sasha milov focus on multiplicity bari june 17, 2004 1 dn ch /dη and de t /dη at mid-rapidity from...

Sasha Milov Focus on Multiplicity Bari June 17, 2004 1

dNdNchch/d/dηη and dE and dETT/d/dηη

at Mid-Rapidity at Mid-Rapidity from SIS to LHCfrom SIS to LHC

Alexander Milov

for the PHENIX collaboration

June 17, 2004


Outline.Outline. Apparatus, Measurements & Errors:

PHENIX detector dNch/dη and dET/dη measurement in PHENIX Centrality & Trigger efficiency analysis using NBD.

Results: PHENX results RHIC and lower energy results

Physics: √sNN dependencies Averaged <ET>/<Nch> Centrality shape

Theoretical Models from Experimental Point of View

Summary


USA Abilene Christian University, Abilene, TX Brookhaven National Laboratory, Upton, NY University of California - Riverside, Riverside, CA University of Colorado, Boulder, CO Columbia University, Nevis Laboratories, Irvington, NY Florida State University, Tallahassee, FL Florida Technical University, Melbourne, FL Georgia State University, Atlanta, GA University of Illinois Urbana Champaign, Urbana-Champaign, IL Iowa State University and Ames Laboratory, Ames, IA Los Alamos National Laboratory, Los Alamos, NM Lawrence Livermore National Laboratory, Livermore, CA University of New Mexico, Albuquerque, NM New Mexico State University, Las Cruces, NM Dept. of Chemistry, Stony Brook Univ., Stony Brook, NY Dept. Phys. and Astronomy, Stony Brook Univ., Stony Brook, NY Oak Ridge National Laboratory, Oak Ridge, TN University of Tennessee, Knoxville, TN Vanderbilt University, Nashville, TN

Brazil University of São Paulo, São PauloChina Academia Sinica, Taipei, Taiwan China Institute of Atomic Energy, Beijing Peking University, BeijingFrance LPC, University de Clermont-Ferrand, Clermont-Ferrand Dapnia, CEA Saclay, Gif-sur-Yvette IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, Orsay LLR, Ecòle Polytechnique, CNRS-IN2P3, Palaiseau SUBATECH, Ecòle des Mines at Nantes, NantesGermany University of Münster, MünsterHungary Central Research Institute for Physics (KFKI), Budapest Debrecen University, Debrecen Eötvös Loránd University (ELTE), Budapest India Banaras Hindu University, Banaras Bhabha Atomic Research Centre, BombayIsrael Weizmann Institute, RehovotJapan Center for Nuclear Study, University of Tokyo, Tokyo Hiroshima University, Higashi-Hiroshima KEK, Institute for High Energy Physics, Tsukuba Kyoto University, Kyoto Nagasaki Institute of Applied Science, Nagasaki RIKEN, Institute for Physical and Chemical Research, Wako RIKEN-BNL Research Center, Upton, NY

Rikkyo University, Tokyo, Japan Tokyo Institute of Technology, Tokyo University of Tsukuba, Tsukuba Waseda University, Tokyo S. Korea Cyclotron Application Laboratory, KAERI, Seoul Kangnung National University, Kangnung Korea University, Seoul Myong Ji University, Yongin City System Electronics Laboratory, Seoul Nat. University, Seoul Yonsei University, SeoulRussia Institute of High Energy Physics, Protovino Joint Institute for Nuclear Research, Dubna Kurchatov Institute, Moscow PNPI, St. Petersburg Nuclear Physics Institute, St. Petersburg St. Petersburg State Technical University, St. PetersburgSweden Lund University, Lund

12 Countries; 58 Institutions; 480 Participants*

*as of January 2004


PHENIX Detector.PHENIX Detector. Pad Chamber Detectors:

MWPC with binary pad readout 2.5m and 5.0m from the IP |η|< 0.35 Δφ = 900

σφ= 1.4mrad (1.7mm PC1)

