Stuff will be happening this year with the LHC, let's talk about it!
I'll start here:I've been wondering about the strange concept of using H- ions in the Linac 4.
I found out that this is actually pretty clever! Even though it is harder to get an hydrogen atom to accept an extra electron than to get its electron off, it behaves more or less the same, so you can accelerate them using the same techniques (with different polarity of course). But then the cleverness starts:
I order to get a beam into an accelerator, you need to very quickly turn a magnet on or off. And since these magnets are inductors, that is pretty hard to do. This means that it is hard to do this neatly: every accelerator's insertion and extraction magnets are very complicated (and just big).
And there lies the trick: if you put an H- beam through a thin foil (with positive charge), the electrons stay behind an the protons continue as if nothing had happened. If you do this in a magnetic field, the beam suddenly changes the bend direction, because the electromagnetic charge is changed. So if you set up your magnets just right, and place the foil at the right spot just next to the accelerator beam, it is much easier to get the beam in.
