Equilibrium negative-charge fractions in swift proton beams emerging from freshly evaporated metal films

1 May 1988

journal article
research article
Published by American Physical Society (APS) in Physical Review B

Vol. 37 (13) , 7182-7188
https://doi.org/10.1103/physrevb.37.7182

Abstract

The equilibrium fraction of negative ions in a beam of proton or deuteron projectiles (0.2–3.5 MeV/u) which have penetrated thin metallic targets has been measured for the first time. Pure beryllium, copper, and gold were evaporated in situ on the exit surface of carbon foils. In this energy interval the equilibrium fractions depend strongly on the atomic number of the last surface layers. The measured equilibrium fractions are compared with those obtained with carbon foils and noble gases, and it is shown that they can be interpreted considering the solid to be a dense atomic gas. Even some subtle details of the atomic charge-changing cross sections become transparent in the solid equilibrium negative-charge fractions.

Keywords

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