Spin-filtering at COSY

The Spin Filtering experiments at COSY and AD at CERN within the framework of the Polarized Antiproton EXperiments (PAX) are proposed to determine the spin-dependent cross sections in (p) over barp scattering by observation of the buildup of polarization of an initially unpolarized stored antiproton beam after multiple passage through an internal polarized gas target. In order to commission the experimental setup for the AD and to understand the relevant machine parameters spin-filtering will first be done with protons at COSY. A first major step toward this goal has been achieved with the installation of the required mini-beta section in summer 2009 and it's commissioning in January 2010. The target chamber together with the atomic beam source and the so-called Breit-Rabi polarimeter have been installed and commissioned in summer 2010. In addition an openable storage cell has been used. It provides a target thickness of 5.10(13) atoms/cm(2). We report on the status of spin-filtering experiments at COSY and the outcome of a recent beam time including studies on beam lifetime limitations like intra-beam scattering and the electron-cooling performance as well as machine acceptance studies.