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DOE Office Of Nuclear Physics Supplemental RequestFor the Purdue Relativistic Heavy Ion Group

Grant DE- FG02-88ER404

The Experimental Study Of The Phase Structure

Of Strongly Interacting Matter

Project Period (1/1/2007) to (12/31/2007)

March 30, 2007

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Faculty R. Scharenberg Prof. of Physics

A. Hirsch Prof. of Physics

F. Wang Assoc. Prof. of Physics

B. Srivastava Asst. Research Professor

New Hire W. Xie Asst. Prof. of Physics

Staff B. Stringfellow Research Scientist

Post Doc. P. Netrakanti

Grad.Student J. Ulery 4th year research

T. Tarnowsky 3rd year research

M. Skoby 2nd year research

Purdue Personnel

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PURDUE’S INTEREST IN THE PHASE STRUCTURE OF

HADRONIC MATTERThe Purdue High Energy Nuclear Physics Group has been a pioneer in the study of the phase structure of hadronic matter. We have found compelling evidence for a nuclear Liquid-Gas critical phase thermal transition at an excitation energy of 5 MeV/nucleon using internal gas jet targets at the Fermi National Accelerator and at the Brookhaven National laboratory (BNL). At the Lawrence Berkeley Laboratory a complete reconstruction of the nuclear multifragmentation of 1 GeV per nucleon Au on C nuclei determined critical indices and the critical scaling function. At (FNAL) we found clear evidence for the Quark-Gluon to Hadron transition at a transition energy density of 1.1 GeV/fm3

from p-pbar collisions at 1.8 TeV. We also found large long range forward-backward multiplicity correlations indicating the presence of multiple parton-parton interactions in these events.

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REDIRECTION OF ~50% OF STAR RESEARCH TO EMCAL RESEARCH AT ALICE

The group presently has major hardware and software responsibilities in STAR which have been critical to the success of the STAR program. We want to redirect some of our efforts from RHIC to the LHC

1. Blair Stringfellow is the TPC subsystem manager and has provided critical service work and supervision over TPC maintenance and data taking. Stringfellow will retire in 2008 and Purdue will phase out of this responsibility in 2008.

2. Srivastava, Tarnowsky and Skoby will phase out their FTPC

calibration, software, and operational maintenance in 2008. We will end this service responsibility by 2009.

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REDIRECTION OF ~50% OF STAR RESEARCH TO EMCAL RESEARCH AT ALICE

3. Hirsch, Wang and Xie will work at STAR. We expect that Purdue will continue to play a very active role in the STAR II program, for example in the construction of upgrades for the STAR detector.

4. Srivastava and Scharenberg are interested in the EMCAL initiative at LHC. We are committed to contributing to detector support and simulation-analysis efforts for EMCAL. We are interested in the analysis of Long Range Forward-Backward multiplicity correlations in Pb-Pb collisions at 5.5 TeV.

5. To summarize: It is proposed that two faculty, one postdoctoral research scientist and two PhD. students will work full time on the ALICE EMCAL program.

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RESEARCH USING THE EMCAL DETECTOR

The Purdue interest in physics using the electromagnetic calorimeter (EMCAL) is in studying jet-jet and -jet tomography of Pb-Pb collisions at s = 5.5 TeV. The new EMCAL detector will provide the essential trigger capability for these 2 to 2 reactions over a wide range of Q2 corresponding to jet energies < 200 GeV . An unambiguous signal for deconfinement is the determination of the number of the degrees of freedom (DOF). At the critical temperature lattice gauge numerical simulations predict DOF 20. At temperatures well above the critical temperature lattice-gauge simulations predict that the DOF 40. The cleanest deconfinement signal is the number of degrees of freedom (DOF) g() at the earliest time after the Pb-Pb collision. We can follow the suggestion by B. Muller and K. Rajagopal entitled “From Entropy and Jet Quenching to Deconfinement”.

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RESEARCH USING THE EMCAL DETECTOR

For a thermalized system this can be done by measuring the ratio of the “initial” entropy density to the initial energy density ie. eliminating the temperature. For entropy density s and energy density the ratio s4/3 1.0 g () is independent of the temperature. An analysis based on the inferred chemical freezeout multiplicities of hadrons has the potential to extract the entropy at chemical freezeout directly. Assuming an isentropic expansion, the initial entropy density could be estimated The initial energy density determination requires the jet quenching studies using the EMCAL trigger signal. A complete theoretical discussion of this approach can be found in their paper.

