Question: what is the most dangerous thing you have ever done to do with science?

Ed Rial answered on 13 Mar 2015:

Hi Lillian

The most dangerous thing I have ever been near was a failing superconducting wiggler (a kind of magnet in our particle accelerator).

The magnet is kept in a bath of 250 litres of liquid helium at -269 degrees C. If liquid helium touches something at room temperature it can boil explosively fast (it expands by 700 times). It is kept that cold by vacuum insulation (very similar to a flask you keep hot drinks in). By insulating it with a vacuum you stop heat from the atmosphere getting to the cold helium through convection, the tank is designed so there is not much conduction, which leaves only radiation transferring heat from the outside to the helium.

Unfortunately one day someone put a hole in the vacuum lining and let the gas in the atmosphere in to where the vacuum should have been, allowing convection to heat up the helium. The helium started boiling VERY quickly, and if there had not been appropriate safety things on the wiggler it would have exploded. It didn’t explode but the safety devices did go bang VERY loudly and the whole accelerator tunnel filled with a cold mist!

It was a scary day and it took me nearly three weeks to repair the damage. Which was lucky – when something similar happened at the Large Hadron Collider it took them over a year to fix it!

Ed