Gated scintillator-photomultiplier neutron detector for time-of-flight measurements in the presence of a strong x-ray background

A highly sensitive, fast rise-time detector has been developed that is capable of neutron time-of-flight (TOF) measurements in the presence of an intense bremsstrahlung background such as that from a relativistic electron beam (REB) accelerator. This detector, used in conjunction with thermal neutron counters, forms an effective neutron detection system. Such a system was used to measure neutrons from the HYDRA REB accelerator. By using a fast-acting and reproducible gating circuit, the inherent sensitivity of the detector has been retained while suppressing all deleterious effects caused by the intense bremsstrahlung burst. At no time during the measurements were any spurious afterpulses observed in the TOF detectors. The timing resolution obtained was sufficient to distinguish between neutrons produced by thermal and fast deuterium ions