Energy straggling of light-ion beams
The dielectric function method is applied to investigate the energy straggling of protons and helium ions using the atomic and the solid local-electron-density models. A partially stripped ion is treated as well as point charges. At low energies, the conventional stragglings of a proton (..cap omega..+/sup 2/) and of helium ions (..cap omega..+/sup 2/,..cap omega..2+ /sup 2/) due to the fluctuation in electronic excitations are proportional to the kinetic energies of the ions even when the local-electron-density models are adopted, and at high energies they approach the values predicted by Bohr. Here we do not consider the bunching term since we assume the probability of exciting an electron is small. The straggling ratio ..cap omega..+/sup 2//..cap omega..+/sup 2/ shows a remarkable feature that it is nearly constant up to approx.50 keV/amu, and increases gradually beyond this energy for solid targets. The estimation of the collisional straggling of helium-ion beams is performed using the charge-state fractions, resulting in displaying Z/sub 2/ (target atomic number) oscillations similar to those of ..cap omega..+/sup 2/ and ..cap omega..2+/sup 2/. The straggling caused by charge-state fluctuations, which enhance the Z/sub 2/ oscillations of the total straggling of helium-ion beams more sharply at the energies considered, is also estimated.
- Research Organization:
- Department of Applied Physics, Okayama University of Science, Ridai-cho 1-1, Okayama 700, Japan
- OSTI ID:
- 6139340
- Journal Information:
- Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 33:3; ISSN PLRAA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Shielding Calculations & Experiments
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYONS
CAPTURE
CHARGED PARTICLES
CHARGED-PARTICLE TRANSPORT
DISTRIBUTION
ELECTRON CAPTURE
ELEMENTARY PARTICLES
ENERGY LOSSES
ENERGY SPECTRA
FERMIONS
HADRONS
HELIUM IONS
ION IMPLANTATION
IONIZATION
IONS
LOSSES
NUCLEONS
PROTONS
RADIATION TRANSPORT
RESOLUTION
SOLIDS
SPATIAL DISTRIBUTION
SPATIAL RESOLUTION
SPECTRA
TRANSPORT THEORY