Tuesday, 20 May 2014

Physicists Propose Breakthrough Experiment to Test Breit-Wheeler Theory



     Physicists from Imperial college London have devised a simple yet ingenious experiment to finally verify the Breit-Wheeler pair production theory. This theory has been around for nearly a century, scientists have assumed its truth but as with all theories they must ultimately survive experiment. The Breit-wheeler theory proposes that if two highly energetic photons (particles of light) collide they can produce an electron- positron pair. This pair production is one of the simplest ways in which the universe can convert light into matter, thus it carries importance in tackling problems of how matter actually came about during the early universe.

     The experiment consists of two important parts. Firstly electrons are accelerated to near light speed and focused into beams using high energy lasers, these beams then become incident on a gold target which allows the electrons to pass through but they become deflected. When a particle becomes deflected it loses some kinetic energy, this loss of energy, in the case of electrons, turns to high energy gamma rays which are extremely high energy photons.

    These photons then travel through the Hohlraum, which has been made into a thermal radiation field through the firing of high energy lasers on the gold cans surface creating photons similar to that of stars, the photons from the first part then collide with the photons created from the radiation field. This collision will then produce electron - positron pairs which can then be detected using simple electromagnet equipment.

   The ingenuity of this experiment is the use of the thermal radiation field which is used in plasma physics, the team at Imperial realized that the hohlraum could be used in creating a photon - photon collision. Now a race to build and carry out this experiment is on. A nobel prize surely awaits the theorists and experimenters.


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