Bombardment of nuclei by slow neutrons

The transuranium elements (Z 93) are almost exclusively all man-made. Other man-made elements include technetium (Tc), promethium (Pm), astatine (At) and francium (Fr). 

Different nuclei show wide variations in their ability to absorb neutrons, and also in their probabilities of undergoing other nuclear reactions such probabilities are often expressed as the cross-section of a nucleus for a particular nuclear reaction. For example, the nuclides gC, jH and Jh have very low cross-sections with respect to the capture of thermal neutrons, but 58 and igCd possess very high cross-sections. 

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Bombardment of nuclei by slow neutrons 3.5 Nuclear fission... 

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