reaction plane reconstruction1 reaction plane reconstruction in extzdc michael kapishin...
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Reaction plane reconstruction 1
Reaction plane reconstruction in extZDC
Michael Kapishin [email protected]
Presented by A.Litvinenko
Reaction plane reconstruction 2
Reaction plane reconstruction in extZDC
Topics discussed in the report
Dependence from:
beam energy ZDC cell size
ZDC length
magnetic field
Position of extZDC within MPD set-up
Reaction plane reconstruction 3
extZDC
Reaction plane reconstruction 4
Methods of reaction plane reconstruction
1-st Fourier harmonics → directed flow:
))φ-cos(φ2v +(12π
N
φd
dNRn
tot ∑=
∑∑
i,xi
i,yi
Rpw
pwarctanφ =
Ew ii =
iii p/Ew =
Reaction plane reconstruction 5
Methods of reaction plane reconstruction
Method 1:
2222 +=
+==
ii
ii
ii
ii
ii
iinuclR
xy
xφcos;
xy
yφsin;
φcosEΔ
φsinEΔarctanφ
∑∑
Method 2:
2π2
2ππ2
δ1+δ1δπ++δ
=)φ()φ(
)φ()φ()φ(φφ
RnuclR
RRnuclR
nuclR
R
→ combine measurements for η<0 and η>0 to improve precision, study as a function of impact parameter b
;
∑∑
ii
iinuclR
xEΔ
yEΔarctanφ =
Extended ZDC detector
Reaction plane reconstruction 6
Simulation of extended ZDC within mpdroot:
• L = 120 (60, 40) cm
• 5 < R < 61 cm (inscribed circle), z0=270 cm, 1<θ<12.5o (2.2<η<4.8)
• dcell = 5x5,10x10 cm
• wi=Σ Evis in active layers of 1 module → use methods 1 and 2 for RP reconstruction
• No π vs p/ion identification
• Geant 4 , QGSP_BIC physics model
dcell = 5x5 cm, 420 cells in each side of MPD
dcell = 10x10 cm, 121 cells in each side of MPD
Resolution δφRP vs b
Reaction plane reconstruction 7
δφRPo = φZDC-φRP
Extended ZDC, QGSM 9 AGeV AuAu, Geant4 QGSP_BIC modeldcell = 5x5cm, L=120cm2.2 < η < 4.8, method 1, w=Evis
No PID (π vs p/ion)
b = 0 – 16 fm in 8 bins, 2 fm / bin
cos δφRP vs b
Reaction plane reconstruction 8
b = 0 – 16 fm in 8 bins, 2 fm / bin
cos(δφRP) = cos(φZDC-φRP)
Extended ZDC, QGSM 9 AGeV AuAu, Geant4 QGSP_BIC modeldcell = 5x5cm, L=120cm2.2 < η < 4.8, method 1, w=Evis
No PID (π vs p/ion)
Resolution δφRP vs b
Reaction plane reconstruction 9
• methods 1 and 2 give consistent results for RP resolution in azimuthal angle φ
• RP resolution for the case if only ZDC from one side of MPD set-up is used vs full ZDC set-up (lower plot)
Resolution δφRP and <cos δφRP> vs b
Reaction plane reconstruction 10
Effects of ZDC cell size and length, beam energy and interaction model
Effect of magnetic field: <φZDC-φRP> vs b
Reaction plane reconstruction 11
→ Systematic effect of magnetic field increases from ~1o at 9 AGeV to ~3o at 3 AGeV, QGSM and UrQMD model give consistent results
QGSM UrQMD
Effect of magnetic field: <φZDC-φRP> vs b
reaction plane reconstruction 12
• Systematic effect of magnetic field increases from ~1o at 9 AGeV to ~3o at 3 AGeV• Magnetic field systematics is small compared to RP resolution• QGSM and UrQMD models give consistent results → systematics could be corrected based on model predictions
• Extended ZDC detector (2.2<η<4.8) provides RP measurement at medium b (4<b<10 fm) with resolution of δφRP~22-35o in AuAu collisions at energies 5-9 AGeV, RP resolution deteriorates to δφRP~45-65o at 3 AGeV
• Sensitivity of extended ZDC to RP azimuthal angle in central (b<3 fm) and peripheral collisions (b>12 fm) is much weaker
• QGSM and UrQMD models give consistent results for RP resolution of extended ZDC, model dependence increases at low beam energies
• ZDC cell size and length is not critical: dcell=10x10cm, L=60cm are sufficient for RP measurement. ZDC length is more crucial for energy flow measurement
• Magnetic field systematics to φRP is ~1o at 9 AGeV which increases to ~3o at 3 AGeV. Reduced magnetic field at the lowest energy would decrease systematics
Summary
13
Backup
Reaction plane reconstruction 14
Reaction plane peconstruction 15
Reaction plane peconstruction 16
LAQGSM generator: all nucleons in 1000 events
directed to rectangle 10x10cm for 3 regions of impact parameter
b <= 10.84 (60%)
19707 nucleons
10.84<b<=12.5 (60-80%)
47826 nucleons
b>12.5 (after 80%)
60431 nucleons
LAQGSM generator: all nucleons in 1000 events
directed to new ZDC for 3 regions of impact parameter
b <= 10.84 (60%)
71041 nucleons
10.84<b<=12.5 (60-80%)
22848 nucleons
b>12.5 (after 80%)4787 nucleons
Elliptic Flow vs. Beam Energy25% most central mid-rapidity
six decades
In-planeelliptic flow
squeeze-out
bounce-off
A. Wetzler
