A study of the transverse fluctuations of hadronic showers in the NOMAD electromagnetic calorimeter

The transverse shower shape of the energy deposition of hadrons in the NOMAD lead glass calorimeter has been studied by exposing a prototype of this calorimeter to pion test beams of various momenta and incident angles. Large event-to-event fluctuations in the shower shape and significant energy depositions far from the incident hadron were observed making it difficult to associate all the deposited energy to the incident hadron that caused it. Since in the NOMAD detector the charged hadrons are measured by the drift chambers, such an association is necessary to be able to subtract from the calorimeter all the energy caused by the observed charged hadrons in order to avoid double counting. ility functions based on the measurements have been developed to describe fluctuations of the lateral shower shape. An algorithm, based on these functions for identifying the energy deposition associated to a charged hadron is described.