From the Detector to Physics Data

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From the Detector to Physics Data

• ATLAS trigger and data acquisition

Doris Burckhart-Chromek CERN ATLAS TDAQ
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Protons collide in the heart of the detector

• 1 000 000 000 times a second

Particles are created
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Particles are created
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Protons collide in the heart of the detector

• 1 000 000 000 times a second

Each collision produces huge amounts of data
which would fill 100 000 CDs each second
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The detector
is made of different parts
in which the particles leave traces
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The traces are recorded in terms of

• time
• location
• charge
• energy
• momentum

from which the particles are identified
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Highly specialized electronics
transform the traces into electric signals
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Hundreds of crates filled with thousands of
modules
convert the signals for the computer
10010100101000111100101001010001111001010010100011
11001010010100011110010100101000101000111100101001
0100011110011100101000111100101
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But only few collisions are interesting

• One out of 5 000 000

A first selection is made by looking for
characteristic patterns
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A slice through the detector showing collision
traces
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The characteristic patterns are examined
only one out of 5 000 000 is kept
the rest are discarded
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The puzzle is assembled
to obtain a complete view
of the collision
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A closer look at the data
to make an even finer selection
needs thousands of computers
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300 000 000 bytes per second are recorded
this would fill
STORAGE
1 CD every 2 seconds
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Around the world
thousands of computers
analyse the data
STORAGE
to find new physics
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Computers control the detector
with custom-build software
The physicists control ATLAS
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