2005/6/28-29 第 59 届东方论坛，上海

中国与 RHIC-STAR 的国际合作

马余刚，陈宏芳，程建平

中国 RHIC-STAR 合作组：中国科大，清华大学，上海应物所，

华中师大，高能所，近物所

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outline

Chinese RHIC-STAR Group

TOFr and Physics Results

Impact of Chinese RHIC-STAR Group

Physics with Full TOF Project

Conclusion

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Chinese RHIC-STAR Group

--History and present

organization

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US-China Collaboration on STAR/ RHIC

A STAR-China collaboration has been established (Six Institutions from China) University of Science and Technology of China, Hefei (USTC) Tsinghua University Shanghai Institute of Applied Physics (SINAP) Central China Normal University, Wuhan (CCNU) Institute of Modern Physics, Lanzhou (IMP) Institute of High Energy Physics, Beijing (IHEP)

Chinese collaborators are playing a major role in physics analyses involving open charm, Cronin effect, and elliptic flow as part of STAR’s focus on studies of a new state of matter (the quark-gluon plasma) at RHIC

Chinese groups are leading in prototyping and development for a large-area MRPC time-of-flight detector for STAR.

This is the first major US-China collaboration on high energy nuclear physics and we have had a very successful beginning.

The STAR-China Time-of-Flight Construction Project has been covered under the US-PRC HEP Agreement since 2001 to ensure smooth construction of the TOF detector and operation of the STAR-China collaboration.

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Major Milestones of STAR-China TOF Project

CCNU and IHEP joined STAR collaboration in 1999 for TOFp; SINAP, USTC, Tsinghua and IMP joined STAR collaboration in Oct. 2001.

USTC team began MRPC R&D in Aug. 2000 with the supports of NSFC, STAR and other Chinese collaboration institutions.

Joined in US/PRC Cooperative Agreement on High Energy Physics since 2001 (22nd Meeting)

Prototype MRPC (multi-gap resistive plate) time-of-flight detectors, produced jointly between USTC and Rice Univ. and operated successfully in STAR (2002-3 and 2003-4 RHIC runs). Physics results on identified particle spectra and on semi-leptonic charm decays have been published.

Approval of "RHIC-STAR Physics and the Construction of Barrel STAR-TOF” by the National Natural Science Foundation of China (Sept 10, 2004, Budget: 1.5M USD)

Approval of the STAR TOF upgrade proposal by BNL Technical Advisory Committee and Submission of the Proposal to DOE (July 2004)

Technical Review of proposal by DOE, planned Aug. 2005

Suppose DOE approval in Oct. 2005, full construction start October 2005

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MRPC TOF Barrel R&D

RUN 2002-3: TOF installed in STAR 24 MRPC modules produced at University of

Science Technology China 6-channel front-end cards, with amplifiers

and discriminators, CAMAC read-out

Run 2003-4: TOF installed in STAR 5 new modules from USTC and 5 from

Tsinghua University, Tsinghua developed automated techniques for manufacturing

24-channel front-end cards with amplifier and discriminator

RUN 2004-5, TOF installed in STAR, 16 new modules from Tsinghua First time use of full on-board read-out

electronics: digitization of data on-board First use of ALICE PCI-PC based DAQ

2002

2004 G. Eppley et al.

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Completed Prototype 28 module MRPC TOF Tray installed in STAR Oct. ‘ 02 in place of existing central trigger barrel tray

NeighborCTB Tray

EMCRails

FEE

MRPC design developed at CERN, built in USTC/China

Prototype Tray Constructionat Rice University

28 MRPC Detectors;24 made atUSTC

The STAR Barrel TOF MRPC Prototype

70 ps, 2 meter path

Strong team including 6Chinese Institutions in place

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batch production

40 MRPC production ， more than 80 ％ of eligible rate , good

performance in on-line testing at RHIC-STAR (Tsinghua)

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Project Leader: Yu-Gang Ma (SINAP)

Deputy Leaders: Hongfang Chen (USTC)

Jian-Ping Cheng (Tsinghua)

Liaison person: Huanzhong Huang (UCLA)

Studies of the strong interaction matter at high temperature/density and searching for QGP

(Yu-Gang Ma, SINAP) (SINAP, CCNU, USTC, Tsinghua etc.)

focus on the collective dynamics of rare particles, heavy quark focus on the collective dynamics of rare particles, heavy quark production, hadronic evolution dynamics and search for multi-quark production, hadronic evolution dynamics and search for multi-quark state particlesstate particles

