Measurement and simulation of the neutron detection efficiency with a Pb-scintillating fiber calorimeter

We have measured the overall detection efficiency of a small prototype of the KLOE Pb-scintillating fiber calorimeter to neutrons with kinetic energy range [5,175] MeV. The measurement has been done in a dedicated test beam in the neutron beam facility ot The Svedberg Laboratory, TSL, Uppsals. The measurement of the neutron detection efficiency of a NE110 scintillator provided a reference calibration. At the lowest trigger threshold, the overall calorimeter efficiency ranges from 28% to 33%. This value largely exceeds the estimated ~8% expected if the response were proportional only to the scintillator equivalent thickness. A detailed simulation ot the calorimeter and the TSL beam line has been performed with the FLUKA Monte Carlo code. The simulated response of the detector to neutrons is presented together with first data to Monte Carlo comparison. The results show an overall neutron efficiency of about 35%. The reason for such an efficiency enhancement, in comparison with the typical scintillator-based counter5s, are explained, opening the road to a novel neutron detector.