Toward the LHC-ALICE experiment

1. Toward the LHC-ALICE experiment Hideki Hamagaki Center for Nuclear Study University of Tokyo

2. CNS+ group • Staff Members • Hideki Hamagaki (Group leader) • Taku Gunji (Deputy leader) • Kyoichiro Ozawa • Students: • 4 students for PhD (Doctoral course) • 3 for RHIC-PHENIX, 1 for LHC-ALICE • 4 students for Diploma (Master course) • 2 for LHC-ALICE, 2 for R&D of GEM detectors ATHIC2008

3. Activity of CNS in ALICE • ALICE-TRD collaboration since 2002. • Natural choice, based on the CNS group activities at RHIC-PHENIX • Prototype TRD beam test @ CERN (2002) • optimize the radiator, study the basic characteristics (dE/dx, TR, gain, space charge, resolution…) and improve analysis technique (Likelihood, neural network) for eID • First realsize TRD beam test @ CERN (2004) • performance test (chamber, readout electronics, material budget) • Final TRD beam-test (2007) and data analysis • 2 diploma thesis from CNS (2004, 2006) • many NIM papers ATHIC2008

4. Current Activity in ALICE-TRD • Development of Detector Control System (DCS) • PVSS • User interface • FS/CE/libTRD • Handle MCM/SCSN/ORI • distribute configuration pars. • read results, status and publish to upper layer. • Applications (hardware access functions) • Testbench at CNS (DCS/ROBs/Other infra.) • Commissioning (installation/tests) @ CERN ATHIC2008

5. Physics Strategies in ALICE • Current major physics topics of the CNS group • Quarkonia in p+p/p+A/Pb+Pb via di-electron decays • Open heavy flavor measurement via electrons and/or hadrons • Multiplicity measurement in p+p and Pb+Pb with TPC • Possible (near-future) topics • Extensive study of gluon PDF at small x --- CGC • New: forward EMCal for direct g, p0, J/y, U • (Exotic) hadrons with multiple heavy quarks • Upgrade: CsI-GEM in HMPID ATHIC2008

6. Color Glass Condensate • High gluon density -> non-linear gluon-gluon fusion • Sizable A dependence • End of independent particle description of partons • Gluon PDF at x < 10-2 is very uncertain -> LHC could be an ideal machine to investigate CGC ATHIC2008

7. A Hint from RHIC data • Saturation hint at RHIC • hadrons from d + Au by BRAHMS: RdAu ~ 0.8 for h = 3.2, pT ~ 3 GeV/c (= x ~ 10-3) • Sizable PDF modification could be possible even at central rapidity in LHC • y = 0, pT ~ 3 GeV/c (= x ~ 10-3) • RdAu ~ 0.8 -> RPbPb ~ (0.8)2 ~ 0.6 • p+A data is crucial, probably more than at RHIC • uncertain gluon PDF at low x • interpretation of RAA needs RpA ATHIC2008

8. X 2000 Hard Collisions • Many jets in central Pb+Pb collisions at LHC • Dnjet/Dh ~ 1.7 x N(coll) ~ 1700 • Dn/Dh ~ 0.2 x N(coll) for RHIC • gluon shadowing is not taken into account • Most of them have low energy • stopped in short-distance, and heat up the system • Energetic jets • fraction grows with energy • jet quenching -- need some distance, before stopping ATHIC2008

9. Hard Collisions (cont.) • Complication of initial state • With much larger number of energetic partons, time needed for thermalization may become longer at LHC? • Space-time evolution may also become complicated • A honeymoon between QGP and Hydro may be disturbed more often at LHC with intruding jets • a part of lost energy may be used to heat up the fluid, while other part may simply escape the system • This should be a quantitative question hopefully to be answered before having collisions at LHC ATHIC2008

10. Outlook • Situation at LHC is NOT a mere extension of RHIC • Tools and knowledge, both experimental and theoretical, acquired at RHIC can be utilized to challenge the new problems. • Surely new findings at LHC • although I cannot guarantee it, since it is beyond my imagination. ATHIC2008

11. Low pT photon production at LHC, pT ~ 2 GeV/c

12. M. G. Song, D. H. Lee, B. K. Kim, B. S. Chang, Y. Kwon, J. H. Kang Department of Physics, Yonsei Univ., Korea

13. Oldhuman record says… • Genesis • In the beginning God created the heaven and the earth. • And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters. • And God said, Let there be light: and there was light. • And God saw the light, that it was good: and God divided the light from the darkness. • And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.

