Measurements required for nonlinearity determination
For nonlinearity determination, you need one or more multi-line measurements. The measurements should have the following properties:
taken with the same measurement setup (same detector, ADC, energy range),
taken roughly in the same time period (preferably within the same day, or within 1 week),
their gamma lines of isotopes have exact energy values in HyperLab's database,
the lines of the isotopes spread across your entire, regularly used energy range,
every measurement has at least 3 proper gamma lines,
every measurement has at least 2-3 identified peaks which overlaps with another measurements' identified peaks. Please be aware that if no overlapping is between the measurements, no proper nonlinearity curve may be constructed.
These are not stringent requirements, so the majority of usual calibration measurements – or even measurements acquired for material analysis – will be usable also for nonlinearity determination. You can also use isotopes with a few problematic lines, as you will be able to individually remove the disturbing or overlapping lines from the nonlinearity curve.