Great interest in the community of hadron physicists has been raised by the recent proposal of the PAX Collaboration to perform experiments using a polarized antiproton beam at the future facility FAIR at Darmstadt. The availability of a beam of polarized antiprotons would allow us to access for the first time a wealth of fundamental physics observables. One of the most important is the so-called transversity, the distribution of the transverse polarized quarks in a transversely polarized nucleon, which is directly measurable by means of the double-spin asymmetry in the production of Drell-Yan pairs in double-polarized proton-antiproton interactions. Other unique measurements address the determination of the phase of the electromagnetic form factors in the time-like region and scattering observables in double polarized hard proton-antiproton reactions. A necessary preliminary step for these experiments is the production of an intense beam of polarized antiprotons. At the moment the most promising technique to polarize antiprotons is the "spin-filtering" technique. Spin-filtering exploits the spin dependence of the interaction between an initially unpolarized proton (or antiproton) beam stored in a storage ring and a polarized internal hydrogen target. The proof of principle of the technique has been carried out with a proton beam stored in the TSR ring in Heidelberg more than ten years ago. The interpretation of the result is at the moment under discussion. In order to gain a full understanding of the spin-filtering technique, a series of experiments must be carried out at the COSY storage ring in Jülich with protons and at the AD storage ring at CERN with antiprotons.

409. WE-Heraeus-Seminar: Polarized Antiprotons

LENISA, Paolo;
2008

Abstract

Great interest in the community of hadron physicists has been raised by the recent proposal of the PAX Collaboration to perform experiments using a polarized antiproton beam at the future facility FAIR at Darmstadt. The availability of a beam of polarized antiprotons would allow us to access for the first time a wealth of fundamental physics observables. One of the most important is the so-called transversity, the distribution of the transverse polarized quarks in a transversely polarized nucleon, which is directly measurable by means of the double-spin asymmetry in the production of Drell-Yan pairs in double-polarized proton-antiproton interactions. Other unique measurements address the determination of the phase of the electromagnetic form factors in the time-like region and scattering observables in double polarized hard proton-antiproton reactions. A necessary preliminary step for these experiments is the production of an intense beam of polarized antiprotons. At the moment the most promising technique to polarize antiprotons is the "spin-filtering" technique. Spin-filtering exploits the spin dependence of the interaction between an initially unpolarized proton (or antiproton) beam stored in a storage ring and a polarized internal hydrogen target. The proof of principle of the technique has been carried out with a proton beam stored in the TSR ring in Heidelberg more than ten years ago. The interpretation of the result is at the moment under discussion. In order to gain a full understanding of the spin-filtering technique, a series of experiments must be carried out at the COSY storage ring in Jülich with protons and at the AD storage ring at CERN with antiprotons.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/532157
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