Post on 22-Jan-2016
1Stefan Spanier, 22 October 2008
Research Participationin
Collider Based Particle Physics
Stefan SpanierUniversity of Tennessee, Knoxville
2Stefan Spanier, 22 October 2008
Cathode Ray TubeCathode Ray Tube
electron
Experiments 111 years ago …
fundamental building block of matter
"Could anything at first sight seem more impractical than a body which is so small that its mass is an insignificant fraction of the mass of an atom of hydrogen?"
J.J. Thompson: Cathode rays are material constituents of atoms! bend in electric and magnetic field
Nobel Prize 1906
G.P. Thompson: electrons have wave characterNobel Prize 1937
3Stefan Spanier, 22 October 2008
Particle Accelerator as Microscope
Length to be resolved R
R 1/Particle Energy
1eV = kinetic energy an electron gains in a electric
field of 1 Volt
1.0 V+-
- > 100 MeV
~ keV
> 10 MeV
> 100 GeV
4Stefan Spanier, 22 October 2008
u c t d s b
d s b u c t
e- e
e e+
_ _ _
_ _ _
_ _ _
Charge
+ 2/3
- 1/3
-1
0
Charge
+ 1/3
- 2/3
0
+1
Quarks
Leptons
mass
particles anti-particles
Standard Model does not ‘predict’ any of the masses (parameters);How do masses come about?
Latest addition 1995Tevatron at Fermilab
The Standard Model
Building Blocks
5Stefan Spanier, 22 October 2008
How particles acquire masses …
The Higgs particle mass generation
The Higgs Field
6Stefan Spanier, 22 October 2008
Electric Magnetic Photons m= 0
Weak W+,W -,Z0 m= 80, 90 GeV
Strong Gluons m = 0
Gravity Gravitons ?
Maxwell
electroweak
~100 GeVStandard Model
Planck energy~ 1019 GeV
today’s acceleratorsjust about …
~ 1015 GeV ?GUT scale
coupling constants unify
Higgs mechanism
Forces
Seems unnatural ?
7Stefan Spanier, 22 October 2008
GUT
Force relative couplingStrong S 1 0.12Electromagnetic 1/137 1/128Weak W 10-6
Gravity G 10-39
Behavior of coupling constants supports idea, but no common intersection?
introduce e.g. Supersymmety ?
least understood
1strength
weak
strong
8Stefan Spanier, 22 October 2008
Supersymmetry ???
Simplest super-symmetric model has 105 new parameters …
Boson Fermion symmetry
Spin ½ quarks spin 0 squarks Spin ½ leptons spin 0 sleptons Spin 1 gauge bosons spin ½ gauginos Spin 0 Higgs spin ½ Higgsino
Many particles to search for! What mass scale? Supersymmetry is broken ...no scalar with mass of electron
Observation: -as missing mass (energy) if non-interacting (lightest neutralino)- from decay into the lower mass standard particles
9Stefan Spanier, 22 October 2008
• What is dark matter?• How are particle physics &
cosmology connected?• What is dark energy?• Where did the anti-matter go?
(CP Violation)
Stars and galaxies are only 0.1%
Neutrinos are ~0.1–10%
Electrons and protons are ~5%
Dark Matter ~25%
Dark Energy ~70%
The Cosmic Connection
10Stefan Spanier, 22 October 2008
The LHC Machine and The LHC Machine and ExperimentsExperiments
LHCf
totem
High Energy factor 7 increase w.r.t. present accelerators High Intensity (# events/reaction/time) factor 100 increaseHigh Energy factor 7 increase w.r.t. present accelerators High Intensity (# events/reaction/time) factor 100 increase
Proton-proton collisions at 14 TeV27 km in circumference, 50-150m deep
11Stefan Spanier, 22 October 2008
LHC
superconducting dipole magnet
Energy stored/beam: 360 MJEnergy stored in magnets: 700GJ
Particle losses fatal !
Superconducting magnets:
1232 dipole magnets (bending)
T=1.9 K (superfluid Helium)
B – field > 8 Tesla
~500 quadrupole (focus)magnets
LHC in LEP tunnel
12Stefan Spanier, 22 October 2008
LHC – Beam 1 first + second turn
13Stefan Spanier, 22 October 2008
A Higgs Event in the Compact Muon Solenoid
Luminosity = 1034 cm-2s-1 = 107 mb-1HzInteraction rate = 8 x 108 Hz Interactions/crossing = 25 (~1000 charged particles)
p p
+ -
-
+
Higgs event+
~25 minimum bias events
Simulation
HZ
14Stefan Spanier, 22 October 2008
The CMS Detector
Muon chambersRPCs, DT(barrel), CSC(end)
Superconducting coil4Tesla, 20000A, -270oC
Iron return yoke
EM Calorimeter#80k PbWO4 crystals
Width: 22m
Diameter: 15m
Weight: 12,500 tons
Hadron CalorimeterBrass + scintillator
Vacuum chamber
CentralTracker66M Si-Pixel 10M Si-StripArea: 220 m2
Very forwardcalorimeter
15Stefan Spanier, 22 October 2008
The Pixel Detector• Barrel layers at radii = 4.3cm, 7.3cm and 10.2cm• Disks at +/-z = cm and cm• Pixel cell size = 100x150 µm2 ~1m2 of silicon / 66 Million pixels• ~15k front-end chips and
~1 m0.3 m
z
16Stefan Spanier, 22 October 2008
The Pixel Detector Principle
~285
m
After 1st year
z
B
Primary signal electrons; Lorentz force smears charges
Resolution: within square: ~25m Charge sharing: 10 – 15 m
MIP 29000 e-
17Stefan Spanier, 22 October 2008
Pixel Diamond Detector – New Technology
Pixel Luminosity TelescopePixel Luminosity Telescope
prototype pixel readout at UTK
18Stefan Spanier, 22 October 2008
Computing
15 Million Gigabytes of data each year (about 20 million CDs!)15 Million Gigabytes of data each year (about 20 million CDs!)
GRID Node at UTK
10 GBit/s connection; 246 processors + 50TByte storage10 GBit/s connection; 246 processors + 50TByte storage
19Stefan Spanier, 22 October 2008
The Commissioning / Operation