First%20Result%20from%20the%20pp2pp%20Experiment%20Wlodek%20Guryn%20for%20pp2pp%20collaboration%20Brookhaven%20National%20Laboratory,%20Upton,%20NY,%20USA - PowerPoint PPT Presentation

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Brookhaven National Laboratory, Upton, NY, USA. Introduction ... BRAHMS & PP2PP (p) STAR (p) PHENIX (p) AGS. LINAC. BOOSTER. Pol. Proton Source. 500 mA, 300 ms ... – PowerPoint PPT presentation

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Title: First%20Result%20from%20the%20pp2pp%20Experiment%20Wlodek%20Guryn%20for%20pp2pp%20collaboration%20Brookhaven%20National%20Laboratory,%20Upton,%20NY,%20USA

First Result from the pp2pp Experiment Wlodek
Guryn for pp2pp collaboration Brookhaven
National Laboratory, Upton, NY, USA
  • Introduction pp2pp physics program
  • Description of the experiment
  • Engineering run in 2002
  • Data analysis and results
  • Summary and outlook.

Total and Differential Cross Sections, and
Polarization Effects in pp Elastic Scattering at
  • S. Bueltmann, B. Chrien, A. Drees, R. Gill, W.
    Guryn, I. H. Chiang, 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, M. N.
  • 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

Polarized Proton Collisions in RHIC
PP2PP Physics program
  • RHIC has the UNIQUE capability for colliding
    POLARIZED proton beams, further elucidating the
    exchange dynamics
  • Beam energy between 25 and 250 GeV
  • Transverse polarization up to 70
  • Polarization can be chosen on a bunch-by-bunch
    basis (good for eliminating detection
  • Allows to measure spin dependence of
    proton-proton elastic scattering
  • CNI region 
  • 0.0004 lt -t lt 0.02 (GeV/c)2 vs 200 GeV 
  • 0.0004 lt -t lt 0.13 (GeV/c)2 vs 500 GeV 
  • stot, r, B, ds/dt, AN(t), ANN(t)  
  • Dstot 600 mbarn (1), Dr 0.005 (4), D
    AN(t), DANN(t) 0.001 
  • Medium t region  
  • 0.02 lt -t lt 1.3 (GeV/c)2 vs 500 GeV
  • diffractive minimum (peaks and bumps) and their
    spin dependence   

Design parameters
pp2pp experiment studies the dynamics and spin
dependence of hadronic interaction through
proton-proton elastic scattering
Perturbative QCD Picture
s (p1 p2 )2 (C.M energy)2 t (p1
p3 )2 - (four momentum transfer)2 s ? ? ?t?? 1
(GeV/c)2 Non-perturbative regime Elastic
scattering ds/dt optical theorem ? total cross
section stot
Summary of Existing Data
Principle of Measurement

Elastically scattered protons have very small
scattering angle ?, hence beam transport magnets
determine trajectory scattered protons The
optimal position for the detectors is where
scattered protons are well separated from beam
protons Need Roman Pot to measure scattered
protons close to beam without breaking
accelerator vacuum
Beam transport equations relate measured
position at detector to scattering angle
x a11 x0 Leff ?x ? Optimize so
that a11 small and Leff large ?x
a12 x0 a22 ?x ? x0 can be eliminated
by measuring ?x
Similar equations for y-coordinate We found that
because of the roll, misalignment, of the
quadrupoles there is a mixing between x and y.
pp2pp Experimental Setup in Engineering run
2002 Elastic and Inelastic Detectors
Running Conditions in 2002
Running conditions during a pp2pp, 14 hour
dedicated run Beam momentum
p 100 GeV/c Number of bunches per beam NB
55 used 35 bunches Beam scraped to
emittance e ? 12 p 10-6 m
and intensity I ? 51011 protons
in each beam Beam optics used
ß 10 m Beam polarization (working )
Pb 0.24 ? 0.02 Closest approach of first
detector strip to beam about 15 mm ?
15 sbeam ? tmin -410-3 GeV2 Collected 1
million triggers of which gt30 are elastic events
Data Analysis Colinearity
Correlation plots of x- and y-coordinates using
elastic triggers with reconstructed tracks of
scattered protons
Beam Angular Divergence
Good agreement between width of ?x and ?y
distributions for measured and simulated events
with emittance of e 12 p 10-6 m And
vertex size sz 70 cm ??x ? 150
µrad ??y ? 70 µrad
N. Öztürk
N. Öztürk
Event Reconstruction
  • Elastic event good track in two opposite set
    of detectors
  • SSD coordinate was calculated using energy
    weighted average of the position of the strips
    belonging to the isolated cluster of no more than
    three hits
  • Correlation between tracks in two Roman Pots

