The First Measurement of the Elastic pp-Scattering Spin Parameters at  s=200 GeV V. P. Kanavets for pp2pp Collaboration S. Bűeltmann, I. H. Chiang, B. Chrien, A. Drees, R. Gill, W. Guryn*, D. Lynn, J. Landgraf, T.A. Ljubičič, C. Pearson, P. Pile, A. Rusek, M. Sakitt, S. Tepikian, K. Yip: Brookhaven National Laboratory, USA J. Chwastowski, B. Pawlik: Institute of Nuclear Physics, Cracow, Poland M. Haguenauer: Ecole Polytechnique/IN2P3-CNRS, Palaiseau, France A. A. Bogdanov, S.B. Nurushev, M.F Runtzo, M.N.Strikhanov: Moscow Engineering Physics Institute (MEPHI), Moscow, Russia I. G. Alekseev, V. P. Kanavets, L.I. Koroleva, B. V. Morozov, D. N. Svirida: ITEP, Moscow, Russia A.Khodinov, M. Rijssenbeek, L. Whithead, S. Yeung: SUNY Stony Brook, USA K. De, N. Guler, J. Li, N. Őztűrk: University of Texas at Arlington, USA A. Sandacz: Institute for Nuclear Studies, Warsaw, Poland *spokesperson IX WORKSHOP ON HIGH ENERGY SPIN PHYSICS, Dubna, September 27 - October 1, 2005

Vadim Kanavets (ITEP) for pp2pp 2 Helicity amplitudes for spin ½ ½ → ½ ½ Matrix elements: Useful notations: Formalism is well developed, however not much data ! At high energy only A N measured to some extent. Matrix elements: Useful notations: Formalism is well developed, however not much data ! At high energy only A N measured to some extent. spin non–flip double spin flip spin non–flip double spin flip single spin flip Observables: cross sections and spin asymmetries also A SL, A LL

Vadim Kanavets (ITEP) for pp2pp 3 Polarized cross-sections and spin parameters - single spin asymmetry.   - cross-section for one beam fully polarized along normal to the scattering plane. - double spin asymmetry.   +  - cross-section for both beams fully polarized along the unit vector normal to the scattering plane. A SS has the same definition as A NN, but   +  is a cross-section for both beams fully polarized along the unit vector in the scattering plane along axis :, where - beam momentum. Cross-section azimutual angular dependence for transversely polarized beams: - blue beam polarization vector - yellow beam polarization vector - single spin asymmetry.   - cross-section for one beam fully polarized along normal to the scattering plane. - double spin asymmetry.   +  - cross-section for both beams fully polarized along the unit vector normal to the scattering plane. A SS has the same definition as A NN, but   +  is a cross-section for both beams fully polarized along the unit vector in the scattering plane along axis :, where - beam momentum. Cross-section azimutual angular dependence for transversely polarized beams: - blue beam polarization vector - yellow beam polarization vector

Vadim Kanavets (ITEP) for pp2pp 4 A N & Coulomb nuclear interference The left – right scattering asymmetry A N arises from the interference of the spin non-flip amplitude with the spin flip amplitude (Schwinger) In absence of hadronic spin – flip Contributions A N is exactly calculable (Kopeliovich & Lapidus) Hadronic spin- flip modifies the QED ‘predictions’. Hadronic spin-flip is usually parametrized as: The left – right scattering asymmetry A N arises from the interference of the spin non-flip amplitude with the spin flip amplitude (Schwinger) In absence of hadronic spin – flip Contributions A N is exactly calculable (Kopeliovich & Lapidus) Hadronic spin- flip modifies the QED ‘predictions’. Hadronic spin-flip is usually parametrized as:  1) p  pp tot needed phenomenological input: σ tot, ρ, δ (diff. of Coulomb-hadronic phases), also for nuclear targets em. and had. formfactors

