Spin Physics at RHIC Abhay Deshpande RIKEN BNL Research Center QCD 2002 Indian Institute of...
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Transcript of Spin Physics at RHIC Abhay Deshpande RIKEN BNL Research Center QCD 2002 Indian Institute of...
Spin Physics at RHIC
Abhay DeshpandeRIKEN BNL Research Center
QCD 2002Indian Institute of Technology, Kanpur
November 19, 2002 Spin Physcis at RHIC 2
OverviewOverviewNUCLEON SPIN• Present status and open questions
RHIC SPIN (Present: RECENT RESULTS)• Relativistic Heavy Ion Collider at BNL• Status of polarized proton Collider (Year 2001-2002) -- Expectation for Year 2002-2003• Polarized p-p physics at RHIC results FY02 -- Expectations FY03• Long term perspective for RHIC Spin (pp)
Electron Ion Collider at RHIC (Future)• Electron ring at RHIC• Physics goals of EIC (… mostly e-p… but also e-A)• Status & Plans
November 19, 2002 Spin Physcis at RHIC 3
Parton Distributions
q
q
g
Nucleon
u u
d
averagehelicity quark)Qq(x 2,
differencehelicity quark )Qq(x 2,
fliphelicty )Qq(x 2,
(well known)
(moderately well known)
(unknown)
onDistributi Gluon)QxG 2,(
(moderately well known)
onPolarizati Gluon )QxG 2,((unknown)
November 19, 2002 Spin Physcis at RHIC 4
Our knowledge of spin structure Our knowledge of spin structure functionfunction
F2
g1
Q2 (GeV2) Q2 (GeV2)10510 1021 10103
November 19, 2002 Spin Physcis at RHIC 5
Nucleon Spin: Status & Open Nucleon Spin: Status & Open QuestionsQuestions
Proton Spin Puzzle remains unsolved!
constrained, need to measure G
SMC, B. Adeva et al. Phys. Rev. D 112002 (1999)
07.023.0)1,( 22
dxQx GeV
5.10.1
1
0
22 99.0)GeV 1,( dxQxgG
Gluon Spin Contribution:
Quark Spin Contribution:
November 19, 2002 Spin Physcis at RHIC 6
Relativistic Heavy Ion ColliderRelativistic Heavy Ion Collider
this is testRHIC accelerates heavy ion beams upto and polarized proton
beams to 250 GeV
Two large detectors PHENIX and STAR
have extensive Spin Physics Programs
PHENIX
STAR
GeVA 100
November 19, 2002 Spin Physcis at RHIC 7
RHIC Accelerator ComplexRHIC Accelerator Complex
BRAHMS & PP2PP (p)
STAR (p)
PHENIX (p)
AGS
LINACBOOSTER
Pol. Proton Source500 A, 300 s
GeVs
L
50050
onPolarizati%70
cms102 2132max
Spin Rotators
Partial Siberian Snake
Siberian Snakes
200 MeV Polarimeter AGS Internal PolarimeterRf Dipoles
RHIC pC Polarimeters
Absolute Polarimeter (H jet)
2 1011 Pol. Protons / Bunch = 20 mm mrad
November 19, 2002 Spin Physcis at RHIC 8
RHIC PolarimetryRHIC Polarimetry
Beam’s View
Si #1
Si #2
Si #4Si #3
left right
down
up
Si #5
Si #6
Carbon filament target (5mg/cm2) in the RHIC beam
Measure recoil carbon ions at q~90º
100 keV < Ecarbon< 1 MeV
Wave-Form Digitizer +FPGA high counting rates (~0.5
MHz) scaler measurement A ~ 310-4 in ~1 minute.
Carbon
ADC values
Arr
ival
tim
e (n
s)
November 19, 2002 Spin Physcis at RHIC 9
Siberian SnakesSiberian Snakes
STARPHENIX
AGSLINAC
RHIC
Effect of depolarizing resonances averaged out by rotating spin by large angles on each turn
4 helical dipoles S. snake2 snakes in each ring -- axes orthogonal to each other
November 19, 2002 Spin Physcis at RHIC 10
Successful Operation of the Successful Operation of the SnakeSnake
• Injection with Spin Flipped: Asymmetry Flipped
• Adiabatically Snake on: Horizontal polarization
• Accelerate equivalent to 180o rotation: 180o rotated
Successful SingleSnake Operation !
November 19, 2002 Spin Physcis at RHIC 11
Cheers!Cheers!
