Partial fission half-lives

In O Fig. 19.11 the partial fission half-lives of the doubly even isotopes of uranium and beyond are plotted on a logarithmic time scale versus the fissility parameter. In accordance with the expectation from the liquid drop model the dashed line labeled Bld, describing the fission half-life calculated with only the liquid drop barrier Bid, crosses the 2. line at nobeKum. The time Te. is needed for the formation of the electron shell of the atom, the lower time limit considered beyond which a chemical element cannot be formed (Barber et al. 1992). The experimental half-lives follow this general trend. They decrease from uranium to nobelium over more than 20 orders of magnitude, from the age of the solar system down to fractions of seconds. The structure of the isotopic chains of elements from curium to nobelium is caused by a subshell closure at M = 152. 

Partial fission half-lives of the even-even isotopes of the transuranium elements dots) compared to the fission half-lives as calculated from a macroscopic model. The dashed lines and the labels are explained in the text after O Eq. (19.7)... 

Nuclide Paitial half-life of spontaneous fission Average number V of neutrons set free Nuclide Partial half-life of spontaneous fission Average number V of neutrons set free... 

Calculated partial fission and a half-lives for elements 108 and 114. Circles and squares mark experimental partial ot half-lives. The limiting half-life for Hs according to data from Dubna is indicated (Oganessian 2007)... 

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