Abstract: In a neutron induced gamma ray well logging instrument, a neutron generator is pulsed at a predetermined clock frequency. Each neutron burst produces inelastically scattered gamma rays and thermal neutron capture gamma rays. Inelastically scattered gamma rays are detected during a time interval coinciding with the neutron source pulsing for a first plurality of neutron bursts. Capture gamma rays are detected during a time interval subsequent to the cessation of the neutron burst for a second plurality of neutron bursts. A detection pulse is transmitted to processing circuitry during each of the detection intervals. Sync pulses generated in the well logging instrument are transmitted to the processing circuitry along with the detection pulses. The sync pulses are used to route the pulse occurring during the inelastic detection interval to one section of a multi-channel analyzer. Similarly, the pulse occurring in the capture interval is routed into another section of the multi-channel analyzer.