C. Hombourger, AN EMPIRICAL EXPRESSION FOR K-SHELL IONIZATION CROSS-SECTION BY ELECTRON-IMPACT, Journal of physics. B, Atomic molecular and optical physics, 31(16), 1998, pp. 3693-3702
An empirical expression is proposed to describe the K-shell ionization
cross sections by electron impact over a wide range of atomic numbers
(i.e. 6 less than or equal to Z less than or equal to 79) and overvol
tages U (i.e. 1 less than or equal to U less than or equal to 10(4)) d
efined as being the ratio between the incident electron energy and the
ionization energy of the electrons in the K shell. The study is based
on the analysis of existing experimental: databases for atoms. Agreem
ent is obtained with an accuracy of 10% over the entire atomic number
and overvoltage ranges including the near-threshold region. Results ar
e compared with those obtained with other analytical expressions.