November 19, 2002 Spin Physcis at RHIC 12
RHIC Luminosity FY02RHIC Luminosity FY02
PHENIX 150 nb-1
0
50
100
150
200
250
300
350
1 3 5 7 9 111315171921232527293133
Days into run (from 12/20/01)
STAR 300 nb-1
Machine Luminosity300 nb-1 /week
Peak 1.8x1030 cm-2s-1
November 19, 2002 Spin Physcis at RHIC 13
Polarization Year 1Polarization Year 1
Yellow Ring Blue Ring
November 19, 2002 Spin Physcis at RHIC 14
Why low polarization?Why low polarization?
10% 20% 30%
PAGS
PRHIC SourceImprovement
AGS power generator failure½ ramp up speed2x resonance effect
New AGSSNAKE2004-5
Ramp upSpead
Injection1st Year
November 19, 2002 Spin Physcis at RHIC 15
Machine Performance Machine Performance ExpectationsExpectations
RUN #proton/bunch
[x109]#bunch Beta*
(m)
Emittance
(m)
Luminosity
1030 cm-2s-1
Pol.
(%)
2001-
2002
70 55 3 25 1.8 15-25
2002-2003
100 112 1 25 16 45-55
2005- ? 112 1 ? ? 70-80
Design 200 112 1 20 80 70
November 19, 2002 Spin Physcis at RHIC 16
RHIC Spin Physics ProgramRHIC Spin Physics Program
• Spin Structure of Nucleon
– 1/2=(1/2)+G+Lq+Lg G: gluon polarization q: Anti-quark polarization
– New Structure Functions• h1: transversity
•NEW tool to study hadronic processes•W,Z @500GeV
•flavor sensitive studies on the structure functions
•cc/bb•Production mechanism
•Spin in fragmentation•Parity,CP violating interaction?
•Test of pQCD •Use asymmetries sensitive ONLY to the higher orders (AN at high PT etc.)
?QCD triumph? or
?beyond ?
November 19, 2002 Spin Physcis at RHIC 17
G :onPolarizati Gluon
RHIC spin programRHIC spin program
Production
),( 0 XgqggALL
Heavy Flavors
),( XbbccggALL
Direct Photon
)( XgqALL
Jet Photon )( XJetgqALL
STA
R +
P
HEN
IX
Spin Transversed
d
d
d
u
u
u
u , , ,
W Production
)( lL lWduA
STAR +PHENIX
STAR +PHENIX
:)Qq(x,ty Transversi 2
:A sAsymmetrie Single N
BRAHMS, STAR, PHENIX, Local Polarimeter
November 19, 2002 Spin Physcis at RHIC 18
PHENIX DetectorPHENIX DetectorEMCal Resolution
35.001.001.0 in
GeV/c 30-25 to up separation
Background/Signal
Muon IDPanels
CentralArms
North MuonArm
South MuonArm
Ring ImagingCerenkov
EM CalorimeterMuon Tracking
Chambers
Beam-BeamCounter
Multiplicity/VertexDetector
Time ExpansionChamber
Drift Chambers
Pad Chambers
Time of FlightPanels
cpT GeV/
GeV 200s
November 19, 2002 Spin Physcis at RHIC 19
PHENIX Preliminary
Normalization error of 30% not shown.
On the way to On the way to G… G… 00 spectrum spectrum
PT spectrum over 8 order of magnitudeComparision with NLO pQCD calculation--CTEQ5M PDFs--Potter, Knielh, Kramer (PKK) fragmentation functions--Uncertainty shown: = pT/2, 2pT
Consistent with data within scaledependence
PHENIX 0 cross section (Preliminary)
November 19, 2002 Spin Physcis at RHIC 20
PHENIX PreliminaryPHENIX Preliminary
µ+µ-e+e-
Br(J/l+l-) (total) = 226 36 (stat.) 79 (syst.) nb
(p+pJ/X) = 3.8 0.6 (stat.) 1.3 (syst.) µb
Total Cross section vs. the Total Cross section vs. the Color-Evaporation Model predictionColor-Evaporation Model prediction
• CEM Parameters are fixed by fitting low energy data• The result agrees with the CEM prediction at s=200GeV
Rapidity distribution compared Rapidity distribution compared with PHITHIA simulationwith PHITHIA simulation
November 19, 2002 Spin Physcis at RHIC 21
STAR Performance
• Time Projection Chamber worked beautifully!
