Measurement of detection efficiency using Pb-scintillating fiber sampling KLOE calorimeter for neutrons between 22 and 174 MeV

We exposed a prototype of the high-sampling lead-scintillating fiber KLOE calorimeter to neutron beam of 21, 46, and 174 MeV, provided by the The Svedberg Laboratory (TSL), Uppsala, to study its neutron detection efficiency. This has been found larger than what what expected considering the scintillator thickness of the KLOE prototype only.We checked the reliability of our method, measuring also the neutron detection efficiency of a 5 cm thick NE110 scintillator. Our results prove the existence of a contribution from passive material to neutron detection efficiency, in a high-sampling calorimeter configuration. The origin of the efficiency enhancement has been studied using the FLUKA Monte Carlo code. We present the TSL beam test results and the reasons for such enhancement, which allows to develop compact, inexpensive, fast, and highly efficient neutron counters.