Physics Opportunities in CMS Experiment at LHC

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Physics Opportunities in CMS Experiment at LHC

• Y. Onel
• University of Iowa
• Iowa City, IA, USA
• UI Colloquium, April 9th, 2007

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Weve Come a Long Way
We Have Come a Long WayMatter Dark Energy
Balanced
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The Large Hadron Collider
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CMS at LHC 2007 Start

• pp ?s 14 TeV L1034 cm-2 s-1
• Heavy ions

CMS
TOTEM
pp, general purpose HI
First Beams 2007 Then Physics
ALICE HI
LHCb B-physics
ATLAS
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LHC Ring
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Proton-Proton Collisions
Each proton is like a bag containing partons
three real quarks (up, up, down) and a whole
spectrum of gluons, and virtual quark-antiquark
pairs, called the sea. At each collision, Q.M.
allows for hard collisions between a parton in
one proton and a parton in the other proton, with
relative probabilities given by the cross
sections and by Parton Distribution
Functions PDF fi(x) the probability density
for finding a parton of type i with a fraction x
of the protons momentum.
Gluon g dominates for x lt 0.2 At large x, u
dominates over d Virtual sea dominates for x lt
0.03
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Experimental Consequences

• The momentum fraction x of each of the partons is
  typically unequal, so the C.M. of the colliding
  parton-parton system is moving along the beam
  direction, with some transverse momentum as well
  due to higher-order QCD effects.
• This parton-parton system is the interesting
  system the energy available for new particle
  production is
• (14 TeV) ? ?(x1x2),
• with probability proportional to PDFs for x1 and
  x2.
• High collision rate can make up for some of the
  drop in beam energy compared to SSC, but we still
  must live with 14 TeV instead of 40 TeV in front.
• What might the colliding partons make?

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LHC Significance
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The CMS Detector
CALORIMETERS



ECAL

HCAL


Scintillating PbWO4 crystals

Plastic scintillator/brass sandwich
IRON YOKE
TRACKER
MUON ENDCAPS

MUON BARREL
Drift Tube

Cathode Strip Chambers ( )
Resistive Plate

CSC
Chambers ( )
Resistive Plate Chambers ( )
RPC
DT

Chambers ( )
RPC
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Building 40 at CERN
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CMS Detector Slice
7 meter lever arm for tracking muons
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The CMS Collaboration
Belgium
Bulgaria
Austria
Finland
CERN
USA
France
Germany
Greece
Russia
Hungary
Italy
Uzbekistan
Ukraine
Slovak Republic
Georgia
Belarus
Poland
UK
Armenia
Portugal
Turkey
Brazil
Serbia
China, PR
Spain
Korea
Pakistan
China (Taiwan)
Switzerland
Mexico
Iran
Colombia
New-Zealand
Ireland
Croatia
India
Cyprus
Estonia
2030 Scientific Authors, 38 Countries, 174
Institutions
May, 04 2006/gm http//cmsdoc.cern.ch/pictures/cms
org/overview.html
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Particles in the Detectors
The only particles which do not decay and which
are detected individually by the detectors are
e, ?, ? u, d, s some survive inside hadrons
some decay to ? ?. ?, c, b, t, W, Z decay
quickly b decay can be identified. neutrinos
escape undetected missing energy. Energetic
quarks and gluons become jets of hadrons.
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Typical HEP Subdetectors
Tracking position measurement, precise and low
mass. EM Cal High-Z, as active light collection
as affordable H Cal Also light collection with
more dead material ideally similar response to
gammas and hadrons. Muon detector after iron
filter.
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Calorimetry and Muon Detectors

• ECAL
• PbWO4 crystals
• ??coverage
• ???????????(barrel)
• ???????????????(endcap)
• - preshower 1.65 ? ? ? 2.6
• finely grained/high energy resolution
• ??x?????0.0175 x 0.0175 (barrel)
• 0.027/?E ? 0.0055 (barrel)
• HCAL
• scint. tile / brass (barrel/endcap) quartz
  fiber / iron (forward)
• near hermetic coverage
• ????????(barrel/endcap)
• ????????????(forward)
• ??? 6.4 including CASTOR
• segmentation and resolution

