The I-meter, a distributor unit for the OPERA RPC HV system

The OPERA RPC HV system has been implemented using custom current measurement/distribution systems developed by the LNF Electronics Workshop.Each system features eight inputs and 24 outputs (1–3 modularity). The current on each channel is measured with 100 pA sensitivity and 3%3% accuracy in the 1 nA–25μA range.In the paper we describe the measurement circuit as well as the results of the tests we have carried out to qualify the system.