Results from the PP2PP Experiment at RHIC and Future Plans

1. Results from the PP2PP Experiment at RHIC and Future Plans Włodek GurynBrookhaven National Laboratory, Upton, NY, USA OUTLINE of the TALK Description of the experiment Description of analysis Results and interpretation Future plans with STAR

2. The Relativistic Heavy Ion Collider RHIC is a QCD Laboratory: Nucleus- Nucleus collisions (AuAu, CuCu…); Asym. Nucl. (dAu); Polarized proton-proton;eRHIC - Future

3. RHIC pp accelerator complex RHIC pC “CNI” polarimeters absolute pH polarimeter BRAHMS & PP2PP PHOBOS RHIC Siberian Snakes PHENIX STAR Siberian Snakes Spin Rotators 5% Snake LINAC BOOSTER AGS quasi-elastic polarimeter Pol. Proton Source AGS AGS pC “CNI” polarimeter 200 MeV polarimeter Rf Dipoles 20% Snake

4. Total and Differential Cross Sections, and Polarization Effects in pp Elastic Scattering at RHIC S. Bültmann, I. H. Chiang, R.E. Chrien, A. Drees, R. Gill, W. Guryn*, J. Landgraf, T.A. Ljubičič, D. Lynn, 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 S. Khodinov, M. Rijssenbeek, L. Whitehead, 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

5. p3 p1 p p p p ? Vacuum QM exchanged p p P, O p p p2 p4 Perturbative QCD Picture + + Pomeron(C=+1) Odderon(C=1) Process of Elastic Scattering s = (p1 + p2 )2 = (C.M energy)2 t = (p1 – p3 )2 = - (four momentum transfer)2 s   t 1 (GeV/c)2 – Non-perturbative regime Elastic scattering ds/dt + optical theorem  total cross section stot

6. One cannot assume that because of the existence of the models, the data in pp at the ISR, and pp data at SppS and the Tevatron one can predict with sufficient accuracy ds/dt and stot in the RHIC s range. 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 the Existing Data(unpolarized) 50 500 M PP2PP

7. 4 p ( a GE2 ) 2 dN [ Depends on detector position C = B = (16.3  1.6  1. ) GeV-2 dt t2 Depends on beam transport element positions ( 1 + r 2 ) stot2 e+Bt + 16 p ] + ( r + DF ) a GE2 stote+½Bt t PP2PP Forward slope B from 2002 engineering run Phys. Lett. B 579 (2004) 245-250 Fit |t|-distribution with Using fits to world data of stot = 51.6 mb and r = 0.13 Fit B for 0.010 GeV2  |t|  0.019 GeV2 B = (16.3  1.6  1.0) GeV-2

8. Cross-section, azimutual angular dependence for transversely polarized beams, with polarizations PB and Py: Cross sections for polarized beams

9. Helicity Amplitudes in Elastic Scattering Five helicity amplitudes describe proton-proton elastic scattering Some of the measured quantities are:

10. AN (t) Source of single spin analyzing power AN Single spin asymmetry AN arises in the CNI region is due to the interference of hadronic non-flip amplitude with electromagnetic spin-flip amplitude. Any difference from the above is an indication if other contributions, hadronic spin flip caused by resonance (Reggeon) or vacuum exchange (Pomeron) contributions. B. Z. Kopeliovich and L. I. Lapidus Sov. J. Nucl. Phys. 114 (19) 1974 N. H. Buttimore, B. Z. Kopeliovich, E. Leader, J. Soffer, T. L. Trueman, Phys. Rev. D59, (1999) 114010.

11. PublishedANMeasurements in the CNI Region pC Analyzing Power E950@BNL p = 21.7 GeV/c PRL89(02)052302 pp Analyzing Power E704@FNAL p = 200 GeV/c PRD48(93)3026 no hadronic spin-flip with hadonic spin-flip AN(%) no hadronic spin-flip r5pCµ Fshad / Im F0had Re r5 = 0.088 ± 0.058 Im r5 = -0.161 ± 0.226 highly anti-correlated -t

12. Asymmetry “False” Asymmetry Experimental Determination of AN Use Square-Root-Formulato calculate spin ( ,  ) and false asymmetries (,  ) . Since the above is a relative measurement the efficiencies (t, f) cancel

13. = 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. x0,y0: Position at Interaction Point Θ*x Θ*y : Scattering Angle at IP xD, yD : Position at Detector ΘxD, ΘyD : Angle at Detector