Vadim Kanavets (ITEP) for pp2pp 5 A N measurements in the CNI region pp Analyzing Power no hadronic spin-flip p = 200 GeV/c PRD48(93)3026 pC Analyzing Power with hadonic spin-flip no hadronic spin-flip Re r 5 =  Im r 5 =   highly anti-correlated p = 21.7 GeV/c PRL89(02)052302

Vadim Kanavets (ITEP) for pp2pp 6 RHIC-Spin accelerator complex BRAHMS & PP2PP STAR PHENIX AGS LINAC BOOSTER Pol. Proton Source Spin Rotators 20% Snake Siberian Snakes 200 MeV polarimeterAGS quasi-elastic polarimeter Rf Dipoles RHIC pC “CNI” polarimeters PHOBOS RHIC absolute pH polarimeter Siberian Snakes AGS pC “CNI” polarimeter 5% Snake RP3,4 RP1,2

Vadim Kanavets (ITEP) for pp2pp 7 The setup of PP2PP

Vadim Kanavets (ITEP) for pp2pp 8 Principle of the measurement Elastically scattered protons have very small scattering angle θ *, hence beam transport magnets determine trajectory scattered protons The optimal position for the detectors is where scattered protons are well separated from beam protons Need Roman Pot to measure scattered protons close to the beam without breaking accelerator vacuum Beam transport equations relate measured position at the detector to scattering angle. x 0, y 0 : Position at Interaction Point Θ* x, Θ* y : Scattering Angle at IP x D, y D : Position at Detector Θ x D, Θ y D : Angle at Detector =

Vadim Kanavets (ITEP) for pp2pp 9 Si detector package 4 planes of 400 µm Silicon microstrip detectors:  4.5 x 7.5 cm 2 sensitive area;  8 mm trigger scintillator with two PMT readout behind Silicon planes. Run 2003: new Silicon manufactured by Hamamatsu Photonics. Only 6 dead strips per active strips. 4 planes of 400 µm Silicon microstrip detectors:  4.5 x 7.5 cm 2 sensitive area;  8 mm trigger scintillator with two PMT readout behind Silicon planes. Run 2003: new Silicon manufactured by Hamamatsu Photonics. Only 6 dead strips per active strips. Trigger Scintillator Al strips: 512 (Y), 768 (X), 50µm wide 100 µm pitch implanted resistors bias ring guard ring 1 st strip  edge: 490 µm Si Detector board LV regulation Michael Rijssenbeek SVX chips

Vadim Kanavets (ITEP) for pp2pp 10 Hit selection Landau fit

Vadim Kanavets (ITEP) for pp2pp 11 Elastic events selection Hit correlations before the cuts Note: the background appears enhanced because of the “saturation” of the main band Only inner roman pots were used. “OR” of X and Y silicon pairs in each roman pot was used. A match of hit coordinates (x,y) from detectors on the opposite sides of the IP was required to be within 3  for x and y-coordinate. The hit coordinates (x,y) of the candidate proton pairs were also required to be in the acceptance area of the detector. If there were more than one match between the hits on opposite sides of the IP the following algorithm was applied: if there is only one match with number of hits equal to 4, it is the "elastic event track". If there is no match with 4 hits or there are more than one such match, the event is rejected. Elastic events loss < 3.5%

Vadim Kanavets (ITEP) for pp2pp 12 Elastic events X Y

Vadim Kanavets (ITEP) for pp2pp 13 Calculation of asymmetry A N Polarized crossection for both beams polarized vertically: Square root formula: where Beam polarization: (P B +P Y ) ++/-- = 0.88±0.12, (P B - P Y ) +-/-+ = -0.05±0.05 Crosscheck:  ` N (predicted)  (P B - P Y ) +-/-+ A N    ` N (measured)= ±0.0023