Design and Mass production of MRPC modules for STAR-TOF

(Jian-Ping Cheng, Tsinghua) (Tsinghua, USTC)

3840 MRPC for 120 tray, additional 6 tray (70% Tsinghua/30% USTC3840 MRPC for 120 tray, additional 6 tray (70% Tsinghua/30% USTC))

Quality control and calibration for STAR － TOF

(Xiao-Lian Wang, USTC) (USTC, Tsinghua)

Chinese Proposal to NSFC

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The Proposal of RHIC-STAR Full TOF Construction

Proposed major construction responsibilities:

Chinese STAR Groups: MRPC Production and Quality Assurance – NSFC/CAS/MoST

(Approved in Sept, 2004) (Special thanks for Huanzhong, Nu, Zhangbu, Xinnian et al. for many important suggestions

and helps)

US STAR Groups: Electronics and Integration etc – DOE Project Manager: G. Eppley

(with DOE)

Monetary Contributions: China ~ US$2.5 M (US$ 1.5M from NSFC/CAS/MoST)

US- DOE ~ US$4.5 M

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STAR TOFr and Physics Results

TOF prototype:TOF prototype:1/120 coverage of Barrel STAR1/120 coverage of Barrel STAR

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PID

TPC alone PID range: pi/k ~0.6 GeV/c,

(pi,k)/p ~1.5GeV/c;

TOF “alone” PID range: pi/k ~1.6GeV/c,

(pi,k)/p ~ 3.0GeV/cm2 m2

TOF=110ps k

p

TPC alone TOF “alone”

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Preliminary pion spectra till high pT

TPC: Pion: 0-~0.6GeV/c Kaon: 0.2-~0.6GeV/c Proton: 0.2-~1 GeV/c

TOF: Pion: 0.2-~1.6GeV/c Kaon: 0.2-~1.6GeV/c Proton: 0.2-~3 GeV/c

TPC+TOF: Pion: 0.-~10 GeV/c Kaon: 0.2-~3GeV/c Proton: 0.2-~5 GeV/c

TPC+TOF:

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Electron identification

Combined with TOF ， electrons can be separated from pions cleanly

Electorns mixed with pions if only dE/dx of TPC is used to identify particles

X. Dong, Z.B. Xu, LJ Ruan, J Wu et al

Lepton decay from heavy quarkLepton decay from heavy quark

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RAuAu and RdAu of

• RdAu of is closer to that of p and k than that of p

•Particle production at intermediate pT region is sorted by the particle’s type, not the mass

ppinelbindAu

TTppineldAu

TTdAu NT

dydppdT

dydppNdR

/,)2/(

)2/(2

2

STAR STAR PreliminaryPreliminary

______________

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Preliminary results v2

1. the elliptic flow of Φ-meson gives similar behavior of Ks but distinguish from Λ

2. a NCQ-scaling has been observed in Φ-meson

3. error bars in higt pt range (2.5GeV,5.0GeV) are still large

0-80%

STAR Preliminary dataSTAR Preliminary data

AMPT calc.

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Impact of Chinese RHIC-STAR Collaboration

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Organizing International workshop

Host:

Aug 2002: 1st International CCAST Summer School and Workshop on “QCD and

RHIC Physics” in CCAST-WL, Beijing. Organized by Profs. X.L. Wang and P. F.

Zhuang. There were ~15 foreign speakers invited, ~100 participants

Oct 2003, 1st STAR Regional Collaboration Meeting, USTC; ~10 STAR speakers

invited

Aug 2004: 2nd International CCAST Summer School and Workshop on “QCD and

RHIC Physics” in CCAST-WL, Beijing. Organized by Profs. Y.G. Ma, E.K. Wang and

J.H. Fu. There were 19 foreign speakers and 22 domestic speakers, ~140

participants.

Oct 2004: International Workshop on “Collective Dynamics in Relativistic Heavy Ion

Collisions” @ USTC, Organized by X.L. Wang and Nu Xu

19 － 24 June 2005: 3rd International Workshop on “QCD and RICH Physics” was

organized by CCNU and CCAST et al.,, Wuhan; 20 foreign speakers, ~140

participants

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Talk @ Int. Conference

QM2006 in Shanghai:

The proposal to host “Quark Matter 2006” in Shanghai was accepted

during QM2004 in Oakland. Shanghai Institute of Applied Physics and

Central China Normal University will co-organize the QM2006 in

Shanghai, preliminary date Nov 16-22, 2006

Co-chairs: Zhiyuan Zhu (SINAP) & Xu Cai (CCNU)

