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Aidan Randle-Conde | Université Libre de Bruxelles | Belgium

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60ns? How about 60mn?

In a couple of hour’s time the clocks go back an hour in Geneva, as European daylight savings time ends. Usually this isn’t a big deal. We adjust our watches, the nights get darker earlier, and some of us turn up an hour early for work while the rest enjoy the extra hour of rest! But what happens in the Control Room? It’s not as trivial as you’d think…

The timing of the detector will be okay, as the passage of “normal” time is full of leap seconds and minor corrections here and there. Protons don’t care about that kind of thing, they just care about the amount of absolute time that has elapsed. But when humans get involved it gets more complicated, because we work with the time of day. Our plots show the hour along the x-axis for the past day or so. If we’re going to keep these plots online we’ve got to make a decision, either to double-count the results for that hour (ugh) or repeat the hour on the plots (and see some protons turn up 60 minutes earlier than expected!) It’ll be made even worse when people try to use the log books to recreate the events of the evening. They’ll see that some experts forgot to change their watches, and some didn’t. For those that did change their watches they’ll have 2am occur twice. Does this means we’ll have 2am(A) and 2am(B)? Will my replacement turn up at 6am or 7am? (I hope he turns up at 6am so I can send him to get some coffee while I sit through my extra hour!)

It’s tempting to write something like this in the electronic log book:
02:00: Some neutrinos arrive. Where did they come from?!
02:59: We have beams! We’ll be getting some data soon.
03:01: Wait a minute.

If only ATLAS could detect neutrinos…

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