Appendix A Calibrating the System
A. Calibrating the System
The
i
Matic system, like any precision analytical instrument, must be calibrated in order
to measure samples with accurate, precise, and reproducible results. The
i
Matic has
features that make calibration easy to set up and repeat. With dedicated calibration
procedures, the system can be set up quickly and calibration repeated easily with
minimal impact on productivity. The
i
Matic allows the user to establish up to 10
independent calibrations.
Calibrating the system requires that some instrument settings be established and the
resulting performance measured. The first step in calibrating the system is to adjust the
sample channel’s amplifier gain to establish a known energy calibration. The
i
Matic
features an automated gain adjustment procedure that uses a successive approximation
technique to place the upper-energy edge of the prominent
241
Am calibration source at
a specific reference channel of the internal Multichannel Analyzer. The system energy
calibration is common to the 10 independent system efficiency and background
calibrations.
Once the system gain calibration has been established, the system background
performance and efficiency are then measured. The resultant background and
efficiency values are unique to the selected calibration. Background and efficiency
measurements must be repeated for each unique system calibration that is being
established.
Although the system is calibrated as part of the manufacturing process, good
laboratory practice dictates that the system should be re-calibrated using calibration
sources appropriate for your procedures and samples.
Note: The sample detector settings and gain adjustment
do not
need to be redone. The
detector used to test your system is also the detector shipped with your system,
and these parameters do not change.
Prior to beginning system calibration, the calibration procedures used should be
defined. In most cases the default settings can be used and will give optimum system
performance.
In summary, a complete system calibration includes the following:
•
Entering calibration source information.
•
Selecting the output mode.
•
Modifying, if necessary, calibration procedures.
•
Measuring the alpha and beta backgrounds for each system calibration
•
Measuring the alpha and beta efficiencies for each system calibration
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iMatic Automatic Counting System User's Manual - 9239221K
