Radiation Detectors
COMPENSATED ION CHAMBER
COMPENSATED ION CHAMBER
Gamma compensation is required at intermediate reactor power levels to ensure
accurate power reading.
EO 2.4
DESCRIBE how a compensated ion chamber
compensates for gamma radiation.
Compensating for the response to gamma rays extends the useful range of the ionization chamber.
Compensated ionization chambers consist of two separate chambers; one chamber is coated with
boron, and one chamber is not. The coated chamber is sensitive to both gamma rays and
neutrons, while the uncoated chamber is sensitive only to gamma rays. Instead of having two
separate ammeters and subtracting the currents, the subtraction of these currents is done
electrically, and the net output of both detectors is read on a single ammeter. If the polarities
are arranged so that the two chambers’ currents oppose one another, the reading obtained from
the ammeter indicates the difference between the two currents. One plate of the compensated
ion chamber is common to both chambers; one side is coated with boron, while the other side
is not.
Figure 19 shows the basic circuitry for a compensated ion chamber.
Figure 19 Compensated Ion Chamber
Rev. 0
Page 35
IC-06
