If Eqs.
1, 2, and 4 are combined into the form of Eq. 3, a rela-
tionship between the net photopeak count rate and the source activity
within the soil will result.
In addition, if the appropriate detector
calibration results are inserted with the appropriate parameters for a
given source distribution and the required numerical integration is
performed, the desired conversion factor is produced.
factor,
°
S/NP,
:
.
.
.
as determined above is in units of
The conversion
3
Yfem -sec
aera
For a
specific radionuclide the results can also be given in terms of total
activity per unit area, Sos using
2 “f
sa
0
zea
soeae
8 e
(5)
oO
Another useful conversion factor relates the net photopeak count
rate to the average concentration in a given layer of soil.
The average
concentration per unit volume in the top z centimeters, $7, 1s given by
st Vv = +zZ gseVv edz
Cat
5011686
(6)