OUTLINE of the TALK Where we left off? What is different in Run 2003? How analysis is done?

1. Status of Run 2003 Analysis of pp2pp Experiment Włodek Gurynfor pp2pp collaborationBrookhaven National Laboratory, Upton, NY, USA OUTLINE of the TALK Where we left off? What is different in Run 2003? How analysis is done? Where do we stand? What are the questions? Where do we go from here?

2. 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 Where we left off: Forward slope B measurement (SB) Phys. Lett. B 579 (2004) 245-250 Fit |t|-distribution with B = (16.3  1.6  1. ) GeV-2 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.) GeV-2

3. Preliminary Preliminary Im [ Φ5* Φ+ ]  for small t N (t) + N(t) -N (t) - N(t) 1 dσ / dt AN(t ) = Pbeam• cos N (t) +N(t) + N (t) + N(t) Fit N/cos =0.016 ± 0.007 f /cos = 0.000 ± 0.007 Where we left off: AN (SB) Single spin asymmetry AN arises in CNI region mainly from interference of hadronic non-flip amplitude with electromagnetic spin-flip amplitude Raw Asymmetry False Asymmetry

4. = 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

5. The pp2pp Experimental Setup

6. What’s new in Run 2003

7. Elastic event analysis ITEP Moscow and Krakow/BNL • ANALYSIS FOSCUS of ANALYSIS IS NOW ON UNDERSTANDING SYSTEMATIC EFFECTS • Pedestal value, pedestal width (s) and dead channels are determined. • Valid hit is dE/dx with 4s above pedestal; • Cluster size is  6 consecutive strips above pedestal cut; • Elastic events are reconstructed using correlations of hits and track reconstruction (ITEP;) • Clean events, one hit per plane in four RPs are used for full reconstruction, offsets calculation, (x0,y0) (Krakow/BNL); • Clean events with one hit per plane in RP1 and RP3 for dN/dt distributions, to get large statistics. • Show 1/3 of the data

8. Elastic Events Hit Distribution ITEP

9. Elastic Events x-x, y-y corerlations (ITEP)

10. Elastic Events: Krakow/BNL Angular correlation

11. Elastic Events: Krakow/BNL

12. Elastic event analysis Krakow/BNL (cut effects on 1/3 data)

13. No acc. corrections made Status of run 2003 analysis (SB) x-y correlations dN/dt (not corrected)

14. Summary • We have a very clean data set, very few dead or noisy channels: • Excellent silicon detection efficiency; • Measurement of local angles with new RPs allows reconstruction of (x0,y0). • Because of less scraping –tmin is not as small as in the Engineering Run, it is not a problem for B or AN. • Given good data sample we have, the systematic errors are very important to determine. • We need more information from the accelerator about the transport, non-linear transport is being calculated, to do off-axis tracking. • We will use data to cross check the transport. • Van der Meer scans will be used to determine luminosity.

15. Yellow Blue Summary continued Knowledge of beam transport, including off-axis, is crucial to improve systematic error Stay tuned for the next RSC meeting and the RHIC/AGS users meeting