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Hadronic Forward (HF) calorimeter
Steel absorbers, embedded quartz fibers // to the
beam. Fast (10 ns) collection of Cherenkov
radiation. Coverage 3lthlt5
Df x Dh 10o x 13 h towers Depth
10 lint
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HF detector
To cope with high radiation levels (gt1 Grad
accumulated in 10 years) the active part is
Quartz fibers the energy measured through the
Cerenkov light generated by shower particles.
Iron calorimeter Covers 5 gt h gt 3 Total of
1728 towers, i.e. 2 x 432 towers for EM and HAD
h x f segmentation (0.175 x 0.175)
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HCAL - Forward
First detector lowered in Nov 2006
(2006)
Staged in bldg 186. Calibration is complete
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HF in 186 - Services
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Picture of HF transport to SX5
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HF Lowering
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HF Lowering
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HF Lowering
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Iowa Team at UX5
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Recent View from UX5
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CMS HCAL
Had Barrel HB Had EndcapsHE Had Forward HF
HO
HB
HE
HF
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HCAL - Barrel
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HCAL Segmentation and Coverage
HF 3lthlt5 Df x Dh 10o x 13 h towers
HB
HE
HF
HB hlt1.3 HE 1.3lthlt3 HF
3lthlt5 Very Fine Granularity Df x Dh
0.087x0.087 for hlt1.7
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All Silicon Tracker
Outer Barrel (TOB)
Barrel and Forward Pixels
End Caps (TEC)
Inner Barrel Disks (TIB TID)
2,4 m
5.4 m
207m2 of silicon sensors10.6 million silicon
strips65.9 million pixels 1.1 m2
volume 24.4 m3 running temperature 20 0C
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Surface above CMS when Shaft was visible (2004)
20 m shaft
Detector assembly
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Transfer CMS Underground started in 2006
Gantry installed over PX56. load test in July and
start HF lowering.
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Installing muon Detectors
Production complete 482 including spares.
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CMS Closing for Magnet Test
YB-1 and YB-2 closed
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Magnet test cosmic challenge
ambitious integration test issues -compatibility
with basic programme of tests -special
installations -cabling services (esp
LV) -controls and safety -trigger -off-det
electronics -DAQ Run Control -DAQ integration
requires -local DAQ (over VME) Common
trigger -databases -data-structure/storage
-analysis software etc etc etc
TK dummy tube
TK cosmic stack (or TIB TEC elements!!)
Tracker support
EB supermodule
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Cosmic Test - Layout
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HB insertion completed
HB- insertion completed
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Hadron Calorimeter (HCAL) Complete
Cosmics in HCAL at SX5
HCAL Barrel (HB)
HCAL Endcap (HE)
HF
Assembly of 2 half barrels HB HB- and two
endcaps HE HE- completed in 03 (brass scint)
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CMS DAQ and Trigger System

• The total interaction rate is 1 GHz. Events are
  selected by a series of trigger cuts which
  reduce the rate to 100 Hz.
• Find a needle in a haystack 1 event out of
  every 10 million interactions that are lost
  forever.

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CMS General Trigger Scheme
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Trigger Integration Progress in Electronics
Integration Center (Pr. 904)
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Event filtering
Start from 40 million events/sec x10 million
sec/year (30 run eff.) x10 years 4x1015 events
End result Search for Higgs particle Look for
data gt background rate 40 events excess 10-14
factor Each Higgs event is like a 1g needle in a
100 million metric ton haystack
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Matter and Force Particles
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Basics of Standard Model
Standard Model classifies all known particles and
forces by giving a consistent picture of the
nature, except gravity.
All particles that are constituents of matter
around us are discovered. Higgs particle is yet
to be discovered. Final triumph of SM!
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Forces and Higgs
In Standard Model particles are required to
interact with Higgs field in order to have mass.
The Higgs field is introduced to break the
electroweak symmetry by using a Higgs potential
(sombrero-Mexican hat).
A famous physicists attracts a cluster of
admirers with each step and this increases his
resistance to movement, in other words, he
acquires mass, just like a particle moving
through the Higgs field ...
Potential is zero
By picking a point in the moat as vacuum state
the rotational symmetry gets broken!!!
Vacuum state
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Higgs Cross Section
CDF and D0 successfully found the top quark,
which has a cross section 10-10 the total cross
section. Rate luminosity cross section LHC
has 100 times the luminosity of the
Tevatron The CMS detector is designed to discover
the Higgs for all masses lt 1 TeV in 1 year of
full luminosity operation.
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Higgs Bosons

• If the coupling to the Higgs field is what gives
  particles mass, then heavier particles have
  stronger couplings to the Higgs.
• The heaviest particle we know, the top quark,
  then provides a virtual path to making the Higgs
• Two gluons collide, make a virtual top-antitop
  pair, which then annihilates into a Higgs.

