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Title: Model of secondary electron yields from atomic and polyatomic ion impacts on copper and tungsten surfaces based upon stopping-power calculations

Abstract

The calculation of the velocity dependence and magnitude of the kinetic secondary electron yield for atomic and polyatomic ions, denoted by gamma-bar/sub a/ and gamma-bar/sub m/, respectively, is modeled on stopping-power equations and compared to experimental results from the dynode materials copper and tungsten. From the experimental data, the relationship gamma-bar/sub m/=..sigma..gamma-bar/sub a/ is verified, which is necessary to the model calculation of gamma-bar/sub m/. The fundamental assumption of this model is that gamma-bar/sub a/ is proportional (even at low ion velocities) to the electronic stopping power (dE/dx)/sub e/ of that projectile in the target. Example calculations are performed for the velocity dependence of gamma-bar/sub a/ for hydrogen, carbon, and fluorine striking copper, and from these results the predicted gamma-bar/sub m/ curves for polyatomic ions are in close agreement with experiment. Analogous calculations for a tungsten surface are outlined and the final results are compared with experiment. The utility of the model is shown by illustrating that the measurement of gamma-bar can provide, not only a relative measurement of (dE/dx)/sub e/ for different ion atomic numbers on the same target, but can also provide a means of determining the nuclear stopping power (dE/dx)/sub n/ at low ion velocities where rangemore » measurements are difficult to perform. Values of (dE/dx)/sub n/ derived from measurements for fluorine and carbon striking copper are the same as values predicted by Lindhard and Scharff; for a tungsten target the experimental (dE/dx)/sub n/ values are a factor of 2 larger than theoretical. The relationship of the stopping power values derived from gamma-bar measurements with this model are compared to the values derived from ion range measurements.« less

Authors:
;
Publication Date:
Research Org.:
Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973
OSTI Identifier:
7219670
Resource Type:
Journal Article
Journal Name:
J. Appl. Phys.; (United States)
Additional Journal Information:
Journal Volume: 48:9
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CARBON IONS; COLLISIONS; COPPER; ION COLLISIONS; FLUORINE IONS; HYDROGEN IONS; TUNGSTEN; CHARGED-PARTICLE TRANSPORT; ELECTRON EMISSION; ENERGY ABSORPTION; ENERGY DEPENDENCE; ENERGY LOSSES; ENERGY SPECTRA; ION BEAMS; MASS SPECTROSCOPY; MEASURING METHODS; RANGE; SECONDARY EMISSION; SENSITIVITY; STOPPING POWER; SURFACES; VELOCITY; ABSORPTION; ATOMIC IONS; BEAMS; CHARGED PARTICLES; ELEMENTS; EMISSION; IONS; METALS; RADIATION TRANSPORT; REFRACTORY METALS; SPECTRA; SPECTROSCOPY; TRANSITION ELEMENTS; 640301* - Atomic, Molecular & Chemical Physics- Beams & their Reactions; 654001 - Radiation & Shielding Physics- Radiation Physics, Shielding Calculations & Experiments

Citation Formats

Beuhler, R J, and Friedman, L. Model of secondary electron yields from atomic and polyatomic ion impacts on copper and tungsten surfaces based upon stopping-power calculations. United States: N. p., 1977. Web. doi:10.1063/1.324267.
Beuhler, R J, & Friedman, L. Model of secondary electron yields from atomic and polyatomic ion impacts on copper and tungsten surfaces based upon stopping-power calculations. United States. https://doi.org/10.1063/1.324267
Beuhler, R J, and Friedman, L. 1977. "Model of secondary electron yields from atomic and polyatomic ion impacts on copper and tungsten surfaces based upon stopping-power calculations". United States. https://doi.org/10.1063/1.324267.
@article{osti_7219670,
title = {Model of secondary electron yields from atomic and polyatomic ion impacts on copper and tungsten surfaces based upon stopping-power calculations},
author = {Beuhler, R J and Friedman, L},
abstractNote = {The calculation of the velocity dependence and magnitude of the kinetic secondary electron yield for atomic and polyatomic ions, denoted by gamma-bar/sub a/ and gamma-bar/sub m/, respectively, is modeled on stopping-power equations and compared to experimental results from the dynode materials copper and tungsten. From the experimental data, the relationship gamma-bar/sub m/=..sigma..gamma-bar/sub a/ is verified, which is necessary to the model calculation of gamma-bar/sub m/. The fundamental assumption of this model is that gamma-bar/sub a/ is proportional (even at low ion velocities) to the electronic stopping power (dE/dx)/sub e/ of that projectile in the target. Example calculations are performed for the velocity dependence of gamma-bar/sub a/ for hydrogen, carbon, and fluorine striking copper, and from these results the predicted gamma-bar/sub m/ curves for polyatomic ions are in close agreement with experiment. Analogous calculations for a tungsten surface are outlined and the final results are compared with experiment. The utility of the model is shown by illustrating that the measurement of gamma-bar can provide, not only a relative measurement of (dE/dx)/sub e/ for different ion atomic numbers on the same target, but can also provide a means of determining the nuclear stopping power (dE/dx)/sub n/ at low ion velocities where range measurements are difficult to perform. Values of (dE/dx)/sub n/ derived from measurements for fluorine and carbon striking copper are the same as values predicted by Lindhard and Scharff; for a tungsten target the experimental (dE/dx)/sub n/ values are a factor of 2 larger than theoretical. The relationship of the stopping power values derived from gamma-bar measurements with this model are compared to the values derived from ion range measurements.},
doi = {10.1063/1.324267},
url = {https://www.osti.gov/biblio/7219670}, journal = {J. Appl. Phys.; (United States)},
number = ,
volume = 48:9,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 1977},
month = {Thu Sep 01 00:00:00 EDT 1977}
}