I can answer that.
Mr. Chair, from primary, if you're referred for a further examination to secondary, we're going to be looking through your baggage. As we're examining your baggage, whether it be an X-ray, an ion scan, or a detector dog.... Let's focus on the ion scan: it is exactly as you said, to either confirm and validate or negate any indicators that the officer might have had.
Obviously, quite often we're looking for concealed narcotics or something of that sort. If there's contraband within your baggage, the ion scan can help give us an indicator of which piece of baggage it might be in, by giving us an alert on the trace residue of potential narcotics.