14. The Setup

15. The PP2PP Experimental Setup Roman Pot above the beam to IR Roman Pot below the beam

16. Si Detector board Signal/noise  20 SVXIIE LV regulation Al strips: 512 (Y), 768 (X), 70µm wide100 µm pitch Si Detector Package implanted resistors • 4 planes of 400 µm Silicon microstrip detectors: • 4.5 x 7.5 cm2 sensitive area • good resolution, low occupancy • Redundancy: 2X- and 2Y-detectors • Closest proximity to the beam ~14 mm • 8 mm trigger scintillator with two PMT readout behind Silicon planes • Run 2003: Silicon manufactured by Hamamatsu bias ring guard ring 1st stripedge: 490 µm

17. Acceptance beam pipe shadow Trigger Active area Only “inner” pots used for trigger and analysis, biggest acceptance Analyze the data for the closest position (¾ of all data)

18. An elastic event has two collinear protons, one on each side of IP • It also has eight Si detector “hits”, four on each side. • Clean trigger: no hits in the other arm and in inelastic counters. • The vertex in (z0) can be reconstructed using ToF. Elastic Event Identification

19. Hit Correlations Before the CutsEvents with only eight hits Note: the background appears enhanced because of the “saturation” of the main band It is due mainly to beam halo and beam-gas interactions Width is mainly due to beam emittance ε= 15 πmm ·mrad spread of vertex position σz = 60 cm Afterthe cuts the background in the final sample is ≈ 0.5% ÷2% depending on y (vertical) coordinate

20. Elastic Event Selection Match of coordinates on opposite sides of IP; within 3σfor x and y coordinates. Hit coordinates to be in the acceptance area of the detector. Events with multiple matches were excluded. After the cuts 1.14 million elastic events in t-interval [0.010, 0.030] (GeV/c)2 Loss of elastic events due to the selections < 0.035

21. s(DQx) = 130 mrad s(DQx) = 100 mrad s(DQy) = 70 mrad Collinearity:DQx before and after z-correction, and DQy

22. Asymmetry Determination of AN • Use Square-Root-Formulato calculate raw asymmetries. • It cancels cancel luminosity dependence and effects of apparatus asymmetries. • It uses ,  bunch combinations. Since AN is a relative measurement the efficiencies (t, f) cancel

23. PB (+-,-+)=0.430  0.089 PY(+-,-+)=0.476 0.085 N Statistical errors Arm AArm B Results: Full bin 0.01 < -t < 0.03 (GeV/c)2 Fit N cos(j) dependence to obtain AN PB (++,--)=0.532  0.106 PY(++,--)=0.345  0.066 PB + PY= 0.8770.149 Note: The calculated false asymmetry F= -0.0011 is consistent with measured F= -0.0016

24. Systematic Errors on AN

25. Determination of r5 for pp→pp in the CNI Region where tc = -8πα/ σtot and κ is anomalous magnetic moment of the proton The fit to measuredAN(t) gives Re r5 , Im r5

26. Results: AN and r5 Re r5 = -0.042 ± 0.037 , Im r5 = -0.51 ± 0.60 Statistical and systematic errors added in quadratures 17.0% normalisation error due to beam polarisation uncertainty, not included

27. stat + sys errors used in fits AN: RHIC Polarized Jet Target s =14 GevA. Bravar, Dubna , Sept. 29, 2005 with hadronic spin-flip Im r5 = 0.002 ±0.029 Re r5 = -0.006 ± 0.007 2/ndf = 10 / 12 preliminary • uncertainty on the • (Dr = ±0.03) parameter can change at the same level hadronic spin – flip contribution consistent with zero (1 s level)

28. Cross-section, azimutual angular dependence for transversely polarized beams, with polarizations PB and Py: Reminder: Cross sections for polarized beams

29. Statistical errors only PRELIMINARY Calculation of double spin asymmetries Raw asymmetry: Luminosity normalization is done using: The machine bunch intensities:Lij~IiB·IjY over bunches with given i,j combination The inelastic counters The two methods agreed. Distributions () were fitted with (P1·sin2+ P2·cos2) where P1=PB·PY·ASS and P2=PB·PY·ANN

30. f2/f+=0.05(1+i) f2/f+=0.05 f2/f+=0.05i T.L. Trueman Odderon Searches at RHIC Workshop Sept. 2005 Results: ANN and ASS E.Leader, T.L. Trueman PRD 61 077504 (2000)

31. p p p p In t-channel it is an exchange with quantum numbers of vacuum p p p p p p p p Non Pert. QCD PQCD picture Future Program: PP2PP and STARPhysics Processes I

32. Gluon Ladders Gluonic Exchanges Physics Processes II These processes are mediated by gloun rich exchanges

33. Elastic and Inelastic Processes For each proton vertex one has t four-momentum transfer p/p MXinvariant mass In terms of QCD, Pomeron exchange consists of the exchange of a color singlet combination of gluons. Hence, triggering on forward protons at high (RHIC) energies predominantly selects exchanges mediated by gluonic matter.