ση= 0.7×10-3 (3.6mm PC1) Double Hit Resolution ~4cm

Electromagnetic Calorimeter: Lead+Scintillator 18 X0 5.1m from the IP |η|< 0.38 Δφ = 900

σE= 8.1%/√E[GeV] ×2.1%

Beam-Beam Counters: 64 Cherenkov Counters 3.1<|η|< 3.9 Δφ = 3600

σvertex= ~5mm (central)

σt= ~100 ps


Multiplicity analysis.Multiplicity analysis. Counting tracks on statistical basis:

Combine all hits in PC1 to hits in PC3 Project lines onto the plane through the beam pipe Count tracks inside the acceptance Subtract combinatorial background by event mixing.

Corrections: Tracks outside acceptance and background subtraction 4.3%±1% Inactive regions 15%±2.3% Double hit resolution

Hit losses 2×7%Background subtraction

3.6% of bkgUncertainty (in central) ±3.6%

Particle in-flow and out-flowLow energy 10%

±5.5%Higher energy 1%

±2%

No Field


Transverse Energy analysis.Transverse Energy analysis. ET definition:

ET = E×sin(θ) ET ≈ mT at Mid-Rapidity in C.M.S. E is full E for leptons and mesons E is E±m for (anti) baryons

EMCal energy scale: Measures full energy of e± and γ (π0) Slow hadrons are fully absorbed. Relativistic hadrons leave M.I.P. peak EMCal measures >75% of energy

Systematic errors: Energy response 3.9%-4.7% Noise in central: <0.5%

in peripheral:3.5%-6.%

In-flow and out-flow 3.0%

AGS testRHIC data


Centrality and trigger analysis.Centrality and trigger analysis.

Np usingGlauber

Nch usingGenerator

Nhits usingDetector MC

Match tothe data

Np, Nc

εtrigger

Shape ofη-profile

Knowledgeof Nch = f(Np)

AssumedNch ~ Np


Centrality and trigger using NBD.Centrality and trigger using NBD.

Np usingGlauber

Nch usingGenerator

Nhits usingDetector MC

Match tothe data

Np, Nc

εtrigger

AssumedNch ~ Np

Shape ofη-profile

Knowledgeof Nch = f(Np)

Use N.B.statistics

UncorrelatedNch production

Negative Binominal Distribution: is the statistics describing distribution of number of trials (n) which are necessary to get a number of successes, if the probability of success (μ) is known:

P(n,,k) = (n + k) / ((k) n!) (/k)n / (1 + /k)n+k

where k is a N.B.D. parameter related to the width of the distribution in a following way:

(/)2 = 1/k + 1/


d-Au example.d-Au example.

Np usingGlauber

Match tothe data

Np, Nc

εtrigger

AssumedNch ~ Np &uncorrelated Nch production

Use N.B.statistics


Other examples:Other examples:

Case |η|<0.35 3<|η|<4 Comment

d-Au 200 GeV No YesMatches pp trigger and tagged spectrum

Au-Au 200 GeV No YesNp is the same as found using standard technique

Au-Au 130 GeV No N/A

Au-Au 62.4 GeV Yes/No NoPreliminary gives the same trigger efficiency as standard

Au-Au 19.6 GeV Yes No Works well on central arm.


Results: The distributions.Results: The distributions.

Only part of the acceptance shown “Classical” Shape: Peak, Valley, Edge. Centrality classes shown. Edge might be modified due to acceptance limitation


Results: Centrality curves.Results: Centrality curves.

Consistent behavior for ET and Nch

Both increase with energy Both show steady rise from peripheral to central


Results: Systematic errors.Results: Systematic errors. Three types of errors All plotted as 1 standard deviation

Statistical error: Point-by-point error (<1%). In all points is smaller than the marker size.

Systematic errors: Band (correlated) allow to tilt points within the limit of the band.

In peripheral (~20%) due to trigger uncertainty. In central (~4%) are due to

DHR of the detectors Scaling (correlated) allow to shift curves up and down.

Total systematic error is a quadratic sum of two. It is shown with the bars.


