A cryogenic storage cell for polarized internal gas targets

A prototype cryogenically-cooled storage cell for the HERMES polarized 3He internal target has been designed and constructed. The storage cell operates at 15 K with a 10 W applied heat load, while maintaining less than a 3 K differential over the 40 cm long cell. When operated at 15 K, the target thickness in the storage cell is a factor of 4.5 larger than for a room temperature cell. The cooling system used a continuous flow cryogenic helium gas loop. Complete details of the system are presented.