World`s most powerful laser used as atom smasher

Physicists at Glasgow University are using the world`s most powerful laser beam as an atom smasher to simulate conditions inside the Sun and to produce radioisotopes vital in medicine. Professor Ken Ledingham from the Department of Physics at Glasgow and his colleagues from Imperial College and the Rutherford Appleton Laboratory (RAL) are using the world`s most intense laser beam, produced by the VULCAN laser at the RAL near Oxford, to initiate nuclear reactions for a variety of exciting applications in science and medicine.

At the Nuclear and Particle Physics Conference, part of the Institute of Physics Congress, Professor Ledingham will today discuss the latest results of his research using a high intensity, but short pulse laser as an alternative to the more traditional large nuclear accelerators. The VULCAN Petawatt laser, can achieve a power of a thousand million million Watts – the equivalent power of a ten million million 100W light bulbs – during short pulses of tiny fractions of a second. In this way a large amount of energy can be delivered in a very short time.

One of the many applications of such laser atom smashers is in medicine. They can produce the beams used in proton oncology – cancer treatment using irradiation by protons – and the radioisotopes used for positron emission tomography (PET) scanners to map the human brain and other organs to diagnose a whole host of problems that do not show up on an X-ray.

When a very intense laser beam is focussed and directed at a solid, it causes high energy electrons to be released in an area less than a hair`s thickness across. These electrons then cause further nuclear reactions as they hit other atoms. Ledingham says: “We are at present carrying out nuclear reactions in micron-sized laser accelerators similar to those I did thirty years ago when I used a 100 metre long accelerator.”

With the present VULCAN arrangement they can produce nuclear fission reactions similar to those inside large nuclear reactors, as well as producing beams of protons, electrons and neutrons. In addition the lasers have generated magnetic fields a factor of ten more than have ever been measured in the lab.
Plans are already in place to develop lasers a further one hundred times more powerful. These would produce conditions similar to those inside the Sun and other stars, but on a tabletop.

This is not as scary as it might sound though, as all the energy is focussed onto a very tiny area of some material – smaller than can be seen with the naked eye. It is this tiny area that feels the full force of the laser beam whereas inside the sun, these conditions happen on a huge scale.

“When these lasers are coupled together or with conventional accelerators then unprecedented energies can be reached,” said Professor Ledingham.