How long will the LHC be on?

Question

do they plan on leaving it on forever or a couple days?

Answer 1

It won't be continuously, but we will be using it for as long as possible - several decades, probably.  It was expensive to build, and pretty much every particle physicist can come up with something they'd like to use it for.

Answer 2

it has taken more than a decade to build and has cost several million dollars, they aren't going to leave it on for only a couple of days. they are going to utilize this machine for as long as possible.

Answer 3

I assume they will be doing tests with it for years.  Since they started it only recently and it must have cost a fortune to build it, it wouldn't make much sense to quit immediately, unless it turned out that Stephen Hawking was wrong and a mini black hole doesn't disappear instantly by Hawking radiation.  Even then, it shouldn't be a problem because they would make certain that nothing was within its event horizon.