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How Does the Higgs Boson Decay?
Branching Ratio is greatest for heaviest
particles allowed by energy conservation, since
Higgs coupling is reason for mass.
But at low mass b-antib decay may be hard to
detect, so also look for gamma-gamma.
At high masses, W and Z immediately decay
further. So, e.g., H ? ZZ ? ????
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SM Higgs (I)
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SM Higgs (II)
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Low mass Higgs (MHlt140 Gev/c2)
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Intermediate mass HiggsZZ
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(Very) High mass Higgs
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New Higgs channels VBF-based
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VBF H?tt
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VBF increased reach
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Higgs channels considered
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One Missing Item in SM Gravity
We physicists try to understand Nature by looking
at small scales (high energies) and finding the
governing laws at that scale. Often we try to
unify the laws from different scales and we are
successful at that, if we ignore gravity.
Understanding gravity with the concepts of
quantum mechanics requires a new symmetry in
nature Supersymmetry or SUSY in short
Building new theories with SUSY may lead us to
Grand Unified Theory where all known forces are
understood by one theory.
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Standard Model and SUSY
For every particle in SM there is a partner
particle so-called sparticle. The CMS experiment
at LHC project will be looking for sparticles
Elementary Particles
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Speculated SUSY Mass Spectrum

• Why SUSY? Indications
• GUT Mass scale, unification
• Improved Weak mixing angle prediction
• p decay rate
• Neutrino mass (seesaw)
• Mass hierarchy Planck/EW
• Dark matter candidate
• String connections

Mass GeV
A whole new spectrum waiting at a few hundred
GeV? Lightest Supersymmetric Particle (LSP), if
stable, is a galactic Dark Matter candidate.
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How Do SUSY Particles Decay?
Production Gluons collide to make Gluinos Decay
Cascade to quarks, leptons, LSP Production q
anti-q collide to make Gaugino pair Decay
Cascade to leptons plus neutrino plus LSP
Examples
Many more examples! In fact, so many that if
SUSY is discovered, sorting it all out will be
quite difficult.
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SUSY Signal Signature
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A Candidate Event
T. Yetkin, Iowa
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We Need to be Ready to Discover and Study New
Physics on Day 1
CMS

Elwk Data Mh lt 251 GeV
The Higgs, SUSY, Other New Physics Might Be
Discovered Early
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Dark Matter
Astrophysical observations indicate that the
amount of predicted mass is much more than can be
explained by the luminous stuff. We do not see
this material because it does not emit light and
hence called dark matter.
Dark Matter???
Standard Model does not provide any candidate
particle for dark matter. The Lightest
Supersymmetric Particle (LSP) of SUSY is a
candiate for dark matter (Weakly Interacting
Massive Particle) and it will give a large
missing energy in CMS detector if it exists.
LSPs as an outcome of pp collisions
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Physics at LHC with CMS
published
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Computing Challenge
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CMS Computing Model Data Flow
Raw Data size 1.5MB for 2x1033 Event Rate 150Hz
for 2x1033
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What do we do with the Data?
A worldwide computing grid is being set up to
exploit computing resources around the Earth.
Fermilab is the U.S. CMS Tier 1 Center.
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The Open Science Grid A Major U.S.
Cyberinfrastructure Supported by U.S. DOE and NSF
GROW is a major contributor to and participant in
the Open Science Grid.
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CMS-HF PMT Test Station_at_ Iowa

• Computer Controlled Setup
• Designed to Test MultiPMTs simultaneously
• Low HV Single Photoelectron Detection Ability
• All data is on SQL Database, secure web site.

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HF Test Beam _at_ CERN
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Engineering Tasks For Iowa
Ianos Schmidt Paul Debbins are Building the CMS
HCAL Source Calibration Units
Source tubes insertion
source drivers
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Engineering Tasks For Iowa

• Ianos Schmidt
• HCAL digital optic link and trigger mapping
• HF Cables and Services Design
• CMS Fiber Insertion Coordinator

