CERN, the European laboratory for high energy physics that Italy funds through a direct grant and the scientific contribution of the National Institute for Nuclear Physics, has announced that while testing the new particle accelerating machine, the record temperature of minus 271 degrees centigrade (1,9 Kelvin) was reached. This temperature is comparable to the ones that are attained in outer space, the darkest and coldest part of the cosmos.
The record was reached in a test on LHC (Large Hadron Collider) the new particle accelerator that will begin to function between the end of this year and the first months of next year. It’s the biggest, most powerful and precise machine ever built by mankind, with its 27 kilometre circumference, a power 200.000 times greater that the earth’s magnetic field and the capacity of observing with a level of detail that was unthinkable until a few years ago the ephemeral life of particles born from the transformation into matter of the energy contained in accelerated proton beams colliding head-on.
The temperature of 271 degrees below zero is reached by the helium surrounding the magnets and it allows them to attain and to maintain superconducting properties, meaning they are able to make an electric current turn inside them without dispersion or resistance.
“It’s a great endeavour, for at last two reasons”, comments Pasquale Fabbricatore, superconductivity and cryogenics expert from the INFN division of Genoa, the scientist who contributed in designing some of the most imposing magnets in LHC.
“The first reason – continues Fabbricatore – is that at that temperature, helium behaves like a super-fluid, meaning a liquid with strange peculiarities, among which that it is completely free of viscosity. It can move without effort in any direction and it can even flow uphill. Such a low temperature can be reached by taking away pressure from the helium, on the basis of the same principle that makes the water boil at a lower temperature in the mountains than on flat land, where the pressure is greater”.
“The second reason – adds Fabbricatore – is that it’s the first time that such a low temperature is reached by a system of such large dimensions. Just think that in total, because of the cooling, the materials over the machine’s 27 km will contract by 9.9 metres, once it’s all finished. The cooling operation, indispensable in order for LHC to be able to bring its scientific mission to completion, will involve the use of 12 million litres of liquid nitrogen and of 700.000 litres of helium”.
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