Results available on ion composition and electron densities from the rocket measurements carried out during the total solar eclipse of November 12, 1966, at Cassino,Brazil, are subjected to a detailed numerical analysis using the presently known ion chemistry models for the D and E region. Solutions of the continuity equations applicable to the individual ionic species are carried out under equilibrium conditions to determine the ion production rates that can best represent the rocket measurements of the ion composition and electron density carried out to represent the full sun conditions. The ion production rates so derived are then inserted in a set of time dependent solutions of the continuity equations to predict the ion density height distribution during the eclipse corresponding to the available rocket measurements. A comparison between the calculated results and the observations during the totality is then made to determine the residual ion production rates in the lower ionosphere, from which the part that cannot be accounted for by solar radiation is attributed to the precipitation of high-energy particles in the South atlantic geomagnetic anomaly. The results are discussed in the light of the previous estimates of the ion production rates based on the nighttime occurence of blanketing type Es, in the anomaly region.