Vadim Kanavets (ITEP) for pp2pp 14 Single spin asymmetry A N |t|-range, (GeV/c) 2, (GeV/c) 2 ANAN  stat Arm A Arm B PRELIMINARY Statistical errors only Raw asymmetry  N for 0.01<|t|<0.03 (GeV/c) 2 Sources of systematic errors background4.5% beam positions at the detectors 1.8% corrections to the standard transport matrices 1.4% uncertainties on L x eff and L y eff 6.4% neglected term with double- spin asymmetries 2.8% All above8.4% Beam polarization error (systematic 13% + statistical) 14.4%14.4% nucl-ex/

Vadim Kanavets (ITEP) for pp2pp 15 A N from PP2PP Preliminary Only statistical errors shown No hadronic spin flip

Vadim Kanavets (ITEP) for pp2pp 16 Fit r 5 where t c = -8πα / σ tot κ is anomalous magnetic moment of the proton N. H. Buttimore et. al. Phys. Rev. D59, (1999) Only statistical errors shown Re r 5 = ± Im r 5 = ± 0.56 PRELIMINARY no hadronic spin flip our fit

Vadim Kanavets (ITEP) for pp2pp 17 Effect of uncertainty of the beam polarization Re r 5 = -0.06±0.04 Im r 5 = ±0.68   (pol.)   (pol.) PRELIMINARY Re r 5 = -0.02±0.03 Im r 5 = ±0.51

Vadim Kanavets (ITEP) for pp2pp 18 Calculation of double spin asymmetries External normalization using the machine bunch intensities: L ij ~  I i B ·I j Y on bunches with given i,j combination Raw asymmetry: E.Leader, T.L.Trueman “The Odderon and spin dependence of high-energy proton- proton scattering”, PR D61, (2000)  2 /  + =0.05(1+i)           i

Vadim Kanavets (ITEP) for pp2pp 19 A NN and A SS from pp2pp |t|-range, (GeV/c) 2, (GeV/c) 2 A SS  Ass (stat.) A NN  Ann (stat.)  2 /n /20 Statistical errors only PRELIMINARY P B ·P Y =0.19±0.05  Distributions in the arms A and B are averaged  Distributions  (  ) were fitted with (P 1 ·sin 2  + P 2 ·cos 2  ) P 1 =P B ·P Y ·A SS P 2 =P B ·P Y ·A NN

Vadim Kanavets (ITEP) for pp2pp 20 Conclusions and plans Conclusions  The first measurement of A N at collider energy: √s=200 GeV, small t;  A N is more than 10  different from 0;  A N systematically ≈ 1σ above CNI curve with no hadronic spin-flip;  The first measurement of A NN and A SS at collider energies. What is next ?  Rotate RP1,3 (full acceptance over  !) and move to STAR IP (spin rotators !!)  (  tot, d  /dt, b, , A N, A NN, A SS, A LL, A LS ):  * =20m, p beam =100 GeV/c  0.003<|t|<0.02(GeV/c) 2 ;  * =10m, p beam =250 GeV/c  0.025<|t|<0.12(GeV/c) 2. Conclusions  The first measurement of A N at collider energy: √s=200 GeV, small t;  A N is more than 10  different from 0;  A N systematically ≈ 1σ above CNI curve with no hadronic spin-flip;  The first measurement of A NN and A SS at collider energies. What is next ?  Rotate RP1,3 (full acceptance over  !) and move to STAR IP (spin rotators !!)  (  tot, d  /dt, b, , A N, A NN, A SS, A LL, A LS ):  * =20m, p beam =100 GeV/c  0.003<|t|<0.02(GeV/c) 2 ;  * =10m, p beam =250 GeV/c  0.025<|t|<0.12(GeV/c) 2.

Vadim Kanavets (ITEP) for pp2pp 21 Rotating RP1 and RP3  s (GeV) ** |t|-range (Gev/c) 2 Typical errors m0.003 < |t| < 0.02  B = 0.3,  tot = 2 – 3 mb  = and  A N =0.002  A NN =  A SS =0.005 With IPM and kicker Full acceptance at  s 200 GeV Without IPM and kicker