34. Central Production in DPE In the double Pomeron exchange process each proton “emits” a Pomeron and the two Pomerons interact producing a massive system MX. The massive system could form resonances or consist of jet pairs. Because of the constraints provided by the double Pomeron interaction, glueballs, and other states coupling preferentially to gluons, will be produced with much reduced backgrounds compared to standard hadronic production processes.

35. STAR Detector Time Projection Chamber: 45 padrow, 2 meters (radius), s(dE/dx)8%, -1<<1 Multi-gap Resistive Plate Chamber TOFr: 1 tray (~1/200), s(t)=85ps

36. STAR TPC: -1.0 <  < 1.0 FTPC: 2.8 <  < 3.8 FPD: ||  3.8 (p+p) ||  4.0 (p+p, d+Au) STAR Detector • Forward  Detector (FPD) • Pb-glass EM calorimeter • Shower-Maximum Detector (SMD) • Preshower

37. TPC dE/dx at low pT M. Anderson et al., Nucl. Instrum. Meth. A 499, 659 (2003)

38. Resonance Signal in p+p and Au+Au collisions from STAR p+p  p+p Au+Au (1385) K(892) Au+Au p+p D++ p+p (1020) p+p (1520) Au+Au Au+Au

39. Charged hadron pT distributions measured up to 12 GeV in Au+Au, d+Au and p+p reference Leading particle spectra`

40. Roman Pots of pp2pp and STAR Implementation at RHIC Need detectors to tag forward protons and detector with good acceptance and particle ID to measure central system

41. Physics with Tagged Forward Protons with the STAR Detector at RHIC H. Spinka Argonne National Laboratory, USA R.E. Chrien, R. Gill, W. Guryn*, B. Hackenburg, J. Landgraf, T.A. Ljubičič, D. Lynn, C. Pearson, P. Pile, S. Tepikian, K. Yip Brookhaven National Laboratory, USA A. A. Bogdanov, S.B. Nurushev, M.F Runtzo 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 B. Surrow MIT, Boston USA S. Khodinov, M. Rijssenbeek SUNY Stony Brook, USA A.Sandacz Soltan Institue for Nuclear Studies, Warsaw, Poland *Contact person E-mail guryn@bnl.gov Phone (631) 344 3878

42. Two protons are detected Single proton in the Roman Pot Acceptance Studies SDD and DPE

43. Summary • We have measured the single spin analyzing power AN in polarized pp elastic scattering at s = 200 GeV, highest to date, in t-range [0.01,0.03] (GeV/c)2. • The AN is  4-5s from zero. • The AN is  s away from a CNI curve, which does not have hadronic spin flip amplitude. • In order to understand better underlying dynamics one needs to map s and t-dependence of AN and also measure other spin related variables (ANN, ASS, ALL, ASL). • Preliminary result on ANN, ASS has been obtained. • The program of elastic scattering measurements will continue by joining STAR experiment.

44. Summary The physics program of tagged forward protons with STAR at RHIC can: • Study standard hadron diffraction both elastic and inelastic and its spin dependence in unexplored t and s range; • Study the structure of color singlet exchange in the non-perturbative regime of QCD. • Search for central production of light and massive systems in double Pomeron exchange process - glueballs. • Search for an Odderon - an eigenstate of CGC. • At RHIC II one would take advantage of smaller TPC, include more coverage to better characterize rapidity gaps. Those studies will add to our understanding of QCD in the non-perturbative regime where calculations are not easy and one has to be guided by measurements. There is a great potential for important discoveries

45. dN/dt x-y Full acceptance at s 200 GeV Without IPM and kicker With IPM and kicker Future Possibility – Big Improvement

46. AN & Coulomb Nuclear Interference the left – right scattering asymmetry AN arises from the interference of the spin non-flip amplitude with the spin flip amplitude (Schwinger) in absence of hadronic spin – flip contributions AN is exactly calculable (Kopeliovich & Lapidus) hadronic spin- flip modifies the QED ‘predictions’ hadronic spin-flip usually parametrized as µ(m-1)pµspphad needed phenomenological input: σtot, ρ, δ (diff. of Coulomb-hadronic phases),also for nuclear targets em. and had. formfactors

47. 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 ppCollider at RHIC

48. Hit selection in Si detectors

49. Two protons are detected Acceptance Study DPE

50. Reconstruction of the Momentum Loss  Need to measure vector at the detection point, hence two RPs are needed on each side of STAR. For a proton, which scatters with  and  we have:  Accelerator transport