Au-Au Collision at STAR
November 19, 2002 Spin Physcis at RHIC 22
Single spin asymmetries: L-RSingle spin asymmetries: L-R
Essential for proton spin orientation information at IPs
0 1 2 3 4 5Rapidity
STARFPD
0o CAL
BBC
PHE
NIX
MU
ON
PHE
NIX
CE
NT
RA
L
STA
R T
PC
pp2pp
E704 at Fermilab at s=20 GeV, pT=0.5-2.0 GeV/c: XF 0.2 0.4 0.6 0.8PT
Possible Origins: Transversity, Higher Twist,Fragmentation, kT, Orbital. Etc.
November 19, 2002 Spin Physcis at RHIC 23
STAR Forward rapidity high xSTAR Forward rapidity high xFF 00 AANN
xF ~ E / 100 GeV
STAR FPD Preliminary DataAssuming AN(CNI)= 0.013pT=1.1 - 2.5 GeV/c
0.0
0.2
0.4
-0.20 0.2 0.4 0.6 0.8 1.0
AN
Systematic uncertainty + - 0.05
0 at s 200p p X GeV 0 at s 20p p X GeV Theory predictions
at pT = 1.5 GeV/c
Collins effectAnselmino, et al.PRD 60 (1999) 054027. Sivers effectAnselmino, et al.Phys. Lett. B442 (1998) 470.
Twist 3 effectQiu and Sterman,Phys. Rev. D59 (1998) 014004.
Y.KoikePaNic02
November 19, 2002 Spin Physcis at RHIC 24
12 o’clock 12 o’clock PHENIX test setup PHENIX test setup
Hadron Cal Base
Pb
Scintillator
W+Fiber Cal
Post-shower
EM Cal Base
PbWO4
Charge Veto
Neutron Veto
0
November 19, 2002 Spin Physcis at RHIC 25
AsymmetriesAsymmetriesEMCal ZDC
November 19, 2002 Spin Physcis at RHIC 26
Asymmetries seen at RHIC so Asymmetries seen at RHIC so far…far…
0 1 2 3 4 5Rapidity
STARFPD
0o CAL
BBC
PHE
NIX
MU
ON
PHE
NIX
CE
NT
RA
L
STA
R T
PC
pp2pp
XF 0.2 0.4 0.6 0.8PT
0
+10 ~ +20%
Charged+1%
Neutron -10%
~0 %
0 ~0%
November 19, 2002 Spin Physcis at RHIC 27
Upcoming Run FY03Upcoming Run FY03
3 pb-1 and 50%Expectation
G will be probed
STAR JET
PHENIX Charged
November 19, 2002 Spin Physcis at RHIC 28
Search for new physics:Search for new physics:
• Anomalous parity violation in jet production – Contact Interaction (Scale )
• CDF>1.8 TeV• D0 >2.4 TeV• RHIC Spin Reach ~3.3 TeV
– New gauge boson Z’
P. Taxil & J-M. Virey, Phys. Rev. D(55) 2457 (1999)
November 19, 2002 Spin Physcis at RHIC 29
RHIC Spin Schedule (PHENIX & STAR)
Year CM Energy Weeks Int. Lum. Remarks
FY2002 200 GeV 5 5 pb-1(1/15) Gluon pol. with pions
FY2003 200 GeV 8(3) 160 pb-1 Gluon pol. with jets500 GeV 2(0)? 90 pb-1 PV W production, u-quark
pol.500 GeV (1) Machine Studies, identify
Ws.FY2004 200 GeV 8 160 pb-1 Gluon pol. with g + jet/ TT
500 GeV 2 120 pb-1 First ubar,dbar pol. meas..
FY2005 500 GeV 8 480 pb-1 Gluon pol. with g+jet, g,jet+jet, heavy flavor, ubar, dbar pol.
