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Introduction
Calculation of Concentration Averages
Activity Concentration
of Radon (C
Calculation of
Concentration
Averages
1-6
Model 5030 SHARP Monitor Instruction Manual
The fraction of the Radon isotope Rn-222 in ambient air is typically less
than 10% and is neglected by most methods. However, the C14 BETA
) Gas
Rn
measures and corrects for this natural activity due to potentially high
interferences with beta attenuation during periods of low ambient
particulate concentrations. The activity concentration (C
be calculated according to the following equation:
where;
ε
α
2
α
n
α
o
Q
T222
This equation is valid as soon as the radiological equilibrium of the Rn-222
decayed daughter nuclides are reached. This is approximately 90 minutes
after a filter change. During this period the C
is displayed. It is should also be mentioned that C
algorithm with a 300 second time constant.
The average concentration is calculated from individual cyclic
concentration measurements. All valid cyclic concentration values are
summed either as a 30-minute or 60-minute average concentration being
calculated, stamped with the time of day and date, and stored within the
internal memory. If at least 2/3
are valid, the average is considered to be valid.
The Model 5030 retains 1 year of 30-minute concentration averages or 2-
years of 60-minute averages via the internal 512 kilo-Byte memory. Each
record is stored with a respective date, time, instrument status, and
classification.
α
⎛
⎛
⎞
1
⎜
=
⎜ ⎜
⎟ ⎟
n
C
*
⎜
ε
Rn
⎝
⎠
⎝
Q
α
2
= detection efficiency of α particles,
= gross count rate [1/s],
= background α count rate with an unloaded filter [1/s],
3
= air flow rate [m
/s], and
= 4,550 seconds; an equilibrium constant for Rn-222 daughter nuclides
Within the sampled aerosol.
rds
of the cyclic concentration measurements
)of Rn-222 can
Rn
α
−
⎞
⎟
0
⎟
*
T
⎠
222
just before the filter change
Rn
is smoothed by an
Rn
Thermo Fisher Scientific
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