New technique to shrink particle accelerators (e.g. CERN)

High-energy particles can be used in cancer treatment, material analyses, and much more. But energizing the particles requires tunnels many kilometers long in which they are accelerated almost to the speed of light. A new technique developed by Olle Lundh aims to shrink the acceleration distance from kilometers to less than half a meter.

Olle Lundh

PhD in Atomic Physics

Wallenberg Academy Fellow 2014

Lund University

Research field:
Particle acceleration using high-power laser

Materials and reactions can be studied right down to atomic level by bombarding them with particles moving at close to the speed of light. The particles acquire their energy by being accelerated in an electric field, which at present must extend over several kilometers. The smaller the things studied, the more energy the particles need to have, and the longer the acceleration distance needs to be. At research facilities where particles are produced, such as CERN and MAX IV in Lund, the accelerators are getting bigger and bigger. The LHC accelerator, which was used to find the Higgs particle, is 27 kilometers long. A machine known as ILC, still in the planning stage, is intended to be about 40 kilometers long.

CERN eyes Lund technique

But a new technique being developed at Lund University makes the field ten thousand times stronger than that generated using current methods. It is all based on a high-power laser at the Department of Physics. Wallenberg Academy Fellow Olle Lundh and his colleagues are using it to bombard gases with a large amount of energy in a very short time. This causes the gas atoms to split up into ions and free electrons. The electric force between them is then so strong that it sends the electrons shooting off.

“It’s like a boat on water. When the laser pulse moves through the gas it pushes aside the light electrons, but they bounce back immediately like swell. The result is strong electric fields that accompany the laser pulse,” Dr. Lundh explains.

Since the field is ten thousand times stronger than those used in current particle accelerators, the required accelerator distance for the particles is one-thousandth as long. The accelerator can therefore be operated in a normal-sized room.

“I wouldn’t say we’re better than CERN, but… One of the future applications will definitely be at CERN – in the experiments in the field of particles physics being done there. But what we are doing is basic research; we don’t have any facilities ready for users,” Dr. Lundh says.

But researchers at CERN are already showing an interest, and Dr. Lundh has been down there to demonstrate the new technique. They are not far off being able to put the technique to practical use.

Research – a childhood dream

Even at middle school, he wanted to be a researcher.

“I remember that I borrowed books from the library at middle school that were for students beginning their university studies, even though I didn’t understand all that much of what was in them.”

First he wanted to be an astrophysicist, but at junior high he developed a growing interest in genetics and biology. At high school he was more interested in mathematics and programming, and began to write his own computer programs.

“Being named a Wallenberg Academy Fellow is an acknowledgement that I am on the right track, that other people think what I am doing is important. Naturally, the money also makes a big difference. The funding means that my research team can grow. We have good equipment, but we need more researchers in the team if we are to make full use of it.”

No-one else in his family is a natural scientist. Both his parents are researchers, but their field is history, and all Dr. Lundh’s siblings are involved with music in some way. He himself was a keen pianist in his youth, and after high school his choice lay between enrolling on a college music program and going to university. He chose the latter, and studied physical engineering. While he was working on his dissertation, he had the opportunity to try using a high-power laser.

“I thought it was cool. And it’s great that my research field is so broad. I started out in optics, but our work involves plasma physics, laser physics, particle physics, and there are also applications in the field of medical physics,” he explains.

Driven by a desire to be first

He has done some work with various types of radiotherapy, and has carried out experiments on skin cancer cells at a laboratory in Paris. X-rays are one area he will be pursuing as a Wallenberg Academy Fellow. He will also be improving the new technique by experimenting with different gas mixtures, different pressures in the gas chamber, and using several lasers at the same time.

“It takes a lot of time to make sure the laser has the highest performance. We have just spent six months on an upgrade, and we finally managed to double the power of the laser. The experiments are complex, and make great demands of the doctoral students operating the equipment. They need to have a thorough grasp of the physics as well as the theory, and also practical skills in handling both lasers and soldering irons. There are benefits to this approach, rather than employing technicians to run the practical side of things. This way, the researchers are fully aware of what they are doing the whole time. It’s not just about putting something in one end and seeing what comes out of the other,” Dr. Lundh says.

He likes supervising doctoral students, and collaborating with other researchers. And he also likes seeing things no-one has seen before.

“That is what drives me – being able to write ‘for the first time’ in a scientific article – that really gives me a buzz.”

Text Lisa Kirsebom
Translation Maxwell Arding
Photo Magnus Bergström