OAM in p T dependent pp - Overview L.C. Bland Brookhaven
National Lab INT Workshop on OAM in QCD 10 February 2012 STAR A N
DY PHENIX Slide 2 2.10.2012 2 Outline Brief (and incomplete)
Summary of Hadron Production Measurements in p +p at RHIC Towards a
Measurement of Drell Yan Production for p +p at RHIC Summary Slide
3 2.10.2012 3 Where is the spin of the proton? Slide 4 2.10.2012 4
RHIC Polarized Collider BRAHMS & PP2PP STAR PHENIX AGS LINAC
BOOSTER Pol. H - Source Spin Rotators (longitudinal polarization)
Siberian Snakes 200 MeV Polarimeter RHIC pC Polarimeters Absolute
Polarimeter (H jet) AGS pC Polarimeter Strong AGS Snake Helical
Partial Siberian Snake PHOBOS Spin Rotators (longitudinal
polarization) Siberian Snakes 2006: 1 MHz collision rate;
Polarization=0.6 Slide 5 2.10.2012 5 capable of colliding
essentially all positive ions over a broad range of s with large L/
s, where L is free space at interaction region large x F possible
with a broad and diverse physics program aimed at important
questions oWhat is quark-gluon plasma? heavy-ion collisions oHow
does the proton get its spin? polarized proton collisions oDoes the
gluon density saturate in a heavy nucleus? d+Au/p+Au collisions
RHIC is a Unique Collider Source:
http://www.agsrhichome.bnl.gov/RHIC/Runs/ Slide 6 2.10.2012 6
arXiv:0901.2828 RHIC Spin (2006) Highlights New insights from RHIC
after 30 years of polarized deep inelastic scattering Where is the
spin of the proton? Gluon polarization is not large If not from
gluons, then is the spin from orbital motion? STAR Slide 7
2.10.2012 7 Kinematics large- p T physics in p+p collisions p beam
-p beam large p T or jet or or Largest p T reached by detecting
produced particles at ~ 90 (midrapidity, ~0) Slide 8 2.10.2012 8
Kinematics large- x F (with sufficient p T ) physics in p+p
collisions p beam -p beam large p L or jet or or Large p L
(produced particle at large ) is required to reach large Feynman-
x, x F = p L / p beam = 2 p L / s Slide 9 2.10.2012 9 gluon quark
pion or jet quark RHIC Spin/Low-x Probes Polarized proton
collisions / d+Au collisions Describe p+p particle production at
RHIC energies ( s 62 GeV) using perturbative QCD at Next to Leading
Order, relying on universal parton distribution functions and
fragmentation functions Slide 10 2.10.2012 10 Does pQCD describe
particle production at RHIC? Compare cross sections measured for
p+p +X at s=200 GeV to next-to-leading order pQCD calculations S.S.
Adler et al. (PHENIX), PRL 91 (2003) 241803 J. Adams et al. (STAR),
PRL 92 (2004) 171801; and PRL 97 (2006) 152302 Cross sections agree
with NLO pQCD down to p T ~2 GeV/c over a wide range, 0 < 3.8,
of pseudorapidity ( = -ln tan /2) at s = 200 GeV. Slide 11
2.10.2012 11STAR-Forward Cross Sections Similar to ISR analysis J.
Singh, et al Nucl. Phys. B140 (1978) 189. Expect QCD scaling of
form: Require s dependence (e.g., measure cross sections at s = 500
GeV) to disentangle p T and x T dependence hep-ex/0505024 Slide 12
2.10.2012 12 STAR Detector Large rapidity coverage for
electromagnetic calorimetry (- 1< 2.10.2012 13 Azimuthal
Correlations with E. Braidot (for STAR), Quark Matter 2009
Uncorrected Coincidence Probability (radian -1 ) p+p +h +X, s=200
GeV requirements: p T, >2.5 GeV/c 2.8< 0 asymmetry is
positive, but doesnt show any Collins effect contributions.
arXiv:1012.0221 Slide 28 2.10.2012 28 The A N DY Project A new
effort at RHIC to make the first measurement of the analyzing power
(A N ) for Drell Yan (DY) production at s=500 GeV Slide 29
2.10.2012 29 E.C.Aschenauer, A. Bazilevsky, L.C. Bland, K. Drees,
K.O. Eyser, C. Folz, Y. Makdisi, A. Ogawa, P. Pile, T.G. Throwe
Brookhaven National Laboratory H.J. Crawford, J.M. Engelage, E.G.
