A mechanism to have different PID systems in ITS has been introduced. Conditional...

A mechanism to have different PID systems in ITS has been introduced. Conditional probabilities are evaluated via the abstract interface AliITSpidESD. Two different implementations are presently available. The default one (origin: Y. Belikov) has been used so far and it is now implemented in AliITSpidESD1. The second implementation, based on fits with a convolution of Landau+gaussian functions of the specific ionization in each ITS layer as a function of the momentum, is implemented in AliITSpidESD2. To select it, the user must use AliReconstruction::SetOption("ITS","LandauFitPID")