News

1
Elementary Particle Physics ExperimentThe ATLAS
experiment at the LHC

University of Massachusetts, AmherstGraduate
Research Orientation8 Feb 2008
2
The UMass ATLAS Group

• Faculty
• Carlo Dallapiccola - LGRT 1038
• Stephane Willocq - LGRT 1042
• Postdoctoral Researchers
• Ed Moyse, Niels Van Eldik, Martin Woudstra - CERN
  
• Graduate Students
• Emily Thompson - CERN
• German Colon, Andrew Meade - LGRT 1036

3
What is Particle Physics About?

• Experiments can address long standing puzzles /
  questions
• What are the fundamental constituents of matter?
• What are the fundamental forces between
  elementary particles?
• Can the forces of nature be unified? Including
  gravity?
• What is the origin of mass?
• What is the origin of the matter-antimatter
  asymmetry of the Universe?
• What is dark matter?
• Are there extra dimensions?
  many more

4
How can we answer these Fundamental Questions?

• Particle Accelerators
• Reach very high collision energies to
  probeextremely small distance scales (lt 10-18 m)
• Research at the energy frontier (a few TeV) with
  theATLAS experiment at the Large Hadron Collider
  (LHC)? 10 x higher energy than previous
  colliders ? search for
• Higgs boson (origin of mass?)
• SuperSymmetric particles (dark matter candidate?)
• New interactions (heavy gauge bosons, extra
  dimensions?)

5
The Large Hadron Collider (LHC)

• Proton-proton collider circumference 27 km
• Energy 7 TeV / beamvs 14 TeV
• Stored energy / beam 350 MJ (!)
• Bunch spacing 25 ns? 40 MHz crossing rate
• Design luminosity 1034 cm-2 s-1
• Number of interactionsper crossing 23
• First collisions expected
• in Summer 2008!!!
• Run for 10-15 years

Lake Geneva ?
CERN Main Site ?
ATLAS
CMS
6
The ATLAS Detector _at_ LHC

EM Calorimeter
Muon Detectors
Inner Tracker
Hadronic Calorimeter
Diameter 25 m Barrel toroid length 26
m End-cap end-wall chamber span 46 m Overall
weight 7000 Tons
7

8

• ?

November 2005
August 2006
September 2006
9
ATLAS Simulated Events
Higgs boson
Mini black hole
10
UMass Work on ATLAS

• Software development for Muon Spectrometer
• Leading muon reconstruction effort(SW
  co-coordinator, EM event data model leader)
• Validation of detector description, performance
  improvements
• Physics analysis Search for new physics
• Search for new heavy gauge bosons (new
  interactions)
• Alternatives to Higgs mechanism (origin of mass)
• Signs of extra (large) dimensions micro black
  holes
• More information at http//people.umass.edu/eppex/