Question: how long did it take you to get good at shooting little targets?

Ceri Brenner answered on 16 Jun 2011:

hi,

It’s quite tricky aligning the laser onto the target. To do this in an experiment we use a low-level laser (not much stronger than a laser pointer for example) and then align it so that it follows the same path as the main laser pulse. We use this mini laser to make sure that the target is roughly in the correct position. We then use a medium sized continuous laser beam to align the last turning mirrors and the final parabola (the parabola is a special kind of mirror with a curved surface that is used to focus the beam from a diameter of 60 cm to spot size that is smaller than the width of a human hair). The parabola is pretty heavy and really delicate so we use motorised drive systems to steer it instead of by hand. It’s taken me up until now (almost 3 years) to learn how to properly align the parabola for a laser shot as only the slightest wrong move and your pointing the laser beam off the target (the targets are only a few mm wide) and we can’t afford for that to happen in a real high power shot or else we’ll damage the chamber or the diagnostics. But thankfully, there are always postdocs around (they’re researchers who have already got their phd) so we learn from them and they pass their experience down onto us. Also, the only time we get to practice shooting little targets is during an experimental campaign and they’re only 6 weeks long at a time. I’ve been on maybe 6 or 7 experiments during my PhD and I think I’ve got the hang of it now.