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9.3
Calibration
This section describes the calibration procedures for NRF51.
Expose NRF51 to the gamma-ray sources such as
137
Cs and
60
Co and neutron sources such
as
252
Cf or Am-Be.
A dose should be measured by placing the source at a certain distance (calibration distance)
from reference point of NRF51 so that true value of the dose is traceable to the National
Standard.
(1) Determination of a reference dose value (R
0
)
-
Determine a reference dose value (R
0
) by the following method:
a. Calculate R
0
from the reference source activity, the distance between the reference
source and reference point of NRF51 (calibration distance) and irradiation time.
b. Or the dose rate value at the reference point may be simply well-known by field
calibration/characterization. In this case, reference dose value (R
0
) can be calculated
by the known dose rate value and irradiation time.
(2) Dose value (R
1
) measurement
-
Place the source at the calibration distance from reference point of NRF51.
-
Take the dose reading (R
1
) after irradiation which gives enough statistical stability.
(e.g. 1 mSv)
