Binary-encounter stopping cross sections. III. Straggling and screening
A previously developed binary-encounter model describing the slowing down of energetic heavy charged particles over a broad range of incident-particle energies is employed to calculate energy straggling as a function of target Z for incident helium and hydrogen. This model seriously overestimates the measured stopping cross sections at high incident-particle energy for helium on heavy target atoms, but appears to yield more reasonable results for energy straggling. The large results in the stopping calculation are attributed to the neglect of the distortion of the electron charge cloud during the collision. A screened interaction, based on screening in a free-electron gas, is employed to estimate the size of the effect on both the stopping and straggling results for 10-MeV incident He/sup + +/ on target atoms 1 < or = Z/sub 2/ < or = 36, and for equilibrium-charge-state beams of hydrogen at energies 1 keV to 1 MeV on a number of targets. It was found that the neglect of distortion may result in errors equivalent to or greater than those due to the neglect of the long-range dipole interactions when estimating S, particularly at higher energies. For the straggling calculation both of these effects result in considerably smaller correction to the binary-encounter method.
- Research Organization:
- Engineering Physics Program, University of Virginia, Charlottesville, Virginia 22901
- OSTI ID:
- 7209892
- Journal Information:
- Phys. Rev., A; (United States), Vol. 16:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HELIUM IONS
ION-ATOM COLLISIONS
HYDROGEN IONS
BINARY ENCOUNTER METHOD
CROSS SECTIONS
ION BEAMS
MEV RANGE 01-10
STOPPING POWER
ATOM COLLISIONS
BEAMS
CHARGED PARTICLES
COLLISIONS
ENERGY RANGE
ION COLLISIONS
IONS
MEV RANGE
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena