Hyunchul Kim Quarkonium 2013, IHEP
Charmonium suppression in Pb-Pb collisions from CMS
Hyunchul Kim 金铉哲 (Korea University)
for the CMS Collaboration
The 9th International Workshop on Heavy Quarkonium
IHEP, Beijing, China, Apr 23rd, 2013
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Hyunchul Kim Quarkonium 2013, IHEP
Contents • Motivation of the study • CMS detector(Muon reconstruction mechanism) • Results (until Quark Matter 2012)
– Charmonia • prompt J/ψ • non-prompt J/ψ • ψ(2S)
• Summary
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https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResultsHIN
– Bottomonia – ϒ(1S, 2S, 3S) : Byungsik Hong’s talk (Next session, 3rd talk)
Hyunchul Kim Quarkonium 2013, IHEP
Theoretical motivation
3 E. Scomparin, CERN seminar (06/11/2012)
Perturbative vacuum Hot-dense matter
Agnes Mocsy: Potential Models for Quarkonia 5
Fig. 5. The QGP thermometer.
In principle, a state is dissociated when no peak struc-ture is seen, but the widths shown in spectral functionsfrom current potential model calculations are not physi-cal. Broadening of states as the temperature increases isnot included in any of these models. At which T the peakstructure disappears then? In [27] we argue that no needto reach Ebin = 0 to dissociate, but when Ebin < T a stateis weakly bound and thermal fluctuations can destroy it.Let us quantify this statement.
Due to the uncertainty in the potential we cannot de-termine the binding energy exactly, but we can never-theless set an upper limit for it [27]: We can determineEbin with the most confining potential that is still withinthe allowed ranges by lattice data on free energies. Forthe most confining potential the distance where deviationfrom T = 0 potential starts is pushed to large distancesso it coincides with the distance where screening sets in[12]. From Ebin we can then estimate, following [28], thequarkonium dissociation rate due to thermal activation,obtaining this way the thermal width of a state Γ (T ).At temperatures where the width, that is the inverse ofthe decay time, is greater than the binding energy, that isthe inverse of the binding time, the state will likely to bedissociated. In other words, a state would melt before itbinds. For example, already close to Tc the J/ψ would meltbefore it would have time to bind. To quantify the dissoci-ation condition we have set a more conservative conditionfor dissociation: 2Ebin(T ) < Γ (T ). The result for differ-ent charmonium and bottomonium states is shown in thethermometer of figure 5. Note, that all these numbers areto be though of as upper limits.
In summary, potential models utilizing a set of poten-tials between the lower and upper limit constrained bylattice free energy lattice data yield agreement with lat-tice data on correlators in all quarkonium channels. Dueto this indistinguishability of potentials by the data the
precise quarkonium properties cannot be determined thisway, but the upper limit can be estimated. The decreasein binding energies with increasing temperature, observedin all the potential models on the market, can yield sig-nificant broadening, not accounted for in the currentlyshown spectral functions from these models. The upperlimit estimated using the confining potential predicts thatall bound states melt by 1.3Tc, except the Upsilon, whichsurvives until 2Tc. The large threshold enhancement abovefree propagation seen in the spectral functions even at hightemperatures, again observed in all the potential modelson the market, compensates for melting of states (yieldingflat correlators), and indicates that correlation betweenquark and antiquark persists. Lattice results are thus con-sistent with quarkonium melting.
And What’s Next?
Implications of the QGP thermometer of figure 5 for heavyion collisions should be considered by phenomenologicalstudies. This can have consequences for the understandingof the RAAmeasurements, since now the Jψ should meltat SPS and RHIC energies as well. The thermometer alsosuggests that the Υ will be suppressed at the LHC, andthat centrality dependence of this can reveal whether thishappens already at RHIC. So measurements of the Υ canbe an interesting probe of matter at RHIC as well as atthe LHC.
The exact determination of quarkonium properties thefuture is in the effective field theories from QCD at finiteT. First works on this already appeared [14] and both realand imaginary parts of the potential have been derivedin certain limits. In these works there is indication thatmost likely charmonium states dissolve in QGP due ther-mal effects, such as activation to octet states, screening,Landau-damping.
The correlations of heavy-quark pairs that is embeddedin the threshold enhancement should be taken seriouslyand its consequences, such as possible non-statistical re-combination taken into account in dynamic models thatattempt the interpretation of experimental data [24].
All of the above discussion is for an isotropic medium.Recently, the effect of anisotropic plasma has been con-sidered [29]. Accordingly, quarkonium might be strongerbound in an anisotropic medium, especially if it is alignedalong the anisotropy of the medium (beam direction).Qualitative consequences of these are considered in an up-coming publication [30]. Also, all of the above discussionrefers to quarkonium at rest. Finite momentum calcula-tions are under investigation. It is expected that a movingquarkonium dissociates faster.
Acknowledgment
I thank Peter Petreczky for collaboration on performingthis work and for carefully reading this manuscript. I amgrateful to the Organizers of Hard Probes 2008 for inviting
Mocsy, EPJ C 61 (2009) 705
T>T d
T<
T d
cc
ccc clight quark Td
Debye screening length
From Matsui & Satz PLB 178 (1986) 416
is melted cc
• Heavy quarks produced in the initial hard-scattering process
• Melting of quarkonia caused by Debye screening • Use sequential melting of the quarkonia states as the
thermometer of the hot and dense matter
Hyunchul Kim Quarkonium 2013, IHEP
Experimental motivation • Puzzles from SPS and RHIC
– Similar J/ψ suppression at SPS(< 20 GeV) and RHIC(200 GeV) – Suppression does not increase with local energy density RAA(forward) < RAA(mid)
– Possible answers • regeneration? • cold nuclear matter effects?
• LHC can give the hint – higher energy([email protected] TeV, [email protected] TeV) – higher luminosity(peak instant luminosity : 0.5 Hz/µb@PbPb) – more charm (possible to regenerate) – more bottom → a new probe : ϒ
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PHENIX, PRL 98 (2007) 232301 PRC 84 (2011) 054912 SPS from Scomparin @ QM06
Npart
RAA : Nuclear Modification Factor RAA>1:regeneration, RAA<1:suppression
Hyunchul Kim Quarkonium 2013, IHEP
Summary of Pb-Pb collision from LHC • Pb-Pb collision
– 2.76 TeV per nucleon pair – ~1 month per year in 2010, 2011 – Integrated luminosity
• 2010 : 7.28 µb-1 • 2011 : 157.6 µb-1 recorded
• pp [email protected] TeV per nucleon – For comparison with Pb-Pb [email protected] TeV per nucleon pair – Equivalent statistics compared to the integrated luminosity of the
2010 HI run
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X20
Hyunchul Kim Quarkonium 2013, IHEP
CMS detector
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Superconducting solenoid : 3.8 T Muon chambers Barrel : 250 DT, 480 RPC Endcaps : 468 CSC, 432 RPC
Silicon Trackers Pixel (100*150 µm) ~ 16m2, 66M channels Microstrips (80*180 µm) ~ 200m2, 9.6M channels
Hyunchul Kim Quarkonium 2013, IHEP
CMS muon reconstruction mechanism
• Global muons reconstructed with information from inner tracker and muon stations
• Apply with additional further muon ID quality cut (χ2, # of hits)
Superconducting Solenoid
inner tracker
muon station
Endcap Barrel
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Hyunchul Kim Quarkonium 2013, IHEP
Acceptance and Efficiency • Because of the magnetic field
and energy loss (2~3 GeV) in the iron yoke, Global muons need minimum pµ to reach the muon stations (3~5 GeV, depending on η)
• Limits J/ψ acceptance – mid-rapidity: pT, J/ψ>6.5 GeV/c – forward: pT, J/ψ>3 GeV/c
8 µη
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2
Effi
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cyµ
Sing
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Trigger Efficiency
- 0.002 + 0.0022011 MC PYTHIA+EvtGen: 0.860
- 0.004 + 0.0042011 Data: 0.915
CMS Preliminary = 2.76 TeVNNsPbPb
6.5 GeV/c≥ ψJ/T
p
(GeV/c)µ
Tp
0 2 4 6 8 10 12 14 16 18 20
Effi
cien
cyµ
Sing
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Trigger Efficiency
- 0.002 + 0.0022011 MC PYTHIA+EvtGen: 0.860
- 0.004 + 0.0042011 Data: 0.915
CMS Preliminary = 2.76 TeVNNsPbPb
6.5 GeV/c≥ ψJ/T
p
• Efficiencies are evaluated with MC
• Crosschecked with tag-and-probe method in data and MC
Hyunchul Kim Quarkonium 2013, IHEP
Prompt, non-prompt J/ψ signal extraction
Inclusive J/ψ
Prompt J/ψ
Direct J/ψ Feed-down from ψ’ and χc
Non-Prompt J/ψ from B decays
• Reconstruct µ+µ− vertex • Separation of prompt and
non-prompt J/ψ – by 2D simultaneous fit of µ+µ− mass
and pseudo-proper decay length
�J/� = LxymJ/�
pT
B Lxy
J/ψ µ− µ+
9 CMS-PAS HIN-12-014
pp 7TeV
Hyunchul Kim Quarkonium 2013, IHEP
Prompt J/ψ RAA : centrality dependence
• With more statistics binning is more finer • Suppressed by factor 5 in most central collision
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partN0 50 100 150 200 250 300 350 400
AAR
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1.4 CMS Preliminary = 2.76 TeVNNsPbPb
|y| < 2.4 < 30 GeV/c
T6.5 < p
ψPrompt J/
partN0 50 100 150 200 250 300 350 400
AAR
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ψPrompt J/
= 2.76 TeVNNsCMS PbPb
|y| < 2.4 < 30 GeV/c
T6.5 < p
2010 2011 CMS-PAS HIN-12-014 JHEP 1205 (2012) 063
Hyunchul Kim Quarkonium 2013, IHEP
Prompt J/ψ RAA : y & pT dependence
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• No strong dependence on pT and rapidity (GeV/c)
Tp
0 5 10 15 20 25 30AA
R0
0.2
0.4
0.6
0.8
1
1.2
1.4 CMS Preliminary = 2.76 TeVNNsPbPb
Cent. 0-100%|y| < 2.4
ψPrompt J/
|y|0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4
AAR
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Cent. 0-100% < 30 GeV/c
T6.5 < p
ψPrompt J/
CMS-PAS HIN-12-014
Hyunchul Kim Quarkonium 2013, IHEP
Prompt J/ψ RAA : y & pT dependence on centrality
partN0 50 100 150 200 250 300 350 400
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4
|y|<1.21.2<|y|<1.61.6<|y|<2.4
CMS Preliminary = 2.76 TeVNNsPbPb
ψPrompt J/
<30 GeV/cT
6.5<p
partN0 50 100 150 200 250 300 350 400
AAR
0
0.2
0.4
0.6
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1
1.2
1.4
<30 GeV/cT
6.5<p<6.5 GeV/c
T3<p
CMS Preliminary = 2.76 TeVNNsPbPb
ψPrompt J/
1.6<|y|<2.4
• No strong dependence on rapidity at higher pT region
• At forward rapidity region, there might be suppression of lower pT J/ψ
Rapidity dependence pT dependence
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CMS-PAS HIN-12-014
Hyunchul Kim Quarkonium 2013, IHEP
Prompt J/ψ RAA : theory comparison
(GeV/c)T
p0 5 10 15 20 25 30
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4 CMS Preliminary = 2.76 TeVNNsPbPb
Cent. 0-100%|y| < 2.4
Rishi,Vitev: 0-100%f max
CNM E-loss + coll dissoc, T
f minCNM E-loss + coll dissoc, T
ψPrompt J/
partN0 50 100 150 200 250 300 350 400
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4
ψPrompt J/
R. Rapp & X. Zhao (V=U)ψPrompt J/
ShadowingCroninFormation time
CMS Preliminary = 2.76 TeVNNsPbPb
|y| < 2.4 < 30 GeV/c
T6.5 < p
• In the high-pT region, no need for regeneration to describe data • Treatment of quarkonia energy loss similarly as open flavor energy loss,
without color-octet included, is not supported by data
NPA 859 (2011) 114 + private communication arXiv:1203.0329 + private communication
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Hyunchul Kim Quarkonium 2013, IHEP
partN0 50 100 150 200 250 300 350 400
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4
ψNon-prompt J/
= 2.76 TeVNNsCMS PbPb
|y| < 2.4 < 30 GeV/c
T6.5 < p
0-20%20-100%
non-prompt J/ψ RAA : centrality dependence
partN0 50 100 150 200 250 300 350 400
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4 CMS Preliminary = 2.76 TeVNNsPbPb
|y| < 2.4 < 30 GeV/c
T6.5 < p
ψNon-prompt J/
• With more statistics we observed the centrality dependent suppression of non-prompt J/ψ.
• Directly measuring the b-quark energy loss in the medium
2011 Suppressed by
factor 2.5
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CMS-PAS HIN-12-014 JHEP 1205 (2012) 063
2010
Hyunchul Kim Quarkonium 2013, IHEP
non-prompt J/ψ RAA : y and pT dependence
(GeV/c)T
p0 5 10 15 20 25 30
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4 CMS Preliminary = 2.76 TeVNNsPbPb
Cent. 0-100%|y| < 2.4
ψNon-prompt J/
|y|0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4 CMS Preliminary = 2.76 TeVNNsPbPb
Cent. 0-100% < 30 GeV/c
T6.5 < p
ψNon-prompt J/
• non-prompt J/ψ is less suppressed in mid-rapidity region than in forward region
• non-prompt J/ψ in lower pT is slightly less suppressed than in higher pT
Rapidity dependence pT dependence
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CMS-PAS HIN-12-014
Hyunchul Kim Quarkonium 2013, IHEP
non-prompt J/ψ RAA : y & pT dependence on centrality
partN0 50 100 150 200 250 300 350 400
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4
|y|<1.21.2<|y|<1.61.6<|y|<2.4
CMS Preliminary = 2.76 TeVNNsPbPb
ψNon-prompt J/
<30 GeV/cT
6.5<p
partN0 50 100 150 200 250 300 350 400
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4
<30 GeV/cT
6.5<p<6.5 GeV/c
T3<p
CMS Preliminary = 2.76 TeVNNsPbPb
ψNon-prompt J/
1.6<|y|<2.4
Rapidity dependence pT dependence
• All rapidity bins at high pT region show centrality dependent suppression • In the forward region, low pT J/ψ has strong centrality dependence and less
suppressed than high pT J/ψ
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CMS-PAS HIN-12-014
Hyunchul Kim Quarkonium 2013, IHEP
non-prompt J/ψ RAA : theory comparison
(GeV/c)T
p0 5 10 15 20 25 30
AAR
0
0.2
0.4
0.6
0.8
1
1.2
1.4
WHDG: 0-80%, y~0Rad+Coll E loss
Vitev: 0-10%, y~0Rad E loss+CNMRad E loss+CNM+Dissoc
Buzatti: 0-100%, y~0CUJET preliminary
He,Fries,Rapp: 0-100%,y~0HF transport
CMS Preliminary = 2.76 TeVNNsPbPb
|<2.4η | b-quarks: 0-100%)) -µ+µ(ψ(via secondary J/
Vitev: J. Phys.G35 (2008) 104011 + private communications Horowitz: arXiv:1108.5876 + private communications Buzzatti, Gyulassy: arXiv: 1207.6020+ private communications He, Fries, Rapp: PRC86(2012)014903+ private communications 17
• For theory comparison, need to shift non-prompt J/ψ pT to higher pT side : J/ψ pT < B pT
• Within large uncertainties, data is described with various theoretical scenarios.
• Model involving only radiative energy loss and cold nuclear matter effects clearly fails to describe the data
Hyunchul Kim Quarkonium 2013, IHEP
b-quark RAA compared with other particles
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partN0 50 100 150 200 250 300 350 400
AAR
0
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1
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b-quarks
)-µ+µ(ψvia secondary J/<30 GeV/c),|y|<2.4
T6.5<p
ALICE: c-quarks*+, D+, D0average D
<12 GeV/c, |y|<0.5T
6<p
In central collisions RAA
charm < RAAbottom
ALICE : arXiv:1203.2160 CMS : CMS-PAS HIN-12-014 b-quark is suppressed distinctly
CMS Highlights from Gunther Roland@QM12
Hyunchul Kim Quarkonium 2013, IHEP
ψ(2S) in pp & PbPb at √sNN = 2.76 TeV
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PAS CMS-HIN-12-007 Low-pT, forward region (pT>3 GeV/c and 1.6<|y|<2.4)
)2 (GeV/cµµm2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2
)2Ev
ents
/ ( 0
.04
GeV
/c
310
CMS Preliminary = 2.76 TeVNNsPbPb
-1bµ = 150 intL
0-20%, 1.6 < |y| < 2.4 < 30 GeV/c
T3 < p
112±: 3510 ψJ/N 0.020±: 0.105 (2S)ψR
2 1) MeV/c± = (50 σ
datatotal fitbackground
Rψ(2S) = Nψ(2S) /NJ/ψ limited by pp statistics Rψ(2S)
PbPb ~ 5 × Rψ(2S) pp
PbPb 2011 pp
PbPb fit
Hyunchul Kim Quarkonium 2013, IHEP
)2 (GeV/cµµm2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2
)2Ev
ents
/ ( 0
.04
GeV
/c
210
310
CMS Preliminary = 2.76 TeVNNsPbPb
-1bµ = 150 intL
0-20%, |y| < 1.6 < 30 GeV/c
T6.5 < p
65±: 3211 ψJ/N 0.008±: 0.024 (2S)ψR
2 1) MeV/c± = (29 σ
datatotal fitbackground
ψ(2S) in pp & PbPb at √sNN = 2.76 TeV
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High-pT, mid-rapidity region (pT>6.5 GeV/c and |y|<1.6) PAS CMS-HIN-12-007
Rψ(2S) PbPb ~ 0.5 × Rψ(2S)
pp Rψ(2S) = Nψ(2S) /NJ/ψ
PbPb fit
PbPb 2011 pp
Hyunchul Kim Quarkonium 2013, IHEP
ψ (2S) results
partN0 50 100 150 200 250 300 350 400
pp]ψ
J/⁄(2
S)
ψ[⁄ Pb
Pb]
ψJ/⁄
(2S)
ψ[
0
1
2
3
4
5
6
7
8
9
10 = 2.76 TeVNNsPbPb
< 30 GeV/c, 1.6 < |y| < 2.4T
3 < p
pp uncertainty (global)
CMS Preliminary
partN0 50 100 150 200 250 300 350 400
0
0.2
0.4
0.6
0.8
1
1.2
1.4 = 2.76 TeVNNsPbPb
< 30 GeV/c, |y| < 1.6T
6.5 < p
pp uncertainty (global)
CMS Preliminary
N (2S)/NJ/ |PbPb
N (2S)/NJ/ |pp = RAA( (2S)RAA(J/ )
R0�100%AA ( (2S)) = 0.11±0.03(stat)±0.02(syst)±0.02(pp)
R0�100%AA ( (2S)) = 1.54±0.32(stat)±0.22(syst)±0.76(pp)
AA AA AA AA
limited by pp statistics from 2011 pp data
Low-pT, forward region
High-pT, mid-rapidity region
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CMS-PAS HIN-12-007
Hyunchul Kim Quarkonium 2013, IHEP
Summary • CMS measured the suppression of prompt J/ψ from
2.76 TeV PbPb collisions. • Also the suppression of non-prompt J/ψ is measured
and this indicates the suppression of the bottom quark in heavy-ion collisions
• In Low-pT, forward region, the enhancement of ψ(2S) relative to prompt J/ψ is observed, but need to more statistics in pp collisions.
• With new 5.02 TeV pPb collision data and enhanced 2.76 TeV pp data, CMS is doing the charmonia analysis.
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Thank you for your attention 谢谢
Hyunchul Kim Quarkonium 2013, IHEP
BACK UP
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Hyunchul Kim Quarkonium 2013, IHEP
Acceptable region for single muon
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JHEP 1205 (2012) 063
• Choose the region which the single muon efficiency is larger than 0.1
• Upper than white line
Hyunchul Kim Quarkonium 2013, IHEP
b fraction of J/ψ production
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(GeV/c)T
p0 5 10 15 20 25 30
b fra
ctio
n
0
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1 = 2.76 TeV (|y|<2.4)NNsCMS PbPb = 2.76 TeV (1.6<|y|<2.4)NNsCMS PbPb
= 2.76 TeV (|y|<2.4)sCMS pp = 2.76 TeV (1.6<|y|<2.4)sCMS pp = 7 TeV (1.6 < |y| < 2.4)sCMS pp = 7 TeV (1.2 < |y| < 1.6)sCMS pp = 7 TeV (|y| < 1.2)sCMS pp = 1.96 TeV (|y|<0.6)s pCDF p
Hyunchul Kim Quarkonium 2013, IHEP
Summary of 2013 pPb & pp collision • proton-Pb ion collisions (2013. Jan. ~ Feb)
– Beam Energy : 5.02 TeV/nucleon (proton : 4 TeV, Pb ion : 1.58 TeV) – Asymmetry collision, boosted to Pb ion backward direction – Beam configuration
– Pbp(B1:p,B2:Pb ion) collision : Jan. 20th ~ 30th
• acceptance : - 2.4 ~ + 1.46 • Integrated luminosity : 18.4 nb-1
– pPb(B1:Pb ion,B2:p) collision : Feb. 2nd ~ 10th • Change beam direction requested by ALICE • acceptance : - 1.46 ~ + 2.4 • Integrated luminosity : 12.5 nb-1
• proton-proton collisions (Feb. 11th ~ 14th) – For the reference to pPb, PbPb data – Beam energy : 2.76 TeV/proton – Integrated luminosity : 5.41 pb-1
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- η CMS + η Beam 2(B2) Beam 1(B1)
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