A new frozen spin target for the measurement of the Gerasimov‐Drell‐Hearn sum rule

For the measurement of the Gerasimov‐Drell‐Hearn sum rule with real photons at the Mainz accelerator facility MAMI a new horizontal polarized frozen spin target is under construction by the Bonn polarized target group. The horizontal 3He/4He‐dilution refrigerator includes an internal superconducting holding coil to maintain the polarization in the frozen spin mode longitudinal to the incoming γ‐beam.