    require that (Dx2 Dy2) be within radius
    (Dx2 Dy2) lt 16 ( sx2 sy2 )
  • At least six out of eight hits belong to the
  • No more than two planes with hits in non
    elastic arm
  • Select events within uniform t-acceptance t-f cut.

t -?-Acceptance
Find region in t - and ?-space with full
acceptance coverage and high statistics
Event Sample 196,000 events 159,250 events (
0 lt f lt 180º ) 122,437 events ( 45º lt f lt 135º
) 58,511 events ( 45º lt f lt 135º ) 0.010
GeV2 ? t ? 0.019 GeV2 )
Extracting B from dN/dt-Distribution
Fit t -distribution with
B ( 16.3 ? 1.6 ) GeV-2
fixing stot 51.6 mb and r 0.13 and keeping B
as a free parameter in range 0.010 GeV2 ? t
? 0.019 GeV2 results in B ( 16.3 ?
1.6 ) GeV-2
Systematic and Correlation Errors
  • Systematic Errors were evaluated using Monte
    Carlo simulations
  • Beam emmitence
  • Vertex position spread in x, y, z
  • Incoming beam angels major source
  • Beam transport uncertainty
  • Total Systematic Error DB 0.9
  • Correlation between fitted parameter B and values
    of stot and r
  • D stot 4 mb gt DB / 0.07 (GeV/c)-2
  • D r 0.02 gt DB 0.32 (GeV/c)-2

b 16.3 1.6 (stat.) 0.9 (syst.) (GeV/c)-2
Analysis done by two independent groups is in
DonnachieLandshoff OPE Model
Bourrely, Soffer, Wu
Single spin asymmetry AN arises in CNI region
mainly from interference of hadronic non-flip
amplitude with electromagnetic spin-flip
Running Conditions 2002-03
  • Systematic error improvement in 2003 due to
  • Excellent silicon detector efficiency
  • Measurement of local angles with new Roman Pot
  • Improved beam optics measurement
  • Van der Meer beam scans for luminosity

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
  • New proposal for 2004 and beyond (to be
    considered by PAC Sept 29, 2003)
  • Run with current setup (?tot, d?/dt, b, ?, AN,
  • ?20 m, pbeam100 GeV/c ? 0.003lttlt0.02(GeV/c)2
  • ?10 m, pbeam250 GeV/c ? 0.025lttlt0.12(GeV/c)2.
  • Put Roman Pots between DX and D0 magnets (d?/dt,
    b, AN, ANN)
  • ?3m, pbeam 250 100 GeV/c ?
    0.2lttlt1.3(GeV/c)2 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

Spin Physics with pp2pp
Five helicity amplitudes describe proton-proton
elastic scattering
F1(s,t ) ? ltMgt F2(s,t ) ? ltM--gt F3(s,t
) ? lt-M-gt F4(s,t ) ? lt-M-gt F5(s,t ) ?
Fn(s,t ) ? lth3 h4 Mh1 h2gt
with hx s-channel helicity
p1 -p2 incoming protons
p3 -p4 scattered
protons F(s,t ) ½ ( F1(s,t ) F3(s,t ) )
Actual transport (x0, y0) not known also coupled
because of the quad roll