Neutron activation detector

A neutron activation detector (NAD) comprising:

• an enclosure that is hermetically sealed;
• a plurality of gas ports, including a first gas port through which to inject a gas into the enclosure and a second gas port through which to remove the gas from the enclosure;
• a plurality of electrical leads, including a first electrical lead and a second electrical lead;
• a plurality of substantially flat electrodes in a stacked arrangement and spaced apart by a plurality of insulative spacers, the plurality of electrodes including one or more anodes each coupled to the first electrical lead and one or more cathodes each coupled to the second electrical lead, the plurality of electrodes spaced apart from each other within the enclosure so as to enable the gas to exist between the plurality of electrodes, each of the plurality of electrodes consisting essentially of a material, an isotope of which is created when struck by fast neutrons including those having an energy of approximately 14 MeV wherein during operation, decay of the isotope in response to activation by neutrons having an energy of approximately 14 MeV produces secondary radiation, and wherein the secondary radiation causes electronic discharge within the gas, and the electronic discharge within the gas cause fluctuations in current between the one or more anodes and the one or more cathodes;
• an amplifier having a first input coupled to the first electrical lead and a second input coupled to the second electrical lead, to amplify current pulses between the one or more anodes and the one or more cathodes;
• a discriminator coupled to receive an output of the amplifier, to detect pulses based on the output of the amplifier and to produce an output indicative of detection of each of the pulses;
• a counter coupled to an output of the discriminator, to count the pulses;
• and
• an output device to produce an output indicative of a rate of the pulses, based on an output of the counter.

A method comprising:

• producing, by a material within a fast neutron detector, secondary radiation in response to impacts on the material by fast neutrons;
• causing electronic discharge within the fast neutron detector in response to the secondary radiation, wherein the electronic discharge induces fluctuations in current between a plurality of electrodes;
• detecting individual fluctuations in the current;
• determining a count of the detected fluctuations in the current;
• and
• producing an output indicative of the count.