14. Leading order diagram in perturbation theory Direct  production • Direct  production in p+p  One of the best known QCD process… Really? Hard photon : Higher order pQCD Soft photon : Initial radiation, Fragmentation function

15. Multiple collision in factorization? Higher twist?

16. ~ 1/Q2 Saturationscale? Qs RHIC Qs ~ 1 GeV  LHC Qs ~ 2-3 GeV

17. e- e+ Why very low mass dileptons? •   * e+e- , R H Dalitz 1951 Proc. Phys. Soc. A64 667-669 • AND we can avoid 0 background!

18. Dalitz pair mass distribution invariant mass of Dalitz pair invariant mass of Dalitz pair invariant mass of virtual photon invariant mass of virtual photon form factor form factor phase space factor phase space factor

20. Particleidentification by ALICE

21. TRD(Transition Radiation Detector) • |η|<0.9, 45°<θ<135° • 18 supermodules in Φ sector • 6 Radial layers • 5 z-longitudinal stack  total 540 chambers  750m² active area  28m³ of gas • In total 1.18 million read-out channels

22. Tsukuba group activities for LHC-ALICE Transition Radiation Detector(TRD) Construction/Installation/Commissioning/ Detector-control/Test-experiment/Analysis with Heidelberg, GSI, Frankfurt, Muenster groups • Outside of TPC, inside of TOF • Electron ID & high pT hadron measurement • Online tracking & higher-level online trigger • J/y, U, jet, di-jet, mini-jet trigger

23. amp(t1) amp(t2) … … amp(tN) ・・・ Input layer ・・・・・・・ middle layer Beam output layer e p Final Test Beam experiment for TRD just before installation in ALICE Transition Radiation photon M. Konno (P.D.) D. Sakata (M2) M. Sano (M2) e p amplitude Neural Network Method e p Amplification region time bin

24. Development of Detector Control System for TRD H.V. control, Front- end Electronics (FEE) control and error log Super Module M. Konno (P.D.) R. Tanabe (D2) K. Watanabe (D1) H. Yokoyama (M1) Chamber with read-out electronics

25. Detector Simulation with GEANT Particle distribution in Jets with PYTHIA Photon detector test with LED: MAPMT, APD, MPPC dh df f h -10 superimposed PYTHIA events 5.5 TeV Pb+Pb central Event 0 10 Hadron Calorimeter Project (JCAL) for ALICE from Particle Identification to Parton Identification Total Energy measurement of Jet Jet Trigger capability Gluon/Quark Jet separation This Project is approved to do the detector R&D and and to make a small proto-type for ALICE. PRL 94 (2005) 171802

26. Jet-Tomography : hadron-hadron, direct gamma-hadron, electron-hadron, identified hadron correlation, two-particle, three-particle correlation, mach-cone, ridge analysis, jet-reconstruction, jet-identification Single (identified) spectra (RAA), event anisotropy (v1, v2) analysis : reaction plane QGP in p+p collisions : <pT>, v2, HBT, Jet-shape, fluctuation, correlation, etc… vs Multiplicity, Geometry

27. Univ. of Tsukuba (High-Energy Heavy-Ion Experimental) Group Staff 三明康郎 Yasuo Miake 江角晋一 ShinIchi Esumi 中條達也 Tatsuya Chujo 稲葉基 Motoi Inaba 金野正裕 Masahiro Konno（technical）加藤純雄 Sumio Katou （secretary）酒井初芽 Hatsume Sakai Doctor course students 下村真弥 Maya Shimomura三木健太朗 Kentaro Miki池田義雅 Yoshimasa Ikeda 田辺嶺 Rei Tanabe渡邊健悟 Kengo WatanabeMaster course students 坂田洞察 Dousatu Sakata佐野正人 Masato Sano横山広樹 Hiroki Yokoyama梶谷緑 Midori Kajigaya浜田英太郎 Eitaro Hamada塩原尚希 Naoki Shiohara木村瑞希 Mizuki Kimura轟木貴人 Takahito Todoroki Undergraduate students 常鵬 Chang Peng関根祐輝 Yuki Sekine竹内理将 Toshimasa Takeuchi