By Helen Briggs BBC News Online

UK scientists are to call for faster progress towards building a giant atom smasher.

The proposed �3bn machine will recreate conditions seen moments after the Big Bang.

We're literally looking for the origin of mass - where does the stuff from which we are all made actually come from?

Dr Philip Burrows, University of Oxford

It could help answer some of the fundamental questions of the Universe.

The huge physics experiment will smash together elementary particles in a 30-kilometre-long tunnel.

An international committee will report this summer on two competing technologies that could be used to build the machine.

The project has been on the drawing board for 10 years. It will need to be approved by ministers in Europe, Asia and the United States if it is to become a reality.

Dr Philip Burrows of the University of Oxford will tell the Physics Congress 2002 in Brighton, UK, on Tuesday that collaboration is needed to build a single world machine.

He told BBC News Online: "There's now agreement from the three regions - Europe, the US and Asia - in the particle physics communities that this should be the next project."

He said they were aiming for a political decision by 2005 and for the machine to be switched on in 2011.

Opposites attract

The giant particle accelerator, known as a linear collider, will smash together electrons and their anti-matter partners, positrons.

When particles and their anti-matter equivalents collide, they annihilate each other in a flash of energy. Other particles may form fleetingly in their wake.

Higgs boson

Proposed by British physicist Peter Higgs more than 30 years ago According to theory, the Higgs is related to a field through which all other subatomic particles must pass As they interact with the field, the particles experience a drag; the more drag, the more massive the particle

Physicists are hoping that the experiments will give an insight into the elusive Higgs boson, the particle that explains why everything mass.

A similar particle accelerator is already being built at the European physics lab Cern. Once it is up and running, it could shed light on the Higgs.

Cern's old machine was switched off last year amid reports that scientists were on the brink of finding something.

A US team at Fermilab in Chicago is also in the race to find the cherished particle.

But if the particle turns out to be relatively heavy, only a new generation of machines - like the one being proposed and the new Cern accelerator - stand a chance of finding the Higgs.

"We're literally looking for the origin of mass," Dr Burrows said. "Where does the stuff from which we are all made actually come from?"