Results: Ratios at different energies.Results: Ratios at different energies.

R200/19.6 is larger for ET than for Nch

Both are flat within systematic errors Both show steady rise from peripheral to central


Results: Ratios <EResults: Ratios <ETT>/<N>/<Nchch>.>.

Ratio <ET>/<Nch> increases by ~20% from 19.6 GeV to 200 GeV and stays the same between 200 GeV and 130 GeV

Consistent with the average particle momentum increase between those two energies.

Ratio <ET>/<Nch> is independent of centrality

Still a puzzle. Same freeze-out conditions? Since trigger and centrality related uncertainties cancel out, the flatness of the curves is quite precise statement.


Comparison to other RHIC results.Comparison to other RHIC results. Spectacular agreement between all 4 RHIC experiments:

All measurements are absolutely independent (including human factor) besides similar approach of using Glauber model.

BRAHMS: Si detectors + tracking PHENIX: PC at 2.5m and 5m PHOBOS: Si detectors STAR: Tracking in magnetic field.

Would allow to calculate averaged values and reduce systematic errors


Recalculation between systems.Recalculation between systems.

In C.M.S.: At Mid-Rapidity: ET~mT

dET/dy ≈ 1.25 dET/dη In Lab:

dmT/dy ≈ 1.25 dET/dy dET/dy ≈ dET/dη

In C.M.S.: dNch/dy ≈ 1.25 dNch/dη

In Lab: dNch/dy ≈ 1.04 dNch/dη

Recalculation parameters are “rather” independent on energy A systematic error of 5% is assigned to any recalculated value


Good agreement between PHENIX measurements at 19.6 GeV and SPS measurements at 17.2 GeV in both measured values. SPS spread of the data is larger than RHIC, but the same averaging should be possible to reduce the systematic errors.

Comparison to other SPS results.Comparison to other SPS results.


At intermediate SPS energy the energy spread between points is relatively large.

Using weighted average and error scaling by S-factor (see PDG)

S=1 if χ2/n.d.f. < 1 S=√χ2/n.d.f. if χ2/n.d.f. > 1

At lower SPS energy the data spread is even larger, a higher quality data is highly desirable.

At AGS energy the Centrality curve is deduced from a combined data.

Comparison of SPS results.Comparison of SPS results.


Averaged SPS data at 17,3 GeV is in very good agreement to averaged RHIC data at 19.6 GeV (expected difference ~4%)

There is a continuous set of measurements from AGS to RHIC data.

Comparison to other results.Comparison to other results.


PHENX suggested ln(sNN) at QM01 and it works well with better and larger data-set. Both in ET and in Nch show log-scaling. Works even better on Nch for Np = 350.

Band on the right is 2σ error! Extrapolation to LHC dNch/dη = (6.1±0.13)×(0.5Np). Extrapolation to lowest energy gives:

for ET: √s0NN = 2.35 ± 0.2 GeV

for Nch: √s0NN = 1.48 ± 0.02 GeV

√√ssNNNN dependence dependence..


That’s what we see

ln(√sNN)2a.m.u.

N ch E T

-0.5 GeV +0.5 GeV

FOPI Energy conservation law.

What √soNN mean?

Caution: they are in GeV!

Now comes FOPI at <0.1 GeV kinetic energy!

Lower energy: √so

NN <ET>/<Nch> <mT>

Higher energy: <ET>/<Nch> ~ constant √so

NN Nch

Low √sLow √sNNNN story story


What happens to <mWhat happens to <mTT>?>? At low √sNN:

ET is “produced” energy only. Nch can benefit from pre-existing particles (baryons).

At higher √sNN: Critical temperature Tc=0.17GeV. Assuming: <Ekin>=3/2Tc ≈ 0.26 GeV

<m0> ≈ 0.25 GeV<mT> = <Ekin> + <m0>

≈ 0.51 GeV<ET>/<Nch> ≈ 1.6 <mT>

≈ 0.82 GeV

Prediction for LHC: 0.93±0.04 GeV How does flow work?


