Study of the Sensitivity of Plastic Scintillator to Fast Neutrons

The Mu2e experiment at Fermilab plans to use a two-out-of-three coincident requirement in a plastic scintillator based detector to veto cosmic ray events. This veto system must operate efficiently in a high-radiation environment. In this investigation, three plastic scintillator bars containing wavelength-shifting fibers represent the veto system. These bars were placed in series in front of a deuterium-deuterium neutron generator, which produced fast neutrons of approximately 2.8MeV. Multi-anode photomultiplier tubes read out the light from the fibers. The collected data was analyzed to determine the rate of interaction, approximate amount of energy deposited, and numerous other aspects of the neutrons' interactions. The rate of coincidental and correlated hits in multiple scintillator bars was the primary investigation, in order to further understand the sensitivity of the plastic scintillators to fast neutrons.