Strongest 'split magnet' built in the US By Katia Moskvitch

Technology reporter, BBC News Published duration 20 July 2011

image caption Scientists say that the magnet opens the door for many new discoveries

The world's most powerful "split magnet" - one that is made in two halves with holes in the middle to observe experiments - has been built in the US.

It operates at 25 tesla, which is equivalent to 500,000 times Earth's magnetic field.

Researchers at Florida State University said the magnet was 43% stronger than its predecessor.

It also has 1,500 times more space inside to carry out tests.

The device, which cost $2.5m (£1.5m) to build, will be used by researchers from a variety of different backgrounds, and could lead to breakthroughs in nanoscience.

When in use, it has to be cooled by pumping 2,500 gallons of water per minute through the centre.

The previous record was set in 1991, when French specialists built a 17.5 tesla split magnet. The system for measuring magnetic field is named after Serbian engineer Nikola Tesla.

Magnetism and access

Head of the National High Magnetic Field Laboratory at Florida State University, Dr Gregory Boebinger told BBC News that building the magnet had been a huge engineering challenge.

"The split magnet is essentially like two magnets brought close together, but kept a few centimetres apart to provide open pathways to the sample," said Dr Boebinger, and explained that by "the sample" he meant the material placed inside the magnet and studied by researchers.

"The spectacular engineering achievement with the magnet is the ability to maintain the very high magnetic field, without having the two halves slam together."

In the past, split magnets have had tiny holes for carrying out experiments in, according to Dr Jack Toth, another member of the Florida team.

image caption Researchers shine lasers through the magnet to measure how materials places react to the force.

Researchers have had to cram all their equipment - including probes, wires and temperature control systems - into a small tube of about a metre long and just 32mm in diameter.

But the new magnet has holes on four sides that are 6cm tall and 15cm wide - making it possible to shine a laser through a port onto the material inside and study, for example, how it scatters the light.

Improving products

Although the project, funded by the US National Science Foundation, is meant primarily for experiments that use optical measurements for materials research and physics, the team expects a number of chemistry and biochemistry experiments as well.

Dr Eric Palm, one of the researchers, said the combination of big ports and high magnetic field will help enhance the study of the electronic structure of materials.

"Discoveries made here will enable researchers to improve their materials and use them to make improved products such as solar cells or semiconductors for the next generation of computers," he said.

And the team has already conducted its first experiment.

The scientists studied how rapidly and in what direction light refracts off a new kind of liquid crystal consisting of long molecules that are bent in the middle.

"The magnetic field changes the orientation of the long molecules in the liquid crystal and the new split magnet offers the unique ability to shine the laser directly on the sample and to measure the light that is scattered in all directions," said Dr Boebinger.

"Already, the researchers think they might have seen a phase transition that does not exist in ordinary liquid crystals with long, straight molecules, but apparently does exist with long molecules that are bent in the middle."

His colleague Dr Jack Toth added that the magnet opens the door to new discoveries.