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Misha Nekipelov, Kolya Nikolaev*, Frank Rathmann Institut für Kernphysik, Forschungszentrum Jülich

Spin Filtering in Storage Rings from a Theorists Perspective: Anno 2009. Misha Nekipelov, Kolya Nikolaev*, Frank Rathmann Institut für Kernphysik, Forschungszentrum Jülich *Landau Institute, Chernogolovka, Russia. DSPIN-2009, 1-5 September 2009, Dubna.

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Misha Nekipelov, Kolya Nikolaev*, Frank Rathmann Institut für Kernphysik, Forschungszentrum Jülich

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  1. Spin Filtering in Storage Rings from a Theorists Perspective: Anno 2009 Misha Nekipelov, Kolya Nikolaev*, Frank Rathmann Institut für Kernphysik, Forschungszentrum Jülich *Landau Institute, Chernogolovka, Russia DSPIN-2009, 1-5 September 2009, Dubna

  2. Even they were puzzled by spin… then A. Krish et al stormed the field N. Bohr  W. Pauli

  3. Why polarized antiprotons? • Quest for the transversity: the last missing leading twist SF of the proton • Without transversity the spin tomography of the proton will be ever incomplete • PAX at FAIR (E.Steffens‘ talk): double spin DY as a direct access to transversity, a unique successor to 4 decades of DIS physics • M.Anselmino et al: Encouraging signals from model-dependent extractions of transversity • Spin filtering: a unique way to HIGH LUMI double polarized proton-antiproton collider • Other ideas on how to polarize antiprotons?

  4. Long way to Tippereray: Dreams &Misconceptions & Enlightenment • 40 years of dreaming of polarized antiprotons • LEAR: missed opportunities • FILTEX! • Meyer & Horowitz: asking key questions • Rathmann et al.: immaculate conception of PAX misdriven by Meyer‘s interpretation of FILTEX • Milstein & Strakhovenko & NNN & Pavlov & infidels (Shatunov...): electrons are useless • Hoegel‘s dialectic spiral: backdoor e‘s Walcher et al. • 1st PAX expt at COSY: back to hadronic spin filtering for antiprotons

  5. What Could Happen to a Spin in a Polarized Internal Target? For an ensemble of spin ½ particles with projections +() and - ()

  6. Spin Filtering Anno 2004: betting on e‘s ~ 5 years ago, PAX proposed a method to polarize antiprotons by „spin-filtering“ Milstein & Strakhovenko & NNN & Pavlov: a no-go theorem

  7. Georg Christoph Lichtenberg (1742-1799) “Man muß etwas Neues machen, um etwas Neues zu sehen.” “You have to make something new, if you want to see something new”

  8. New ideas: spin flip in polarized e-cooler

  9. 10.1016/JNIMB.2008.04.010 No effect expected ! Confirmed by PAX-ANKE at COSY. The corollary: bet on hadronic spin filtering of anti-p‘s

  10. Antiproton-nucleon interactions: more in Nurushev‘s talk • A wealth of good data from LEAR • Nice measurements of single-spin asymmetries • No substantial data on double spin observables: only low statistics recoil proton polarization estimates • Ask theorists: Could the theory help?

  11. Good and not so good news from models: • A good news: All models „predict“ non-vanishing double spin observables • 10-20 percent polarization of filtered antiprotons is feasible • Not so good news: Predictions differ by factor 2-3 in magnitude and wildely regading the energy dependence: hence I omit slides • K. Adenauer: „Why should I care about that nonsense I promised yesterday?“ --- go to AD CERN and measure youself!

  12. Summary and oulook: • We possess a quantitative theory of spin-filtering & spin-flip phenomena in storage rings • Still it is prudent to check everything with protons at COSY where the theory is under tight control (SAID & Nijmegen databases) • The deuterium PIT must not be forgotten! • Antiprotons: neither solid theory no exptl database for double spin observables: do it yourself at AD CERN (PAX) • A consolation: still the models do “predict“ a nonvanishing filtering cross section and 10-20 per sent polarization of filtered antiprotons

  13. Georg Christoph Lichtenberg (1742-1799) “Man muß etwas Neues machen, um etwas Neues zu sehen.” “You have to make something new, if you want to see something new”

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