Neutrons, capture reaction inelastic scattering

Neutrons may collide with nuclei causing one of the following reactions inelastic scattering, elastic scattering, radiative capture, or fission. 

Lutetium-177 produced by neutron capture reactions Iodine-125 produced by neutron capture followed by Tungsten-188 produced by double neutron capture Tin-117m produced by neutron inelastic scattering Copper-67 produced by fast neutron-induced reactions... 

Here, the subscript i denotes any one of the following nuclear reactions inelastic scattering radiative capture 2), fission Z/, and elastic scattering 2. The symbol S denotes an appropriate total" cross section for the fast neutrons it is defined by [cf. Eq. (2.50)]... 

Thru 1967, emphasis was given to the use of neutrons as the bombarding source of radiation. Almost all possible neutron reactions were considered including moderation of fast neutrons by hydrogen in the expl, thermal capture reactions, elastic and inelastic scattering of neutrons and neutron activation reactions. These neutron reactions are listed as follows ... 

The measured thermal neutron capture cross section (cTth) and resonance integral (Jo) for the Sn(n,y) Sn reaction are 5.8 1.2 and 350 53 mb, respectively. As demonstrated in this case, in the determination of neutron capture cross sections, the contribution from inelastic neutron scattering to the overall reaction is significant and appropriate corrections are required even when highly emiched target isotopes are used. Consequently, measured cross sections for capture reactions to metastable states are often lower than reported values. 

The two competing nonproductive neutron-capture processes are(l) radiative capture and (2) inelastic scattering. The radiative-capture reaction can be symbolized by the equation... 

The second nonproductive process, inelastic scattering, does not physically remove neutrons from the system, it merely degrades (as a rule) the kinetic energy of the neutron population. For the nuclei of primary interest to reactor technology (heavy nuclei), the inelastic-scattering process is conveniently described with the aid of the compound-nucleus model. In these reactions the nucleus captures a neutron at one energy and releases it at another thus,... 

Inelastic scattering and radiative capture are the two processes which compete with the fission reaction. The extent of this competition is determined by the relative magnitudes of the rate at which nonproductive reactions occur as compared to the rate at which fissions occur. If the nonproductive reactions for a particular fissionable material constitute only a small fraction of all neutron-nucleus reactions, then the possibilities of this substance as a nuclear fuel are greatly enhanced. The deciding factor, however, is the number of neutrons released by fission. For a given substance, the likelihood of fission taking place may be very... 

For the present discussion, all the neutron-nucleus reactions defined above will be included under the general heading collision. Thus, when we talk about the probability of a nuclear collision, we imply any one of the four principal reactions capture, fission, elastic scattering, or inelastic scattering. 

The first step in the production of nuclear data for applied purposes is measurement. Nuclear theory cannot provide accurate nuclear data. Nevertheless theory plays an important part in the interpretation of measurements, and is used for interpolation and extrapolation of measured data. Theory also provides much of the data for reactions of lesser importance, such as secondary energy and angular distributions of inelastically scattered neutrons, and also capture cross-sections for materials which are difficult to measure, such as radioactive fission products and minor actinide isotopes. If the resonance structure of a cross-section needs to be known, when... 

Each possible type of reaction which a neutron may undergo with the nucleus is associated with a specific cross section. The most important cross sections are g, elastic scattering g i, inelastic scattering Gy, radiative capture Gf, fission (Tp, (n, p) reaction g, (n, a). 

The relevant nuclear reactions for NIPPS are the inelastic scattering of fast neutrons, e.g. 19F (n, n, y) or the capture of thermal neutrons, e.g. 35C1 (n, y) 36C1. Hydrogen, chlorine and arsenic can be detected with high sensitivity and without any problems. 

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