameter dependence
of capture probabilities is compared to continuum-distorted-wave eikonal-initial-state calculations, extrapolated
to n5 final states.91+ ions has been studied by means of
channeling in a 11-m-thick silicon crystal. Such ions are far from their equilibrium charge state in matter, and
channeling offers a unique opportunity to study electron capture in conditions going from the extreme case of
a single capture event for the best channeled ions to the case of multiple charge exchange events leading to
charge state equilibrium for unchanneled ions. For each incident ion, the charge states at emergence, energy
loss, electron emission-, and x-ray yields are measured. The correlations between these quantities are studied.
The data are reproduced by simulations based on the ion flux distribution. We show that the mechanical
electron capture dominates at impact parameters smaller than 0.5 Å, whereas radiative electron capture is the
only process occurring beyond. Specific features associated with highly charged heavy ions at intermediate
velocities are discussed, in particular the ionization following capture into highly excited states and the local
electron density enhancement due to the electron gas polarization. The measured impact-parameter dependence
of capture probabilities is compared to continuum-distorted-wave eikonal-initial-state calculations, extrapolated
to n5 final states.m-thick silicon crystal. Such ions are far from their equilibrium charge state in matter, and
channeling offers a unique opportunity to study electron capture in conditions going from the extreme case of
a single capture event for the best channeled ions to the case of multiple charge exchange events leading to
charge state equilibrium for unchanneled ions. For each incident ion, the charge states at emergence, energy
loss, electron emission-, and x-ray yields are measured. The correlations between these quantities are studied.
The data are reproduced by simulations based on the ion flux distribution. We show that the mechanical
electron capture dominates at impact parameters smaller than 0.5 Å, whereas radiative electron capture is the
only process occurring beyond. Specific features associated with highly charged heavy ions at intermediate
velocities are discussed, in particular the ionization following capture into highly excited states and the local
electron density enhancement due to the electron gas polarization. The measured impact-parameter dependence
of capture probabilities is compared to continuum-distorted-wave eikonal-initial-state calculations, extrapolated
to n5 final states.for the best channeled ions to the case of multiple charge exchange events leading to
charge state equilibrium for unchanneled ions. For each incident ion, the charge states at emergence, energy
loss, electron emission-, and x-ray yields are measured. The correlations between these quantities are studied.
The data are reproduced by simulations based on the ion flux distribution. We show that the mechanical
electron capture dominates at impact parameters smaller than 0.5 Å, whereas radiative electron capture is the
only process occurring beyond. Specific features associated with highly charged heavy ions at intermediate
velocities are discussed, in particular the ionization following capture into highly excited states and the local
electron density enhancement due to the electron gas polarization. The measured impact-parameter dependence
of capture probabilities is compared to continuum-distorted-wave eikonal-initial-state calculations, extrapolated
to n5 final states.for unchanneled ions. For each incident ion, the charge states at emergence, energy
loss, electron emission-, and x-ray yields are measured. The correlations between these quantities are studied.
The data are reproduced by simulations based on the ion flux distribution. We show that the mechanical
electron capture dominates at impact parameters smaller than 0.5 Å, whereas radiative electron capture is the
only process occurring beyond. Specific features associated with highly charged heavy ions at intermediate
velocities are discussed, in particular the ionization following capture into highly excited states and the local
electron density enhancement due to the electron gas polarization. The measured impact-parameter dependence
of capture probabilities is compared to continuum-distorted-wave eikonal-initial-state calculations, extrapolated
to n5 final states.n5 final states.