Satellite population measurements in PB-PB collisions with the ALICE ZDC

The ALICE experiment is equipped with a set of Zero Degree Calorimeters: two for spectator neutrons (ZN) and two for spectator protons (ZP), located on both sides of the interaction point. Due to their location and to their timing performance, the neutron calorimeters are an ideal device for measuring the longitudinal structure of colliding beams. In this contribution, we present a measurement of the satellite charge of the LHC Pb beams in a fill (1533) where luminosity calibration experiments (vdM scans) were performed. The collisions of satellites located in the various RF buckets around the nominal one are separated via the signal arrival time in the two ZNs. The ZDC results are compared to the results obtained by the LHC Longitudinal Density Monitors (LDM).