LHCb Preshower(PS) and Scintillating Pad Detector (SPD): commissioning, calibration, and monitoring

The calorimeter system of the LHCb experiment comprises in front to the electromagnetic and hadronic calorimeters a double detector, aimed at tagging the electric charge and the electromagnetic nature of the calorimeter clusters for the first level of trigger. It consists of two planes of scintillating pads separated by a 2.5 radiation lengths lead sheet. The first scintillating plane is the SPD. The second plane and the lead form the Preshower. Their design and construction are recalled. Their performance and calibration strategies are discussed and illustrated by recent results.