Despite it being so famous, and the memes, I still don't understand what Slotin was doing.

So I get it, it was a demonstration of how to perform an experiment. But I can't understand how the screwdriver makes any sense at all. What's being measured? What does success and failure look like? What does the experiment produce, what data in what format?

Because in my head, a proper experiment has data collection and precise measurements. Somebody's working on a data table that says "At position X, we measured value Y". But randomly wiggling stuff around with a screwdriver, I can't see how one can do anything of the sort. And I figure at this level, "more coverage = more radiation" is kind of a trivial point that doesn't really need to be demonstrated.