Judd University of. California, Berkeley/Space Sciences Laboratory
C.W. Perkins University of. California, Berkeley/Space Sciences
Laboratory /Stony Brook University A. Derevshchikov, N. Minaev, D.
Morozov, L.V. Nogach Institute for High Energy Physics, Protvino G.
Igo University of California, Los Angeles M.X. Liu Los Alamos
National Laboratory H. Avakian Thomas Jefferson National
Accelerator Facility E.J.Brash Christopher Newport University and
TJNAF C.F.Perdrisat College of William and Mary V. Punjabi Norfolk
State University Li, Xuan Shandong University, China Mirko
Planinic, Goran Simatovic University of Zagreb, Croatia A. Vossen
Indiana University G. Schnell University of the Basque Country and
IKERBASQUE,Spain A. Shahinyan, S. Abrahamyan Yerevan Physics
Institute K. Gnovo, N. K. Liyanage University of Virginia E.
Cisbani INFN Roma, Italy A N DY Large Rapidity Drell Yan Production
at RHIC Letter of Intent submitted 24 May 2010:
http://www.bnl.gov/npp/docs/pac0610/Craw ford_LoI.100524.v1.pdf PAC
presentation: http://www.bnl.gov/npp/docs/pac0610/asch
enauer_DY-collider_june10.pdfe10.pdf Proposal to 2011 PAC:
http://www.bnl.gov/npp/docs/pac0611/DY_ pro_110516_final.2.pdf
Construction Proposal Nearing Completion JLab-SBS GEM experts Slide
30 2.10.2012 30 Simple QED example: DIS: attractive Drell-Yan:
repulsive Same in QCD: As a result: Attractive vs Repulsive Sivers
Effects Unique Prediction of Gauge Theory ! Transverse Spin
Drell-Yan Physics at RHIC (2007)
http://spin.riken.bnl.gov/rsc/write-up/dy_final.pdf Slide 31
2.10.2012 31 Goal of A N DY Project Measure the analyzing power for
forward Drell-Yan production to test the predicted change in sign
from semi-inclusive deep inelastic scattering to DY associated with
the Sivers function Projected precision for proposed A N DY
apparatus GEANT model of proposed A N DY apparatus (run-13) Slide
32 2.10.2012 32 Why A N DY? Largest spin effects are found at RHIC
when Feynman-x > 0.1 Predicted change of sign for Sivers
function between transverse single spin measurements for
semi-inclusive deep inelastic scattering and the analyzing power
for Drell Yan is likely best done in this range, but limited to x F
< 0.3 to match HERMES/COMPASS (SIDIS) kinematics as closely as
possible Forward upgrades of STAR and PHENIX are major undertakings
and would benefit from a feasibility demonstration of forward DY
production (i.e., A N DY). Forward DY production is of interest for
more than just the analyzing power, e.g. most robust observable to
low-x parton distributions for intercomparison to a future
electron-ion collider. A N DY can run in parallel with RHIC W
program. Slide 33 2.10.2012 33 Previous Work on Low-Mass DY at a
Collider p+p DY at ISR, s=53,63 GeV Phys. Lett. B91 (1980) 475
Comments (note: large x F at collider breaks new ground) e+e-
low-mass DY done at ISR and by UA2 [see review J.Phys. G19 (1993)
D1] UA2 [PLB275 (1992) 202] did not use magnet / CCOR did [PLB79
(1979) 398] most fixed target experiments do + - DY Slide 34
2.10.2012 34 Comments RHIC pp luminosity largest at s=500 GeV
partonic luminosities increase with s net result is that DY grows
with s in any case, largest s probes lowest x Consider large-x F DY
at s=500 GeV Collision Energy Dependence of Drell Yan Production
Transverse Spin Drell-Yan Physics at RHIC (2007)
http://spin.riken.bnl.gov/rsc/write-up/dy_final.pdf Forward DY
production probes valence region for beam and x 2 for target for
s=500 GeV (M>4 GeV/c 2 ) Slide 35 2.10.2012 35 Pair mass from
bare EMcal arXiv:0906.2332 arXiv:0907.4396 pair mass backgrounds
well modeled J/ e+e- observation at ~0.67 emboldens DY
consideration p+p J/ +X e + e +X, s=200 GeV ~0.67 Slide 36
2.10.2012 36 Backgrounds h /e discrimination requires estimates of
p+p collisions and EMcal response charged/neutral discrimination
photon conversion background requires estimates of p+p collisions