200 GeV 2 48 pb-1 Gluon pol. with g, g+jet, heavy
flavor/TT
FY2006 500 GeV 5 300 pb-1 More statistics200 GeV 5 120 pb-1
FY2007 200 GeV 10 210 pb-1
November 19, 2002 Spin Physcis at RHIC 30
Summary & OutlookSummary & Outlook
• RHIC spin program has begun: -- Polarized protons were injected and stored for extended
times in RHIC -- CNI polarimeters have measured non zero asymmetries
indicating polarization at 100 GeV proton beam energies -- Detectors are functional and will be 100% completed in
2004-5 -- A first round of single spin asymmetries have been measured• Next run 2002-3 promises to be the first one to
get us a first look at G -- First trials of 500 GeV run will be made and Ws produced
• A 5 year run plan exists for the RHIC spin physics -- to explore G, transversity, q & qbar is on the way
November 19, 2002 Spin Physcis at RHIC 31
The Electron Ion ColliderThe Electron Ion Collider
A high energy, high intensity polarized electron beam facility at BNL to collide
with the existing RHIC heavy ion and polarized proton beam
would significantly enhance RHIC’s ability to
probe fundamental and universal aspects of QCD
November 19, 2002 Spin Physcis at RHIC 32
Deep Inelastic ScatteringDeep Inelastic Scattering
•Observe scattered electron/muon & hadrons in current jets•Observe spectator or remnant jet
November 19, 2002 Spin Physcis at RHIC 33
Why Collider in the Future?Why Collider in the Future?
• Past polarized DIS experiments: MOSTLY FIXED TARGET• Collider has distinct advantages --- Confirmed at HERA
• Better angular separation between scattered lepton & nuclear fragments
Better resolution of electromagnetic probe Recognition of rapidity gap events (recent diffractive physics)• Better measurement of nuclear fragments• Higher center of mass (CoM) energies reachable• Tricky integration of beam pipe – interaction region -- detector
November 19, 2002 Spin Physcis at RHIC 34
EIC vs. DIS Facilities (I)EIC vs. DIS Facilities (I)
• New kinematic region
• Ee = 2-10 GeV
• Ep = 30 – 250 GeV
• Sqrt(s) = 20 – 100 GeV
• Kinematic reach of EIC x = 10-4 0.6 Q2 = 0 104 GeV
• High Luminosity L= (0.3 – 1.0) X 1033 cm-2 sec-1
November 19, 2002 Spin Physcis at RHIC 35
EIC vs. Other DIS Facilities (II)EIC vs. Other DIS Facilities (II)
Variable beam energy
Variable hadron species
Hadron beam polarization
Large luminosity
TESLA-N
November 19, 2002 Spin Physcis at RHIC 36
Scientific Frontiers Open to EICScientific Frontiers Open to EIC
• Nucleon Structure: polarized & unpolarized e-p/n scattering -- Role of quarks and gluons in the nucleon -- Spin structure: polarized quark & gluon distributions -- Unpolarized quark & gluon distributions -- Correlation between partons hard exclusive processes leading to
Generalized Parton Distributions (GPD’s)
• Nuclear structure: unpolarized e-A scattering -- Role of quarks and gluons in nuclei -- e-p vs. e-A physics in comparison
• Hadronization in nucleons and nuclei & effect of nuclear media
-- How do partons knocked out of nucleon in DIS evolve in to colorless hadrons?
• Partonic matter under extreme conditions -- e-A vs. e-p scattering; study as a function of A
November 19, 2002 Spin Physcis at RHIC 37
Unpolarized DIS e-p at EICUnpolarized DIS e-p at EIC
• Large(r) kinematic region already covered at HERA but additional studies at EIC are possible & desirable
• Uniqueness of EIC: high luminosity, variable Sqrt(s), He3 beam, improved detector & interaction region
• Will enable precision physics: -- He3 beams neutron structure d/u as x0, dbar(x)-ubar(x)
-- precision measurement of S(Q2)
-- flavor separation (charm and strangeness) -- precision gluon distribution in x=0.001 to x=0.6 -- slopes in dF2/dlnQ2
-- precision photoproduction physics -- exclusive reaction measurements -- nuclear fragmentation region measurements
November 19, 2002 Spin Physcis at RHIC 38
Polarized DIS at EICPolarized DIS at EIC• Spin structure functions g1 (p,n) at low x, high precision
-- g1(p-n): Bjorken Spin sum rule better than 1% accuracy• Polarized gluon distribution function G(x,Q2) -- at least three different experimental methods
• Precision measurement of S(Q2) from g1 scaling violations• Polarized structure function of the photon from photo-
production• Electroweak structure function g5 via W+/- production• Flavor separation of PDFs through semi-inclusive DIS• Deeply Virtual Compton Scattering (DVCS) Gerneralized
Parton Distributions (GPDs)• Transversity• Drell-Hern-Gerasimov spin sum rule test at high • Target/Current fragmentation studies• … etc….
