The first results from alice
This presentation is the property of its rightful owner.
Sponsored Links
1 / 25

The First Results from ALICE PowerPoint PPT Presentation


  • 62 Views
  • Uploaded on
  • Presentation posted in: General

The First Results from ALICE. In-Kwon Yoo (Pusan National Univ.) for the ALICE Collaboration. Outline. A Large Ion Collider Experiment at LHC Experimental Scheme PID and Performances Some Results to remark Strange Particles Jets Pion HBT Discussions. ATLAS. CMS. ALICE. The ALICE.

Download Presentation

The First Results from ALICE

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


The first results from alice

The First Results from ALICE

  • In-Kwon Yoo (Pusan National Univ.)

  • for the ALICE Collaboration


Outline

Outline

  • A Large Ion Collider Experiment at LHC

  • Experimental Scheme

  • PID and Performances

  • Some Results to remark

    • Strange Particles

    • Jets

    • Pion HBT

  • Discussions


The alice

ATLAS

CMS

ALICE

The ALICE

  • Pb+Pb @ 5.5 TeV in Large Hadron Collider


Why hmpid

LHC Workshop 2009

PID in ALICE

Solenoid magnet 0.5 T

ALICE: the dedicated HI experiment

Why HMPID?

  • Forward detectors:

    • PMD

    • FMD, T0, V0, ZDC

Full azimuthal coverage : ITS, TPC, ToF

ITS, TPC upto p ~ 600 MeV/c

ToF upto ~ 1.2 – 1.4 GeV/c

Single-arm detector : HMPID for 1 – 5 GeV/c

  • Specialized detectors:

    • HMPID

    • PHOS

  • Central tracking system:

    • ITS

    • TPC

    • TRD

    • TOF

  • MUON Spectrometer:

    • absorbers

    • tracking stations

    • trigger chambers

    • dipole


Alice 2010

ALICE 2010

  • ITS, TPC, TOF, HMPID, MUON, V0, T0, FMD, PMD, ZDC completed

  • TRD 7/18

  • EMCAL 4/10

  • PHOS 3/5


Installation 2010 11

ALICE Status

2x

2x

2x

4

5

3

2x

6

2

7

1

2x

8

0

9

17

10

16

15

11

14

12

13

4

0

3

1

2

Installation 2010/11

  • Install 6 EMCAL, 3 TRD

  • Continuous 2 shifts operation

  • Significant Physics Gain

    • J/Ψ at TRD

    • Jets at EMCAL


Motivation in pp

Motivation in pp

  • Necessity of the Hadronic reference for the observables

    • For Quark-Gluon Plasma study in AA collisions

    • Many Signals ‘relative’ to the pp results

  • Understanding the particle production in the new energy domain

    • Soft & Semi-hard QCD

  • Collective effects at the partonic level ?(Multiplicity dependence of the results)


Trigger data samples

Trigger / Data samples

  • MinBias : at least one ch. particle in 8 units of eta (All ALICE is read out)

    • MBSPD / MBOR / MBAND

  • Single Muon Trg. (MUON, SPD, V0, FMD, ZDC are read out)

  • Available Statistics

  • 2009 (0.9 and 2.36 TeV) : ~ 0.5 M min.bias

  • 2010 (0.9 and 7 TeV) : ~ 700M min.bias, ~ 50M Muon trig.


Event classes

Event Classes

σtot= σelas+ σs.dif+ σd.dif+ σn.dif

  • 0.9 and 2.36 TeV

  • INEL and NSD

  • MBOR / MBAND

  • MC : Apply the fractions of SD/INEL, DD/INEL

  • Pythia and Phojet

  • 7 TeV

  • MBSPD with |𝝶|<1


Mul evolution with e cm

ALICE

CMS

Mul. Evolution with ECM

Inelastic Nch ≥ 1 in |h|<1

  • Power law dependence fits quite well

  • Evolution is higher than expected in MCs.