and materials hep-ex/0403012 PYTHIA 5.7 compared well to s=200 GeV
data [PRL 97 (2006) 152302] Little change until underlying event
tunings for LHC created forward havoc Stick to PYTHIA 6.222 for
estimates Slide 37 2.10.2012 37 Strategy for estimates ~10 12 p+p
interactions in 50 / pb at s=500 GeV full PYTHIA/GEANT not
practical Parameterize GEANT response of EMcal and use
parameterized response in fast simulator applied to full PYTHIA
events Estimate rejection factors from GEANT for hadron calorimeter
and preshower detector (both critical to h /e discrimination)
Explicit treatment in fast simulator to estimate pathlengths
through key elements (beam pipe and preshower), to simulate photon
conversion to e+e- pair Estimate effects from cluster merging in
EMcal (d < d cell / use =1 for estimates) Estimate/simulate
EMcal cluster energy and position resolutions. E =15%/ E and x(y)
=0.1d cell, used to date for rejection. GEANT simulation of EMcal
response to E>15 GeV from PYTHIA 6.222 incident on (3.8cm) 2
x45cm lead glass calorimeter. GEANT response not so different from
57-GeV pion test beam data from CDF [hep-ex/0608081] Slide 38
2.10.2012 38 Background Estimate Comments: Conversion photons
significantly reduced by veto Preshower thickness tuned, although
perhaps is not so critical given photon veto Linearly decreasing
dN/df (fast-simulation model for hadronic response of ECal)
estimates smaller hadronic background increased sophistication
needed for reliable estimates, although other model uncertainties
could easily dominate. Open heavy flavor backgrounds also estimated
and found small due to large rapidity Slide 39 2.10.2012 39
Dileptons from open beauty at large x F Comments open beauty
dileptons are a background 2x larger than DY for PHENIX direct
production of open beauty results in ~15% background at large xF
large forward acceptance for the future would require
discrimination (isolation) Slide 40 2.10.2012 40 What did we learn
from run-11 A N DY? Left/right symmetric HCal Left/right symmetric
ECal Left/right symmetric preshower Trigger/DAQ electronics
Blue-facing BBC Beryllium vacuum pipe Slide 41 2.10.2012 41
Schematic of detector for Run-11 Polarized proton collisions at
s=500 GeV from February to April 2011 Beam-beam counter (BBC) for
minimum-bias trigger and luminosity measurement from PHOBOS [NIM
A474 (2001) 38] Zero-degree calorimeter and shower maximum detector
for luminosity measurement and local polarimetry (ZDC/ZDC-SMD, not
shown) Hadron calorimeter modules (HCal) are 9x12 modules from
AGS-E864 (NIM406,227) Small (~120 cells) ECal loaned from BigCal at
JLab Pre-shower detector Slide 42 2.10.2012 42 Jet Trigger Jet
trigger sums HCal response excluding outer two perimeters (rather
than just two columns closest to beam) Definition is consistent
with objective of having jet thrust axis centered in hadron
calorimeter modules HCal energy scale is now determined >750M
jet-triggered events acquired during RHIC run 11 Hadron calorimeter
is quiet ~107ns before jet event Hadron calorimeter is quiet again
~107ns after jet event Slide 43 2.10.2012 43 Select from
jet-trigger events for HCal high-tower to be centered in module
Display for each detector of each module the ADC count as color
scale (black=greatest count yellow=lowest count) Events look jetty,
as expected Cosmic ray trigger is essentially the same as jet
trigger, except that the threshold on the summed calorimeter
response is set at 5 pC (20 counts) This is a trigger that will
work without beam. We have other cosmic-ray triggers that will work
with beam, when commissioned, for continuous monitoring. The tracks
test noise, patterns, etc. HCal Events Slide 44 2.10.2012 44
Calibration of Hadron Calorimeter Based on reconstruction require:
(1) 1-tower clusters; (2) E>1.8 GeV; (3) |x|>50 cm to avoid
ECal shadow; (4) >1 clusters to form pairs; (5) E pair >5
GeV; (6) M pair
