Mirion Technologies GEM-5 - Page 152

Chapter 5 Parameters Definition
136
Equation 3 Statistical error of the background corrected activity
VAE
K
S
RRß
BSB
⋅⋅=
+
ε
σσ
22
(3)
Where:
K
ß
= Confidence (nominally 1.96 or 95%)
E = Allowed Range (in fraction form, nominally 0.2 or 20%)
σ
RSB
= error in source + background
σ
RB
= error in background
Substituting for σ, one obtains:
Equation 4 Statistical error of the background corrected activity
b
b
m
bE
ßE
T
R
T
RR
KRE +
+
×=⋅
(4)
Where:
R
B
= Background Average Count Rate (cps)
T
B
= Time in Background Average (s)
Solving for T
m
one obtains:
Equation 5 Measurement Time
B
B
ß
E
BE
m
T
R
K
RE
RR
T
−








⋅
+
=
2
)(
(5)
where T
m
= Measurement time (s)
Wait between Detectors (Verification Test only)
This allowed for moving source between detectors. See F2 – (Zone) Settings screen
for additional time for specific detectors when in Verification Test mode (called
Verification Test Extra Time).
Allowed Range (Verification Test only)
Sets Minimum and Maximum Count Rate deemed as “Passed”.
Confidence (K Beta) (Verification Test only)
Used for count time formula.