Lead Matching and Consequences on the EM Module 0 Constant Term

We present in this note the mathematical algorithms that have been used to sort and pair the lead plates during the construction of the Module 0 of the Liquid Argon barrel calorimeter. This pairing is done to reduce as much as possible the contribution to the constant term that arises from lead thickness inhomogeneities. It is planned to use similar algorithms also during the construction of the complete detector, for the same reason. In addition to the pairing itself, we describe the physical considerations that have led us to the choice of a particular class of algorithms. At the end, we show how the chosen algorithm performs using the thickness data available for the lead plates that have been used for the construction of module 0