Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron Impact Ionization of Atoms   A one parameter expression for the single ionization cross-section of atoms
by electron impact is presented. Using this expression, the agreement obtained
with available experimental data for 45 elements (from ionization threshold up
to 200 eV ionizing electron energy) is shown to be comparable with (or better
than) that achieved using other multi-parameter approaches. We suggest that the
single parameter used here is associated with the effective reduction in the
number of equivalent electrons within a given shell accessible for ionization
by electron impact. We attribute this reduction effect to intra-shell shadowing
of part of the shell electrons by other electrons of the same shell. For atoms
with 2s^2p^i (i = 3,4,5,6) outer shell configurations we suggest also an
intershell shadowing effect. Finally, we discuss the possibility of a
meaningful contribution of inner shell ionization to the single ionization
cross-section due to various post-collision interactions. These interactions
may be responsible for decreasing the formation probability of doubly charged
ions.

2
The categories of this paper are: math
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int