Honor Chair: T. D. Lee

Taks in some international conferences: Conference Talks: QM2004: one oral presentation (Ruan) SQM2004: three oral presentations (Cai, Ruan, Ma) ICEHP2004: one oral presentation (Wu) QM2005: one Plenary Talk (Dong, from TOF phys results) one parallel talk (Cai) ……

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Our excellent students

PhD Dissertations (incomplete statistics) : Jinghua FU (CCNU): 获二○○五年全国优秀博士学位论文 Shengli HHUANG (USTC), Lijuan RUAN (USTC) ， Zhixi LIU (CCNU)

Xing DONG (USTC): 获二○○四年中国科学院院长奖学金特别奖

More PhD Students are involved in RHIC-STAR physicsMore PhD Students are involved in RHIC-STAR physics

Chinese Principal authors of STAR Publications or works: Jinghua Fu et al.: Flow of Ks and for 130GeV/c Au+Au (Phys. Rev. Lett. 89, 132301 (2002).)

Xin Dong et al. : electron spectra fro open Charm (nucl-ex/0407006), PRL94, 062301 (2005)

Lijuan Run et al.: Cronin Effect (nucl-ex /0309012 ), Phys Lett B 616, 8 (2005)

Lijuan Ruan (for the STAR Collaboration), π, K, p and production from Au+Au collisions at 62.4 GeV, J. Phys. G: Nucl. Part. Phys. 31 S1029-S1033 (2005)

Xiangzhou Cai (for the STAR Collaboration) Production of K0s, Λ and Ξ from 200 GeV d+Au collisions at RHIC, J . Phys. G: Nucl. Part. Phys. 31 S1015-S1018 (2005)

Ming Shao, Pion, Kaon, and (Anti-) Proton Production in Au+Au Collisions at \srt = 62.4 GeV, J.Phys. G31 (2005) S85-S92

Shengli Huang et al.: azimuthal dependent fluctuation

Zhixu Liu et al.: flow of Ks and for 63 GeV/c Au+Au

Guoliang Ma et al. : flow and spectra of for 63 63 GeV/c Au+Au

Jinhui Chen et al., phi flow

Jiaxu Zuo et al., multi-strange partcile spactra, …………….

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Physics with the Physics with the full coverage of full coverage of

TOFTOF

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STAR TPC + TOF (MC)STAR TPC + TOF (MC)

Central (top 10%) collisions

acceptance with TPC: : ~ 60% K: ~ 60% p: ~ 50%

acceptance with TPC+TOF: > 95% for all particles

S/N for reconstruction willincrease by a factor of 5-10 v2 measurement possible

Z. Liu, F. Liu, et al.

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STAR TPC + TOFSTAR TPC + TOF

1) TOF will increase V0 reconstruction efficiency. In the case of , a factor of 5 – 10 increase expected in the region pT ~ 3-5 GeV/c!

2) TOF will also help future D meson reconstruction – increasing S/N ratios, same way for other resonances.

(D0 → K−+) (D0-bar → K+−)3) In the case for , a factor

of 5-10 increase in S/N ratio is expected.

=>K + + K - (49.1%)H. Long et al.

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STAR TPC + TOF

v2 measurements

For integrated v2 : needs ~ few 106 MiniBias events. More events without TOF Multi-years running.Multi-years running.

pT dependence v2: for <20% around pT ~ 5 GeV/c, needs ~ few 10th 106 MiniBias events with TOF almost impossible without TOF in middle Pt

STAR 200 GeV results: T = 0.45 GeV dN/dy = 0.64, sum of - and +

< v2 > ~ 8% all are usable events (1.5 -3 factor)

ideal With TOF

w/o TOF

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TOF and Hyperon

Embedded Data: reconstruction with and without PID information!A Factor of 3 !!

Tmmf ttSB /exp Input spectrum:T = 350 MeV

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Chinese interests

Collective dynamics for rare particlesHeavy flavor quarksSearch for multi-quark state particlesFluctuationsCorrelation of rare particlesHadronic evolution dynamics:

resonance …….

