measurement of v 2 and v 4 in au+au collisions at different beam energy from phenix
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Measurement of v2 and v4 in Au+Au Collisions at different beam energy
from PHENIX
Shengli Huangfor PHENIX Collaboration
Vanderbilt University
Outline
1. Physics motivations 2. The analysis methods 3. The v2 measurements from PHENIX
4. The v4 measurements from PHENIX
5. Summary and Outlooks
2S. HuangWWND2011,Colorado
Physics motivation (1)
S. Huang 3
M. Luzum, J-Y Ollitrault, Phys.Rev.C82:014906,2010
RHIC data indicates the partonic collectivity has been generated at RHIC.
Viscous hydro-dynamics calculations with a small value of η/s is compatible with v2 measurements
Beam energy scan will search for the collision energy where the partonic matter starts to turn off
WWND2011,Colorado
η/s = 0.08 CGC η/s = 0.16 Glauber
Physics motivation (2)
4S. Huang
The differential v2 saturates at RHIC energy from 62.4 GeV to 200 GeV
Softening of equation of
state
Locate the collision energy for the critical point searching
To measure the v2 and v4 in same rapidity for the same collision system will supply better information for extracting collision energy dependence
Phys.Rev.Lett.94:232302,2005.
WWND2011,Colorado
Physics motivation (3)
S. Huang 5
v4/v22 is sensitive to the η/s and the freez-out
temperatureSimultaneous measurements of differential v2
and v4 are important for extraction of transport
propertiesGombeaud & J-Y.Ollitrault, PRC 81,014901(2010)Luzum, &,J-Y. Ollitrault, PRC 81,054910(2010)Phys. Rev. Lett. 105, 062301 (2010)
WWND2011,Colorado
PHENIX Detectors for Event Plane
6S. Huang
Large η gap away central arm |η|<0.35 Systematic study the non-flow effect for the measurement of v2 and v4
Event plane detectors:Reaction plane detector
RXNIN (1.5<||<2.8)RXNOUT (1.0<||<1.5)
Muon position EMCal
MPC (3.1<||<3.9)
Beam-beam counter
BBC (3.1<||<3.9)
The event plane Resolution
S. Huang 7
σRP for v2, Au+Au at 7.7 GeV
WWND2011,Colorado
Robust Measurements
S. Huang 8
The measurements from different event plane detectors are consistent quite well
WWND2011,Colorado
The Energy dependence of v2 (1)
S. Huang 9
There is no energy dependence of v2(pT) for collision energy from 39 GeV to 200 GeV for different collision centrality bins
WWND2011,Colorado
The Energy dependence of v2 (2)
S. Huang 10
The v2 at 7.7 GeV Au+Au is much lower than v2 of 39 GeV,
62.4 GeV and 200 GeV
Partonic flow -- Hadronic flow ?
WWND2011,Colorado
The Baryon contribution
S. Huang 11
Proton yield dominates in the positive hadrons, while pion yield dominates in the negative hadrons
The v2 of negative hadron at 7.7 GeV Au+Au is lower than v2 of pion at 200 GeV AuAu
WWND2011,Colorado
The Energy dependence of v4 (1)
S. Huang 12
Similar to v2, the v4 does not show energy dependence for collision energy from 39 GeV to 200 GeV
WWND2011,Colorado
The Energy dependence of v4 (2)
S. Huang 13
At mid-centrality, the v4/v22 is around 0.8 as a function of pT in
Au+Au collision from energy 39 GeV to 200 GeV
The v4/v22 is similar from 39 GeV to 200 GeV at different Npart in
Au+Au collisionsWWND2011,Colorado
Summary and outlooks 1. The v2 measurement from PHENIX further indicates that the
v2 saturates from 39 GeV to 200 GeV, but larger than the v2 of
7.7 GeV in AuAu collision
2. The v4 also saturates from 200 GeV to 39 GeV and the
v4/v22 is almost constant from 39 GeV to 200 GeV
3. These results will supply new information for comparison with results from viscous hydro-dynamics models. It will also shed light on the path for further research on the critical point
4. The PID v2 and v4 results from PHENIX will be out soon
S. Huang 14WWND2011,Colorado
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