Cockroft & Walton Experiment


Pair Production

Pair Annihilation

Particle Accelerators

Four Fundamental Forces

Familes of Particles

Quark Model

Fun Stuff!





Particle Accelerators

Converting Energy into Matter

In particle accelerators such as that of Cockroft and Walton, the energy of the incident protons is quite small. It disrupts the nucleus with which it collides, and some mass is converted into energy as the kinteic energy of the products.

When particles of much higher energies collide, it is found that some of this extra energy is itself converted into matter in the form of new particles. Thus energy is being converted into matter.


CERN accelerators

CERN, Switzerland



What are Particle Accelerators?

Beginning in about 1945, improved circular particle accelerators were made. In them, magnetic fields were used to confine and control the position of the particle beams. Electric fields are used repeatedly for accelerating purposes.

Scientists then discovered that by accelerating known particles, such as protons, to very high speed and causing them to collide with other protons, many new particles were produced.

These particles were almost always very unstable with incredibly small half-lives. Over 400 unstable temporary particles have been found.

The aerial photograph above is of the accelerator centre in CERN in Switzerland. The smaller accelerator has a circumference of 7 km, the larger one 27 km. The tunnels for both accelerators are underground.


P + P + energy = P + P + additional particles
The higher the energy made available by better particle accelerators, the greater the mass and variety of the additional particle produced.