Pictures By Alan

Near the helium container is an even larger liquid nitrogen tank. It stands upright rather than lying down. The tank must be extremely well insulated, probably with vacuum dewars, but the pipes that exit at the bottom are insulated primarily with an inches-thick layer of ice that persists even on hot days. The liquid nitrogen is probably colder than -300 degrees (nitrogen boils at -320 at atmospheric pressure). That would explain the ice.