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Test set up at IRRAD (T7 beam)
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Iowa Deliverables
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Iowa Deliverables
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Iowa Deliverables
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Iowa Deliverables
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Description of ZDC
POINT 5
ZDC2
140 m
INTERACTION POINT
140 m
ZDC1
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Zero Degree Calorimter
Detector slot
HAD
EM
HAD
LM
EM
Zero Degree Calorimeter
Neutral particle absorber (TAN)
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Description of ZDC
The physical characteristics of the ZDC
Schematic illustration of the detectors design.
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Description of ZDC
Prototype of longitudinal tower of HAD Section
Structure of Quartz/Quartz fiber
0.6 mm diameter of core
0.63 mm diameter of doped silica clad
0.05 mm - thickness of
polyamide buffer
Fiber bundle
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LHC Luminosity Profile
Z_at_6TeV
SUSY_at_3TeV
3000
300
30
SHUTDOWN
200 fb-1/yr
10-20 fb-1/yr
100 fb-1/yr
1000 fb-1/yr
First physics run O(1fb-1)
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If we are lucky
The SppS turned on at 1 of final instantaeous
luminosity, but in the first run of a few months
discovered the W and Z bosons.
While these experiments did some nice
measurements after this, they never again did
anything anywhere near as exciting as this early
discovery.
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What NEXT
Next Objectives MTCC, and preparing for the
physics commissioning and first data.
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Goals of Nuclear Physics Program

• Quark Gluon Plasma
• QCD at high T, high density
• Many Body QCD
• Use Heavy Ion Collisions to Create Hot Nuclear
  Matter
• SPS (10 GeV/u), RHIC (200 GeV/u), LHC (5.5
  TeV/u)

Lattice QCD
Hard Interactions
Parton Cascade (QGP?)
Hadrons e, m, g
Nuclei
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A New Viewpoint for QCD Matter at LHC
Factor 30 Higher sqrt(s) Initial state dominated
by low-x components. Abundant production of
variety of perturbatively produced high pT
particles for detailed studies Higher initial
energy density state with longer time in QGP
phase Access to new regions of x
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Heavy Ion Physics Program in CMS

• Soft physics and global event characterization
• Charged particle multiplicity
• Azimuthal asymmetry (Flow)
• Centrality
• Spectra Correlations ?0, direct photons,
  decay topology
• High pT Probes
• Quarkonia (J/?, ?) and heavy quarks (bb)
• High pT Jets - detailed studies of jet
  fragmentation, centrality dependence, azimuthal
  asymmetry, flavor dependence, leading particle
  studies
• High energy photons, Z0
• Leading particle correlations a la RHIC
• jet-?, jet-Z0, multijet events
• Forward Physics
• Limiting Fragmentation, Saturation, Color Glass
  Condensate
• Ultra Peripheral Collisions
• Exotica

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Outlook for HI Physics

• LHC will extend energy range - in particular high
  pT reach - of HI physics to provide a new window
  on QCD matter
• CMS detector offers superb capabilities for
• studying HI physics
• Full calorimeter coverage
• Superior momentum resolution due to 4T magnetic
  field
• High mass resolution for quarkonia
• Centrality, multiplicity, spectra, energy flow to
  very low pT
• No modification to detector hardware
• New High Level Trigger (HLT) algorithms for HI
• Zero Degree Calorimeter, CASTOR and TOTEM provide
  unique access to forward physics

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FUTURE UPGRADES
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Quartz Plate Calorimeter Prototype
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Quartz Plate Calorimeter Prototype
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Backup Slides
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SUSY Cross Sections
The SUSY cross sections for squarks and gluinos
are large because they have strong couplings. R
parity means cascade decays to LSP. Simplest
signature is jets and MET, independent of
specific SUSY model. Dimensionally ? ?s2/(2M)2
or 1 pb for M 1 TeV.
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SUSY Reconstruction
Mass of from MET, then others from
observed decay products. Earliest searches are
with jets MET, semi-inclusive. Here use
dilepton end point? Note plots are for 1 year at
10 of design luminosity.
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SUSY Mass Reach
1 month at 1/10 design luminosity, or first
physics run in 2008 covers gt 1 TeV gluino
mass.. SUSY discovery could happen quickly.
WMAP
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Cosmology and LHC
The universe is flat and composed largely of dark
energy (75) and dark matter (25 ). What are
they? We understand only about 5 of the Universe
by weight. Assume that DM is a fact and that some
form of SUSY with R parity is the most likely
thermal relic candidate.
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Generalized SUSY
DM gives confidence that SUSY search at LHC is
crucial and should be generalized. Assume
non-universal gaugino masses, M1, M2, M3. Evade
the constraints on the MSSM. (H. Baer). Implies a
model independent search for SUSY signals using
Jets MET leptons. Experimentally it is best
to look at the simplest final states arising from
cascades to LSP, but leptons appear to be needed
to improve S/B ratios..
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LHC Dipoles
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4 Tesla Coil Design 4 Layer Winding
Central magnetic induction 4 T Nominal
current 20 kA Stored energy 2.7 GJ Magnetic
Radial Pressure 64 Atmospheres!
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CMS Solenoid
swiveled August 25th
Coil inserted 14 Sep.
Vacuum Tank welded (Nov-Jan)
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Status of ECAL
Barrel 36 Supermodules with 1700 crytals.
26/36 bare SM assembled.

