(a) The ratio of Nf/Nt represents that fraction of the total
number of fragments which have a weight greater than Wf. This
relationship is shown schematically in Figure 27a and as a cumulative
distribution function in Figure 27b.
(b) It is interesting to observe that the average fragment
weight, 2M2A, corresponds to an Nf/Nt value of 0.243, indicating
that (1 - Nf/Nt)100 or 75.7 percent of all primary fragments generated
by the detonation have a weight less than the overall average fragment
weight. Hence, the Mott equation predicts the release of a continuous
distribution of fragments ranging in size from a large number of lightweight
particles to a small number of very heavy casing fragments.
(2) For design purposes a Confidence Level, CL, where 0 < CL < 1,
can be defined as the probability that the weight Wf is the largest weight
fragment released. An expression can then be developed for the design
fragment weight corresponding to a prescribed design confidence level: