View
55
Download
0
Category
Preview:
DESCRIPTION
First Physics at the LHC ALICE. Bjørn S. Nilsen Creighton University. CERN and the LHC. 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 - PowerPoint PPT Presentation
Citation preview
First Physics at the LHCALICE
Bjørn S. NilsenCreighton University
2
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
3
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
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
4
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
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
5
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
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
6
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( )
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
7
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.
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
9
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
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
14
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
15
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
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
17
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
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
18
PHOS Finds π0
π0 ® 1 < pt < 1.5 GeV
PHOS (9 m2)
€
mπ = 2Eγ 1Eγ 2
1− cosθγ 1γ 2( )
Noise
π0
Preliminary
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
19
Track reconstruction in TPC
TPC Rods
SSD TPC Vessel 1
TPC Vessel 2
SDD
SPD
-ray image of ALICEphoton conversion vertices
€
+* → e+ + e−
Preliminary
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
20
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
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
22
Still more
PDG: 497.6 MeV
K0s ® ππ
F ® K+K- PDG: 1019.5 MeV
Preliminary
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
23
Once particles are identified
p/p ratio to study Baryon Transport via
di-quark stopping or gluon junctions
And Many other Ratios
Preliminary
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
24
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∫
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
25
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.
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
27
First Cosmic seen in ALICE TPCApril 7 2008
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
28
First Beam Gas Events in ITS
6/4/2008
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
29
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.
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
30
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
April 14 2010 Bjorn S. Nilsen, Creighton U. Mount Michael High School
31
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
Recommended