This novel detector for characterizing IFE implosions is an alternative to the current RTNADs to measure neutron fluxes > 3x10¹¹ neutrons/cm² at high shot rates. The detector consists of a stack of small square metal wafers separated by thin insulating spacers. Every other wafer is held at high voltage while the remaining wafers are grounded. The stack acts as an ionization chamber and will detect the passage of charged particles in a manner similar to a Geiger counter. To detect high energy neutrons, the stacks are made of metals containing isotopes that become activated when struck by high energy neutrons. The activated isotopes decay into electrons or gamma rays, some of which interact in the wafers and also produce electrons that enter the gap between wafers producing a detectible avalanche pulse at the signal terminal. The detector produces an electrical pulse proportional to the neutron yield of each target implosion thus allowing the energy output of the IFE facility to be continuously monitored.