Quartz fiber ZDCs at CERN SPS and LHC

A quartz fiber zero degree calorimeter (ZDC) is operating in the NA50 experiment at CERN SPS since its first lead ion run in November 1994. This unusually small detector (5×5×65 cm3) is a spaghetti calorimeter with quartz optical fibers embedded in tantalum slabs. The ZDC performances are presented with special emphasis on the 1996 lead ion run results. The plans for ALICE ZDCs at LHC are also presented.