ALICEstudy of proton-proton and Pb-Pb collisions at the LHC

(JINR participation)

A.VODOPYANOV

JINR Scientific CouncilDubna, September 2011

ALICE Set-up

HMPID

Muon Arm

TRD

PHOS

PMD

ITS

TOF

TPC

Size: 16 x 26 metersWeight: 10,000 tons

Number of events stored in 2010-2011 by ALICE:

8106 -- p-p at 0.9 TeV; 70106 – p-p at 2.76 TeV; 800106 – p-p at 7 TeV; 30 106 -- Pb-Pb at 2.76 TeV.

p-p data taking at 7 TeV is ongoing and

Pb-Pb data taking at 2.76 is planed for this year.

Display of high multiplicity events

in p-p at 7 TeV in Pb - Pb at 2.76 A·TeV

ALICE physics publications

20 ALICE physics publications appeared in the journals (16 on p-p (mostly at 0.9 TeV) and 4 for Pb-Pb);

20 publications on p-p at 7 TeV and10 publications on Pb - Pb are under preparation dedicated to : Charged and neutral particle spectra, strange and charmed particles, particle flows, Photons; Quarconia and light vector mesons.

Main fields of interest and activity of JINR group

• Bose-Einstein correlations (femtoscopy physics): - Participation in the preparation of two published articles for Two- pion Bose-Einstein correlations in p-p and in Pb-Pb central collisions.

- Responsibility for an analysis of Two-charged kaons Bose- Einstein correlations.

• Physics of resonances: - Participation in the analysis software creation.

- Responsibility for the analysis using mixed-events background.

• Quarkonia physics: - Responsibility for the special Cocktail generator.

- Participation in the analysis of J/ -

Particle Identification in ALICE

Two-pion Bose-Einstein Correlation results

p-p

Pb-Pb(Au-Au)

Source volume anddecoupling time are2 and 1.5 times Larger than at the RHIC energy(STAR and PHOBOS)

(Volume of the particle source) ( Decoupling sytem time)

FIRST TIME SEEN: Bose-Einstein Correlation for two charged kaons in p-p at 7 TeV for different charged partice numbers (Nch) and pair transverse momentum (Kt)

Nch<11 10<Nch<22 Nch>21 (3108 events)

Kt (0.2-0.35)

Kt (0.35-0.5)

Kt (0.5-0.7)

Kt (0.7-1.0)

The lines are special fit results to extract the particle source radius R(fermi) The results were obtained & presented by JINR group in the Quark Matter 2011 Conference

Two-particle Bose-Einstein Correlation resultsp-p at 7 TeV

KT (GeV/c)

(fm)

Comparison of particle source radiifor different particle pairs:

pion-pion - open points,

Kch-Kch – small full points,

K0-K0 – large full points.

(Quark-Matter 2011 Conference)

The same comparison using chargedkaon data integtated over the full kTrange.

All these results are under discussionnow in the collaboration.

(ALICE, preliminary)

Resonance study in p-p at 7 TeV (Quark Matter 2011)

Very good tracking system andeffective mass resolution in ALICE

Comparison of ϕ mesonpT spectrum with the predictions of different models.

(Quark Matter 2011 Conference)

p – p collisions at 7 TeV

Resonance study in Pb-Pb at 2.76 A·TeV

K*(890)

ϕ (1020)→K+K-

before and after backgroundsubtraction.

(ALICE preliminary)

Muon spectrometer, J/

(Preliminary)

The hint at the recombination of charm and anticharm quarks in the QGP formation in Pb-Pb collisions at LHC (CERN Courier, V.51, N7, September 2011)

J/

RAA

(nuclear modification factor) is the ratio of the yield measured

in A-A collisions scaled by the number of binary N-N collisions to that obtained in the p-p interactions.

The recombination of charm and anticharm quarks is hinted instead of dissociation of charmonium through the mechanism of colour -screening in the QGP.

ALICE GRID

Contribution of JINR computing to the whole ALICE statistics

Summary (simulated & analysis )DONE events

Analysis: the contribution of analysis jobs to summary DONE jobs for whole ALICE in time from April till December of 2010 was equal 60.9%, so at JINR ~252650 jobs have been DONE in the analysis. 250 users of ALICE, including 6 users from JINR did their analysis at JINR.

International conference presentations V International Conference "Distributed Computing and Grid-technologies in Science and Education" , Dubna , 28 June- 3 July 2010 - plenary talk of Galina Shabratova “The ALICE GRID operation” - session talk of Andrey Zarochentsev “RDIG in Simulation and Analysis of ALICE Data from LHC” А. International Conference “Computing in High Energy and Nuclear Physics (CHEP2010)” , Taipey, 16 -22 October 2010. - poster “. Distributed Russian Tier2 centre – RDIG in Simulation and Analysis of ALICE data from LHC”,presented by Galina Shabratova.

414858 jobs have been DONE by JINR in time from April to December of 2010.

What is 1.69 % of jobs DONEby whole ALICE in the same time.

ALICE UPGRADE in 2017-2018

1. Barrel detectors:• Inner Tracking System; • Time-Projection Chamber;• Photon Spectrometer;

2. Forward spectrometers:• Muon spectrometer;• New forward spectrometer;

PHOTON SPECTROMETER UPGRADE

DESIGN AND CONSTRUCTION OF THE NEW READOUT ELECTRONICS:

• TIMELINES: R&D (design, prototypes, test setup) 2012-2014 Production 2014-2017 Installation 2017-2018

• FUNDING (850 KUSD): R&D: 150 KUSD 50 KUSD in

2012 Production & Testing (16 K channels): 700 KUSD

• RESPONSIBILITY: JINR

• EXPERIENCE:

Similar work has been done for the NICA project already!

The plans for the next years:

• the data analysis for the chosen physics topics;

• the support of the GRID ALICE system in JINR;

• the shifts in the ALICE runs (180 shifts in 2010 year were held according to the ALICE plan) ;

• ALICE UPGRADE: Design and Construction of the new readout electronics for Photon Spectrometer.

Thank you for your attention

Спасибо за внимание

Backup

Momentum pseudorapidity dependence of dNch/d at centre-of-mass energy of 0.9

TeV, 2.36 TeV, 7 TeV.

Centre-of-mass energy dependence of the dNch/d

obtained in the || < 0.5 range

Correlation Femtoscopy.

t

~ fm/c

CGC (?)

Mixed phase

Hadron gas

Thermal freeze-out

Chemical freeze-out

Prethermal partonic state ~ fm/c

~ 7fm/c

GLP’60: enhanced ++ , -- vs +-

at small opening angles – interpreted as BE enhancement

Kopylov and Podgortsky ’71-75: settled basics of correlation

femtoscopy

Analogy in Astronomy: Hanbury Brown and Twiss (HBT effect)

Correlation femtoscopy : measurement of space-time characteristics R, c ~fm of particle production using particle correlations due to the effects of QS and FSI

CF

(Qin

v)

Qinv, GeV/c

K+K- CF: comparison with PYTHIA (LHC10d4)

- KK Gamov-factor MC EXPKt (0.2-0.35)

Kt (0.35-0.5)

Kt (0.5-0.7)

Kt (0.7-1.0)

Nch<20 20<Nch<40 Nch>40