To preserve the paramagnetic centers in the target material it has to be kept all the time at cryogenic temperatures typically below 100 K. A horizontal dilution cryostat with the possibility to load directly the target material into the helium-3/4 mixing chamber from a liquid nitrogen bath is needed for this reason. While the beam should interact with the target material scattering from the target construction materials is not desired. This leads to an additional requirement of small material budget in terms of radiation length. Thin and low density construction materials are used for this reason in the region of the incoming beam and the scattering products.