Recent modification of the internal target source setup at the experimental storage ring (ESR) led to a significant improvement of its performance. In particular, a reliable operation of the light target gases helium and hydrogen at unprecedented area densities up to values of 10¹⁴ cm^-2 was demonstrated [1]. In the course of these optimization efforts, a remarkably versatile target source was established, enabling operation over the whole range of desired target gases (from H₂ to Xe) and area densities (~10¹⁰ to ~10¹⁴ cm^-2).

For more general, future applications at storage rings a completely new inlet chamber was proposed based on the experience gained during previous modification processes [2]. The much more compact chamber design will maintain the demanding storage ring vacuum requirements while enabling the operation of the target beam at an interaction length down to 1 mm. This is of paramount importance with respect to the realization of high precision experiments, e.g. by reducing the inaccuracy of the observation angle causing the relativistic Doppler broadening [3].

The new inlet chamber design is currently being assembled and commissioned at GSI. A thorough investigation of the exact target properties is mandatory prior to the deployment of this design as a unified target station at the storage rings of the FAIR facility.