moderator material such that the neutron and gamma capabilities can be integrated into a single unit further cd cadmium or another thermal neutron absorber could be placed around the moderator to reduce neutron background and to enable the differential dieaway technique dda dda allows for the detection of prompt neutrons resulting from the active interrogation the thermal neutron absorber prevents thermal neutrons from impinging on the detector to produce a signal with a time structure similar to the one produced from fission the neutron detector e g he 3 tubes may be partially or completely disposed within the plastic scintillator also the neutron detector e g he 3 tubes may be placed in front of the plastic scintillator behind the plastic scintillator and or between the plastic scintillator further by embedding the he 3 tubes directly inside the plastic scintillator of the gamma detector such an arrangement will allow the entire neutron moderator e g a plastic scintillator to be sensitive to gamma rays thus increasing detection efficiency of the gamma rays and reducing space additionally based on design preferences those skilled in the art may choose to include an additional moderator material to assist with neutron detection for example the tube can.