To achieve the element specific separation in the fragment separator sheets of matter are used in which the energy-loss of heavy ions of other atomic numbers differs considerably.

These layers of matter must be very precise in shape (in the few micrometer range) as they act like optical elements. Material are aluminium or glass. For different ion species, energies and separation needs these layers are adjustable in thickness and shape.
Two wedge shaped plates moved against each other can form a layer of adjustable but constant thickness over the beam spot area. Two rotatable wedge shaped disks can form an overall wedge shape of adjustable wedge angle. In addition different plates of constant thickness are used. Before the stopping cell a gas filling of the last beamline section will act as adjustable matter layer.