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Collective flow in partonic level:Collective flow in partonic level:Does the Recombination model work for heavy particles or strange quark?Does the Recombination model work for heavy particles or strange quark?

how about flow of electron, , , D, J/ v2(p) ? Need Full TOF for good efficiency and statistics

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Without TOF With TOF

All pT 12M 2.6M

pT>2. 59M 23M

2>pT>4. 85M 42M

4>pT>6. 115M 115M

D0 Sensitivity in pT

Important Measurement: Open CharmTOF helps by a factor of ~5 (all PT)TOF + Active Pixel Sensitive: x8Other Open Charm States Possible only with TOF

Full Coverage needed

Heavy flavor quarkHeavy flavor quark•Initial condition •J/ suppression•Heavy quark energy loss

Charm quark mostly produced from the initial fusion of partons (mostly gluons)

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Time scale of resonance state

Resonance K*(892) (770) f0(980) (1020) (1232) (1520) (1385)Decay channel K K K ee p p K Branching Ratio % ~100 ~100 dominant 49.2 0.3 >99 22.5 88.2Width [MeV] 50.7 150 40 to 100 4.46 ~120 15.6 35.8Life time [fm/c] 4 1.3 40 ~1.6 13 5.6

Resonance Parent PT(GeV/c) TPC+TOF

K*0 0-1 2.0K*0 1-2 1.85K*0 2-3 1.74K*0 3-5 1.39

______________________(1020) 0-2 5.0(1020) 2-5 3.42

___________________________(1520) 0-1.6 11.4

Chemical Freeze-out --- formation of hadrons

Kinetic Freeze-out --- Interaction ceases

Increasing factor for statistical significance of the signal

Hadron evolution dynamicsHadron evolution dynamics ：： resonanceresonance

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Discoveries from Unexpected Areas?!

RHIC -- Frontier for bulk partonic matter formation (quark clustering and rapid hadronization) -- Factory for exotic particles/phenomena

Potential exotic particles/phenomena:penta-quark states (uudds, uudds!)

di-baryonsH – (, uuddss) [] (ssssss)

strange quark matter…….

penta-quark states?

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Search for multi-quark state particles

Z.Y. Zhang et al., Phys. Rev. C 61, 065204 (2000); Phys. Rev. C66, 015205 (2002) 3 body decay ：

2 body decay ：

A chrial SU(3) model and analyses of the symmetry properties of two-baryon systems, some features:

A deeply bound, Eb ~ 100MeV; A compact object, Rrms~0.63fm, <<Rd may be six strange quark state rather than a di-baryon configuration Phenomenological estimation (coalescence/statistical): yield 10-4_10-7/central

Au-Au; Full barrel TOF ~ 100M central AuAu events needed. It is impossible to search di-omega in RHIC without STAR-TOF

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ConclusionConclusion

We have strong team to collaborate with RHIC-STAR, especially we have excellent young students and excellent overseas Chinese Americans

Chinese Proposal to make B35arrel TOF has been approved by NSFC, we are playing leading role in STAR TOF upgrade

We have great opportunity to do some new and important physics with full TOF

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Quark Confinement ？

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Recall Shanghai TOF meeting for

Discussion of NSFC

proposal draft, Jan 2003

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别有洞天We have a new

scenery !

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Traditional Cronin Effect is not the whole story at RHIC

STAR d+Au from TOFr analysis (USTC+BNL+RICE)

Results on KS, and will reach higher pT (SINAP+UCLA)

Hadron spectra and Cronin effectHadron spectra and Cronin effect

With TOFrTPC

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PID dependent CroninPID dependent Cronin effecteffect

With TOFr

PID Cronin Effectnucl-ex /0309012 )

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recentlyIn order to know about the elliptic flow of ,, D, J/, Full TOF is necessary for good efficiency and statistics.

In order to improve the measurements of Open Charm, TOF helps by a factor of ~5 (all PT) and Full Coverage needed

In order to investigate the hadronic evolution dynamics, TOF increases important factor for statistical significance of the resonance production.

TOF will significantly enhance the hyperon detection efficiency. RHIC provides a unique environment for possible production of multiply strange di-baryons.

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Bottom:Ratios of the inclusive electrons over the total back-grounds.signal excesses are visible with pT > 1 GeV/c.

The total photonic backgrounds are shown as solid lines.Dashed lines depict the various contributing sources. The fractions were derived from simulations.

Heavy flavorHeavy flavor （（ D-->e+X)D-->e+X)

With TOF tray

D meson and electron spectra :Dong, ZB, Ruan et al

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Rcp of for different collision system

• yield suppression at intermediate PT in central Au+Au collisions

•no clear suppression is showed in the 62.4 GeV Au+Au collision. It become flat at PT>1GeV/c2

• RCP in d+Au collision is enhanced

It is difficult to draw some definite conclusion due to the large error bar

Low pT, RCP <1 High pT, RCP >1

STAR STAR PreliminaryPreliminary