ANALYTICAL PARTITIONING OF TOTAL CROSS-SECTIONS FOR ELECTRON-SCATTERING ON NOBLE-GASES

Empirical analytical formulae are proposed, aiming at the description of partial cross sections for electron scattering on noble gases. Sele cted measurements of total, excitation and ionization cross sections f or these gases have been fitted by these analytical formulae in the 20 -5000 eV energy range. The elastic cross sections, obtained as the dif ference, compare quite well with the elastic experimental data for all gases but for helium. The difference elastic cross sections were fitt ed by a cross section formula derived from electron scattering on a si ngle or double Yukawa potential in the first Born approximation. Our a nalysis shows a good consistency between partial and total cross secti ons for the four heavier gases. For helium, we suggest the possibility of large errors in the high energy part of total, elastic and excitat ion cross sections. The analytical expressions given in this paper all ow to reproduce the total and partial cross sections within the measur ement errors in a large energy range from a few tens of eV, up to seve ral keV.