1 Stefan Spanier, 22 October 2008 Research Participation in Collider Based Particle Physics Stefan Spanier University of Tennessee, Knoxville

1Stefan Spanier, 22 October 2008

Research Participationin

Collider Based Particle Physics

Stefan SpanierUniversity of Tennessee, Knoxville


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


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


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


How particles acquire masses …

The Higgs particle mass generation

The Higgs Field


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 ?


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


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


• 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


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


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


LHC – Beam 1 first + second turn


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


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


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


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-


Pixel Diamond Detector – New Technology

Pixel Luminosity TelescopePixel Luminosity Telescope

prototype pixel readout at UTK


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


The Commissioning / Operation

Documents

1 Stefan Spanier, 22 October 2008 Research Participation in Collider Based Particle Physics Stefan Spanier University of Tennessee, Knoxville