1/30/2016Douglas E. Fields for the p+C CNI collaboration 1 Test of Small Angle Elastic Proton-Carbon Scattering as a High Energy Proton Beam Polarimeter for RHIC G. Bunce, H. Huang, Y. Makdisi, T. Roser, M. Syphers Brookhaven National Laboratory, Upton, NY 11973, USA J. Doskow, K. Kwiatkowski, H.O. Meyer, B. v.Przewoski, T. Rinckel * Indiana University Cyclotron Facility, Bloomington, IN K. Imai Kyoto University/ RIKEN B. Bassalleck, L.L. Chavez, D.E. Fields *, K. Knight, R. Stotzer, T.L. Thomas, D. Wolfe University of New Mexico * Co-spokesmen  Motivation  Theory  Measurements  Experimental Apparatus  Beam Time Request

1/30/2016Douglas 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 (  G)  BUT: Need relative polarimeter for First Year commissioning !

1/30/2016Douglas 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.

1/30/2016Douglas E. Fields for the p+C CNI collaboration 4 Motivation p + C CNI polarimeter Pros  Inexpensive setup  Solid target  High figure of merit  Little energy dependence  Pol. vs. y possible Cons XDifficult Carbon recoil detection XNot absolute

1/30/2016Douglas E. Fields for the p+C CNI 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 )”

1/30/2016Douglas E. Fields for the p+C CNI collaboration 6 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 A N is large (~50%) But, at GeV, Hadronic A N ~ 0% Theory

1/30/2016Douglas E. Fields for the p+C CNI collaboration 7 CNI Analyzing Power

1/30/2016Douglas E. Fields for the p+C CNI collaboration 8 Measurements MeV p+ 12 C elastic, Tamii et al. AIP Conf. Proc. 339, page 395

1/30/2016Douglas E. Fields for the p+C CNI collaboration 9 Measurements 800 MeV p+p Pauletta et al. Physical Review C27 (1983)

1/30/2016Douglas E. Fields for the p+C CNI collaboration 10 Measurements pp elastic at 200GeV/c (E704) Physical Review D48 (1993) Curve has no hadronic spin flip

1/30/2016Douglas E. Fields for the p+C CNI collaboration 11 Experimental Setup Silicon array (4 - 3mm x 7mm, 12 cm from target) Channel Plate detector Electrostatic mirror Target (6  g/cm 2 x 20  m) u,v Chambers x,y Chambers

1/30/2016Douglas E. Fields for the p+C CNI collaboration 12 Experimental Setup Forward Proton Detector Nuclear Physics A539 (1992)

1/30/2016Douglas E. Fields for the p+C CNI collaboration 13 Experimental Setup Carbon Recoil Detector Silicon detectors Nuclear Instruments and Methods 171 (1980)

1/30/2016Douglas E. Fields for the p+C CNI collaboration 14 Kinematics

1/30/2016Douglas E. Fields for the p+C CNI collaboration 15 Kinematics

1/30/2016Douglas E. Fields for the p+C CNI collaboration 16 Kinematics

1/30/2016Douglas E. Fields for the p+C CNI collaboration 17 Kinematics

1/30/2016Douglas E. Fields for the p+C CNI collaboration 18 Beam Time Request  Beam current = 200  A  flux density = cm -2 s -1  luminosity = 2.6 x cm -2 s -1  cross section = 15 mb/sr at  p =20 deg 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 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.

1/30/2016Douglas E. Fields for the p+C CNI collaboration 19 Recoil Rates and Time Request

1/30/2016Douglas E. Fields for the p+C CNI collaboration 20 Beam Time Request

1/30/2016Douglas 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