first physics at the lhc alice

First Physics at the LHCALICE

Bjørn S. NilsenCreighton University

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CERN and the LHC

ALICE

LHCb

CMS

ATLAS

Genevé

• 9/29/1954 CERN born• 11/24/1959 PS Starts• 1976 SPS Starts• July 1989 LEP starts• 12/13/1990 ALICE

collaboration formed• 1993 ALICE proposed• 11/2/2000 LEP ends• 3/27/2007 Small Explosion

Inner Triplet damaged• 9/19/2008 Big Explosion

53 magnets damaged• 11/23/2009 LHC’s First Collisions• 12/14/2009 2.36 TeV Collisions• 3/30/2010 7.0 TeV Collisions

April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School

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LHC Experiments• ATLAS

• Higgs Search• New Particle Search• Peripheral Heavy-Ion

program– LHCf

• CMS• Higgs Search• New Particle Search• Heavy-Ion Physics

– Jets– Heavy resonances

– TOTEM

• ALICE– Comprehensive Heavy-

Ion program– Complementary p+p

program• LHCb

– B factory


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A Large Ion Collider Experiment

• PHOS, cpv

• Muon, MTRG

• VHMPID?• ADD• Dcal (EMCAL compleation)

• T0

PMD••

V0

FMD •

• ZDC

• ACORDE

HMPID •

TRD • TOF •

• TPC • ITS, SPD, SDD,

SSD EMCAL •

Measuring the Properties of the Quark Gluon Plasma


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QG

P

The Quark Gluon Plasma, QGP, is a state of matter dominated by the nuclear strong force.

Hottest Thing on Earth• Ice Freezes 0 C• Water Boils 100 C• Melting Point Iron 2750F (1510 C)• Surface of Sun 6,000 C• Center of Sun ~15,000,000 C• Plasma (Tokamak) ~100,000,000 C• QGP ~4,000,000,000,000 C


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Particle Physics in a Nutshell• Atoms

– Electrons– Nucleus (Quarks + gluons)

• Protons (uud)• Neutrons (ddu)

• • • • •

• Leptonse±, ±,±

• Quarksu c t 2/3 ed s b -1/3 e

• Force partials, W±, Z0, g, graviton

• Higgs (Weak symmetry breaking)

h

€

π + = u od ( )

€

π 0 = 12

u ou ( ) + 12

d od ( )

€

K + = u os ( )

€

KL0 = 1

2d os ( ) + 1

2d os( )

€

KS0 = 1

2d os ( ) − 1

2d os( )


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Kinematics in a nut shell

€

y ≡ 12 ln

E + pz

E − pz

⎛

⎝ ⎜

⎞

⎠ ⎟= ln

E + pz

mT

⎛ ⎝ ⎜

⎞ ⎠ ⎟= tanh−1 pz

E ⎛ ⎝ ⎜

⎞ ⎠ ⎟

€

y p>>m ≅ η = 12 ln

p + pz

p − pz

⎛

⎝ ⎜

⎞

⎠ ⎟= −ln tan θ

2( )( )

€

mT2 ≡ m2 + px

2 + py2

pz

€

y β ⏐ → ⏐ y − tanh β( ) ⇒ dNdy

β ⏐ → ⏐ dNdy

− tanh β( )

Mandelstam Variables

€

s ≡r p 1 +

r p 2( )

2 =r p 3 +

r p 4( )

2

t ≡r p 1 −

r p 3( )

2 =r p 2 −

r p 4( )

2

u ≡r p 1 −

r p 4( )

2 =r p 2 −

r p 3( )

2

s + t + u = m12 + m2

2 + m32 + m4

2

€

r p 1

€

r p 2

€

r p 3

€

r p 4

?

= cm Energy2

FlowEquation of State

Physical Review C, Volume 68, 034903 (2003)

How pressure gradients affect the QGP fluid.


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Jet Suppressionat STAR

Elena Bruna, for the STAR Collaboration Yale University, presentation at Winter Workshop on Nuclear Dynamics, Ocho Rios, Jamaica January 2 - 9, 2010

QGP

Jet How fast moving colored objects behave in a strong force dominated medium

First ALICE p-p Event √s=900 GeVNovember 11 2009

Muon Spectrometer

ITS

On 6th December, ‘stable beams’ were declared & we could switch onall ALICE detectors for the first time..

