Searching for the Higgs – spearheading grid

Tara Shears

University of Liverpool

Particle physics

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WEAKELECTROMAGNETICSTRONG

What is mass?

…property mediated by “Higgs Particle”

AnalogyInteraction with Higgs field ( mass) ~ movement of body through medium

Light particles do not interact much (move fast)

More interaction – slower movement – more mass conferred

Heaviest particles …. most interaction

What is mass?

…property mediated by “Higgs Particle”

nb …… we haven’t seen it yet …..

???

Looking for Higgs - LHCWorld’s most powerful particle accelerator

2 beams of protons collide 40 million x a second

4 large experiments

Due to start in 2007

27 km

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aside: LHC vs. circle line

LHC Circle line

Length 27km 22.5km

Depth 100m 15m

Diameter 3.8m 3.4m

Looking for Higgs - experiment

eg. …the ATLAS experiment:

5 storey building 7,000 tonnes 42m long 22m wide 22m high2,000 Physicists 150 Institutes 34 Countries

Starting from this event…

We look for this “signature”Selectivity: 1 in 1013

Like looking for 1 person in a thousand world populations

Or for a needle in 20 million haystacks!

Finding Higgs• 800,000,000 proton-

proton interactions per second

• ~100,000,000 electronic channels

• 0.0002 Higgs per second

HOW do we find the Higgs?

Distributed Computing Solution – Grid

Concorde(15 Km)

Balloon(30 Km)

CD stack with1 year LHC data!(~ 20 Km)

Mt. Blanc(4.8 Km)

…. a needle in 20 million haystacks!

LHC produces enough data to fill 14 million cds / year (1,000,000 times world annual book production!!)

Estimated we need 100,000 computers to analyse it all …..

grid!

summarySearch for origin of mass and Higgs major unanswered question

Hope for discovery at LHC

Immense technological and computing challenge: grid!