"Time of flight spectrometers for the study of neutrons emitted in charged particle reactions have become important in recent years, following the development of suitable photomultiplier tubes and electronic circuits for nanosecond (ns) timing measurements. The principle of operation is simple. The particles exciting the nuclear reactions in which the neutrons are produced fall on the target in bunches of the order of a nanosecond in width. the arrival of product neutrons at a organic scintillation counter (proton recoil) detector placed a few meters from the target gives signals which can be used to determine the flight time of the neutrons from target to detector. A time-reference pule corresponding to the arrival of beam pulses at the target is required."

Abstract. Some diffusion parameters of water are computed with various thermal-neutron scattering laws. It is found that the diffusion cooling coefficient, in particular, is reasonably sensitive to the scattering law, but that the diffusion cooling coefficients predicted by the Radkowsky and Nelkin kernels are in fortuitious agreement. The coefficients computed for the Nelkin kernel, when treated in a manner consistent with the way in which experimental data are treated, are in reasonable agreement with the results of a recent experiment.