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Acta Polytechnica Vol. 50 No. 3/2010

The ATLAS Experiment Entering into Operation:
Overview, Motivation and Status of the Project

P. Jenni

The Large Hadron Collider LHC at the European
Laboratory for Particle Physics CERN near Geneva
will deliver particle collisions at the highest energy ever
achieved in a laboratory. After more than 15 years of
design and construction efforts, the LHC and its ex-
periments are finally starting operation. Besides the
giant accelerator, which is installed in a ring tunnel 27
km in length about 100 m underground, the no less
impressive and complex detectors are ready for data
collection.
A general overview of ATLAS, one of the key exper-

iments, has been given. The LHC will allow ATLAS to
study for the first time fundamental physical phenom-
ena as they occurred very shortly after the Big Bang.
ATLAS will address questions like: Why do particles
have a mass, What is the non-visible dark matter in
the Universe, Are there more than four dimensions in
Nature, and What are the smallest building blocks of
matter? The expectations for new discoveries are high,
since physicists have for decades been eagerly awaiting
this exploratory step into the unknown.
The technically sophisticated and highly com-

plex ATLAS detector has been developed and con-
structed through world-wide collaboration, and the
Czech teams have made remarkable contributions to
the project since its conception some 20 years ago,
very much so thanks to the constant strong support
and encouragement provided by Professor Niederle.
One important and most pleasant milestone in the his-
tory of ATLAS was the yearly Overview Week. The

September 2003 overview took place in Prague, and
was opened with an address by Professor Niederle.
Some highlights of the construction and commis-

sioning of the detector have been illustrated, as well
as several examples of anticipated discovery signals. It
would be artificial and almost impossible to attempt to
summarize the huge amount of work done by the col-
laborating teams within just a few pages. The reader
is therefore referred to the two following references.
A comprehensive and detailed description of the con-
struction of the ATLAS detector and its expected per-
formance can be found in Ref. [1], while Ref. [2] is part
of an overall LHC project publication that provides an
account of the ATLAS experiment as a whole.

References

[1] Aad, G., et al.: The ATLAS Collaboration, ‘The
ATLAS Experiment at the Large Hadron Collider’,
JINST 3 (2008), S08003.

[2] Jenni, P.: In: The Large Hadron Collider: a Mar-
vel of Technology, edited by L. Evans, EPFL Press,
2009, p. 182–199. ISBN 978-2-940222-34-2.

Peter Jenni
CERN, former Spokesperson
of the ATLAS Collaboration
European Organization for Nuclear Research
CERN CH-1211, Genève 23, Switzerland

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