Introduction – pp2pp physics program; Description of the experiment; Engineering run in 2002;

1. First Result from the pp2pp Experiment Włodek Gurynfor pp2pp collaborationBrookhaven National Laboratory, Upton, NY, USA Introduction – pp2pp physics program; Description of the experiment; Engineering run in 2002; Data analysis and results; Summary and outlook.

2. Total and Differential Cross Sections, and Polarization Effects in pp Elastic Scattering at RHIC S. Bueltmann, B. Chrien, A. Drees, R. Gill, W. Guryn*, I. H. Chiang, D. Lynn, C. Pearson, P. Pile, A. Rusek, M. Sakitt, S. Tepikian 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 Moscow Engineering Physics Institute (MEPHI), Moscow, Russia I. G. Alekseev, V. P. Kanavets, B. V. Morozov, D. N. Svirida ITEP, Moscow, Russia M. Rijssenbeek, C. Tang, S. Yeung SUNY Stony Brook, USA K. De, N. Guler, J. Li, N. Ozturk University of Texas at Arlington, USA A. Sandacz Institute for Nuclear Studies, Warsaw, Poland * spokesman Włodek Guryn

3. Absolute Polarimeter (H jet) RHIC pC Polarimeters BRAHMS & PP2PP (p) e ~12  10-6m after scraping PHENIX (p) STAR (p) Siberian Snakes Spin Rotators Partial Siberian Snake Pol. Proton Source 500 mA, 300 ms Strong AGS Snake 2  1011 Pol. Protons / Bunch e = 20 p mm mrad LINAC BOOSTER AGS 200 MeV Polarimeter AGS Internal Polarimeter Rf Dipoles AGS pC Polarimeters Polarized Proton Collisions in RHIC Włodek Guryn

4. p p p p p p P, O p p + + Pomeron(C=+1) Odderon(C=1) Proton - Proton Elastic Scattering Phenomenology pp2pp experiment studies the dynamics and spin dependence of hadronic interaction through proton-proton elastic scattering Vacuum QM exchanged Perturbative QCD Picture s = (p1 + p2 )2 = (C.M energy)2 t = (p1 – p3 )2 = - (four momentum transfer)2 s   t 1 (GeV/c)2 – Non-pertutrbative regime Elastic scattering ds/dt + optical theorem  total cross section stot Włodek Guryn

5. Highest energy so far: pp: 63 GeV (ISR) pp: 1.8 TeV (Tevatron) pp2pp energy range: 50 GeV  s  500 GeV pp2pp t-range: (at s = 500 GeV) 4•10–4 GeV2 |t|  1.3 GeV2 Summary of Existing Data M 50 500 PP2PP Włodek Guryn

6. PP2PP Physics program • RHIC has the UNIQUE capability for colliding POLARIZED proton beams, further elucidating the exchange dynamics: • Beam energy between 25 and 250 GeV; • Transverse polarization up to 70%; • Polarization can be chosen on a bunch-by-bunch basis (good for eliminating detection systematics!); • Allows to measure spin dependence of proton-proton elastic scattering • CNI region:  • 0.0004 < -t < 0.02 (GeV/c)2 √s = 200 GeV  • 0.0004 < -t < 0.13 (GeV/c)2 √s = 500 GeV  • stot, r, B, ds/dt, AN(t), ANN(t)   • Dstot = 300 mbarn (0.5%), Dr = 0.005 (4%), D AN(t), DANN(t) = 0.001 • Medium |t| region: • 0.02 < -t < 1.3 (GeV/c)2 √s = 500 GeV • diffractive minimum (peaks and bumps) and their spin dependence Design parameters Włodek Guryn

7. 8 π 2 π dσ σtot = Im [ Φ+(s,t ) ]t=0 = ( |Φ1|2 + |Φ2|2 + |Φ3|2 + |Φ4|2 | + 4|Φ5|2 ) s s 2 dt 8 π ΔσT = - Im [ Φ2(s,t ) ]t=0 = σ-σ s 8 π   ΔσL = Im [ Φ1(s,t ) - Φ3(s,t ) ]t=0 = σ-σ s Spin Physics with pp2pp Five helicity amplitudes describe proton-proton elastic scattering Φ1(s,t )  <++|M|++> Φ2(s,t )  <++|M|--> Φ3(s,t )  <+-|M|+-> Φ4(s,t )  <+-|M|-+> Φ5(s,t )  <++|M|+-> Φn(s,t )  <h3 h4 |M|h1 h2> with hx = s-channel helicity p1 = -p2 incoming protons p3 = -p4 scattered protons Φ+(s,t ) = ½ ( Φ1(s,t ) + Φ3(s,t ) ) Measure: Włodek Guryn

8. dN • N(t) = • = Azimuth Pblue = Beam Polarization dt Im [ Φ5* Φ+ ]  N (t) + N(t) -N (t) - N(t) 1 dσ / dt AN(t ) = Pbeam• cos N (t) +N(t) + N (t) + N(t) Spin Physics with pp2pp Single spin asymmetry AN arises in CNI region mainly from interference of hadronic non-flip amplitude with electromagnetic spin-flip amplitude pp2pp will measure t- later also s-dependence of: for small t Statistical Precision with 2002 data set ΔAN  0.02 N.H. Buttimore, B.Z. Kopeliovich, E. Leader, J. Soffer, T.L. Trueman, “The Spin Dependence of High-Energy Proton Scattering”, PRD 59, 114010 (1999) 2002 run pp2pp t-range Data from E704 (1993) Włodek Guryn

