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Comparison of experimental and theoretical electron ejection cross sections in helium by proton impact from 5 to 100 keV. [Charge transfer]

Journal Article · · Phys. Rev., A; (United States)
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Absolute values of doubly differential cross sections are obtained for electron production in helium by 5- to 100-keV proton impact. The measured values along with earlier data at higher energies are compared with theoretical plane-wave Born-approximation functions obtained from a Hartree-Fock potential. Not only is good agreement obtained at high impact energies (above 300 keV), but fairly good agreement is found at low energies (below about 20 keV). For electrons ejected in the backward hemisphere, unexpectedly poor agreement is noted at intermediate energies where the measured cross sections dip to 50% of the calculated values in some cases. Singly differential cross sections integrated over all angles agree quite well with the theoretical calculations over all ranges of parameters studied. Singly differential cross sections integrated over all electron energies tend to be more isotropic in angle as the proton energy is decreased from 100 to 5 keV. Total cross sections for electron production are also obtained which compare reasonably well with those of Solov'ev et al. but which are higher than those of de Heer et al. It is shown that the contribution to the cross section by the mechanism of charge transfer to the continuum decreases as the impact energy decreases, contrary to the prediction of Salin's treatment. (AIP)
Research Organization:
Behlen Laboratory of Physics, University of Nebraska, Lincoln, Nebraska 68588
OSTI ID:
7279149
Journal Information:
Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 14:1; ISSN PLRAA
Country of Publication:
United States
Language:
English

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Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
BEAMS
CATIONS
CHARGED PARTICLES
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
DIFFERENTIAL CROSS SECTIONS
ELEMENTS
ENERGY RANGE
FLUIDS
HELIUM
HYDROGEN IONS
HYDROGEN IONS 1 PLUS
ION COLLISIONS
ION-ATOM COLLISIONS
IONIZATION
IONS
KEV RANGE
KEV RANGE 10-100
NONMETALS
NUCLEON BEAMS
PARTICLE BEAMS
PROTON BEAMS
RARE GASES