Secondary cosmic-ray e+- from 1 to 100 GeV in the upper atmosphere and interstellar space, and interpretation of a recent e+ flux measurement

Secondary fluxes of cosmic-ray e from the decay of mesons produced by nuclear interactions are calculated for depths under 10 g cm-2 of atmosphere or interstellar space for energies from 1 to 100 GeV. Secondary meson spectra applicable for energies > or =5 GeV are obtained from the recently measured spectra of Carey et al. using Monte Carlo techniques. An analytic model is presented which identifies all essential parameters and enables easy calculation of efluxes for various parameter values. This model is used to interpret the e+ measurement of Buffington, Orth, and Smoot. We find the mean thickness of interstellar and source material to be 4.3 (+1.8,-1.2) g cm-2 for cosmic-ray e+ above 4 GeV. This result is difficult to reconcile with the recently proposed two-containment-volume propagation models of Cowsik and Wilson; Rengarajan, Stephens, and Verma; and Meneguzzi: all of the models predict a result near 1.8 g cm-2 at these energies due to the energy dependence of the measured (Li+Be+B)/(C+O) ratio. Single-containment-volume (galactic) models invoking an energy-dependent leakage lifetime are compatible with the e+ data, but lack a mechanism to explain the energy dependence