B. Mueller, K. Rajagopal Eur. Phy. J. C. 43, 15-21 (2005)

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LONG RANGE FORWARD-BACKWARD MULTIPLICITY CORRELATIONS

Recently we have discovered very large long range forward-backward multiplicity correlations (LRC) in central Au-Au collisions at 200 GeV. Both the dual parton model (DPM) and color glass condensate considerations (CDC) argue that these correlations are due to multiple parton-parton interactions ie. indicating the presence of dense quark-gluon matter. This suggests that there is a central core surrounded by a halo of hadrons. It is very important to explore this lateral structure using the LRC signal in Pb-Pb collisions and correlate it with the jet quenching energy density and jet fragmentation function measurements.

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22 >>≠<< nnLRC exists only if:

F-B Multiplicity Correlations

•Predicted in context of DPM.•Test of multiple [partonic] scattering.•Linear expression relating Nb, Nf found in hadron-hadron experiments (ex. UA5),

•“b” is correlation strength.–Function of √s and A.–Coefficient can be expressed as,

ffb bNaNN +=>< )(

2

2

22ff

bf

ff

bfbf

D

D

NN

NNNNb =

><−><

>><<−><=

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( )[ ] >><<><−><∝>><<−>=< bfbfbfbf NNnnNNNND 00222

Fluctuation in # of inelastic collisions

Measurement of Long-Range Multiplicity Correlations

•A gap about midrapidity will reduce the effect of short- range correlations .•DPM assumes short-range correlations confined to individual strings. •Long-range correlations are due to superposition of strings.

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Long Range Long Range Short + Long Range

Low Energy

Strings

High Energy Forward nfBackward nb

η2 η

Rapidity Gap

η10- η

1- η2

Rapidity interval

12Centrality Dependence of b coefficient vs rapidity gap

STAR

Preliminary

13p-p at 200 GeV b coefficient versus rapidity gap

STAR

Preliminary

14 Centrality dependence of b coefficient for Au-Au (200 GeV)

STAR

Preliminary

15Comparison of Data with HIJING and PSM

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FB Correlation StrengthPt cut studies

Pt > 0.15 GeV

1.0 > Pt > 0.15

0.8 > Pt > 0.15

0.6 > Pt > 0.15

STAR Preliminary

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FB Correlation Strength QM 2006

Long range correlationAfter subtracting the short range using pp data

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PURDUE DELIVERABLES 1

FABRICATE/ TEST LED SYSTEM COMPONETS

2007-2010

2007 - Hire and train 2 undergraduate students to

fabricate (cut and polish) ~ 3000 fibers

- Begin assembly of test boards

2008 - Install quality testing system for fibers

- Quality testing system approved

- Cut and polish ~3000 additional fibers

- Finish assembling test boards (~1000 total)

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PURDUE EMCAL DELIVERABLES 2

FABRICATE/TEST LED SYSTEM COMPONENTS

2009 - Hire and train 2 undergraduate students

- Cut and polish 3000 fibers

- Test ~6000 fibers

- Deliver batch of ~ 6000 tested fibers

2010 - Cut and polish ~3000 fibers (12,000 total)

- Finish testing of all fibers

- Deliver final 6,000 tested fibers

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PURDUE INSTITUTIONAL PLAN MILESTONES 1

2007 - p-p multiplicity distributions for 3< dNc/d <70

- Emcal detector simulations.

- Finish long range forward-backward multiplicity

studies at STAR.

2008 - Emcal calibration measurements

- p-p long range forward-backward correlations

and Handbury-Brown Twiss (HBT) physics

analyses as a function of dNc/d.

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PURDUE INSTiTUTIONAL PLAN MILESTONES 2

2009 - Emcal calibration measurements

- p-p -jet and jet-jet reference analyses

- finish HBT physics analysis.

2010 - Online Data acquasition with Emcal and

other ALICE subsystems

- LRC analysis of Pb-Pb data

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PURDUE INSTITUTIONAL PLAN MILESTONES 3

2011 - Compare LRC and jet quenching and determine

initial energy density at to = 1fm/c.

- Determine freezeout entropy density for central

Pb-Pb collisions.

2012 - Measure centrality dependence of LRC in Pb-Pb

collisions

- Determine quantitative quark-gluon matter fraction

using LRC in both peripheral and central Pb-Pb

collisions

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Site Differential EstimatesBased on 2006 travel

Domestic Travel Year Foreign Travel

29 trips 2006 4 trips

25 trips 2007 8 trips

21 trips 2008 12 trips

Cost differential between the average domestic trip and the average foreign trip ~ $ 2000 .

Estimated site differential costs for: 2007 2008 $8000 $16,000

Unexpended funds for 2007 are expected to be: $ 0.00 .

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