Experiment pp2pp at RHIC I.G. Alekseev for pp2pp Collaboration S. Bűeltmann, I. H. Chiang, B. Chrien, A. Drees, R. Gill, W. Guryn*, D. Lynn, C. Pearson, P. Pile, A. Rusek, M. Sakitt, S. Tepikian: Brookhaven National Laboratory, USA J. Chwastowski, B. Pawlik: Institute of Nuclear Physics, Cracow, Poland M. Haguenauer: Ecole Polytechnique/IN2P3-CNRS, Palaiseau, France A. A. Bogdanov, S.B. Nurushev, M.F Runtzo: Moscow Engineering Physics Institute (MEPHI), Moscow, Russia I. G. Alekseev, V. P. Kanavets, L.I. Koroleva, B. V. Morozov, D. N. Svirida: ITEP, Moscow, Russia M. Rijssenbeek, C. Tang, S. Yeung: SUNY Stony Brook, USA K. De, N. Guler, J. Li, N. Őztűrk: University of Texas at Arlington, USA A. Sandacz: Institute for Nuclear Studies, Warsaw, Poland *spokesperson

I.G. Alekseev (ITEP) 2 Main goal Measurement of pp elastic scattering in collider regime with UNIQUE capability due to polarized proton beams. Kinematical range: 50 <   s <500 GeV, 4 x <|t|<1.3 GeV 2 Measurement of pp elastic scattering in collider regime with UNIQUE capability due to polarized proton beams. Kinematical range: 50 <   s <500 GeV, 4 x <|t|<1.3 GeV 2 pp2pp Interference Term Coulomb Term Combined Term Nuclear Term pp2pp

I.G. Alekseev (ITEP) 3 Formulas Coulomb interaction Hadronic interaction Interference term |t | < 10 –3 GeV –3  |t |  1 GeV 2 (CNI) Helicity amplitudes: Ф   h 3 h 4  M(s,t)  h 1 h 2 , where h i  s- channel helicity of proton i Ф 1       no helicity flip, Ф 2       double helicity flip Ф 3       no helicity flip, Ф 4       double helicity flip Ф 5       single helicity flip, Frequently used: Ф  = (Ф 1  Ф 3 )  2, Ф  = (Ф 1  Ф 3 )  2 At small t: Coulomb interaction Hadronic interaction Interference term |t | < 10 –3 GeV –3  |t |  1 GeV 2 (CNI) Helicity amplitudes: Ф   h 3 h 4  M(s,t)  h 1 h 2 , where h i  s- channel helicity of proton i Ф 1       no helicity flip, Ф 2       double helicity flip Ф 3       no helicity flip, Ф 4       double helicity flip Ф 5       single helicity flip, Frequently used: Ф  = (Ф 1  Ф 3 )  2, Ф  = (Ф 1  Ф 3 )  2 At small t:

I.G. Alekseev (ITEP) 4 The AGS-RHIC complex pC polarimeters Siberian snakes

I.G. Alekseev (ITEP) 5 Experimental Idea MAIN IDEA  In colliding beam mode scattered proton follow trajectories determined by LATTICE of the collider because it has the same momentum as a beam proton and scattering angle is small.  The coordinates of scattered particles at the detector position with respect to the reference orbit are given by TRANSPORT EQUATION: Y  a 11 y   L eff   y y  is position of interaction vertex,   y is scattering angle OPTIMUM CONDITION --- ” PARALLEL to POINT FOCUSING” :  * =10m a 11   L eff - large y  L eff   y  * =20m MAIN IDEA  In colliding beam mode scattered proton follow trajectories determined by LATTICE of the collider because it has the same momentum as a beam proton and scattering angle is small.  The coordinates of scattered particles at the detector position with respect to the reference orbit are given by TRANSPORT EQUATION: Y  a 11 y   L eff   y y  is position of interaction vertex,   y is scattering angle OPTIMUM CONDITION --- ” PARALLEL to POINT FOCUSING” :  * =10m a 11   L eff - large y  L eff   y  * =20m RP1,3 RP2,4

I.G. Alekseev (ITEP) 6 Experimental Setup Need special tune of accelerator and detectors approaching the proton beams closely via Roman Pots to measure very small angles of elastically scattered protons Two pairs of silicon microstrip detectors measuring (x,y) coordinates with 100  m pitch plus one trigger scintillator per Roman Pot One Roman Pot above and below the beam for each Roman Pot Station to IR Roman Pot Station with Detectors ( used in 2002 and 2003 ) RP Station used in 2003 Roman Pot above beam Roman Pot below beam Inelastic Detectors: Four planes of scintillation counters on either side of Interaction Region (IR) detecting particles from inelastically scattered protons Stephen Bűltmann

