form of the decay law, the time interval between ‘the explosion
end collection dates, and the time interval between collection
and counting.
.
Radioactivities on the gummed papersgiven in this report
are corrected to the date of sampling, and recorded in the units
"disintegration per minute per square foot per day", referred to
‘hereafter es td/m", sin filter ectivity, also corrected to the
date of. sampling, is expressed in "disintegration per minute per
cubic meter of filtered air" and is abbreviated Nd/n/n3".
1b
SOTRCES - or ERROR in RADIOLOGICAL DATA
In order to interpret ‘the radiological measurements, sources
. of error must.be appraised. Any series of measurements of this ~
nature must include inaccuracies, some inhsrent in the methods,
others the result of human error.
‘The sources of error and limitations of the data can be considered in two categories: “errors in the radiological data, and
the representativeness of the gummed paper Samples as a
of the ground contamination.
1.4.1
.
measure .
Observers! Errors
The most frequent error appears to be misdating the |
data cards. It is also possible that on some occasions gummed
‘papers were mailed with the wrong card. Errors originating at
the collection station cannot, in general, be corrected.
1.4.2
Tabulation Errors. .
Mistakes are known to occur in punching the ITEM
‘cards which were used for computing and tabulating the data. A
recheck of questionable observations resulted in the correction
of a large nimber of such errors.
Tabulation error undoubtedly
remain, but they comprise a very small fraction of the data.
1.4.3
Contamination of Samples in Processing
In processing such a large number of samples by
routine procedures, cross-contauination is possible, especially
if a very active sample is present. Evidence that such errors
exist can be seen from an examination of samples processed on
Lo
.
gd
fea
-
s
-
‘
1: November 1952, the date on which a very active gummed paper