Observation of radiation induced latchup in the readout electronics of NA50 multiplicity detector

During the data taking of the NA50 experiment, the CMOS digital pipeline chips (CDP) used for the readout of the multiplicity detector were exposed to high levels of radiation resulting in an ionizing radiation dose of more than 200 krad and displacement damage equivalent to 1 MeV neutron fluence of more than 5×1011 eq. neutrons cm−2. Some of these chips showed anomalies of behaviour which we attribute to radiation induced latchup phenomena. Here we present the analysis of the data taken during the 1996, 1998 and 1999 ion runs together with the results of measurements performed in the laboratory.