Time-of-flight measurement for energy-dependent intrinsic neutron detection efficiency

Shortage in the current ³He supply has prompted a search for potential alternatives to the neutron detectors currently used in many nuclear nonproliferation and safeguards applications. An alternative detector must be efficient in detecting fission neutrons, and in rejecting or discriminating against gamma-ray radiation. For characterization of numerous detector types, it is helpful to have a technique for evaluating these two characteristics which is relatively fast and easy to perform. Here, a bench-top time-of-flight technique is presented which is based on a coincidence measurement with two `independent´ liquid scintillators (no direct source tagging is employed). The neutron source used is ²⁵²Cf. The technique can be used to measure energy-dependent intrinsic neutron detection efficiency for incident neutron energies of 0.5-5 MeV, as well as gamma-neutron discrimination efficiency. Measurement results are presented for three 2×2-inch cylindrical liquid scintillation detectors: EJ309, EJ315, and an additional EJ315 with naphthalene added.