November 19, 2002 Spin Physcis at RHIC 39
Spin structure function gSpin structure function g1 1 at low at low xx
~5-7 days of data3 years of data
A. Deshpande & V. W. Hughes
Studies included statistical error & detector smearing to confirm that asymmetries are measurable. No present or future approved experiment will be able to make this measurement
November 19, 2002 Spin Physcis at RHIC 40
Low x measurement of gLow x measurement of g11 of of NeutronNeutron
• With polarized He3 or deuteron
• ~ 2 weeks of data at EIC
• Compared with SMC(past) & possible HERA data
• If combined with g1 of proton results in Bjorken sum rule test of better than 1% within a couple of months of running (G.Igo & T. Sloan, AD & V. Hughes)
EIC 1 inv.fb
A. Deshpande & V. W. Hughes
November 19, 2002 Spin Physcis at RHIC 41
Polarized Gluon Measurement at Polarized Gluon Measurement at EICEIC
• This is the hottest of the experimental measurements being pursued at various experimental facilities:
-- HERMES/DESY, COMPASS/CERN, RHIC-Spin/BNL & E159/E160 at SLAC
• Measurements at EIC will be complimentary with RHIC with a very different set of systematic uncertainties
- high Q2 assures no problems with interpretation of results
• Deep Inelastic Scattering kinematics at EIC -- Scaling violations (pQCD analysis at NLO) of g1
-- (2+1) jet production in photon-gluon-fusion process -- 2-high pT hadro production in PGF
• Photo-production (real photon) kinematics at EIC -- Single and di-jet production in PGF -- Open charm production in PGF
November 19, 2002 Spin Physcis at RHIC 42
G from Scaling Violations of gG from Scaling Violations of g11
• World data (today) allows a NLO pQCD fit to the scaling violations in g1 resulting in the polarized gluon distribution and its first moment.
• SM collaboration, B. Adeva et al. PRD (1998) 112002 G = 1.0 +/- 1.0 (stat) +/- 0.4 (exp. Syst.) +/- 1.4 (theory)• Theory uncertainty dominated by the lack of knowledge of
the shape of the PDFs in unmeasured low x region where EIC data will play a crucial role.
• With approx. 1 week of EIC data, statistical and theoretical uncertainties on G will be reduced by a factor of 3
-- coupled to better low x knowledge of spin structure -- less dependence on factorization & re-normalization
scale uncertainty
A. Deshpande, V. W. Hughes & J. Lichtenstadt
November 19, 2002 Spin Physcis at RHIC 43
Photon Gluon Fusion at EICPhoton Gluon Fusion at EIC
• “Direct” determination of G -- Di-Jet events -- High pT leading hadrons
• High Sqrt(s) at EIC -- no theoretical ambiguities• Both methods tried at HERA
for un-polarized gluon determination & both are successful!
-- NLO calculations exist -- H1 and ZEUS results -- Consistent with scaling
violation F2 results on G
Signal: PGF
BackgroundQCD Compton
November 19, 2002 Spin Physcis at RHIC 44
Di-Jet events at EIC: Analysis at Di-Jet events at EIC: Analysis at NLONLO
• Stat. Accuracy for two luminosities
• Detector smearing effects considered
• NLO analysis
G. Radel, A. De Roeck, A. Deshpande, V. W. Hughes & J. Lichtenstadt
• Easy to differentiate different G scenarios: factor 3 improvements in ~2 weeks• If combined with scaling violations of g1: factors of 5 improvements in uncertainties observed in the same time.• Better than 3-5% uncertainty can be expected from EIC G program
November 19, 2002 Spin Physcis at RHIC 45
Di-Jet at EIC vs. World Data for Di-Jet at EIC vs. World Data for G/G G/G
Good precisionClean measurement in x
range 0.01< x < 0.3Constrains shape of
G(x)Polarization in HERA
much more difficult than RHIC.
G. Radel & A. De Roeck
EIC Di-Jet DATA 2fb-1
November 19, 2002 Spin Physcis at RHIC 46
Polarized PDFs of the PhotonsPolarized PDFs of the Photons
• Photo-production studies with single and di-jet
• Photon Gluon Fusion or Gluon Gluon Fusion (Photon resolves in to its partonic contents)
• Resolved photon asymmetries result in measurements of spin structure of the photon
• Asymmetries sensitive to gluon polarization as well… but we will consider the gluon polarization “a known” quantity!
