of the
easureslightly
the
ange in
de.
ap
1 sampling
sent in
;
Peak Counts
Peak Counts
,
(100 mc/mi2)
(ur /hr)
(100 mc/mi2)
0.17
27500
4700
6.4 (denser soil or
0.15
26000
3900
3.2 (less dense soil
0.20
29000
5800
0.41
36500
15000
4.8
(assumed typical
model)
deeper penetration)
in Soils
a
Dose Rate
or shallower
penetration)
dose
These
inations
ese sites
ield
0
(ideal
plane
source)
‘Thus a 33% change from our assumed typical model in relaxation
in the
length or density results in only about a 5% change in peak
area per unit dose rate, about a 15% change in the actual dose
dad Spo is
elaxation
activity.
Since soil density and isotope penetration probably
vary significantly from site to site, the soil concentration
e S
(mc/cm?) rate,
(average
n.
The
stribution
For
a
round
the
unts for
ber
of
or
activity
and about a 20% change in the peak area per 100 me /mi 2
of 137cs inferred from a spectrum taken at a single location
could be considerably in error;
four depth distribution model
however,
represents
to the extent that
an
average
situation,
our estimates of 137cs activity for a large number of
locations should reasonably reflect the variation in activity
from area to area.
Indeed preliminary comparison with the
‘few radiochemical results available at present indicate that
this is indeed the case and that field spectrometric estimates
ef 137cs soil activity can play an important role in
studying fallout deposition.
The table above also indicates the fortuitous relative
insensitivity of our spectrometric dose rate estimates to
of a and Oo.
differences in density and relaxation length.
This results
Since the dose rate estimates are based on the ratio of
gPrimary flux to total dose rate and both these quantities
the
above
fchange in the same direction for a given change in ap.