downtime

He learned that a high voltage underground transmission line had experienced a fault, costing the City tens of thousands of dollars per hour in lost capacity and downtime.

So, the job of finding enough water, making it safe to use, and then reliably distributing it to the system customers with almost no downtime is a monumental task that requires a lot of infrastructure.

So a nanogram, one billionth of a gram, so that means at that rate, with that facility, it would take a billion years running with very little downtime to make a single gram of antimatter.