PC2x/y
A second set of muon beam chambers, 
PC2x and PC2y will
be placed in the hydrogen gas, about 70 mm in front of the TPC volume. Anode
and cathode frames of PC2 will be constructed as for the TPC with
special low out-gasing quarz-glass material bakeable to 150 
C.
The chamber parameters are given in table
2. In combination with the external wire chambers PC1x/y,
these chambers permit precise muon entrance tracking towards the
TPC and strongly reduce possible ambiguities in the muon track assignment.
The tracking in the TPC volume to the muon stop location is done using
the TPC signals.