| measure of the probability of a nuclear reaction of a specific type, stated as the effective area which target particles present to incident particles for that process
Note 1 to entry: The standard unit for measuring a nuclear cross-section is the barn, which is equal to 10−28 m2 or 10−24 cm2.
Note 2 to entry: A microscopic cross-section can be measured for each process of nuclear reaction (capture, fission, n-n′, n-2n, n-g, …..).
Note 3 to entry: The macroscopic cross-section allows the calculation of the number of interactions for a given nuclear reaction in a given material; this value is the produce between the corresponding cross-section and the volumic number of particles in this material; it is expressed in m−1 or cm−1.
Note 4 to entry: This entry was numbered 393-14-37 in IEC 60050-393:2003.