Several methods for measuring neutron flux and neutron energy spectra in and around reactors are discussed, including proton recoil spectroscopy, crystal spectroscopy using thallium activated lithium iodide, photographic plates and emulsions, and activation analyses. For irradiation tests in high flux intensity reactors where space is severely limited and gamma intensity is high, activation analysis appears to offer the best means for determination of the irradiation test flux environment. Techniques of activation analysis are reviewed under the subjects of thermal flux monitors, fission detectors for both thermal and high-energy neutrons, charged particle neutron-proton and neutron-alpha reactions, neutron-neutron (n, n1 and n, 2n) reactions, and resonance reactions. Practical methods are presented for optimum use of these reactions in obtaining the required information concerning the test environment. Instrumentation available is reviewed and advantages and disadvantages are assessed.
Five methods of analyses of activation data are briefly described that range from the simplest calculations required for minimum information to the most complex methods that, with the aid of high-speed electronic computing machines, reproduce incident spectra with high-energy resolution. Finally procedures are recommended for tailoring the requirements of the experiment to the experimental and analytical methods available.