TPC, TRD, TOF, HMPID

First ALICE Events

First Publication

This is the first (and easiest) ofmany numbers we need to (re)measure toget confidence in our detectors, tune thesimulations, study background, ....

last time measured at the ISR for pp

The average number of charged particlescreated perpendicular to the beam

in pp collisions at 900 GeV is:dN/dh = 3.10 ± 0.13 (stat) ± 0.22 (syst)

Most Recent Preliminary Resultsp-p interactions

Charged particle multiplicity triggered by at least one charged particle within |h|<1.

√s 0.9 TeV 2.36 TeV 7.0 TeV

Inclusive>0|h|<1

3.78±0.008+0.088-0.066 4.68±0.010+0.132

-0.079 6.02±0.004+0.021-0.018

Most Recent Preliminary Resultsp-p interactions


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Calculated in Offline from tracklets in Silicon Pixel Detector:

sx ~ 475 µm sy ~ 475 µm sz ~ 4.2 cm

Interaction Vertex

Particle ID by dE/dx

TPCNo vertex cut !

ITS

Preliminary


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Particle ID working within each detector

15/2/2006 LHCC Status Report J. Schukraft

TRD

Electrons

Pions

velocity v/c

TOF Protons

Kaons

Pions

all plots:preliminary calibration & alignment !

Preliminary


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PHOS Finds π0

π0 ® 1 < pt < 1.5 GeV

PHOS (9 m2)

€

mπ = 2Eγ 1Eγ 2

1− cosθγ 1γ 2( )

Noise

π0

Preliminary


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Track reconstruction in TPC

TPC Rods

SSD TPC Vessel 1

TPC Vessel 2

SDD

SPD

-ray image of ALICEphoton conversion vertices

€

+* → e+ + e−

Preliminary


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π0 using TPC

π0 ® ® e+e- e+e-

mπ0=134.9766 MeV

Preliminary

PDG: 1115.7 MeV

L ® πp

PDG: 1115.7 MeV

L ® πp

Finding the Zoo of Particles

X ® Lπ ® πp πPrelim inary


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Still more

PDG: 497.6 MeV

K0s ® ππ

F ® K+K- PDG: 1019.5 MeV

Preliminary


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Once particles are identified

p/p ratio to study Baryon Transport via

di-quark stopping or gluon junctions

And Many other Ratios

Preliminary


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Including more complicated measures

π- HBT correlation function to study space-time evolution

(also reference for heavy ion data)

Data

Monte Carlo (no HBT correlations)

€

c(q ) ≡P1,2 p 1, p 2( )

P1 p 1( )P2 p 2( )

€

q ≈ p 1 − p 2

Preliminary€

r r ( ) = c q ( )e− q −r ( )d4q∫


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Conclusion• Finally after many years, data is coming

– At injection energy, 900 GeV– At LHC’s first acceleration to 2.36 GeV– Now LHC operating at 7.00 GeV

• Things are working better than expected• There still is a lot of work to go• Many exciting results are anticipated• A number of unexpected things will happen• A number of unexpected results will surprise us all.

Upcoming ScheduleEnd of 2010, First Ion-Ion run at 2.75 ? TeV/n cm.

2011, full p-p run at 7 TeV cm, at/near design luminosity.

End of summer 2011, Pb-Pb run at 2.75 TeV/n cm.

After summer 2011, long shutdown to finish repairs and get machine working at 14 TeV p-p cm.


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First Cosmic seen in ALICE TPCApril 7 2008


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First Beam Gas Events in ITS

6/4/2008


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First beam in LHCSeptember 10 2008

Signals as seen in ALICE’s V0A (blue) and V0C (red) Detectors

Machine group has placed, up stream of ALICE, a small Wire Chamber which the beam interacts with producing a particle shower seen by ALICE.


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During down time

• Removed and reinstalled Mini-space frameCabling nightmare, Please don’t do it again

• Installed 4 EMCal Super Modules• Repaired TPC and other detectors• Fixed and many sundries things• Significant improvements in software,

Online, Offline, and Grid


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ALICE V0 Timing

V0-A side

V0-C side

from interaction region

from beam line

from interaction region

from beam line

V0-A

V0-C

first physics at the lhc alice

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