physics old-fashioned a former name for electron capture (sense 1)
electron capture in British English
noun physics
1.
the transformation of an atomic nucleus in which an electron from the atom is spontaneously absorbed into the nucleus. A proton is changed into a neutron, thereby reducing the atomic number by 1. A neutrino is emitted. The process may be detected by the consequent emission of the characteristic X-rays of the resultant element
Former name: K-capture
2.
the spontaneous or induced recombination of free electrons with ions or by transfer from other atoms or ions