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Big Bang at the atomic lab after
scientists get their maths wrong
Jonathan Leake
London
Times
Monday April 9, 2007
A £2 billion project to answer some of the biggest mysteries
of the universe has been delayed by months after scientists building
it made basic errors in their mathematical calculations.
The mistakes led to an explosion deep in the tunnel at the Cern
particle accelerator complex near Geneva in Switzerland. It lifted
a 20-ton magnet off its mountings, filling a tunnel with helium
gas and forcing an evacuation.
It means that 24 magnets located all around the 17-mile circular
accelerator must now be stripped down and repaired or upgraded.
The failure is a huge embarrassment for Fermilab, the American national
physics laboratory that built the magnets and the anchor system
that secured them to the machine.
It appears Fermilab made elementary mistakes in the design of the
magnets and their anchors that made them insecure once the system
was operational.
Last week an apparently furious and embarrassed Pier Oddone, director
of Fermilab, wrote to his staff saying they had caused “a
pratfall on the world stage”. He said: “We are dumb-founded
that we missed some very simple balance of forces. Not only was
it missed in the engineering design but also in the four engineering
reviews carried out between 1998 and 2002 before launching the construction
of the magnets.”
The machine, the Large Hadron Collider (LHC), aims to recreate
the conditions of the Big Bang, when the universe is thought to
have exploded into existence about 14 billion years ago. However,
the November start-up may now have to be delayed until next spring.
Dr Lyn Evans, who leads the accelerator construction project at
Cern, the European organisation for nuclear research, said the explosion
had been potentially very dangerous.
“There was a hell of a bang, the tunnel housing the machine
filled with helium and dust and we had to call in the fire brigade
to evacuate the place,” he said. “The people working
on the test were frightened to death but they were all in a safe
place so no-one was hurt.” An investigation by Cern researchers
found “fundamental” flaws that caused the explosion,
close to the CMS detector, one of the LHC’s most important
experiments.
The accelerator is designed to smash together protons, a kind of
sub-atomic particle, at near light speed. The hope is that such
collisions will generate exotic new particles — especially
the so-called Higgs boson which, theorists predict, could help explain
key properties of matter, such as how it acquires mass and, hence,
weight.
The LHC itself comprises two pipes, each containing a beam of protons
travelling at near-light speed that are steered around the circular
tunnel by powerful magnets. Such magnets are “superconducting”
meaning they and the whole LHC are cooled to below -268C, using
pipes filled with liquid helium.
The two proton beams travel in opposite directions but, at various
points around the ring, their pipes merge, allowing the protons
in each beam to collide.
However, since the thickness of each beam is less than that of
a human hair, they have to be focused. This is the task of a second
set of magnets, and it is these that were under test at the time
of the explosion.
Coincidentally, Fermilab stands to gain most from delays at Cern.
Its researchers also operate a rival but less powerful particle
accelerator, the Tevatron.
Fermilab staff are pushing the Tevatron to ever-higher energies
hoping that they might find the Higgs boson before the LHC switches
on. An LHC researcher said: “Ironically, this delay could
be all they need.”
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