My RA walks the halls all night with one of those hand cranked flashlights. The ones you are supposed to charge up cranking them with the plastic crank. It makes a whirring sound.

My RA grinds it furiously for a few seconds, and it glows a little then fades away. My RA takes a step. Then my RA starts grinding it again, and takes a couple steps, then stops grinding and it goes dark again.

My Ra does this over and over again, all night.

That's how they keep the ghosts away.