Photoneutron spectrometry by time of flight

A general account is given of the methods of photoneutron spectrometry using nanosecond time of flight techniques and a pulsed electron source. Included are some details of the Massachusetts Institute of Technology electron linac facility with emphasis on the experimental geometry, the electron gun, the neutrons detectors and timing and logic circuitry. Problems associated with the gamma flash, the specific bremsstrahlung associated contributions to timing accuracy and resolution, optimum pulse width and neutron detection efficiency are discussed. By means of a specific example, C 13 ( γ ,n)C 12 , the reduction of data to differential cross section is elaborated. The sources and magnitudes of backgrounds are reviewed in this example.