Download ATLAS experiment at the CERN Large Hadron Collider

ATLAS experiment at the
CERN Large Hadron Collider
Peter Watkins,
Head of Particle Physics Group,
University of Birmingham, UK
[email protected]
Large Hadron Collider (LHC)
Point 1 activities and
perspectives
Marzio Nessi
plenary
ATLAS
d
Outline of talk
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Building blocks of the universe
Why do experiments at the LHC ?
LHC, ATLAS and collaboration
Searching for a new particle
Recent LHC news
Acknowledgements –
Many slides from LHC colleagues
4
The very
small
electron
nucleus
10-10 m
(thickness of human
hair ~ 10-5 m)
10-14 m
proton
neutron
10-15 m
up quark
down quark
< 10-18 m
Fundamental Forces
All forces are carried by particles !
Gravity – solar system, galaxies …- extremely weak force
Electromagnetic – atoms, electricity …..
- carried by photons
Weak force
– beta decay and how stars generate energy
- carried by massive W and Z bosons
Strong – binds quarks inside
proton carried by gluons
Higgs
boson?
The Higgs Boson
One key objective of the LHC is to understand the origin of mass
– is it due to a universal Higgs field?
(A Higgs field everywhere with the Higgs boson as the force carrier?).
Massless particles are not impeded by the Higgs field and,
thus, travel at the speed of light. Analogy: Downhill skier
experiences no drag by the snow field.
Light particles interact weakly with the Higgs field and travel
slower. Analogy: Snowshoes on the top of the snow field
experience some drag.
Heavy particles interact strongly with the Higgs field and
travel very slowly. Analogy: Wading through the snow field is
a big drag! We call this drag “Mass”.
What else is out there?
• Various ideas considered…
• Dark matter
•
• Extra dimensions of space
•
Suggested by superstring theory
• Microscopic black holes
The
The LHC
LHC experiments
experiments can
can look
look for
for all
all of
of these
these..
Also
Alsosensitive
sensitiveto
tosomething
something“completely
“completelydifferent”
different”
The Large Hadron Collider (LHC)
Mont Blanc
Geneva
Airport
The LHC is a 27km
accelerator that collides
counter-rotating beams
of protons of up to 7 TeV.
(Tev = million million eV)
Energy densities similar
to billionths of a second
after the big-bang will be
recreated at collision
points
CERN laboratory on Swiss
– French border
Building the LHC
In the main ring:
1746 superconducting magnets
… including 1232 15m SC
dipoles
… weighing 27 tonnes each
… producing 8.36 Tesla
… and running at –270c
… needs 700,000 litres liquid He
… and 12 million litres liquid N2
The fastest racetrack on the
planet
The protons will
reach
99.9999991%
speed of light,
and go round the
27km ring 11,000
times per second
Collision points
At four places the
beams intersect
Hot spots too !
When the two beams of
protons collide, they will
generate temperatures
1000 million times
hotter than the heart
of the sun,
but in a minuscule space
ATLAS Detector
7,000 tonnes
42m long
22m wide
22m high
(About the
height of a 5
storey
building)
2,800 Physicists
169 Institutes
37 Countries
Electromagnetic Calorimeter
A basic calorimeter
Basics
The past
Challenges
Where to start?
Detector Design
Tracker
Calorimetry
Particle ID
LHC detectors
“Events”
Final thoughts
Total # of particles is proportional to energy of incoming particle
Active detector slices produce a signal proportional
to the number of charged particles traversing
Muon Detectors
E2 = p2c2+ m2c4
Discovering a new particle
The collision rate challenge
• Proton bunches collide 40 million
times a second
• ~25 proton-proton collisions occur
each time
• 1000000000 collisions per sec –
200 per second limit for recording
• Select the most ‘interesting’
collisions in few microseconds
Searching for Rare Phenomena
9 orders of magnitude
Number of
collisions
All interactions
The HIGGS
Collision
energy
50 magnets
repaired
3 km of beam
pipe cleaned
LHC status and plans
• Large Hadron Collider restarted in Nov 2009 and
is working well
• World record was set for collision energy in
December 2009
• On March 30th 2010 the collision energy was
increased to 7 TeV
• Some early measurements already published
• Search for Higgs boson needs more collisions
Z boson candidate
Summary
• Many people are interested in the LHC and
the key ideas are widely accessible
• The searches for new particles are only just
beginning and will last for a decade
• We work on sharing the excitement of the
project with the widest possible audience
• We need your help to do this to an even wider
audience!
Thanks for listening