LI-COR Li-189, Инструкция по эксплуатации

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Sensor Calibration
9
2.2 Sensor Calibration
All LI-COR radiation sensors produce a current that is pro-
portional to the radiation intensity. During the factory cali-
bration, the sensor output (in microamps) is measured while
the sensor is exposed to a standard lamp of known
intensity. The sensor output at this intensity has the general
units of microamps per radiation unit and is called the
Calibration Constant (Calconstant). Each sensor has a
slightly different output for a given radiation intensity and
will therefore have a unique Calconstant.
The LI-189 measures the current output of the sensor, and
converts the measured current to units of radiation. In
order to make this conversion, the LI-189 uses the sensor
Calibration Multiplier
. The Calibration Multiplier is the
negative reciprocal of the Calconstant.
Multiplier
Calcons t
=
−
1
tan
The Calibration Multiplier is always a negative number be-
cause the shield (ground) in the coaxial cable is positive
instead of negative.
Since the Calibration Multiplier is unique for each sensor, it
must be entered into the LI-189 each time the sensor is
changed or recalibrated (see Section 2.3).
N O T E : When using the LI-189, always enter the
Calibration Multiplier,
n o t
the Calconstant. If the
Calconstant is entered any data collected will be erroneous.