Neutrino events from up to 
protons on target will be overlaid in the detector and have to be
disentangled by the pattern recognition software.
The main contributions to the hit density in the tracking system come from events in the emulsion target (2.4 t) and events in the upstream part of the magnet coil (9 t). About 0.9 emulsion events and 3 coil events are expected per double extraction. A detailed simulation of the shower development of these events in the TOSCA setup has been done, taking into account the emulsion targets, silicon trackers and a (light-weight) tracking system. Bursts could be lost for analysis if the hit density becomes too high.
The average number of charged tracks, crossing a 
plane
perpendicular to the beam, was found
to be smaller than 50 per burst.
99% of all bursts can be analysed if the readout as well as the
pattern recognition is able to handle up to 100 hits per plane per
burst.
Various options for tracking systems are currently under study but
all of them can safely handle such hit densities. A study of high
multiplicity events in NOMAD confirms this calculation.
For pattern recognition performance, the rate of double hits per detector element is another important parameter. Its increase due to the overlay of events in a burst is negligible.