Process of uranium dating
Uranium series disequilibrium: Unequal radioactivity of the intermediate radioisotopes (e.g., Ra) in the U-series decay chains resulting from changes in the respective elemental ratios (or called elemental fractionation) during a geological or environmental event or process.
Once disequilibrium occurs, secular equilibrium status will be rest ...
J., postulated that the uranium isotope uranium-235 was the one undergoing fission; the other isotope, uranium-238, merely absorbed the neutrons.
It was discovered that neutrons were also produced during the fission process; on average, each fissioning atom produced more than two neutrons. Neutron capture may also be used to create quantities of plutonium-239 from uranium-238, the principal constituent of naturally occurring uranium.
The term U–Pb dating normally implies the coupled use of both decay schemes in the 'concordia diagram' (see below).
Thus, the yield of a nuclear weapon can be increased by surrounding the device with uranium-238, in the form of either natural or depleted uranium,...
Of these naturally occurring isotopes, only uranium-235 is directly fissionable by neutron...
..differences in chemical properties and, once fixed, can decay to new isotopes, providing a measure of the time elapsed since they were isolated.
..two nearly equal fragments (nuclei of lighter elements) and liberate a large amount of energy. Among these nuclides, those with lower mass numbers generally have longer half-lives. ..system has penetrated the barrier by the process of quantum mechanical tunneling.
Spontaneous fission, discovered (1941) by the Russian physicists G. This process is called spontaneous fission because it does not involve any outside influences.