9. Beam transport equations relate measured position at detector to scattering angle x = a11 x0 +Leff θx Optimize so that a11 small andLeff large θx = a12 x0 + a22 θxx0 can be eliminated by measuring θx * * x : Position at Detector θx : Angle at Detector x0 : Position at Interaction Point θx : Scattering Angle at IP * Principle of 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 beam without breaking accelerator vacuum Similar equations for y-coordinate We found that because of the roll, misalignment, of the quadrupoles there is a mixing between x and y. Włodek Guryn

10. S. Tepikian Beam Transport pp2pp RP Position

11. = Actual transport: (x0, y0) not known also coupled because of the quad roll Yellow Blue Włodek Guryn

12. pp2pp Experimental Setup in Enginnering run 2002Elastic and Inelastic Detectors Włodek Guryn

13. Running Conditions in 2002 Running conditions during a pp2pp, 14 hour dedicated run: Beam momentum p = 100 GeV/c Number of bunches per beam NB = 55 used 35 bunches Beam scraped to emittance ε 12 π •10-6 m and intensity I 5•1011 protons in each beam Beam optics used β* = 10 m Beam polarization (working #) Pb= 0.24  0.02 Closest approach of first detector strip to beam about 15 mm  15 sbeam tmin = -4•10-3 GeV2 Collected ~1 million triggers of which >30 % are elastic events O. Jinnouchi Włodek Guryn

14. Włodek Guryn

15. Data Analysis: Collinearity Correlation plots of x- and y-coordinates using elastic triggers with reconstructed tracks of scattered protons Włodek Guryn

16. Hit Pattern and Transport Correction Distribution of y- vs. x-coordinate in sector 2 andθyvs. θx calculated using the beam transport, which includes the quadrupole roll Włodek Guryn

17. Beam Angular Divergence Good agreement between width of θx and θy distributions for measured and simulated events with emittance of: ε = 12 π •10-6 m And vertex size: sz = 70 cm Δθx  150 μrad Δθy  70 μrad Δθy Δθx N. Öztürk N. Öztürk Włodek Guryn

18. y x y x x y x y RP1 RP3 Silicon Microstrip Detector Efficiency First order efficiency calculated for combination of two x- or y-planes inside any given Roman Pot 14 out of 16 total silicon detectors have an average efficiency > 0.98 Detection efficiency for elastic arm A is almost 100% Arm A Włodek Guryn

19. Event Reconstruction • Elastic event: good track in two “opposite” set of detectors • SSD coordinate was calculated using energy weighted average of the position of the strips belonging to the isolated cluster of no more than three hits; • Correlation between tracks in two Roman Pots: require that (Dx2 + Dy2) be within “radius” : (Dx2 + Dy2) < 16 ( sx2+sy2 ); • At least six out of eight hits belong to the track; • No more than two planes with hits in “non” elastic arm; • Select events within uniform t-acceptance t-f cut. Włodek Guryn

20. t= - ( pbeam•θ )2 = azimuthal angle |t|--Acceptance Find region in |t|- and -space with full acceptance coverage and high statistics Event Sample 196,000 events: 159,250 events ( 0 < f < 180º ) 122,437 events ( 45º < f < 135º ) 58,511 events ( 45º < f < 135º ) & 0.010 GeV2  |t|  0.019 GeV2 ) Włodek Guryn

21. 4 p ( a GE2 ) 2 dN [ C = dt t2 Depends on detector position ( 1 + r 2 ) stot2 e+Bt + Depends on beam transport element positions 16 p ] + ( r + DF ) a GE2 stote+½Bt t Extracting Bfrom dN/dt-Distribution Fit |t|-distribution with B = (16.3  1.6 ) GeV-2 fixing stot = 51.6 mb and r = 0.13 and keeping B as a free parameter in range 0.010 GeV2  |t|  0.019 GeV2results in B = (16.3  1.6 ) GeV-2 Włodek Guryn

22. Systematic and Correlation Errors • Sytematic Errors were evaluated using Monte Carlo simulations: • Beam emmitence; • Vertex position spread in x, y, z; • Incoming beam angels – major source; • Beam transport uncertainty; • Total Systematic Error DB = 0.9 (Gev/c)-2 • Correlation between fitted parameter B and values of stot and r: • D stot = ±4 mb => DB = ±0.07 (Gev/c)-2 • D r = ±0.02 => DB = ±0.32 (Gev/c)-2 Włodek Guryn

23. RESULT B = 16.3 ± 1.6 (stat.) ± 0.9 (syst.) (Gev/c)-2 Analysis described here was done by S. Bültmann (BNL) An independent analysis by ITEP group agrees with result of S.B. Arm A Włodek Guryn

24. = pp2pp Experimental Setup in 2003Two RP stations on each side Measurement of angle and position at RP to solve for x0, y0 and scatt. angles will reduce systematic errors. Włodek Guryn

25. = Actual transport: (x0, y0) not known also coupled because of the quad roll Yellow Blue Włodek Guryn

26. PP2PP Future Plans • Equip two more Roman pot stations not to depend on vertex position ( in x0 and y0 ) in calculation of scattering angles; • Measure beam tune under pp2pp running conditions to reduce systematic uncertainty in beam transport calculation; • Include Van der Meer beam scans for luminosity determination; • Run longer to improve statistics in view of physics goals (and also systematic uncertainties) pp2pp will measure spin-dependent elastic proton-proton scattering in a new kinematic region probing large distance QCD (Pomeron, Odderon) 2003 – at √s = 200 GeV: stot, B, ds/dt, AN(t), ANN(t) 2004 – at √s = 500 GeV: stot, B, ds/dt, AN(t), ANN(t) 2005 – at √s = 500 GeV: B(t), ds/dt, diffractive minimum Exciting opportunities at RHIC for pp2pp over the next few years Włodek Guryn