Hard/Soft approach: Might be deceiving: e.g. strangeness turn on. Negatively correlated errors are huge.

Npα parameterizations: assumes a power law what does α mean? Still large errors

PHOBOS as of June 2,2004 nucl-ex/0405027:

Bottom line: inconclusive!

Centrality shapes.Centrality shapes.


three centrality bins divided by ln(√sNN)-parameterization.

Central bin Np = 350 is just consistent with 1 as expected

Mid-central bin Np=100 with large systematic errors is just an offset

Most peripheral: Np = 2 (pp) for a moment needs more data at low energy. Turns out to be quite difficult to get it right.

Centrality shapes: basic approachCentrality shapes: basic approach


Bjorken energy.Bjorken energy.

Done at all three energies

STAR advocates another approach taking for overlap area S ~Np

3/2.

Difference to standard approach:area of the nuclei vs.area of the nucleons

Makes some difference at low Np

Recent STAR finding: (nucl-ex/03011017) dET/dy / (0.5 Np) decreases with Np ?!


Models: experimentalist’s viewModels: experimentalist’s view

Model vs. Generator: Do you know why we are such in love with HIJING? IMHO: Model is a precursor to the Generator. Major difference besides completeness and ease of use:

Generator does partial probabilities!

What happened to systematic errors? How well defined a model is within itself? Only Mini-Jet gives a band. How should experimentalist compare models to data?

Thanks to all authors who sent us their data!


Models IModels I

LUCIFER Hadronic cascade model, input fixed from lower energy.D.E.Kahana & S.H.Kahana, nucl-th/0208063.

Minijet Multiphase transport model, includes both initial partonic and final hadronic interactions.

S. Lee and X.N. Wang, Phys Lett B527, 85 (2002)

EKRT K.J. Eskola, et al., Nucl. Phys. B570, 379 (2000), Phys Lett B497, 39 (2001).

SSHM Saturation for Semi-Hard Minijetis. pQCD-based for semi-hard partonic interactionWNM for soft particle production. A.Accardi, Phys Rev C64, 064905 (2001).

KLN D. Kharzeev and M. Nardi, Phys Lett B507, 121(2001), D. Kharzeev and E. Levin, Phys Lett B523, 79 (2001).


Models IIModels II

DSM: Dual String Model, Dual Parton Model + strings. R. Ugoccioni, Phys Lett B49, 253 (2000). A. Capella et al, Phys Lett C236, 225 (1994).

HIJING: pQCD for initial minijet production and the Lund string model for jet fragmentation and hadronization, +jet quenching +nuclear shadowing. X.N. Wang et al. PRC 68, 054902 (2003).

LEXUS: Linear EXtrapolation of UltraRrelativsitic nucleon-nucleon scattering data to nucleus-nucleus collisions. S. Jeon and J. Kapusta, Phys Rew C63, 011901 (2001)

AMPT: multiphase transport model +initial partonic and final hadronic interactions. Z. Lin et al. Phys Rew. C64, 011902 (2001).

SFM: String Fusion Model string model, includes hard collisions, collectivity in the initial state (string fusion), and final state. N. Armesto Perez et al., Phys Lett B527, 92 (2002)


Models Models IIIIII


What else do we need.What else do we need. We expect collaboration to fill the missing gaps in the paper and give it more physical impact:

what do parameters of the ln(√sNN)-scaling mean? help with quality pp data at low energy polish the model section

62 GeV data.62 GeV data. PPG19 draft to be released to collaboration today without 62 GeV Michael Mendenhall from VU is working on the data. We might have results + an analysis note in scope of weeks. Impact on the paper:

for physics: minimal for completeness: desirable for future references: good text/structure change to incorporate: minimal (~1 day)

If we have the data my suggestion is to bring it to convenor’s meeting to decide when it happens, if not too late.

sasha milov focus on multiplicity bari june 17, 2004 1 dn ch /dη and de t /dη at mid-rapidity from...

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