Experiment pp2pp at RHIC

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Experiment pp2pp at RHIC

• I.G. Alekseev for pp2pp Collaboration

S. Bueltmann, 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. Ozturk University of Texas at Arlington,
USA A. Sandacz Institute for Nuclear Studies,
Warsaw, Poland spokesperson
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Main goal

• Measurement of pp elastic scattering in collider
  regime with UNIQUE capability due to polarized
  proton beams.
• Kinematical range 50 ltÖ-s lt500 GeV, 4 x
  10-4lttlt1.3 GeV2

pp2pp
pp2pp 2002-03
Nuclear Term
Combined Term
Coulomb Term
Interference Term
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Formulas

• Coulomb interaction Hadronic
  interaction Interference term
• t lt 103 GeV2 5103
  ? t ? 1 GeV2 (CNI)
• Helicity amplitudes
• ? ? ?h3h4 ?M(s,t)? h1h2 ? , where hi ? s-
  channel helicity of proton i
• ?1 ? ? ?? ??? ?? ? no helicity flip, ?2 ? ? ??
  ??? ?? ? double helicity flip
• ?3 ? ? ?? ??? ?? ? no helicity flip, ?4 ? ? ??
  ??? ?? ? double helicity flip
• ?5 ? ? ?? ??? ?? ? single helicity flip,
• Frequently used ?? (?1 ? ?3)?2, ?? (?1 ?
  ?3)?2
• At small t

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The AGS-RHIC complex
pC polarimeters
Siberian snakes
Siberian snakes
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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 ? a11 y?? Leff ??y
• y? is position of interaction vertex, ??y is
  scattering angle
• OPTIMUM CONDITION --- PARALLEL to POINT
  FOCUSING
• ?10m
• a11 ? ?
• Leff - large y ? Leff ??y
• ?20m

RP1,3
RP2,4
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Experimental Setup
Roman Pot Station with Detectors ( used in 2002
and 2003 )
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 mm
pitch plus one trigger scintillator per Roman
Pot One Roman Pot above and below the beam for
each Roman Pot Station
Roman Pot above beam
RP Station used in 2003
to IR
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 Bultmann
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Si Detector Package
Al strips 512 (Y), 768 (X), 70µm wide100 µm
pitch

• 4 planes of 400 µm Silicon microstrip detectors
• 4.5 x 7.5 cm2 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.

implanted resistors
bias ring
Trigger Scintillator
guard ring
Si
Detector board
1st strip?edge 490 µm
LV regulation
Michael Rijssenbeek
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New silicon readout (2003)

• New 4 channel sequencer to control SVXes was
  designed for run 2003.

VME interface
VIRTEX II
Chain A
Data FIFO A
Chain B
Data FIFO B
Data FIFO C
Data FIFO D
Chain C
Chain D
Microprogram
VME logic
LED indication
Timing logic
TTL signals
Bunch0
28MHz
Trigger
Busy
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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.

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Engineering Run 2002 results

• Two completely independent data analysis gave
  similar results
• Result in this slide arXivnucl-ex/0305012.
• one arm 58,511 elastic events
• fit with ?tot51.6mb (A. Donnachie and P.V.
  Landshoff, 1992), ?0.13 (UA4/2 collab., 1993)
• b16.31.6(stat.) 0.9(syst.) (GeV/c)-2

Depends on beam transport elements positions
Depends on detectors positions
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Engineering Run 2002 results (cont.)

• Raw asymmetry and square root fromula
• For both arms
• ?N/cos?AN(PbluePyellow)0.0160.007
• using preliminary estimate
• PbluePyellow0.24 0.10
• For random bunch polarization pattern
• ?Nfake/cos?0.0000.007

Preliminary
AN 0.0330.018
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Run 2003 detector performance

• Only 6 dead strips per 14112 active strips
• Average pedestal drift during the run 0.05-0.2
• Pedestal value variation 2.5-3.0
• Very large detectors efficiency

• Preliminary

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Conclusions and Plans

• Conclusions
• A promising physics result for b and AN 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, ?, AN,
  ANN)
• ?20m, pbeam100 GeV/c ? 0.003lttlt0.02(GeV/c)2
• ?10m, pbeam250 GeV/c ? 0.025lttlt0.12(GeV/c)2.
• Put Roman Pots between DX and D0 magnets (d?/dt,
  b, AN, ANN)
• ?3m, pbeam250 GeV/c ? 0.2lttlt1.3(GeV/c)2.
• ?3m, pbeam100 GeV/c ? 0.02lttlt0.12(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, ?, AN, ANN)
• ?100m, pbeam100 and 250 GeV/c ? t- CNI
  region.