In order to see if the inscrease of the dE/dx fluctuations, observed by Yuri, at large rapidities in for some TPC sectors, could be explained by the misplaced or dislocated fat fiels/anode wire.

The GARFIELD simulation was performed for the inner section of the TPC with normal and 1mm offset fat field wire.

Geometry with offset wire belot:

The result is shown below.

The plot shows the grid leak between the inner sector and the inner field cage. The leak when the wire is moved inward (closer to the inner field cage) stars by 1 mm closer to the IFC, as expected, but still extands to the same depth as for the wire that is not moved. It gives about 20% more grid leak into the TPC volume. If this is the case and some wires are offset from the nominal position, the effect could acount for part of the observed fluctuations in dE/dx resolution but not all of it.