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I Z -J (R B + RDA x eff)jT
I
,~ RB + RDA x eff
R B -+- R A(mex)
Figure 8
Eq. 42 expresses the computation of RA(MAX)'
JRDA X Eft + R,
RA(MAX) = RDA X Eff - Z ----:r=---­
Eq.42
Optimization
Figure 9 will be used as the basis of discussing how a counting exercise can be set up so as to
maximize its desired performance. Figure 8 illustrates the relationship of RA(MIN) and RA(MAX) on a
single number line whose domain is non-negative count rates. First of all, it is important that RA(MIN)
be kept less than or equal to RA(MAX)' Whereas the spread of the distribution curve is determined by
the standard deviation associated with it, adjusting a will adjust the breadth of its curve and, along
with it, the position of R A relative to the curves peak. Studying the expressions for a B and as (the
radical terms in Eq. 35 and Eq. 42), it should be apparent that the parameter most likely to be
controlled by the operator of a radiation monitor is the length of the counting interval, T. Because T
is in the denominator, larger values of T will reduce a. There can be several interpretations of how a
counting exercise can be optimized. Each is discussed separately.
1J'Vr-7(-R.-+-R-DA-x-e-ff-')/~T
R + R
• o("'n)
LL R. + RDA • .ff
RI + R0(.....)
Figure 9
PCM7.MAN