Adhesives are set to play an essential role in the construction of a
huge particle detector at the European Centre for Nuclear Research (CERN)
in Geneva, Switzerland, which will help scientists gain a better
understanding of the origins of the universe
Engineers from the National Institute of Physics in Padua (INFN -
www.infn.com), Italy are currently working on a £1bn project to construct
key parts of a 125,000 tonne Compact Muon Solenoid (CMS) particle
detector. When it is completed, the detector will be placed 100m below
ground to monitor the activity of the Large Hadron Collider (LHC) - an
enormous particle accelerator that mimics conditions less than a
billionth of a second after the 'Big Bang'. The LHC will be switched on
in 2007 and will project a beam of high-energy particles 30km along a
tunnel 100m below the earth's surface. During this process very high
energy particles will collide at over 800 million times a second. The CMS
detector will monitor what happens as particles interact, processing ten
million pieces of information per collision.
The CMS particle detector comprises individual chambers constructed from
aluminium sandwich panels and honeycomb composite structures. The
majority of the chambers (some 74 pieces) are under construction at the
INFN's National Laboratories of Legnaro with the help of teams from Padua
and Bologna, while other chambers are being built in Madrid, Aachen and
Turin. Each panel comprises 2m x 3m metal sheets bonded to a middle layer
of aluminium, using Araldite 2011 (a multi-purpose, two-component paste)
as the bonding medium. Each middle layer consists of numerous empty cells
where wiring is inserted and where gas will flow during the experiment.
The chambers will be assembled at the INFN laboratory in Legnaro, near
Padua, and shipped to CERN in Geneva where the final 21 metre long
structure, which measures 16m in diameter, will be assembled.
The reliability of the CMS detector is pivotal to understanding what
happens when the particles collide, and is central to the success of the
entire project at CERN, comments INFN researcher, Dr Paolo Checchia.
The scale of the experiment means there is absolutely no margin for
error. Our engineers need unequivocal guarantees that materials employed
will deliver the highest performance levels and maintain the structural
integrity of the detector under the most extreme conditions.
We have been using Araldite adhesives for many years because of the
brand's reliability, excellent resistance and bonding strength to
aluminium substrates. Its sealing properties are vital to maintaining an
insulated environment where argon and carbon dioxide gas will be
injected. A series of tests have proved Araldite 2011's excellent shear
and peel resistance at over-pressures of up to 50mbar (equivalent to a
force of around 30,000N on the 6m2 chamber surface area). Additionally,
Araldite 2011 does not release any residues which would otherwise
contaminate gas within the chamber.
Engineers at INFN have designed novel equipment to mix and dispense
Araldite 2011 for the CMS project. The kit consists of a wide table and a
mechanical arm moving in three axes. After cleaning the surface of the
aluminium, the substrates are bonded and kept together using weights.
Curing at room temperature is complete after 12 hours.