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1899 P. & M. Curie in Compt. Rend. CXXIX. 714 Nous avons constaté que les rayons émis par ces matières, en agissant sur des substances inactives, peuvent leur communiquer la radioactivité, et que cette radioactivité induite persiste pendant un temps assez long.]

1900 Rutherford in London, Edinb. & Dublin Philos. Mag. 49 169 Two or three layers of ordinary foolscap-paper completely cut off the ordinary radiation given out by thorium compounds, but do not much diminish the amount of induced radio~activity.

1904 F. Soddy Radio-activity ii. 33 With the power of a radio-active element to produce a radio-active emanation is bound up its power to impart radio-activity to objects in the neighbourhood. Rutherford discovered this property for the thorium emanation, and designated it the excited activity. M. and Mme. Curie..called it the induced activity.

1913 E. Rutherford Radioactive Substances x. 391 The activity thus produced on inactive substances was..known as ‘induced’ or ‘excited’ radio-activity.

1926 R. W. Lawson tr. G. von Hevesy & F. A. Paneth Man. Radioactivity viii. 90 Before the material nature of the active deposit had been recognised, it was customary to call the activity acquired by bodies that had been in contact with emanation by the name of ‘induced activity’.

1963 B. Fozard Instrumentation Nucl. Reactors i. 7 When the irradiated material is removed from the neutron flux the induced activity is measured.

1966 McGraw-Hill Encycl. Sci. & Technol. (rev. ed.) XI. 277/2 The yield of any induced radioactivity is the initial rate of production of the activity under the particular conditions of nuclear bombardment.