Phenix Global Observables and Hadrons Anuj K. Purwar SUNYSB-Physics June 12, 2003 Phenix...
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Transcript of Phenix Global Observables and Hadrons Anuj K. Purwar SUNYSB-Physics June 12, 2003 Phenix...
Phenix Global Observables and Hadrons
Anuj K. Purwar SUNYSB-Physics
June 12, 2003 Phenix Collaboration Meeting, Nashville
June 12, 2003 Anuj K. Purwar 2
The patient
In order to “diagnose” the collision zone at RHIC we need to measure global properties like: Multiplicity or just counting Temperature and energy density Source size Shape of spectra
June 12, 2003 Anuj K. Purwar 3
But first, a little bit about the Doctor
The doctor has two arms (would you like to be treated by a doctor who has no arms?).
June 12, 2003 Anuj K. Purwar 4
Lots of Doctors from 12 countries
June 12, 2003 Anuj K. Purwar 5
Back to the patient now…First diagnostic measure: counting particles….
June 12, 2003 Anuj K. Purwar 6
Charged multiplicity with energy
June 12, 2003 Anuj K. Purwar 7
Second diagnostic: energy density or how hot and dense
June 12, 2003 Anuj K. Purwar 8
Bjorken Energy Density
o
yT
BJ R
dydE
2
0/
Bjorken Estimate
R
E = 5.5 GeV/fm3
E814/E877 [0.2%]
WA98 [5%]
NA49 [2%]
PHENIX [2%]
PHENIX Preliminary [2%]
June 12, 2003 Anuj K. Purwar 9
PHENIX [2%]
PHENIX Preliminary [2%]
NA49 [2%]
WA98 [5%]E814/E877 [0.2%]
Transverse energy to multiplicity is almost flat
June 12, 2003 Anuj K. Purwar 10
Bertsch-Pratt source radii 2 2 2 2 2 2
2 side side out out long longC 1 exp R q R q R q The duration time
2 2TO TSR R /
Rside (RTS)
Rout (RTO)
Detector
source
Beam axis
Au
Au
Beam axisRlong (RL)
x
y
z
Detector
source
•Hanbury-Brown Twiss (HBT) Correlations
•Coalescence parameter B2 from deuterons/anti-deuterons
T T1 T2k (p p ) / 2
Third Diagnostic: source size
June 12, 2003 11Akitomo Enokozino, Steve Johnson, Ron Soltz, Mike Heffner
λ = 0.397 ± 0.015Rside = 4.40 ± 0.12Rout = 3.73 ± 0.12 [fm]Rlong = 4.82 ± 0.15
λ = 0.434 ± 0.018Rside = 4.58 ± 0.14Rout = 3.88 ± 0.14 [fm]Rlong = 5.24 ± 0.18
200 GeV Au+Au 、 Top 30% Centrality, 0.2<kT<2.0GeV/c, <kT>=0.46GeV/c
PHENIX PRELIMINARY PHENIX PRELIMINARY
3-D correlation results for charged pions
June 12, 2003 Anuj K. Purwar 12
Centrality is 0-30%
• Broad <kT> range : 0.2 - 1.2 GeV/c • All Radius parameters decrease as a function of kT consistent with collective expansion picture. • Stronger kT - dependence in Rlong has been observed.
kT : average momentum of pairkT dependence of the Radii
June 12, 2003 Anuj K. Purwar 13
Source Size Evolution
June 12, 2003 Anuj K. Purwar 14
The HBT Puzzle?
Npart
June 12, 2003 Anuj K. Purwar 15
Why a puzzle?• Old expectation: large duration times
lead to Rout/Rside>>1 in presence of a QGP phase transition.
• More recent expectation: shell-like position distribution of low q and high k pairs.
• Some possibilities:• Hollow shell• Highly opaque• Peaked velocity at the edge
• However theory is unable to get Rout/Rside below 1.2 in a physical scenario.