“old” and extended ZDC
cell 10 x 10 (cm x cm)
PHENIXReaction Plane Resolution
O30ΔΨ 0.4)ΔΨ2cos( == ⇒
O40ΔΨ 0.2)ΔΨ2cos( == ⇒
Reaction plane resolution vs. numbers of particle and value of the flow
PHENIXReaction Plane Detector
L=38 cm 2.8< η< 0.8
O18ΔΨ 0.8)ΔΨ2cos( == ⇒
GeV .SNN 98=
GeV .SNN 98=
Fast evaluations: the movement of spectators at NICA/MPD
bpXY
Z
T 1 B
QB0.3Ap
- Ap
zQB0.3cos
QB0.3Ap
)z(y
ApzQB0.3
sinQB0.3Ap
)z(x
T
z
T
z
T
ApzQB0.3
cos12QB0.3Ap
yx )z,B(z
T22
Ap
zQBz
p
pzB
Ap
zQB
zz
T
z
0.3
2
1 ; ),( 0.2
0.3
The conclusion:Magnetic field of MPD will not change the polar angles for spectators at ZDC position it will only slightly changes the azimutal angles
06
zT p/p
LAQGSM generator: all nucleons in 1000 events
directed to new ZDC for 3 regions of impact parameter
b <= 10.84 (60%)
71041 nucleons
10.84<b<=12.5 (60-80%)
22848 nucleons
b>12.5 (after 80%)4787 nucleons
G4 physics model: QGSP_BIC vs QGSP_BERT
Reaction plane peconstruction 29
Gean4 physics models:
QGSP_BERT uses Geant4 Bertini cascade for primary protons, neutrons, pions and Kaons below ~10GeV. In comparison to experimental data we find improved agreement to data compared to QGSP which uses the low energy parameterised (LEP) model for all particles at these energies. The Bertini model produces more secondary neutrons and protons than the LEP model, yielding a better agreement to experimental data.
QGSP_BIC uses Geant4 Binary cascade for primary protons and neutrons with energies below ~10GeV, thus replacing the use of the LEP model for protons and neutrons In comparison to the LEP model, Binary cascade better describes production of secondary particles produced in interactions of protons and neutrons with nuclei. QGSP_BIC also uses the binary light ion cascade to model inelastic interaction of ions up to few GeV/nucleon with matter.
QGSP_BIC is selected → more reasonable description of interactions of light ions (A=2,3,4) with medium, see also next slides
Shower radius in ZDC: hadrons, light ions (A=2,3,4), em particles
G4 physics model: QGSP_BIC vs QGSP_BERT
Reaction plane peconstruction 30
Evis (0.1zdc) / Evis (full zdc) Evis (zdc) / Egen
hadrons, light ions (A=2,3,4), em particles
G4 physics model: QGSP_BIC vs QGSP_BERT
Reaction plane peconstruction 31
Evis (zdc) vs Egen Evis (zdc) / Egen vs Egen
hadrons, light ions (A=2,3,4), em particles
Non-linear response because of shower leakage
Reaction plane peconstruction 32
Extended ZDC: Evis vs impact parameter b
b = 0 – 16 fm in 8 bins, 2 fm / bin
b measurement using Evis (ZDC):
QGSM model: Evis has peak at b=8-10 fm, → double solution in b measurement based on Evis
UrQMD model: monotonic dependence of Evis on b
QGSM, 9 AGeV
Reaction plane peconstruction 33
Extended ZDC: Fvis(R<25cm) vs b
b = 0 – 16 fm in 8 bins, 2 fm / bin
b measurement using Fvis=Evis(R<25cm)/Evis(full zdc):
QGSM model: Fvis is monotonic except at highest b>12fm→ large fluctuations of Fvis
→ double solution for b measurement based on Fvis
UrQMD model: monotonic dependence of Fvis on b
QGSM, 9 AGeV
Reaction plane peconstruction 34
QGSM vs UrQMD: particle and energy flow
extZDC
QGSM and UrQMD generate very different particle and energy flow spectra in pseudo-rapidity range of extZDC
Reaction plane reconstruction 35
ExtZDC: <Evis> and <Fvis> (R<25cm) vs b
QGSM vs UrQMD:
• model dependence is big for Evis at large b (b>10fm)
• effect is smaller for Fvis(ZDC, R<25cm), but is not negligible
• QGSM and UrQMD predictions for particle and energy flow in ZDC pseudo-rapidity range are very different→ energy flow measurement in extended ZDC will distinguish between models
What can one get from TPC data?
Effect of beam energy and AuAu interaction model
Reaction plane peconstruction 36
Multiplicity and Σ p (π,K,p in TPC) vs b
• Σ p of charged tracks in TPC (|η|<1.2) is a measure of impact parameter b or centrality of nucleus-nucleus interaction. It is less model dependent (QGSM vs UrQMD) in comparison with multiplicity of TPC tracks (lower plot) • Model dependence of b measurement with Σ p of charged particles in TPC decreases at low beam energies
Reaction plane peconstruction 38
Relation between b and centrality
Impact parameter b: 0 - 3 fm 3 – 6 fm 6 – 9 fm 9 – 12 fm
Fraction of σincltot : 0 - 5% 5 – 15% 15 – 30% 30 – 60%
Total multiplicity of charged tracks is a measure of impact parameter b (and centrality of nucleus-nucleus interaction)