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


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?).


Lots of Doctors from 12 countries


Back to the patient now…First diagnostic measure: counting particles….


Charged multiplicity with energy


Second diagnostic: energy density or how hot and dense


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%]


PHENIX [2%]

PHENIX Preliminary [2%]

NA49 [2%]

WA98 [5%]E814/E877 [0.2%]

Transverse energy to multiplicity is almost flat


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


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


Source Size Evolution


The HBT Puzzle?

Npart


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.


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:


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


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


Comparison of Anti-deuteron B2 vs with other experiments

S

E864(AGS)


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


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


Elliptic Flow of identified hadrons

Bottom left shows comparison with hydro.

Bottom right shows scaled v2 in quark recombination picture.

Ref: nucl-ex/0305013


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


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


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


Towards some colorful stuff: the spectra


-

+

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


Proton/pion ratio

P/pi ratio goes up with centralitynucl-ex/0305036


Deuteron/Anti-deuteron minimum bias spectra with mT fits


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)


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


Auxillary Slide(s)


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


• 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


• 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


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

phenix global observables and hadrons anuj k. purwar sunysb-physics june 12, 2003 phenix...

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