IAFE   05512
INSTITUTO DE ASTRONOMIA Y FISICA DEL ESPACIO
Unidad Ejecutora - UE
artículos
Título:
Calculation of energy-loss straggling of C, Al, Si, and Cu for fast H, He, and Li ions
Autor/es:
C. C. MONTANARI; J. E. MIRAGLIA; S. HEREDIA-AVALOS; R. GARCÍA-MOLINA; ISABEL ABRIL
Revista:
PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS
Editorial:
APS
Referencias:
Año: 2007 vol. 75 p. 229030 - 22903011
ISSN:
1050-2947
Resumen:
We present theoretical calculations of the energy-loss straggling of C, Al, Si, and Cu targets for H, He, and
Li ions in the range of intermediate to high energies 0.0110 MeV/u. These calculations have been done by
employing the dielectric formalism and by considering the different equilibrium charge states of the swift ion
inside the solid as a function of its energy. Two different models are used: the Mermin energy-loss functions
combined with generalized oscillator strengths MELF-GOS and the shellwise application of the local plasma
approximation SLPA. The MELF-GOS describes the target outer-electron excitations through a fitting to
experimental data in the optical limit, employing a linear combination of Mermin-type energy-loss functions;
the excitations of the inner-shell electrons are taken into account by means of generalized oscillator strengths.
The SLPA employs a free-electron-gas model for the target valence electrons and the local density approximation
for each shell of target electrons separately by using Hartree-Fock atomic wave functions. The results
of the energy-loss straggling obtained by the two independent models show good agreement with the available
experimental data. The calculated energy-loss straggling tends at high energies to the Bohr value and takes
values below it at intermediate energies. The Bethe-Livingston shoulder or overshooting at intermediate
energies does not appear in the present calculations.0.0110 MeV/u. These calculations have been done by
employing the dielectric formalism and by considering the different equilibrium charge states of the swift ion
inside the solid as a function of its energy. Two different models are used: the Mermin energy-loss functions
combined with generalized oscillator strengths MELF-GOS and the shellwise application of the local plasma
approximation SLPA. The MELF-GOS describes the target outer-electron excitations through a fitting to
experimental data in the optical limit, employing a linear combination of Mermin-type energy-loss functions;
the excitations of the inner-shell electrons are taken into account by means of generalized oscillator strengths.
The SLPA employs a free-electron-gas model for the target valence electrons and the local density approximation
for each shell of target electrons separately by using Hartree-Fock atomic wave functions. The results
of the energy-loss straggling obtained by the two independent models show good agreement with the available
experimental data. The calculated energy-loss straggling tends at high energies to the Bohr value and takes
values below it at intermediate energies. The Bethe-Livingston shoulder or overshooting at intermediate
energies does not appear in the present calculations.MELF-GOS and the shellwise application of the local plasma
approximation SLPA. The MELF-GOS describes the target outer-electron excitations through a fitting to
experimental data in the optical limit, employing a linear combination of Mermin-type energy-loss functions;
the excitations of the inner-shell electrons are taken into account by means of generalized oscillator strengths.
The SLPA employs a free-electron-gas model for the target valence electrons and the local density approximation
for each shell of target electrons separately by using Hartree-Fock atomic wave functions. The results
of the energy-loss straggling obtained by the two independent models show good agreement with the available
experimental data. The calculated energy-loss straggling tends at high energies to the Bohr value and takes
values below it at intermediate energies. The Bethe-Livingston shoulder or overshooting at intermediate
energies does not appear in the present calculations.SLPA. The MELF-GOS describes the target outer-electron excitations through a fitting to
experimental data in the optical limit, employing a linear combination of Mermin-type energy-loss functions;
the excitations of the inner-shell electrons are taken into account by means of generalized oscillator strengths.
The SLPA employs a free-electron-gas model for the target valence electrons and the local density approximation
for each shell of target electrons separately by using Hartree-Fock atomic wave functions. The results
of the energy-loss straggling obtained by the two independent models show good agreement with the available
experimental data. The calculated energy-loss straggling tends at high energies to the Bohr value and takes
values below it at intermediate energies. The Bethe-Livingston shoulder or overshooting at intermediate
energies does not appear in the present calculations.or overshooting at intermediate
energies does not appear in the present calculations.