I understand that the LHC can collide protons with protons, heavy ions with heavy ions, or protons with heavy ions, giving three main configurations. But, I'm wondering: is that the only property that physicists would vary in order to perform different experiments?
For example, might they run the LHC at less than the maximum energy in order to facilitate a certain kind of experiment? Or, use different heavy ions? Or, vary the beam collision parameters in some way?
If not, then do they just fire up the LCH and continuously collect data for months at a time, only stopping to switch the particles used?
(Note that I'm not talking about the probably millions of properties that must be tweaked to get it running at its best; I'm only asking about properties where the optimal value depends on the experiment being run.)