Copper activation detector for high energy-pulsed neutron measurements

A first of its kind threshold activation proportional counter is developed using copper for the measurement of pulsed 14 MeV neutrons. The detector is of 26 mm outer diameter and 200 mm overall length. Tests at D-T facility showed that the detector is capable of measuring high-energy neutrons. The high-energy neutron sensitivity of the detector is estimated as 7.6 × 10^-5 counts/neutrons cm^-2/s, and pulsed neutron sensitivity is estimated as 3.3 × 10⁷ neutrons pulse^-1 count^-1. The low-energy response of the detector can be discriminated by curve fitting method to the decay counts. An identical dimension silver-lined proportional counter with 0.5 counts/neutrons cm^-2/s thermal neutron sensitivity is developed for comparison with the copper detector. The silver activation detectors are conventionally used for neutron yield measurement of D-T-pulsed source. Experiments confirmed that compared to silver detector which is sensitive to low-energy neutrons, the copper detector is able to measure high-energy neutrons directly by threshold reaction. (author)