  The CMS Zero Degree Calorimeters, ZDCs, will measure photons and neutrons
emitted with |eta|> 8.6 from Pb+Pb, p+Pb and p+p collisions at sqrt(Snn)=5.5,
8.8 and 14 TeV respectively. The calorimeter consists of an electromagnetic
part segmented in the horizontal direction and an hadronic part segmented into
four units in depth. In addition CMS will have access to data from a segmented
shower maximum detector being built for luminosity measurements. We will
present detailed results from tests beam measurements taken at the CERN SPS.
These data will be used to extrapolate the utility of the ZDCs to measure
photons, and possibly pi0s in p+p and ultra-peripheral heavy-ion collisions.
Data from the hadronic section can be used to estimate the number of
participants in heavy ion-collisions. In addition we will discuss plans to use
the detector to measure the reaction plane, thereby extending the sensitivity
of the central detectors in CMS.
