Neutron Kinetic energy

Inelastic neutron scattering, on the other hand, usually employs a monochromatic neutron beam and records the intensity of the scattered neutron beam as a function of neutron kinetic energy. Such inelastic collision spectra are monitored as a function of the applied field and the (usually low) temperature. The observed peaks then represent the energy differences of thermally populated and excited unpopulated multiplet states. Inelastic neutron scattering experiments can be conducted using triple-axis, backscattering, or time-of-flight spectrometers. 

The neutron kinetic energy E is related to the neutron speed by... 

If B + AT /iA + 1) E, fission may occur and the final state is the one shown as fission products in Fig. 3.18. For E = 5.3 MeV and B = 6.4 MeV. Therefore, even a neutron with zero kinetic energy may induce fission, if it is absorbed. For which is formed when a neutron is absorbed by U, B = 4.9 MeV and E = 5.5 MeV. Therefore, fission cannot take place unless the neutron kinetic energy satisfies... 

Example 11.4 The following table gives neutron-absorption cross-section values and their errors as a function of neutron kinetic energy. Determine the analytic function that fits this data set. 

The cross section for this exothermic reaction peaks at a deuteron kinetic energy of about 120 keV with a value of about 5 b. The neutrons produced have an energy of about 14 MeV. (The neutron kinetic energy changes slightly with the direction of neutron emission.) The maximum neutron flux provided by a neutron generator is of the order of 10 neutrons/(m s). 

The spectrum of thermal neutrons is characterized by an equilibrium of the neutrons kinetic energy with that of the surrounding moderator. Like for any gas the speed distribution can be described by the MaxweU equation ... 

It is sometimes more convenient to describe the neutron population in terms of the neutron kinetic energy instead of the speed. In this event, the neutron density and the flux are defined per unit of energy. In order to show the relationship between the speed and the energy definitions, let us consider the function... 

How many times k will the neutron kinetic energy decrease after N consecutive collisions with atomic nuclei which practically do not capture neutrons. Consider the collisions to be elastic and central with atoms deuterium H, carbon and tungsten Let be 3. 

Solution The problem with the single collision of a moving and motionless particle is solved in the text where formulas for the speed of each of the particles after collision (see formulas (1.5.16) and (1.5.17)) are given. Using these results it is possible to obtain expressions for neutron kinetic energy after collision K[ in relation to its initial energy K. ... 

After the second collision the kinetic energy TfJ should be treated as initial. Then the neutron kinetic energy K is... 

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