Misha Nekipelov, Kolya Nikolaev*, Frank Rathmann Institut fr Kernphysik, Forschungszentrum Jlich *Landau Institute, Chernogolovka, Russia Spin Filtering in Storage Rings from a Theorists Perspective: Anno 2009 DSPIN-2009, 1-5 September 2009, Dubna 2 W. Pauli N. Bohr Even they were puzzled by spin then A. Krish et al stormed the field 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 Meyers interpretation of FILTEX Milstein & Strakhovenko & NNN & Pavlov & infidels (Shatunov...): electrons are useless Hoegels dialectic spiral: backdoor es 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 particles with projections + ( ) and - ( ) 6 7 8 9 10 11 12 Spin Filtering Anno 2004: betting on es ~ 5 years ago, PAX proposed a method to polarize antiprotons by spin-filtering Milstein & Strakhovenko & NNN & Pavlov: a no-go theorem 13 14 15 16 17 18 19 20 Georg Christoph Lichtenberg ( ) Man mu etwas Neues machen, um etwas Neues zu sehen. You have to make something new, if you want to see something new 21 New ideas: spin flip in polarized e-cooler 22 No effect expected ! Confirmed by PAX-ANKE at COSY. The corollary: bet on hadronic spin filtering of anti-ps /JNIMB 23 Antiproton-nucleon interactions: more in Nurushevs 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? 24 25 Good and not so good news from models: A good news: All models predict non-vanishing double spin observables 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! 26 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 per sent polarization of filtered antiprotons 27 Georg Christoph Lichtenberg ( ) Man mu etwas Neues machen, um etwas Neues zu sehen. You have to make something new, if you want to see something new 28