R744 cooling helps study the Big Bang

Two experiments set up to explore two opposing scientific theories of what happened to the antimatter right after the Big Bang are both relying on CO₂ as the cooling fluid. In the first of the particle physics studies, the Alpha Magnetic Spectrometer experiment (AMS) on board the ISS will investigate the remains of the Big Bang in space. The second experiment is simulating a mini Big Bang in the newly constructed Large Hadron Collider (LHC) at CERN in Switzerland. Both experiments will be using a CO₂ cooling system able to withstand large doses of radiation, while also allowing for the use of small cooling tubes in the detector.

Finding a reliable high-pressure heat exchanger for the experiments proved to be one of the most difficult items in the development of the CERN VELO cooling system. The decision was made in favour of Swedish heat exchanger expert SWEP who supplied its double-wall high-pressure model to the tests. The double wall design as well as the small wave patterns ensured reliable operation at pressures of 170 bar.

R744 reduces the mass in detectors

For the detector applications used in both experiments minimal hardware needed for the cooling inside the detectors as well as a completely maintenance-free system were key requirements. By using smaller tubing, the selected CO₂ systems proved to be not only a cost-competitive, but also efficient solution reducing the disturbance of the particle track measurements.

As a result, both physics experiments are applying the same technologies in CO₂ cooling. However, the CO₂ system of the ISS experiment uses the cold of outer space to reject the waste heat of the experiment via radiator panels, while the CO₂ system in the CERN experiment rejects the heat towards a commercial HFC-chiller.

The CO₂ cooling system for CERN is now operating 100 metres underground in the Large Hadron Collider (LHC) tunnel and the detector has already measured particle interactions from the LHC tests since September 2008. The CO₂ cooling system for the International Space Station was installed at the beginning of this year and the launch of the satellite for the AMS experiment is planned for 2010.

European Organization for Nuclear Research (CERN)

CERN (Conseil Européen pour la Recherche Nucléaire) is one of the main centres for scientific research worldwide. Its work concentrates on the fundamentals of physics and studies the basic constituents of matter - the fundamental particles - by using the most complex scientific tools currently available. The instruments applied in particular are particle accelerators and detectors. The accelerators are used to boost beams of particles to high energies before they are made to collide with each other or with stationary targets. The detectors’ task is to monitor and to record the outcome of the particles’ collisions.