EGS is a general purpose Monte Carlo electron-photon transport system developed at Stanford. [1] The upgrade from EGS3 to EGS4 permitted lower energy tracking limits for both photons and electrons. Simulations for Soudan 2 were done entirely with the earlier EGS3 code, limiting tracking of electrons and photons to 1 MeV. Previous studies were done to quantify the effect of lowering tracking thresholds, which came out with a 10-30% increase in number of hits.
The aim of this study is to use EGS4 to examine electron showers in a simple geometry, called Pseudo 2, with similar gross properties to the more complicated Soudan 2 geometry. The consequences of lower tracking thresholds are examined in an environment where we can view the physical behavior of showers with an uncomplicated geometry.
The Pseudo 2 detector geometry is not intended to reproduce the exact characteristics of Soudan 2. Rather, our intent is to produce showers with similar characteristics(number of hits, size, shape, ...) to those in Soudan 2. By lowering the tracking cutoffs in Pseudo 2 from 1 MeV to 10 keV we can observe the change in these characteristics. It is then reasonable to assume that the Soudan 2 detector simulation would produce similar changes for a lowered tracking cutoff.