15
The volatile/refractory ratio of a fallout sample can be deduced
from the ratios of the amount of volatile or partly volatile fission
product mass chains to the amount of a refractory fission product mass
chain.
The number of atoms, A, of a given mass chain in a sample is
A = R(A) + V(A),
where
R(A) =
number of atoms of mass chain A refractory at 20 sec
postshot,
V(A) =
number of atoms of mass chain A volatile at 20 sec
postshot.
Dividing by the number of atoms, R, of a mass chain containing only
refractory members, and transposing, we obtain
V(A) . A_ RUA)
R “RR
Refractory masses do not fractionate; therefore,
a * a ~ [Ra
R
,
where the subscript u denotes the ratio calculated for unfractionated
debris.
The value of [R(A)/R],, and [V(A)/R],, are known from the
fissioning nuclides and neutron spectrum of the detonation (Ne73).
Dividing the above equation by [v(a)/R],, gives r(A), the
volatile/refractory ratio for mass chain A.
r(A) = [v(A)/R]/[V(A) Re], -{§ - aca] FDA)= L/f
The quantity r(A) is the reciprocal of the quantity, f, the fraction of
refractories present in the sample and is equivalent to Edvarson's