• 12/36 Supermodules (SM) integrated.
• Every integrated Supermodule is pre-calibrated
  with cosmic rays for 1 week.
• 3 absolute calibration achievable with cosmics.

79 of crystals delivered (49,000).
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ECAL HCAL Energy Resolution
Combined Test ECAL SM HCAL Wedge in Summer 06
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ECAL PbWO4 Crystals
Barrel 2.4x2.4x23 cm3 Endcap 3x3x22 cm3
RMoliere 2.2 cm Radiation Resistance 105 Gy (10
Mrad)
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ECAL performance
Energy resolution 2004 test beam 18 crystals
Noise distribution of the 1700 channels of SM13
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Inner Tracker
TOB 6 Layers
TEC 6 Layers
TOB
TEC
TID 3 disks
TIB 4 Layers
TIB
TID
Pixels 3 Layers and 2 disks
Strips Pitch 80 mm to 180mm Hit Resolution
20 mm to 50mm
Pixels 100 mm x 150mm rf and z resolution
15-20 mm
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Si Strip Module Components
HPK Silicon Sensors
Carbon Fiber Frame
HV Kapton
Pitch Adaptor
Readout Hybrid
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Tracker Outer Barrel (TOB)CERN USA
Installing rods since March 400/700 Rods
constructed (US) 200/688 inserted 140 validated
Scheduled Complete Oct. 06
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From Design to a Working Detector MTCC
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Muon System
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Cosmics Signal
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Cosmic Calibration

• We will test calibrate most (if not all) Super
  Modules in cosmic rays.
• Each SM stays 1 week
• Change from 1 SM to next is very fast (lt12 h,
  including thermalisation)
• 3 absolute calibration achievable with cosmics

Energy deposition of cosmic rays versus
pseudorapidity
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Electronics Integration Center (Bat 904)
HCAL
ECAL
RCT
GCT
GT/GMT
TTC
DTTF
CSCTF

• Maximize commissioning time of all
• Electronics
• Large scale integration activity with all
  subdetectors
• Find many Infrastructure system level issues
  early

• Burn in and test electronics, PS
• E.g. Integration of trigger chain
• with test patterns

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ICs and Circuit Boards of All Sorts

• Front End, Trigger, DAQ
• ASICS, FPGAs, Optical links

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Jet Reconstruction and Resolutions
Mjj resolution at 120 GeV
Jet ET resolution
Calo only
Using tracks
Mjj resolution?? 15
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Backup-Early Physics
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Cosmic Rays
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The Two Frontiers of Physics
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The Forces in Nature
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Sparticle Cascades
At parton level
In detector 2 jets with b quarks, 2 leptons
(muons or electrons) Missing energy from escaping
neutralino all embedded in a bigger mess
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Sparticle Masses
An example of the kind of analysis done, from 1
year at 1/10th design luminosity.
Sequential 2-body decay edge in Mll
10 fb-1
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Higgs Decay, H -gt ZZ -gt4?
Golden mode for H mass gt135 GeV. Muon endcaps
important. Muons in green.
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The Golden Channel
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New Heavy Neutral Gauge Bosons?
Red line Z? Peak above background expected for 3
TeV mass after 1 year of running at full
luminosity. Blue line If no Z?.
GeV
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OSG Troubleshooting
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CMS Testing and Troubleshooting

• CRAB
• dCache/SRM
• Condor-G
• LCG Resource Broker
• PhEDEx

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Particle Physics-HEP
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Why do we really need the LHC?

• Our current understanding of the Universe is
  incomplete
• The question of mass is most perplexing
• Forces are also perplexing
• Antimatter poses another riddle the LHC will help
  us solve

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Mass Problem?
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Fundamental Scales
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Particles and Forces
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The Standard Model of Elementarty Particle Physics
139
Interactions Coupling of Forces to Matter
140
Interactions
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Unification of Forces
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Collisions at LHC
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Collisions at LHC
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Towards the Origin
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The Next Step
146
Evolution of LHC luminosity
147
Mass Reach vs L - SLHC
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Higgs Self Coupling
149
Detector Environment
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Full Analyses Heavy-Ions
151
Overview of CMS Detector
152
Full Analyses Heavy-Ions