constituents.
Of military importance are the initial level of this induced activity and its rate of
decay. It appears that the most-significant isotopes produced in most soils are Na™‘, Al’, and
Mn* (Table 1.1).
The results of experimental measurements made during Operations Teapot, Redwing, and
Plumbbob are given in References 12, 13, 14, and 15. Although early measurements of the
TABLE 1.1 ISOTOPE HALF LIVES AND ENERGIES
Isotope
Formed By
Energy of Emitted
y Radiation
Half Life
_
“APs
Mn*
Na?#
Mev
al (n, y) Al?
Mn (n, 7) Mn
=—-Na® (n, y) Na’
2.3 min
2.58 hrs
15 hrs
.
1.78
-
0.85, 1.8, 2.1
2.8, 1.4
intensity and decay of the induced field were attempted during these operations, no successful
documentation was accomplished, owing to various technical or operational difficulties. With
the advent of fractional-kiloton ground weapons, the decay rate at a few minutes after the detonation can be a significant parameter in their employment. Aluminum, with the shorthalf life
indicated in Table 1.1, is the primary contributor to the dose levels at these times.
11