P-Decay Rate Constant

The decay constant is now reduced to an expression with the nuclear- matrix element, M(= Mjf ), and the strength parameter, g, written  

The left-hand side of this equation is called the comparative half-life, or ft value because this value can be readily measured in experiments and should only depend on the nuclear matrix element and the (3-decay strength constant. Recall that (3 decay half-lives span many orders of magnitude so the ft values will span a similarly large range. It is therefore convenient to use the common logarithm of the ft value (with t]/2 in seconds) to characterize observed (3 decays. 

This is a neutron-rich nucleus and undergoes (3 decay, thus  

The creation of relative angular momentum in 3 decay is even more difficult than that in a decay and causes more severe hindrance for each unit of relative angular momentum. The difficulty is easy to see with a simple calculation. We can write the relative angular momentum for two bodies as the cross product L= r x p where r is the radius of emission and p is the momentum. Taking a typical nuclear radius of 5 fm and a typical 3-decay energy of 1 MeV, we find the maximum of the cross product to 

The quantum mechanical selection rules for (3 decay with no relative angular momentum in the exit channel (/ = 0) are Al = 0, 1 and An = 0. The two values 

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