In the beginning . . .
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Probing the origins of the Universe By Virginia Heffernan
Late in 2009 scientists hope to recreate conditions nearer to the “Big Bang” than ever before achieved. The implications for our understanding of elemental physics are enormous . . . as are all the innovations that could flow from such understanding.
In their experiments, scientists and engineers will be depending on special nickel-containing grades of stainless steel to help keep the fast-moving particle beams from straying off course. Two high-alloy stainless steels supplied by ThyssenKrupp Nirosta GmbH of Krefeld, Germany, are able to withstand the extreme conditions that will occur in the 27-kilometre circular tunnel of the US$2-billion Large Hadron Collider (LHC), the world’s largest particle accelerator, as scientists seek to understand the origin of the universe.
The experiment will attempt to recreate conditions moments after the Big Bang by accelerating protons to a whisker below the speed of light in opposite directions in two separate vacuum pipes 100 metres beneath the Jura Mountains which straddle Switzerland and France. There are 4 separate areas where the protons can collide and the experiments can be closely observed by scientists.
Extreme operating conditions About 500 magnets fabricated using 860 tons of Nirosta® 4375 (EN No.1.4375), a manganese-containing austenitic stainless steel will produce fields to accelerate and guide the particles. This alloy can withstand the near absolute zero (minus 271º Celsius) temperatures and the strong forces within the magnet coil, while its low magnetic permeability ensures the steel itself does not become magnetized.
“This special high quality material was essential for the smooth production and outstanding properties of the magnets,” says Detlef Krischel, senior manager of ACCEL Instruments, responsible for the magnets.
Stainless steel is also a crucial component of the pipes that carry liquid helium to cool the magnets. To develop magnetic fields high enough to accelerate the particles to close to the speed of light, the magnet coils must be cooled to near absolute zero so that they can become superconducting and transfer almost all of their energy into magnetic fields. The distribution system of pipes that runs parallel to the magnets and supplies them with helium is made of EN No.1.4307, a chromium-nickel stainless steel similar to 304L (S30403) that also does not embrittle at these extremely low temperatures. Approximately 450 tons of the material were needed for the 120 kilometres of pipe.
Although the European Organization for Nuclear Research was forced to halt the project in September, 2008, because of a faulty electrical connection between segments of the LHC’s superconducting cable, it is scheduled to resume in late September 2009 and make the first collision experiments in late October.
Pure science, innovation and nickel The LHC is already an engineering triumph notwithstanding the start-up problem. Moreover, the insights gained from it will influence technologies and human ambitions for decades, indeed generations. It is appropriate that nickel – that is, part of the nickel formed at the nano-instant after the Big Bang – is essential to its success.
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