Absolute Scintillation Measurements of Neutron Pulses Generated in a Hot Plasma
Fluxes of fast neutrons generated in a hot plasma are characterized by particular properties. These fluxes are generated within a short time interval, and the repetition rate of the neutron pulses is usually very low. The number of neutrons in a pulse can vary from unity to 1010–1014 neutrons, depending upon the type of the plasma device. The neutron energy is determined by the energy of the interaction between deuterons or between deuterons and titanium. Thus, the neutron counting method involving a piece-by-piece neutron count can seldom be used in plasma studies, and one has to resort to integral methods. Measurements of neutron pulses involving the activation of silver or indium and the ensuing counting of the number of decays of radioactive isotopes formed belong to the most widely employed techniques. This method is characterized by the disadvantage that the background resulting from the accumulation of longlived isotopes increases slowly in time; apart from this, it is necessary to use neutron fluxes of a known intensity and with an appropriate neutron energy spectrum for calibration purposes.
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