Calibration of the Breit-Rabi Polarimeter for the PAX Spin-Filtering Experiment at COSY/Jülich and AD/CERN

The PAX(PolarizedAntiproton eXperiment) experiment is proposed to polarize a stored antiproton beam for use at the planned High Energy Storage Ring (HESR) of the FAIR facility at GSI (Darmstadt, Germany). The polarization build-up will be achieved by spin-filtering, i.e., by a repetitive passage of the antiproton beam through a polarized atomic hydrogen or deuterium gas target. The experimental setup requires a Polarized Internal gas Target (PIT) surrounded with silicon detectors. The PIT includes an Atomic Beam Source (ABS), the target cell and a Breit-Rabi Polarimeter (BRP). The first phase of the Spin-Filtering Studies for PAX covers the commissioning of the PIT components and themeasurement of an absolute calibration standard for the BRP at the COSY ring in Jülich. The spin-filtering with protons aim at confirming the results of the FILTEX experiment and determine the pp hadronic spin dependent cross sections at 50MeV.The second phase will be realized in the Antiproton Decelerator ring (AD) at CERN to polarize antiprotons for the first time using spin-filtering. This diploma thesis summarizes aspects of the polarization and calibration theory based on the hyperfine structure of hydrogen and deuterium, provides the implemented algorithms necessary to solve the calibration and presents the results of the calibration of the BRP. Additionally, the atomic polarization of the hydrogen gas targetmeasuredwith a prototype openable storage cell is presented and the error analysis is discussed. The effect of the magnetic holding field on the hyperfine state occupancy is examined. Finally, the stability of the polarization between opening cycles of the storage cell and during an ABS nozzle cycle is presented.