I.G. Alekseev (ITEP) 7 Si Detector Package 4 planes of 400 µm Silicon microstrip detectors:  4.5 x 7.5 cm 2 sensitive area  good resolution, low occupancy  Redundancy: 2X- and 2Y-detectors  Closest proximity to the beam ~14 mm  8 mm trigger scintillator with two PMT readout behind Silicon planes Run 2003: new Silicon manufactured by Hamamatsu Photonics. 4 planes of 400 µm Silicon microstrip detectors:  4.5 x 7.5 cm 2 sensitive area  good resolution, low occupancy  Redundancy: 2X- and 2Y-detectors  Closest proximity to the beam ~14 mm  8 mm trigger scintillator with two PMT readout behind Silicon planes Run 2003: new Silicon manufactured by Hamamatsu Photonics. Trigger Scintillator Al strips: 512 (Y), 768 (X), 70µm wide 100 µm pitch implanted resistors bias ring guard ring 1 st strip  edge: 490 µm Si Detector board LV regulation Michael Rijssenbeek

I.G. Alekseev (ITEP) 8 New silicon readout (2003) New 4 channel sequencer to control SVXes was designed for run VME interface VIRTEX II Chain A Chain B Chain C Chain D Microprogram Data FIFO A Data FIFO B Data FIFO C Data FIFO D Timing logic VME logic LED indication TTL signals TriggerBunch028MHzBusy

I.G. Alekseev (ITEP) 9 Run summary Systematic error improvement in 2003 due to:  Excellent silicon detector efficiency;  Measurement of local angles with new Roman Pot stations;  Improved beam optics measurement;  Van der Meer beam scans for luminosity measurement. Systematic error improvement in 2003 due to:  Excellent silicon detector efficiency;  Measurement of local angles with new Roman Pot stations;  Improved beam optics measurement;  Van der Meer beam scans for luminosity measurement.

I.G. Alekseev (ITEP) 10 Engineering Run 2002: results Two completely independent data analysis gave similar results Result in this slide: arXiv:nucl-ex/  one arm: 58,511 elastic events;  fit with:  tot =51.6mb (A. Donnachie and P.V. Landshoff, 1992),  =0.13 (UA4/2 collab., 1993)  b=16.3±1.6(stat.) ±0.9(syst.) (GeV/c) -2 Two completely independent data analysis gave similar results Result in this slide: arXiv:nucl-ex/  one arm: 58,511 elastic events;  fit with:  tot =51.6mb (A. Donnachie and P.V. Landshoff, 1992),  =0.13 (UA4/2 collab., 1993)  b=16.3±1.6(stat.) ±0.9(syst.) (GeV/c) -2 Depends on detectors positions Depends on beam transport elements positions

I.G. Alekseev (ITEP) 11 Engineering Run 2002: results (cont.) Raw asymmetry and square root fromula: For both arms:  N /cos  =A N (P blue +P yellow )=0.016±0.007 using preliminary estimate: P blue =P yellow =0.24 ±0.10 For random bunch polarization pattern:  N fake /cos  =0.000±0.007 Raw asymmetry and square root fromula: For both arms:  N /cos  =A N (P blue +P yellow )=0.016±0.007 using preliminary estimate: P blue =P yellow =0.24 ±0.10 For random bunch polarization pattern:  N fake /cos  =0.000±0.007 A N = 0.033±0.018 Preliminary

I.G. Alekseev (ITEP) 12 Run 2003: detector performance Only 6 dead strips per active strips Average pedestal drift during the run Pedestal value variation Very large detectors efficiency Only 6 dead strips per active strips Average pedestal drift during the run Pedestal value variation Very large detectors efficiency

I.G. Alekseev (ITEP) 13 Conclusions and Plans Conclusions  A promising physics result for b and A N from engineering run 2002  Excellent silicon detector performance in physics run 2003  Good statistics obtained - waiting for physics results. New proposal for 2004 and beyond  Run with current setup (  tot, d  /dt, b, , A N, A NN )  * =20m, p beam =100 GeV/c  0.003<|t|<0.02(GeV/c) 2 ;  * =10m, p beam =250 GeV/c  0.025<|t|<0.12(GeV/c) 2.  Put Roman Pots between DX and D0 magnets (d  /dt, b, A N, A NN )  * =3m, p beam =250 GeV/c  0.2<|t|<1.3(GeV/c) 2.  * =3m, p beam =100 GeV/c  0.02<|t|<0.12(GeV/c) 2.  Upgrade RHIC quadrupoles power supply at our IP to run with  * =100m and move Roman Pots to 70m position (  tot, d  /dt, b, , A N, A NN )  * =100m, p beam =100 and 250 GeV/c  |t|- CNI region. Conclusions  A promising physics result for b and A N from engineering run 2002  Excellent silicon detector performance in physics run 2003  Good statistics obtained - waiting for physics results. New proposal for 2004 and beyond  Run with current setup (  tot, d  /dt, b, , A N, A NN )  * =20m, p beam =100 GeV/c  0.003<|t|<0.02(GeV/c) 2 ;  * =10m, p beam =250 GeV/c  0.025<|t|<0.12(GeV/c) 2.  Put Roman Pots between DX and D0 magnets (d  /dt, b, A N, A NN )  * =3m, p beam =250 GeV/c  0.2<|t|<1.3(GeV/c) 2.  * =3m, p beam =100 GeV/c  0.02<|t|<0.12(GeV/c) 2.  Upgrade RHIC quadrupoles power supply at our IP to run with  * =100m and move Roman Pots to 70m position (  tot, d  /dt, b, , A N, A NN )  * =100m, p beam =100 and 250 GeV/c  |t|- CNI region.