1. Thomas Roser Snowmass 2001 June 30 - July 21, 2001 Proton Polarimetry Proton polarimeter reactions RHIC polarimeters

2. Proton polarimeters for circulating beams p + C  p + XGood FOM at low energy (< 3GeV) [COSY] p + p  p + p (t ~ 0.15 GeV 2 ) Good FOM up to ~ 20 GeV [AGS] Plastic target: intensity beams limited p + C   + X (x~0.5,pt~0.5 GeV)Good FOM at high energy Requires large spectrometer p + p  p + p (t ~ 0.001 GeV 2 ) Good FOM at all energies [RHIC abs. pol.] Jet target: low luminosity Pol. H jet: absolute polarimeter p + C  p + C (t ~ 0.001 GeV 2 ) Good FOM at all energies [RHIC rel. pol.] Carbon target: high luminosity Good and fast relative polarimeter

3. BRAHMS & PP2PP (p) STAR (p) PHENIX (p) AGS LINAC BOOSTER Polarized proton collisions in RHIC Pol. Proton Source 500  A, 300  s Spin Rotators Partial Siberian Snake Siberian Snakes 200 MeV Polarimeter AGS Internal Polarimeter Rf Dipoles RHIC pC Polarimeters Absolute Polarimeter (H jet) 2  10 11 Pol. Protons / Bunch  = 20  mm mrad

4. Proton polarization at the AGS Full spin flip at all imperfection resonances using partial Siberian snake Full spin flip at strong intrinsic resonances using rf dipole Remaining polarization loss from coupling and weak intrinsic resonances New tune working point and smaller horizontal emittance will reduce polarization loss

5. Proton-Carbon CNI Polarimeter (AGS E950) l 2-3% energy independent analyzing power for small-angle elastic scattering in the Coulomb-Nuclear Interference (CNI) region l Slow recoil Carbon detected in between bunch crossings l Fiber target allows for polarization profile measurement Ultra-thin Carbon ribbon approx. 100 atomic layers thick Polarized Proton Beam Forward proton Recoil Carbon, 100 … 800 keV Silicon detector Carbon Target OutTarget In ADC distribution TDC distribution

6. 4 Large cross section 4 Simple equipment 4 Weak energy dependence of the asymmetry 4 Fast measurement 4 Small influence on the beam by the target 8Small analyzing power (1-4)% 8No precise theoretical predictions Elastic scattering in small t region (0.002<t<0.05) (GeV/c) 2 Physical asymmetry (cancels acceptance and luminosity asymmetries)

7. Carbon foil (3.7  g/cm 2 ) Electrostatic mirror Carbon ribbon target (3.7  g/cm 2, 6  m) Silicon strip detector (6  4 mm) 1 cm AGS internal beam:  5·10 9 p/bunch 1 bunch in the ring: 2.7  s between bunches Bunch length  25 ns 22 GeV Polarization  40% DAQ: LeCroy FERA ADC 4300 LeCroy 2367 as FERA memory IBM/PC with Linux Readout between spills Dead time 15  s per event A RIKEN BNL Research Center Workshop E950 setup

8. A RIKEN BNL Research Center Workshop E950 results A RIKEN BNL Research Center Workshop A=0.00533  0.00027  2 /N df ~ 1

9. RHIC year-0 detector set-up 15 cm Thin carbon target ~ 5  g/sm 2  10  m; Horizontal and vertical targets; 4 Detectors 12strips  2 mm; Strips in vertical direction; Trigger as ‘or’ of all strips; DAQ with LeCroy FERA 4300 ADC/TDC; Dead time ~ 10  s per event + 1.5s per 40000 events; 6-bunch mode; Upto 5  10 10 p/bunch; About 10 5 carbon events/min; Carbon identification by time of flight/energy dependence: E, keV -t (GeV/c) 2 T, ns 1000.0022118 2000.004584 5000.011253 10000.022337 20000.044627 1 2 3 4 112 blue ring

10. A RIKEN BNL Research Center Workshop Data A RIKEN BNL Research Center Workshop C  Carbon over strips distribution

11. A RIKEN BNL Research Center Workshop Energy calibration A RIKEN BNL Research Center Workshop Energy calibration of the detector by the time of flight Agreement with the Tandem test at 10МэВ ~ 10%  -peak М  4. Elastic cone slope is in a good agreement with the theoretical predictions

12. A RIKEN BNL Research Center Workshop Results with p  A RIKEN BNL Research Center Workshop Sign changed Zero polarization from the source Statistically significant asymmetry Right correlation with beam changes Small systematic errors The first nonzero measurement A=0.00203±0.00021 Beam polarization ~20%

13. Commissioning with a single snake in RHIC snake polarimeter -12º G  = 46.5 or 55.7 G  = 48 or 60.3 Inject vertically pol. beam with snake off Turn on snake  Horizontally pol. beam Accelerate

14. RHIC year-1 configuration 6 1 34 25 15 cm 1 6 43 52 blue ringyellow ring Shaper WFD CAMAC PC Si Preamp. 12 Si detectors. one event per bunch crossing all channels have independent WFD readout. zero dead time. 72

16. Polarized proton injection into RHIC Sensitive to betatron tune setting y = 29.11 Injection at G  = 46.5 without snake: vertical polarization! y = 29.23

17. Snake operating points Single snake RUN2000 B1 = B2 Two snakes for RUN2001

18. Acceleration with single snake G  =46.5 G  =48.0 G  =55.7 G  =60.3

19. Measured RHIC asymmetries Asymmetry (  10 -3 ) GG P  19 % P  40 % at AGS 24.325.129.131.5 GeV

20. Test of WFD t e Carbon MIPs Fast particles 1 WFD module, 4 channels Common trigger Everything read to PC off-line event reconstruction

21. Polarized Hydrogen Jet Target l pC polarimeter is used as fast relative polarization monitor and was calibrated in AGS at 22 GeV to about 15 %. l Polarized hydrogen jet target allows for absolute beam polarization measurement: l Jet target thickness of 3  10 11 cm -2 achievable (HERMES, PINTEX, NIKHEF) l Jet polarization measurable to better than 3% using Stern- Gerlach method l Collaboration started with Wisconsin, IUCF, and Amsterdam Pol. H jet target at Bates from NIKHEF

22. Summary l RHIC proton polarimeter successfully tested l Efficient relative and absolute high energy proton polarimetry possible