June 12, 2003 Anuj K. Purwar 16
Coalescence parameter B2
n
p
d
pp
pp
pd=2pp
2
3
3
23
3
p
pp
d
dd dp
NdEB
dp
NdE
•Defined as:
June 12, 2003 Anuj K. Purwar 17
Coalescence and HBTCoalescence is governed by same “homogeneity lengths” extracted from HBT measurements [Scheibl and Heinz, 97]. B2 can be related to Vhom by:
Measures size of baryonic source and relates it to HBT
hom
2/3
2 2
3
Vm
CB
t
d
June 12, 2003 Anuj K. Purwar 18
Coalescence parameter B2 vs pT for d, dbar
B2 increases a function of pT, which is consistent for a source with an increasing velocity profile.
Anuj K. Purwar
June 12, 2003 Anuj K. Purwar 19
Comparison of Anti-deuteron B2 vs with other experiments
S
E864(AGS)
June 12, 2003 Anuj K. Purwar 20
Target
Projectile
b:impact parameter
React
ion
plane
Reaction plane
dN/d(-) = N (1 + 2vn’cos(n(-)))
Can give information on Equation of State.
initial geometry
final momentum anisotropy
Collective motion: Elliptic Flow
June 12, 2003 Anuj K. Purwar 21
v2
reaction plane based analysisCharged hadrons
(r.p. ||=3~4)
pT (GeV/c)
min. bias
Au+Au at sqrt(sNN)=200GeV
Hydro-dynamical model (*)Hydro+pQCD (dNg/dy=1000,500,200) (**)
PHENIX Preliminary
(*) P.Huovinen, P.F.Kolb, U.W.Heinz, P.V.Ruuskanen and S.A.Voloshin, Phys. Lett. B503, 58 (2001)
dNg/dy=1000
dNg/dy=500
dNg/dy=200
(**) M.Gyulassy, I.Vitev and X.N.Wang, Phys. Rev. Lett. 86, 2537, (2001)
Shinichi Esumi
Elliptic Flow vs transverse momentum
Crosscheck sin0
June 12, 2003 Anuj K. Purwar 22
Elliptic Flow of identified hadrons
Bottom left shows comparison with hydro.
Bottom right shows scaled v2 in quark recombination picture.
Ref: nucl-ex/0305013
June 12, 2003 Anuj K. Purwar 23
Tp
Tp )(Var
random
randomdatapT
F
NrandomTpF
* AuAu 200 GeV, preliminary
o AuAu 130 GeV, published Phys. Rev. C66, 024901 (2002)
Maximum for semi-central collisions. FpT related to T:
PHENIX Preliminary
FpT
(%)
Fpt represents the fraction of non-random fluctuations with respect to a mixed event baseline.
Jeffery Mitchell
Fluctuations in Event-by-Event Average Transverse Momentum
June 12, 2003 Anuj K. Purwar 24
FpT vs. PT range (0.2<pT<pT, max)
PHENIX Preliminary
FpT
(%)
NOTE: The non-random fluctuations are being introduced primarily by high pT particles.
A simulation of elliptic flow shows that there is a negligible contribution due to that effect.
A Hint of Something New
Increase in fluctuation magnitude with pT
June 12, 2003 Anuj K. Purwar 25
Observed signal is not consistent with temperature fluctuations due to a phase transition.
Observed signal is consistent with jets suppressed by the preliminary PHENIX RAA values.
HIJING, no jetsHIJING, suppressed jets
HIJING, unsuppressed jets
Quark FF, no RAA scalingQuark FF, with RAA scaling
HIJING 1.3 filtered through PHENIX
acceptance
A Simple Model:
• Throw inclusive spectra and <N> distributions to match data.
• Define hard collision probability (Phard) vs. pT from data excess over mT exponential fit.
• For hard collisions, generate jets by sampling the fragmentation function (FF).
• Calculate FT.
• The only adjusted parameter vs. centrality is Phard scaled by measured RAA.
Explaining the Source of the Excess Fluctuations
June 12, 2003 Anuj K. Purwar 26
Towards some colorful stuff: the spectra
June 12, 2003 Anuj K. Purwar 27
-
+
PHENIX PreliminaryPHENIX Preliminary
centrality 0 - 5 % 5 - 10 %10 - 15 %15 - 20 %20 - 30 %30 - 40 %40 - 50 %50 - 60 %60 - 70 %70 - 80 %80 - 91 %
Tatsuya Chujo, Julia Velkovska, Akio Kiyomichi
K+
K-
p
p
PHENIX Preliminary PHENIX Preliminary
PHENIX Preliminary PHENIX Preliminary PHENIX Preliminary
Shapes:- Pions: Power law- Kaons: mT exponential- Protons: Boltzmann function
Identified Particle pT Distributions vs. Centrality
June 12, 2003 Anuj K. Purwar 28 Note: The proton yield is comparable to the pion yield @ 2 GeV.
