AN ANALYTIC FORMULA FOR THE EXTRAPOLATED RANGE OF ELECTRONS IN CONDENSED MATERIALS

A single analytic formula for the extrapolated range r(ex) of electron s in condensed materials of atomic numbers from 4 to 92 is given. It h as the form of the product of the continuous-slowing-down approximatio n (CSDA) range r(0) and a factor f(d) related to multiple scattering d etours. The factor f(d) is expressed as a function of incident electro n energy T-0 and atomic number Z of medium. Values of adjustable param eters in f(d) have been optimized for data on the ratio r(ex)/r(0), in which the Monte Carlo evaluated values of Tabata et al. [Nucl. Instr. Meth. B 95 (1995) 289](from 0.1 to 100 MeV) and experimental data col lected from literature (from 1 keV to 0.1 MeV) for r(ex) have been use d together with NIST-database values of r(0). For r(0) in the extrapol ated-range formula, accurate database values or an approximate analyti c expression developed as a function of T-0, Z, atomic weight A and me an excitation energy I of medium can be used. The maximum deviation of the resultant formula from the Monte Carlo data is about 2% for eithe r option of r(0). The determination of the expression for f(d) at ener gies below 0.1 MeV is tentative. By using an effective atomic number a nd atomic weight, the formula can also be applied to light compounds a nd mixtures.