Epoxy adhesive plays crucial role at CERN

Paul Boughton

Epoxy adhesives are set to play a vital role in Europe’s biggest-ever scientific experiment at the European Centre for Nuclear Research (CERN) in GenevaSwitzerlandthereby helping scientists gain a better understanding of the origins of the universe.

Engineers from the National Institute of Physics in Padua (INFN)Italywho are working on the E1.5billion projecthave specified an epoxy adhesive to construct key parts of a 125000 tonne compact muon solenoid (CMS) particle detector. Developed by Huntsman Advanced MaterialsAraldite2011 was qualified to meet the stringent design parameters and withstand extreme experimental conditions.

When completethe detector will be placed 100m below ground to monitor the activity of the large hadron collider (LHC)which is an enormous particle accelerator that mimics conditions less than one billionth of a second after the ‘big bang’ to reveal clues relating to laws governing nature and matter in the universe. The LHC will be switched on in 2007 and will project a beam of high-energy particles 30km along a tunnel. During this process very high energy particles will collide at over 800million times a second. The CMS detector will monitor what happens as particles interactprocessing 10million pieces of information per collision.

The muon detector is a key component and comprises individual chambers constructed from aluminium sandwich panels and honeycomb composite structures. The majority of the chambers (74) are under construction at the INFN’s National Laboratories of Legnaro with the help of teams from Padua and Bologna.

Each panel is made of 2x3m metal sheets bonded to a middle layer of aluminium with Araldite2011a multipurposetwo-component paste. Each middle layer consists of numerous empty cells where wiring is inserted and where gas will flow during the experiment. The chambers will be shipped to CERN in Geneva where the final structurewhich measures 16m in diameterwill be assembled.

Dr Checchiaa researcher at INFN in Italysays: “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. The scale of the experiment means there is absolutely no margin for error. We have been using Araldite adhesives for many years because of the brand’s reliabilityexcellent resistance and bonding strength with 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 that Araldite 2011 demonstrates excellent shear and peel resistance at pressures up to 50mbar.”

Engineers at INFN have designed a piece of equipment to automatically mix and dispense Araldite2011 for the CMS project. The rig consists of a wide table and a mechanical arm moving in three directions and powered by a small computer controlled engine. After cleaning the surface of the aluminiumthe substrates are bonded and kept together using weights. Curing at room temperature is complete after 12hours. 

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