It is sort of an antimatter factory, uniquely capable of trapping antiprotons and slowing them to speeds where scientists can study them. The researchers working in the AD are looking for differences in how matter and antimatter behave.
Antimatter is something like a mirror image of matter.
Researchers think that if there are differences between them, they might help us understand why matter won out against antimatter just after the Big Bang. The diagonal pipe is part of the stochastic cooling system, which takes measurements and transports them to the other side of the ring before the antiprotons arrive. There are three experiments underway in the AD , and each of them will trap antimatter, see how it behaves, and compare this behavior the behavior of matter. The antiprotons arrive at the AD like a blast from a garden hose, scattered in various directions and moving at different speeds. The first task of the machine is to focus the antiprotons into a tidy, controllable beam.