A Si-PIN-stack detector for 14 MeV pulsed neutrons measurement

We have developed a high-sensitivity fast neutron stack detector for use in the current mode by introducing a readout circuit that is capable of operating with a single detector's time response, while its neutron sensitivity, statistics, and n–γ sensitivity ratio are greatly improved compared to the single detector. The neutron stack detector sandwiches large-area Si-PIN semiconductor detectors and 2-mm-thick polyethylene disks used as the n–p converter and sensitivity enhancement medium. A neutron stack detector composed of 9 ∅80 mm×0.8 mm Si-PIN detectors has been built and used to measure a pulsed 14 MeV neutron flux of dense plasma focus devices (DPF). We have acquired its sensitivity to 14 MeV neutrons and 1.25 MeV γ-rays, the n–γ sensitivity ratio, and time response experimentally or theoretically. The study shows that this neutron stack detector can be applied for the diagnosis of DPF and neutron tubes. The results of this investigation also suggest a general model for developing high-sensitivity detectors based on a single radiation detector of another type.