München 2006 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 3: Elektromagnetische und Hadronische Sonden

HK 3.1: Gruppenbericht

Montag, 20. März 2006, 14:00–14:30, G

PAX: How to polarized antiprotons and what to do with them — •Frank Rathmann — Institut für Kernphysik, Forschungszentrum Jülich

The PAX collaboration has proposed to produce polarized antiprotons at the new Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt, Germany. An intense beam of polarized antiprotons will provide access to a wealth of single and double spin observables, thereby opening a new window to QCD transverse spin physics. The proposed physics program includes a first measurement of the transversity distribution of the valence quarks in the proton, a test of the predicted opposite sign of the Sivers function, related to the quark distribution inside a transversely polarized nucleon, in Drell Yan (DY) as compared to semi inclusive Deep Inelastic Scattering, and a first measurement of the moduli and the relative phase of the time like electric and magnetic form factors G_E,M of the proton. Spin filtering to achieve the aspired goal has been shown to work already in the 1993 FILTEX test experiment. An interpretation of the result obtained there based solely on the hadronic interaction has recently been presented. Very recently, PAX has suggested to carry out spin filtering experiments with antiprotons at the AD ring at CERN to determine for the first time the two total spin dependent cross sections σ₁ and σ₂ at beam energies in the range from 50 to 200 MeV. These data will allow the definition of the optimum working parameters of a dedicated Antiproton Polarizer Ring for FAIR. Spin filtering tests at COSY are also foreseen to optimize the technique and to test the equipment for the AD experiments.