Direct Photon Resolved Photon
November 19, 2002 Spin Physcis at RHIC 47
Will measure the photon PDFs…Will measure the photon PDFs…• Stat. Accuracy
estimated for 1 fb-1 running (2 weeks at EIC)
• Single and double jet asymmetries
• ZEUS acceptance
• Will resolve photon’s partonic spin contents
Direct Photon Resolved Photon
M. Stratmann & W. Vogelsang
November 19, 2002 Spin Physcis at RHIC 48
Parity Violating Structure Parity Violating Structure Function gFunction g55
• This is also a test
For EIC kinematics
• Experimental signature is a huge asymmetry in detector (neutrino)• Unique measurement• Unpolarized xF3 measurements at HERA in progress• Will access heavy quark distribution in polarized DIS
November 19, 2002 Spin Physcis at RHIC 49
Measurement Accuracy PV gMeasurement Accuracy PV g55 at at EICEIC
Assumes:1. Input GS Pol.
PDfs2. xF3 measured by
then3. 4 fb-1 luminosity
Positrons & Electrons in EIC g5(+)
>> Issues for linac vs. ring design of EIC
J. Contreras & A. De Roeck
November 19, 2002 Spin Physcis at RHIC 50
Drell Hern Gerasimov Spin Sum Drell Hern Gerasimov Spin Sum RuleRule
• DHG Sum rule:
• At EIC n range: GeV few TeV
• Although contribution from to the
this sum rule is small, the high n behavior is completely unknown and hence theoretically biased in any present measurements at:
Jefferson Lab., MAMI, BNL
S. Bass, A. De Roeck & A. Deshpande
• Inclusive Photo-production measurement
• Using electron tagger in RHIC ring Q2 ~ 10-6 10-2 GeV2
Sqrt(s) ~ 25 85 GeV
November 19, 2002 Spin Physcis at RHIC 51
DVCS/Vector Meson ProductionDVCS/Vector Meson Production
• Hard Exclusive DIS process
• (default) but also vector mesons possible
• Remove a parton & put another back in!
Microsurgery of Baryons!
•Claim: Possible access to skewed or off forward PDFs? Polarized structure: Access to quark orbital angular momentum?
On going theoretical debate… experimental effort just beginning…
November 19, 2002 Spin Physcis at RHIC 52
Strange Quark Distributions at Strange Quark Distributions at EICEIC
• After measuring u & d quark polarized distributions…. Turn to s quark (polarized & otherwise)
• Detector with good Particle ID: pion/kaon separation
• Upper Left: statistical errors for kaon related asymmetries shown with A1 inclusive
• Left: Accuracy of strange quark distribution function measurements possible with EIC and HERMES (2003-05) and some theoretical curves on expectations.
E. Kinney & U. Stoesslein
November 19, 2002 Spin Physcis at RHIC 53
Highlights of e-A Physics at EICHighlights of e-A Physics at EIC
• Study of e-A physics in Collider mode for the first time• QCD in a different environment
• Clarify & reinforce physics studied so far in fixed target e-A & -A experiments including target fragmentation
QCD in: x > [1/(2mNRN) ] ~ 0.1 (high x)
QCD in: [1/(2mNRA)] < x < [1/(2mNRN)] ~ 0.1 (medium x)
• …. And extend in to a very low x region to explore: saturation effects or high density partonic matter also called
the Color Glass Condensate (CGC) QCD in: x < [1/(2mNRA)] ~ 0.01 (low x)
November 19, 2002 Spin Physcis at RHIC 54
DIS in Nuclei is Different! DIS in Nuclei is Different!
Regions of:• Fermi smearing• EMC effect• Enhancement• Shadowing• Saturation?
Regions of shadowing and saturation mostly around Q2 ~1 GeV2
An e-A collision at EIC can be at significantly higher Q2
F2D/F2A
Low Q2!
E665, NMC, SLAC Experiments
November 19, 2002 Spin Physcis at RHIC 55
Statistical Precision at EIC for e-Statistical Precision at EIC for e-AA
• High precision at EIC shown statistical errors for 1 pb-1
• Recall: EIC will deliver ~85 pb-1 per day
• NMC data F2(Sn/D)
• EIC’s Q2 range between 1 and 10 GeV2
• Will explore saturation region!