PHENIX Preliminary PHENIX Preliminary
Au+Au at sqrt(sNN) = 200GeV
• (Peripheral) Almost parallel to each other.
Identified Particle Spectra
June 12, 2003 Anuj K. Purwar 29
Proton/pion ratio
P/pi ratio goes up with centralitynucl-ex/0305036
June 12, 2003 Anuj K. Purwar 30
Deuteron/Anti-deuteron minimum bias spectra with mT fits
June 12, 2003 Anuj K. Purwar 31
open symbols : 130 GeV data
Systematic error on 200 GeV data (10 %), K (15 %), p (14 %)
• Increase of <pT> as a function of Npart.Tends to saturate in the order < K < proton (pbar)
• This is consistent with a hydrodynamic expansion picture.
<p
T>
[G
eV
/c]
<p
T>
[G
eV
/c]
<pT> vs. Centrality (Nparticipants)
June 12, 2003 Anuj K. Purwar 32
DiagnosisBjorken energy density e = 5.5 GeV (approx.)KT dependence of HBT radii and B2 (coalescence parameter), indicative of a rapidly expanding source. => Thermalized medium?Flow consistent with hydro below 2 GeVRo/Rl puzzle still undiagnosed…
Shape of spectra satisfactorily explained at low pT a hydrodynamic expansion picture, but p/pi ratio not well understood.
Special Thanks to Jeff Mitchell whose slides have been used extensively in this talk
Dr. Phenix says more tests required
June 12, 2003 Anuj K. Purwar 33
Auxillary Slide(s)
June 12, 2003 Anuj K. Purwar 34
Radial position on freeze-out surface = r/R
Particle density distribution f() is independent of
Parameters:normalization Afreeze-out temperature Tfo
surface velocity T
t
mt
1/m
t dN
/dm
t
TfoA
Fit range chosen to: a) Minimize contributions from hard processes
(mt-m0) < 1 GeV
b) Exclude resonance region pT < 0.5 GeV/c
Linear flow profile () = T <T > = 2T/3
S. Esumi, S. Chapman, H. van Hecke, and N. Xu, Phys. Rev. C 55, R2163 (1997)
t()
1
f()
Shape of spectra is important
Reproducing the Shape of the Single Particle Spectra
June 12, 2003 Anuj K. Purwar 35
• Simultaneous fit in range
(mt -m0 ) < 1 GeV is shown.
• The top 5 centralities are scaled for visual clarity.
• Similar fits for negative particles.Jane Burward-Hoy
Fitting the Transverse Momentum Spectra
June 12, 2003 Anuj K. Purwar 36
• Expansion parameters in each centrality
• Overall systematic uncertainty is shown.
• A trend with increasing Npart is observed:– Tfo and T
• Saturates at mid-centrality
Fit Parameters Tfo and T vs. Npart
June 12, 2003 Anuj K. Purwar 37
Charged particle multiplicity
nch = n+ + n– Net charge
Q = n+ - n– Define:
v(Q) Var(Q)/<nch>
For stochastic emission, v(Q) = 1Globally, one expects v(Q) = 0 – charge conservation
If we observe a fraction p of all produced particles v(Q) (1 – p ) from global charge conservation
For the 10% most central collisions, ||<0.35, pT > 200 MeV/c, =/2:
v(Q) = 0.965 ± 0.007(stat.) – 0.019 (syst.) snn = 130 GeV
v(Q) = 0.969 ± 0.006(stat.) ± 0.020 (syst.) snn = 200 GeV (PRELIMINARY)
Systematical error estimated from GEANT simulations (reconstructionefficiency and contribution from background tracks), and by comparing theresults for the 2 arms (200 GeV).
Joakim Nystrand
Net Charge Fluctuation Measures and Results