NonSingleDiffractive

all Inelastic

KLN CGC

fits ~ s0.1


Particle identification

Particle Identification

TPC dE/dx

7 TeV pps ≈5-6%

Vertex detector

pT(min)<100MeV

TOF

150k channels!

s ≈ 90 ps


Strangeness at 0 9 7 tev

Strangeness at 0.9 / 7 TeV


K 0 at 0 9 7 tev

ϕ / K*0 at 0.9 / 7 TeV


Further performances at 7 tev

Further Performances at 7 TeV

J/Y → e+e- |y| < 0.9

w → p0p+p-(PHOS + TPC)

J/Y → m+m-, y = 2.5 - 4

w/r/f → m+m-


Open charm at 7 tev

Open Charm at 7 TeV

  • Hadronic Decay of Open Charms

  • Even distinct Signal for D*+

  • Heavy Flavors from Single Leptons (ongoing)

Impact Parameter Resolution vs pT

80 mm @ 1 GeV


Results

Results

  • Final Results

    • Nchmultiplicity & distributions

      • 900 GeV: EPJC: Vol. 65 (2010) 111

      • 900 GeV, 2.36 TeV: EPJC: Vol. 68 (2010) 89

      • 7 TeV: EPJC: Vol. 68 (2010) 345

    • pbar/p ratio (900 GeV & 7 TeV)PRL: Vol. 105 (2010) 072002

    • Momentum distributions(900 GeV) PLB: Vol. 693 (2010) 53

    • Bose-Einstein correlations (900 GeV) PRD: Vol. 82 (2010) 052001

  • Under Collaboration Review

    • Identified particles (p,K,p)

    • Strangeness (K0,L,X,W,f)

  • Ongoing analyses

    • 7 TeV event properties: spectra, HBT, identified particles, strangeness, high multiplicity

    • Heavy flavour: charm (D0,D+, D*), heavy quarks (c,b) -> m, e-

    • J/y -> mm, e+e-

    • pQCD: Event topology, 2-particle correlations, jet fragmentation, …


K p ratio at 900 gev

K/p Ratio at 900 GeV

  • Prel. Results:

  • very large K/p ratio at high pT

  • not reproduced by event generators

  • - practically no energy dependence


Decays k 0 s l x f at 900 gev

X + X → L p

Decays: K0S, L, X, f at 900 GeV

L → p p

K0S → pp

  • Prel. Results:

  • MC well below Data

  • more so at high pT

  • more so for L & X

  • f ~ ok (at least some MC)

f → K K

13/10/2010 29th RRB J. Schukraft

* 2009 Data (~300 k events)


L k 0 s ratio 900 gev

|h| < 1

L/K0SRatio 900 GeV

13/10/2010 29th RRB J. Schukraft

  • very good agreement between STAR (200 GeV) and ALICE (900 GeV)

  • very different from CDF (630/1800) and UA1 (630) for pT > 1.5 GeV

  • - UA1(630) and CDF(630) don’t agree either …

  • to be further investigated (different triggers, acceptance, feed-down correction ?)


Pqcd high p t particle correlations

Associated

pTt

Δf

Trigger

pQCD: High pT Particle Correlations

‘near’ side

‘away’ side

UE

Trigger Particle

Trigger Particle: highest pT particle in event (pTt)

Associate Particle: all the others (pTa)


Jet in pp at 0 9 tev

Jet in pp at 0.9 TeV

  • internal structure of the jet : JT dispersion

identical for 0.9 & 7 TeV


More on event shapes

More on ‘Event Shapes’

CMS result: unexpected ‘ridge’ in high Mult. pp

somewhat similar phenomenon

seen at RHIC in HI collisions

  • Particle Correlations in 2D

ALICE acceptance smaller: Dh < 2

Atlas/ALICE/CMS WG established

to compare results


Bose einstein correlation

Bose-Einstein correlation

  • Space-Time Freeze-out configuration in pp

  • pion-pion HBT

  • 1D HBT (Qinv) vs. multiplicity and kT


R inv vs mul k t

Rinv vs. Mul. & kT

  • Rinv grows with dN/d𝝶

  • NO kT dependency


Discussions

Discussions

  • ALICE pp program

    • Do we correctly understand the hadron productions in pp?

      • Multiplicity Evolution with ECM?

      • Strangeness Production?

      • Ridge in pp?

      • HBT in pp?

    • Any collective behavior in high-mul events?

      • Multiplicity dependency

  • Ongoing

    • Efficiency Corrections

    • Identified Hadron Spectra / HBT

    • Jet Correction w.r.t. UEs

    • Further heavy flavors

    • Standby for AA physics in Nov. 2010 : 10-100 Hz Event rate / 107 MB evts. expected

    • ALICE Upgrade in 2012-13


  • Login