T. Sloan
November 19, 2002 Spin Physcis at RHIC 56
A Case for EIC (I)A Case for EIC (I)
• Through its large luminosity, beam energy & beam species variability, the EIC will explore a new universal and fundamental aspects of QCD
• It is natural to assume that these measurements probe the initial conditions in the nuclei for parton distributions… as such this knowledge would be essential to fully understand the QGP which is being pursued at RHIC
• The e-A physics at RHIC will allow for the first time a large number of measurements which have never been performed beyond the fixed target regime… They will be at high energies where pQCD could be used reliably to understand the nuclear structure
November 19, 2002 Spin Physcis at RHIC 57
A Case for EIC (II)A Case for EIC (II)
• The polarized e-N facility at the EIC will enable the polarized DIS studies of nucleons in a completely new x-Q2 that no other present or future facility will be able to access
• The variety of measurements at low Sqrt(s) will also include: -- inclusive physics in DIS as well as photoproduction regime -- semi-inclusive physics -- exclusive physics leading to DVCS, DES GPDs
• In addition a lot of spin measurements which would clearly study target and current fragmentation for the first time in polarized DIS will be possible with EIC
November 19, 2002 Spin Physcis at RHIC 58
Moving Towards EIC….Moving Towards EIC….• September 2001: EIC grew out of joining of two communities: 1) polarized eRHIC (ep and eA at RHIC) BNL, UCLA, YALE and people from DESY & CERN 2) Electron Poliarized Ion Collider (EPIC) 3-5 GeV e X 30-50 GeV polarized light ions Colorado, IUCF, MIT/Bates, HERMES collaborators
• February 2002: White paper submitted to NSAC Long Range Planning Review Received enthusiastic support as a next R&D project (see: US/DoE Nuclear Report on the Web)
• Steering Committee: 7 members, one each from BNL, IUCF, LANL, LBL, MIT, UIUC, Yale + Contact person (AD)
• ~20 (~13 US + ~7 non-US) Institutes, ~100 physicists + ~40 accelerator physicists
• See for more details: EIC Web-page at “http://www.bnl.gov/eic”
• Subgroups: Accelerator WG, Physics WG, Detector WG
November 19, 2002 Spin Physcis at RHIC 59
Present Collider LayoutPresent Collider Layout• Proposed by BINP & MIT/Bates• E-ring is ¼ of RHIC ring• Collisions in ONE interaction region• Collision energies 5-10 GeV• Injection linac 2-5 GeV• Lattice based on “superbend”
magnets• Self polarization using Sokolov
Ternov Effect: (14-16 min pol. Time)
• IP12, IP2 and IP4 are possible candidates for collision points
p
e2GeV (5GeV)
2-10 GeV
IP12
IP2
IP4
IP6
IP8
IP10
RHIC
OTHER : Ring with 6 IPS, Linac-Ring, Linac-Re-circulating ring
November 19, 2002 Spin Physcis at RHIC 60
Interaction Region Design….Interaction Region Design….
B. Parker’s (BNL) ProposalBudker/MIT Proposal
November 19, 2002 Spin Physcis at RHIC 61
A Detector for EICA Detector for EIC A 4 A 4 DetectorDetector
• Scattered electrons to measure kinematics of DIS• Scattered electrons at small (~zero degrees) to tag photo
production• Central hadronic final state for kinematics, jet measurements,
quark flavor tagging, fragmentation studies, particle ID• Central hard photon and particle/vector detection (DVCS)• ~Zero angle photon measurement to control radiative
corrections and in e-A physics to tag nuclear de-excitations
• Missing ET for neutrino final states (W decays)
• Forward tagging for 1) nuclear fragments, 2) diffractive physics
• EIC will provide: 1) Variable beam energies 2) different hadronic species, some of them polarization, 3) high luminosity
November 19, 2002 Spin Physcis at RHIC 62
Detector Design (I)… others Detector Design (I)… others expectedexpected
J. Chwastowski & W. Krasny
November 19, 2002 Spin Physcis at RHIC 63
Detector Design (I)… others Detector Design (I)… others expectedexpected
J. Chwastowski & W. Krasny
November 19, 2002 Spin Physcis at RHIC 64
A time line for EIC…A time line for EIC…
“Predictions are very difficult to make, especially when they are about the future” --- A very wise man….
• Proposal/CDR0 by 2004-2005• Expected formal approval 2005-6 Long Range Review• R&D money could start for hardware 2007• Construction of IR and Detector begin 2007-2008• 3-5 years for staged detector and IR construction
without interfering with the RHIC running• First collisions (2011)???
If any one knows how to do this earlier… -- I am listening.