1. 7/30/99Douglas E. Fields for the E950 Collaboration 1 A CNI Polarimeter for RHIC Spin Results from IUCF CE75 & AGS E950 M. Bai, G. Bunce*, H. Huang, Y. Makdisi, T. Roser, A. Rusek, M. Syphers Brookhaven National Laboratory K. Imai*, M. Nakamura, J. Tojo, K. Yamamoto, L. Zhu K. Imai*, M. Nakamura, J. Tojo, K. Yamamoto, L. Zhu Kyoto University/ RIKEN B. Bassalleck, S. Eilerts, D.E. Fields, B. Lewis, B. Smith, T.L. Thomas B. Bassalleck, S. Eilerts, D.E. Fields, B. Lewis, B. Smith, T.L. Thomas University of New Mexico Y. Goto, M. Ishihara*, K. Kurita*, N. Saito*, A. Taketani RIKEN D. Underwood D. Underwood Argonne National Laboratory J. Doskow, K. Kwiatkowski, B. Lozowski, H.O. Meyer, B. v. Przewoski, T. Rinckel Indiana University Cyclotron Facility I. Alekseev, D. Svirida, V.Kanavets ITEP A. Deshpande, V. Hughes A. Deshpande, V. Hughes Yale University *RIKEN/BNL Research Center

2. 7/30/99Douglas E. Fields for the E950 Collaboration 2 A CNI Polarimeter for RHIC Spin Results from IUCF CE75 & AGS E950 →Motivation for CNI Polarimeter →CNI Theoretical Status →Initial tests - IUCF CE75 and Kyoto tests →AGS E950 Experimental Setup →E950 Analysis →E950 Results →RHIC Polarimeter Preliminary Design

3. 7/30/99Douglas E. Fields for the E950 Collaboration 3 Motivation  RHIC schedule  First Year running Oct.’99 - Aug. ‘00  Siberian Snakes installed  Spin Rotators not installed yet  Commissioning only, No Spin Physics  Second Year running Oct. ‘00 - Aug. ‘01  Spin rotators installed  Higher (Blue Book) Luminosity  Good Physics (  G)  BUT: Need relative polarimeter for First Year commissioning !

4. 7/30/99Douglas E. Fields for the E950 Collaboration 4 Motivation p + C CNI polarimeter Pros  Inexpensive setup  Solid target  High figure of merit  Little energy dependence  Polarization profile Cons XDifficult Carbon recoil detection XNot absolute

5. 7/30/99Douglas E. Fields for the E950 Collaboration 5 Theory p+C Coulomb Nuclear Interference CNI is an interference effect between the purely Coulombic spin-flip term and the hadronic non spin-flip term in the scattering potential. For the interference term to be important, the scattering must take place “outside of the nucleus (r>>R), but well within the screening radius of the atomic electrons (r<<a o )”.

6. 7/30/99Douglas E. Fields for the E950 Collaboration 6 CNI analyzing power is given by: so no direct energy dependence. At 25 - 250 GeV, Hadronic A N is thought to be <10% of the CNI A N. Theory

7. 7/30/99Douglas E. Fields for the E950 Collaboration 7 Theory 900keV pp pC E950 450keV q p k q=p-k t = -q 2 12 C

8. 7/30/99Douglas E. Fields for the E950 Collaboration 8 Measurements pp elastic at 200GeV/c (E704) Physical Review D48 (1993) 3026-3036. Curve has no hadronic spin flip.

9. 7/30/99Douglas E. Fields for the E950 Collaboration 9 Initial tests - IUCF CE75

10. 7/30/99Douglas E. Fields for the E950 Collaboration 10 CE75 Silicon Two standard Silicon detectors around 90 o. Off-the-shelf on- board pre-amps. Cooled FET’s and silicons.

11. 7/30/99Douglas E. Fields for the E950 Collaboration 11 IUCF CE75 Results Red points are for detector closer to 90 o. So, green points (more forward detector) have higher Carbon energy. Matches predicted angle vs. energy. ~200KeV threshold.

12. 7/30/99Douglas E. Fields for the E950 Collaboration 12 Silicon Detector Re-design 12 Channel 6 channel. On-board pre-amps. Cooled by mount. Silicon Detector Pre-amp location

13. 7/30/99Douglas E. Fields for the E950 Collaboration 13 Initial tests - Kyoto

14. 7/30/99Douglas E. Fields for the E950 Collaboration 14 Kyoto Results Could resolve down to 200keV Carbon recoils.

15. 7/30/99Douglas E. Fields for the E950 Collaboration 15 AGS E950 Experimental Setup

16. 7/30/99Douglas E. Fields for the E950 Collaboration 16 AGS E950 Experimental Setup ee MCP Silicon strip detector C Micro ribbon Carbon target 013 Carbon foil Energy measurement TOF measurement 25 cm

17. 7/30/99Douglas E. Fields for the E950 Collaboration 17 Targets Carbon Ribbons 6  m wide 3.7  g/cm 2 thick 3cm long

18. 7/30/99Douglas E. Fields for the E950 Collaboration 18 Micro-Channel-Plate Detectors Mirror MCP Si PC board Mirror Silicon Repeller Accelerator C foil e-e- 12 C MCP

19. 7/30/99Douglas E. Fields for the E950 Collaboration 19 Data Acquisition Read out events at end of spill. Home made Linux based acquisition. On-line analysis capable.

20. 7/30/99Douglas E. Fields for the E950 Collaboration 20 E950 On-line Analysis Carbon Target OutTarget In ADC distribution TDC distribution Target out configuration still had a frame. Rate was sensitive to beam position.

21. 7/30/99Douglas E. Fields for the E950 Collaboration 21 E950 Analysis Si only Si -MCP s=7.5ns s=2.5ns Projection along the profile Bunch width was ~25ns. TDC start was beam RF. Inherent 7.2ns width from beam bunches. Using Si - MCP gives inherent Si time resolution of 2.5ns.

22. 7/30/99Douglas E. Fields for the E950 Collaboration 22 E950 Analysis TDC Values (ns) 4 sigma cut 6 time bins prompt Carbon band ADC values(ch) Since E calibration not good (yet), use time slices to get -t bins.

23. 7/30/99Douglas E. Fields for the E950 Collaboration 23 E950 Results Time bins Asymmetry Error bars are statistical only Follows general trend expected. Not yet absolute (at any scale). -t

24. 7/30/99Douglas E. Fields for the E950 Collaboration 24 RHIC Polarimeter Preliminary Design

25. 7/30/99Douglas E. Fields for the E950 Collaboration 25 RHIC Polarimeter Preliminary Design