A CNI Polarimeter for RHIC Spin Results from IUCF CE75 & AGS E950

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 Kyoto University/ RIKEN 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 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 Yale University *RIKEN/BNL Research Center Douglas 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 Douglas 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 (DG) • BUT: Need relative polarimeter for First Year commissioning ! Douglas E. Fields for the E950 Collaboration

4. Pros Inexpensive setup Solid target High figure of merit Little energy dependence Polarization profile Cons Difficult Carbon recoil detection Not absolute Motivationp + C CNI polarimeter Douglas E. Fields for the E950 Collaboration

5. Theoryp+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<<ao)”. Douglas E. Fields for the E950 Collaboration

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

7. q Theory p k q=p-k pp 12C pC t = -q2 E950 900keV 450keV Douglas E. Fields for the E950 Collaboration

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

9. Initial tests - IUCF CE75 Douglas E. Fields for the E950 Collaboration

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

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

13. Initial tests - Kyoto Douglas E. Fields for the E950 Collaboration

14. Kyoto Results • Could resolve down to 200keV Carbon recoils. Douglas E. Fields for the E950 Collaboration

15. AGS E950 Experimental Setup Douglas E. Fields for the E950 Collaboration

16. AGS E950 Experimental Setup TOF measurement Micro ribbon Carbon target MCP MCP e e C Silicon strip detector Carbon foil 0 13 25 cm Energy measurement Douglas E. Fields for the E950 Collaboration

17. Targets • Carbon Ribbons • 6mm wide • 3.7mg/cm2 thick • 3cm long Douglas E. Fields for the E950 Collaboration

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

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

21. E950 Analysis • 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 . Si only Si -MCP s=2.5ns s=7.5ns Projection along the profile Douglas E. Fields for the E950 Collaboration

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

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

24. RHIC Polarimeter Preliminary Design Douglas E. Fields for the E950 Collaboration

25. RHIC Polarimeter Preliminary Design Douglas E. Fields for the E950 Collaboration