The decay constant of Uranium II

Abstract
The relations between the radioactive elements which occur in “uranium” have attracted attention since Boltwood’s discovery that uranium gave two α-particles for each α-particle emitted by the radioactive elements in equilibrium with it. As is well known, Geiger and Rutherford, Marsden and Barrett and Geiger and Nuttall, proved that this was due to the existence of two uraniums with separate decay constants. The primary relationships having been established, it was not until recently that attention was again turned to the group of radioactive elements in "uranium.” Clearly, no advance can be made in elucidating the relationships between the various branches, or series starting with unknown isotopes of uranium, until the decay constant of UII is well established. Also, until this constant is known, no information of theoretical value can be drawn from the atomic weight of uranium; quite different conclusions being arrived at if uranium II exists in a measurable or negligible proportion in uranium. Three estimates have been made of the range of the α-particles from uranium II, and so, using the Geiger-Nuttall rule, three estimates of its period of half life. These are :— ( a ) Geiger and Nuttall ( loc. cit .) = 2 × 10 6 years. ( b ) Gudden = 10 8 years. ( c ) Laurence = 1·3 × 10 4 years.

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