Physics with the ALICE TRD Ken Oyama Physikalisches

Physics with the ALICE TRD Ken Oyama Physikalisches Institut, Heidelberg for the ALICE Collaboration Physics at LHC, Jun. 7, 2006, Krakow 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration

Overview TRD 2006 Jul. 3 to 8 ITS TRD TPC n ALICE studies the characteristics of the quark matter produced in the Pb+Pb collisions at sqrt(s. NN) = 5. 5 Te. V. n Expected d. N/d = 1500 ~ 3000. n TRD is for electron ID and trigger. Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 2

Physics Motivations for the ALICE TRD Systematic measurements of the following observables in p+p, p+A and A+A collisions n Single electron momentum spectra n D e + X (17 % b. r. ) n B e + X … talk by R. Turrisi. n Di-electron mass spectra n J/ (3. 1 Ge. V) e+e- (6 % b. r. ) n ’ (3. 7 Ge. V) e+e- (0. 76 % b. r. ) n Y (9. 5 Ge. V) e+e- (2. 4 % b. r. ) n Y’ (10 Ge. V) e+e- (1. 3 % b. r. ) n q+q e+e- Thermal n q+q e+e- Drell-Yan n Jet spectra & shape n Medium induced momentum and shape modification 2006 Jul. 3 to 8 Information about the de-confined QGP medium state : l Color potential screening J/ suppression, Upsilon suppression Initial scattering information and effect of the medium to it : l Jet quenching Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 3

ALICE TRD Principle n Charged particles at > 1000 give T. R. photons. n Thin (< 0. 25 X 0) detector with low power (~ 60 k. W for 1. 2 M channels) readout electronics on it. 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 4

TRD: Requirements and Performance n Purpose : n Electron ID at p > 1 Ge. V/c. n Fast (6 s) trigger for high-p. T+ PID. n Improved momentum resolution. n Parameters : n | | < 0. 9, 0 < < 2 n 540 modules (18 super-modules) n 28 m 3 Xe/CO 2 (85: 15) n 1. 2 M readout channels p. T resolution < 4 % at 100 Ge. V/c for d. Nch/dy ~ 5000 central Pb–Pb pp beam test @ PS simulation 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 5

SPS / RHIC LHC x 20 n Charmonium melting pattern will be seen clearly. n Much larger Initial production rate will enhance the charmonium yield. n Strong centrality dependent secondary J/ production by statistical hadronization J/ enhancement. Overall understanding is necessary T<Tc T>>Tc [H. Satz, hep-ph/0602245] c and b Initial production rate [P. Braun Munzinger, K. Redlich, and J. Stachel, nucl-th/0304013] 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 6

J/Ψ and Upsilon Measurements (I) 120 k J/ S/N=1. 2 10 % Centrality 2 x 108 events 106 run time (a. y. ) [W. Sommer, ALICE PPR] 900 Y S/N=1. 1 250 Y’ S/N=0. 4 n Simulation with n. PDF+shadowing predicted[*] quarkonia yields embedded into HIJINGpara events (<d. N/dy> ~ 3000). n Separations of J/ , ’, Y, Y’ and Y’’ are possible. [*] A. Accardi et al. , ar. Xiv: hep-ph/0308248 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 7

J/Ψ and Upsilon Measurements (II) n Momentum dependence and S/N. n J/ yield can be measured for more than 10 Ge. V/c. 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 8

Jet Energy and Shape Measurements (I) Pb n hard/ tot ~ 98 % (RHIC: 50 %) [K. Kajantie, QM 2002]. n Leading particle energy reaches more than 100 Ge. V. x 1000 yield at 20 Ge. V compare to RHIC. n In Pb+Pb: n Jet quenching as probe of medium property. n Ncoll scaling violation. n Modification in j. T distribution. q Pb Q q vacuum Phys. Lett. B 595: 165 -170, 2004 e > 15 Ge. V/fm 3; d. Ng/dy > 1100 medium j. T p. T 2006 Jul. 3 to 8 ü Softer p. T distribution ü Broader j. T distribution ü Less collimation Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration PHENIX QM 2005 9

Jet Energy and Shape Measurements (II) n Underlying background from hot matter ~ 2 Te. V in R < 1. 0, ~ 150 Ge. V in R < 0. 3 (assumption: d. N/dy ~ 5000 and <p. T> ~ 500 Me. V/c). n 1 ALICE year collects enough statistics of jets. n Jet quenching is visible already in ET spectrum. n S/N becomes smaller than 1 at 1 Ge. V j. T energy. j. T: momentum transverse to the jet-direction A. Morsch, ALICE PRR Effective month of running 106 s (107 central events). RC<0. 4 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 10

Jet Triggering with TRD n One TRD module (size : R 2 = d 2 + d 2 = 0. 362+0. 352 ~ 0. 52) can count the number of high p. T charged tracks available online at L 1. n Expected jet rate exceeds 1 Hz for ET > 100 Ge. V. n Jet trigger becomes efficient at ET ~ 100 Ge. V where triggering is necessary to have statistics. Expected jet rate [D. Miskowiec] CKIN(3)=50 CKIN(3)=100 CKIN(3)=200 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 11

ALICE TRD Construction Status in Heidelberg Current plan of 1 st super-module delivery to CERN: Aug. 15 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 12

Summary n ALICE with TRD can measure Quarkonia signals (J/ , ’, Y, Y’’) and study properties of the Quark Gluon Plasma (good for also B-decay). n TRD can provide trigger for jet at ET > 100 Ge. V. n The first TRD super-module (out of 18) construction is on going. It will be delivered to CERN in August. 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 13

Backup Slides 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 14

J/Ψ and Upsilon Measurements (III) 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 15

Jet Shape Measurement in Other Way n = ln( 1/x ) = ln( ETjet / p ) (x = p / ETjet : momentum fraction) is sensitive for energy loss. leading particle region <q> = 1. 7 Ge. V 2/fm 10 50 leading particle region non-leading fragments region q = 2/ : transport coefficient : typical momentum transfer, : mean free path 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 16

Position and Angle Resolution Large chambers 2006 Jul. 3 to 8 Prototype Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 17

TRD Mechanical Construction Polypropylene fibers (Freudenberg LRP 375 BK) 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration Rohacell foam (HF 71) 18

Electron Identification by TRD Counts Total charge spectra LQ Method: Integrated Charge Likelihood with total charge Depos. Energy (ke. V) Max. cluster position Extract probabilities Likelihood distribution Distribution of maximum cluster position 2006 Jul. 3 to 8 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 19

Quarkonia Production Rate Color Evapolation Model prediction for 5. 5 Te. V p+p collision [A. Accardi et al. , ar. Xiv: hep-ph/0308248] Ncoll scaling (Glauber model) Shadowing (EKS 98) Branching ratio 2006 Jul. 3 to 8 2. 6 x 10 -2 * ~1000 26 Physics at LHC, Cracow, Ken Oyama for the ALICE Collaboration 20