DTL field renormalization
The field in the DTL tanks was calculated assuming a gap length inferred from the Tracewin files. That introduced a factor with respect to the actual field. In this version I recomputed the gap lengths to match the design cavity field. The values are taken from [1].
The BCM that are between tanks were taken out of the tank element in the lattice file.
[1] F. Grespan, "ESS DTL Design and Drift Tube Prototypes," Linac2014