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409. WE-Heraeus-Seminar: Polarized Antiprotons
No full textGreat 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
PAX - Polarized Antiproton Experiments
No full textThe PAX Collaboration, is proposing to study the producation and subsequent utilization of the first intense beam of polarized antiprtons
Perspectives for Polarized Antiprotons
No full textOne of the most challenging aspects of hadron physics is represented by the proton spin and its interpretation in terms of its internal constituents. The issue rose dramatically in the late 1980s when the European Muon Collaboration (EMC) conducted experiments suggesting that, contrary to the naive expectation, the spin carried by quarks is only a small fraction of the total spin of the proton. The problem of where the missing spin lies is referred to as the “proton spin crisis.” Although more than twenty years have passed since these first pioneering experiments, during which our theoretical and experimental knowledge have enormously deepened, the proton-spin has not yet revealed all of its mystery
The Road towards Polarized Antiprotons
No full textThe PAX-Collaboration is pursuing studies to find a method for producing an intense beam of polarized antiprotons. The following write-up gives a physics motivation, the possible methods and previous tests that have been performed. Currently spin-filtering in a suitable storage ring is the only viable method to achieve this goal. PAX has recently performed a spin-filtering measurement with protons in the COSY storage ring at Forschungszentrum Jülich (Germany) as a step towards an experiment with antiprotons, planned at CERN/AD. An outlook is also given as to what the possibility would be for exploiting a polarized antiproton beam in HESR at FAIR. All of the issues are discussed in a concise way – for more details the reader is referred to the
given references
Measurement of the depolarizing p(pol)e cross section using co-moving electrons
No full textUnderstanding the inteplay of the nuclear interaction with the polarized (anti) protons and the electromagnetic interaction interaction with polarized electrons in polarized atoms is crucial to the progress towards the PAX goal to eventually produce stored polarized antiprotons beams in FAIR. The PAX Collaboration proposes a series of dedicated experiments in the COSY ring to solve this ambiguity
ANKE/PAX Workshop on Spin Physics - 29 may - 1 june IUSS Ferrara 2007
No full textWorkshop of the collaboration ANKE and future plan for the project PAX
2nd Caucasian-German School and Workshop on Hadron Physic
No full textThe Conference has been held in Tbilisi, Georgia from September 4-8, 2006. The workshop mainly covered two aspects: 1. SPIN PHYSICS FROM COSY TO FAIR covering the current research activities and the physics program at COSY-Juelich, using the existing ANKE and TOF experiments, and the new WASA detector. 2. HADRON PHYSICS WITH POLARIZED ANTIPROTONS addressing the QCD physics part of the upcoming FAIR facility at GSI, Darmstadt, and the production of polarized antiprotons. The meeting was held at the Tbilisi State University, Tbilisi, Georgia, where in 2004 we already had a very successful and exciting meeting, that mostly covered aspects of HADRON PHYSICS AT COSY. We wanted to attract also students to our field, therefore a number of Lectures has been given along with specialized talk
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