Modified X-ray cell test

detected above the baseline through barriers up

A third experiment used several polyethylene

to 1 cm in thickness, even when the moisture

31-mm X-ray cells, modified so that they were

content was increased.

only 0.5, 1.0, and 1.5 cm high. Each was covered

In Table 5, the measured intensities of Pb bur-

on the bottom with a single sheet of 0.2-mil

ied beneath the air-dried CRREL soil were lower

polypropylene. After packing the modifed cells

than established in the previous experiment

with soil, they were buried in the large soil-filled

(Table 4). An explanation for this decrease in sig-

jar so that the top rim was flush with the surface.

nal intensity between experiments is that greater

The cells were buried with and without the pack-

soil densities most likely were present in the

ets of metal salts positioned beneath. With these

modified cell experiment. In addition, measure-

cells the mass (density) of soil between the

ments through the moistened soil barriers ap-

source and the metal target could be established,

peared to decrease the Pb-line intensity, and the

and soil moisture experiments could be per-

measurement of this line became inconclusive

formed.

when the barrier was increased to 1.5 cm.

Table 5 shows the manually measured peak

Table 6 shows values for both Pb and Hg

intensities for the K lines of Pb and Hg on and

based on manually measured intensities and for

beneath an air-dried soil and for Pb beneath a

instrumental measurement of Pb using a 96-s

soil of 20 and 40% moisture content. All measure-

analysis period. The targets for this experiment

ments used a 24-s analysis period, and only the

consisted of pillows containing 0.5 g of both of

CRREL soil was used. As indicated by the previ-