  The combined zero degree calorimeter (ZDC) is a combination of sampling
quartz/tungsten electromagnetic and hadronic calorimeters. Two identical
combined calorimeters are located in the LHC tunnel at CERN at the straight
section ~140 m on each side of the CMS interaction vertex and between the two
beam pipes. They will detect very forward photons and neutrons. ZDC information
can be used for a variety of physics measurements as well as improving the
collision centrality determination in heavy-ion collisions. Results are
presented for ZDC performance studies with the CERN SPS H2 test beam.

Nuclear Experiment;Instrumentation and Detectors