Digilert 100 and the source is correct to produce the appropriate dose rate.
Place the Digilert with the end panel facing the source and the center of the
alpha window aligned with the center of the source. When using Cs-137 for
gamma calibration, place the Digilert with the rear of the instrument facing the
source (to filter the beta emissions) and the center of the Geiger tube (indicated
by the symbol on the rear label) aligned with the center of the source. This
filters the beta emissions. Follow these steps:
1. Start with the Digilert 100 turned off and the Mode switch set to mR/hr.
2. Hold down the - button on the end panel while you turn the On/Off/Audio
switch to On. (Don't use the Audio setting.)
The display shows CAL, and the Digilert 100 counts down for 15 seconds,
beeping each second. This delay gives you a chance to move out of the
field and then expose the source. At the end of the 15 seconds, the
Digilert 100 beeps several times.
3. The Digilert 100 collects data for 60 seconds, beeping as it does so, with
CAL and the hourglass indicator flashing. At the end of the 60 seconds, it
beeps several times. The display shows CAL and SET. You can now seal
or close the source.
4. Press the + and - buttons to adjust the reading to what it should be. When
the reading is correct, press the Set button. The new calibration factor is
automatically calculated from the adjustment you make.
5. The new calibration factor is displayed for several seconds, then the
Digilert 100 beeps and resumes regular operation.
The calibration factor is set to 100 (percent) at the factory. If you change the
reading, for example, to 20% higher than the factory reading, the new
calibration factor would be 120. The current calibration factor is displayed
during the system check when the Digilert 100 is first turned on.
Calibrating Electronically
You can calibrate electronically using a pulse or function generator. Electronic
calibration requires a cable with a 2.5 mm plug, with the tip carrying the signal.
Follow these steps:
1. Set the signal height to 3.3 volts (positive pulse) and the pulse width to 80
microseconds.
13
