\section{Conclusions}
\label{sec:conclusions}

Measurements of the core shower densities of electromagnetic showers have been
made at very high granularity. Their dependence on energy and shower depth have
been presented. Having carefully modelled the sensor response, the simulation 
of showers shows good agreement with the densities measured in data.

The biggest uncertainty in estimating the performance of a future digital 
electromagnetic calorimeter has been the lack of measurements verifying the
simulation at the small granularities required. The measurements presented
here indicate that the simulation does a reasonable job, even at a granularity
around a factor of two finer than being proposed for a digital calorimeter.
Hence, these measurements have put the projections of digital calorimeter
performance on a firmer footing.
