For the studies presented above, we have been considering 36
bunch (396 ns) running.
At some point during Run II, we expect to switch to
132 ns running (see Sec 3.3.3).
The FPD will be able to run effectively
in this mode. We will be using standard DØ data structures which
were designed to handle 132 ns.
The time for a Level 1 decision will not be changed.
The multiple interaction profile should be quite similar to the 396 ns
mode, since at a given luminosity there are three times fewer interactions
at 132 ns, but this improvement is offset by the increased luminosity.
As shown in Sec 3.3.3, the overall acceptance
is comparable (within a factor of two). The early time rejection of
halo might not be as effective as in the 36 bunch scenario, but the
amount of halo per bunch will be reduced, and halo
can easily be expunged by a slight increase in the 
cut.