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In nuclear physics, the concept of a neutron cross section is used to express the likelihood of interaction between an incident neutron and a target nucleus. The neutron cross section σ can be defined as the area in cm 2 for which the number of neutron-nuclei reactions taking place is equal to the product of the number of incident neutrons that would pass through the area and the number of ...
The neutron cross section of graphite was investigated during the Second World War in Germany by Walter Bothe, P. Jensen, and Werner Heisenberg. The purest graphite available to them was a product from the Siemens Plania company, which exhibited a neutron absorption cross section of about 6.4 mb [14]: 370 to 7.5 mb. [15]
The predecessor group to the NNDC was founded in 1951 when a group known as the Brookhaven Neutron Cross Section Compilation Group was formed at the Brookhaven National Laboratory. In 1955 this group published the reference book "BNL-325," which had to do with the cross-sections of neutrons. After being renamed the Sigma Center, the group was ...
Nuclear cross sections are used in determining the nuclear reaction rate, and are governed by the reaction rate equation for a particular set of particles (usually viewed as a "beam and target" thought experiment where one particle or nucleus is the "target", which is typically at rest, and the other is treated as a "beam", which is a projectile with a given energy).
Neutron capture; Neutron cross section; Neutron emission; Neutron number; Neutron research facility; Neutron transport; Neutron–proton ratio; Nilsson model; Non-extensive self-consistent thermodynamical theory; NPDGamma experiment; Nuclear binding energy; Nuclear clock; Nuclear drip line; Nuclear emulsion; Nuclear explosion; Nuclear explosive ...
Se-79, half-life of 327k years, is one of the long-lived fission products.Given the stability of its next lighter and heavier isotopes and the high cross section those isotopes exhibit for various neutron reactions, it is likely that the relatively low yield is due to Se-79 being destroyed in the reactor to an appreciable extent.
While exposed to the neutron flux during normal operation in the core environment, a small percentage of the 238 U in the fuel absorbs excess neutrons and is transmuted into 239 U. 239 U rapidly decays into 239 Np which in turn rapidly decays into 239 Pu. The small percentage of 239 Pu has a higher neutron cross section than 235 U.
The discovery of the neutron by James Chadwick in 1932 created a new means of nuclear transmutation. Enrico Fermi and his colleagues in Rome studied the results of bombarding uranium with neutrons, and Fermi concluded that his experiments had created new elements with 93 and 94 protons, which his group dubbed ausenium and hesperium .