Beam path inside the monochromator drum, from the neutron source onto the monochromator. Some of the wedges of the monochromator drum are shown in a cutaway view. The tube that transports the neutron is stationary, and the wedges rotate with the drum and open to slide past the beam tube. A guide field is included in the design in the event that the 3He polarizers can be used in the high flux polychromatic incident beam.