The first results from alice
Download
1 / 25

The First Results from ALICE - PowerPoint PPT Presentation


  • 82 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.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

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

  • 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

  • Pb+Pb @ 5.5 TeV in Large Hadron Collider


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

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

  • TRD 7/18

  • EMCAL 4/10

  • PHOS 3/5


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

  • 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

  • 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

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


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

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


ϕ / K*0 at 0.9 / 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

  • 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

  • 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

  • Prel. Results:

  • very large K/p ratio at high pT

  • not reproduced by event generators

  • - practically no energy dependence


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)


|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 ?)


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

  • internal structure of the jet : JT dispersion

identical for 0.9 & 7 TeV


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

  • Space-Time Freeze-out configuration in pp

  • pion-pion HBT

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


Rinv vs. Mul. & kT

  • Rinv grows with dN/d𝝶

  • NO kT dependency


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


ad
  • Login