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Motivation Theory Measurements Experimental Apparatus Beam Time Request

gretchen-morgan
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Motivation Theory Measurements Experimental Apparatus Beam Time Request

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  1. Test of Small Angle Elastic Proton-Carbon Scattering as a High Energy Proton Beam Polarimeter for RHICG. Bunce, H. Huang, Y. Makdisi, T. Roser, M. SyphersBrookhaven National Laboratory, Upton, NY 11973, USAJ. Doskow, K. Kwiatkowski, H.O. Meyer, B. v.Przewoski, T. Rinckel*Indiana University Cyclotron Facility, Bloomington, IN 47405K. ImaiKyoto University/ RIKENB. Bassalleck, L.L. Chavez, D.E. Fields*, K. Knight, R. Stotzer, T.L. Thomas, D. WolfeUniversity of New Mexico* Co-spokesmen • Motivation • Theory • Measurements • Experimental Apparatus • Beam Time Request Douglas E. Fields for the p+C CNI collaboration

  2. Motivation • RHIC schedule • First Year running Oct.’99 - Aug. ‘00 • Siberian Snakes installed • Spin Rotators not installed yet • Commissioning only, No 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 p+C CNI collaboration

  3. Motivation • Need fast relative and 5 % absolute polarimeter in RHIC • Polarimeter options: • Inclusive Pion production (Analyzing power measured by E704) • Polarimeter designed, but… • Expensive and Complex • May have smaller analyzing power due to Carbon target (vs. Hydrogen used by E704) • Other polarimeters are complex: • i.e. gas jet target, intense polarized electron beam, etc. Douglas E. Fields for the p+C CNI collaboration

  4. Pros Inexpensive setup Solid target High figure of merit Little energy dependence Pol. vs. y possible Cons Difficult Carbon recoil detection Not absolute Motivationp + C CNI polarimeter Douglas E. Fields for the p+C CNI 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 p+C CNI collaboration

  6. Theory CNI analyzing power is given by: so no direct energy dependence. At small |-t| values, the Hadronic analyzing power goes as At 200 MeV, Hadronic AN is large (~50%) But, at 25 - 250 GeV, Hadronic AN ~ 0% Douglas E. Fields for the p+C CNI collaboration

  7. CNI Analyzing Power Douglas E. Fields for the p+C CNI collaboration

  8. Measurements200-400 MeV p+12C elastic, Tamii et al.AIP Conf. Proc. 339, page 395 Douglas E. Fields for the p+C CNI collaboration

  9. Measurements800 MeV p+p Pauletta et al.Physical Review C27 (1983) 282-295. Douglas E. Fields for the p+C CNI collaboration

  10. Measurementspp elastic at 200GeV/c (E704)Physical Review D48 (1993) 3026-3036. Curve has no hadronic spin flip Douglas E. Fields for the p+C CNI collaboration

  11. u,v Chambers Experimental Setup Silicon array (4 - 3mm x 7mm, 12 cm from target) Channel Plate detector Electrostatic mirror Target (6mg/cm2 x 20mm) x,y Chambers Douglas E. Fields for the p+C CNI collaboration

  12. Experimental SetupForward Proton Detector Nuclear Physics A539 (1992) 633-661. Douglas E. Fields for the p+C CNI collaboration

  13. Experimental SetupCarbon Recoil Detector Silicon detectors Nuclear Instruments and Methods 171 (1980) 71-74. Douglas E. Fields for the p+C CNI collaboration

  14. Kinematics Douglas E. Fields for the p+C CNI collaboration

  15. Kinematics Douglas E. Fields for the p+C CNI collaboration

  16. Kinematics Douglas E. Fields for the p+C CNI collaboration

  17. Kinematics Douglas E. Fields for the p+C CNI collaboration

  18. Beam Time Request • Beam current = 200 mA • flux density = 1.8 1016 cm-2 s-1 • luminosity = 2.6 x 1030 cm-2 s-1 • cross section = 15 mb/sr at qp=20 deg - 400 mb/sr at 6 deg • count rate for each of the 8 angle bins is then 4.5 kHz • adjust luminosity to 3.5 x 1028 cm-2 s-1 • the data rate at the largest angle of interest is 10 Hz • statistical accuracy of better than 1% can be carried out in about one hour • From the above, we conclude that the time for actual data taking under various conditions will be of the order of 5-6 shifts. Douglas E. Fields for the p+C CNI collaboration

  19. Recoil Rates and Time Request Douglas E. Fields for the p+C CNI collaboration

  20. Beam Time Request Douglas E. Fields for the p+C CNI collaboration

  21. Beam Time Request • 5 shifts beam preparation, electronics adjustments, target manipulation, general overhead • 6 shifts data acquisition at 200 MeV • 6 shifts data acquisition at 450 MeV • Total = 17 shifts Douglas E. Fields for the p+C CNI collaboration

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