Scintillator fiber optic long counter for neutron detection

A fiber optic long counter for neutron detection has been developed which uses 30 cm long, 6Li-loaded Tb3+-doped scintillator fiber optics as the detection element. The element is surrounded by polyethylene moderator and configured to allow neutrons to enter from one direction. The penetration depth of thermalization into the moderator is related to incident neutron energy. By determining the absorption position of the thermalized neutron along the fiber, the incident energy of the neutron can be estimated. The absorption position is measured by determining the differential signal collected by photomultiplier tubes at each end of the fiber element. The system is capable of low resolution neutron spectroscopy while retaining the flat response of conventional long counters.