Particle Accelerator
Written by John Carl Villanueva
Particle accelerators are devices that propel and accelerate particles, the usual purpose of which is to smash them into smaller pieces. As such, they are also known as atom smashers. A cathode ray tube like your old television set can be considered a particle accelerator since it accelerates electrons along the tube using an electric field. Needless to say though, the purpose is not to smash the electrons.
The reason why we would like to smash particles is because we would like to know what they are made of – much like smashing a cellphone or a watch to know what's inside. Of course, you won't be able to make a call or tell the time after the exercise, but we would be able to glean a lot of information regarding its insides that we wouldn't have seen from the outside.
Much of the discoveries made in particle physics were obtained with the use of particle accelerators. Even the earliest models of the atom were based on the observations from crude particle accelerators that used alpha particles coming from radioactive substances aimed at certain targets.
One good example of such a crude setup was that of Rutherford's which made use of alpha particles to bombard a sheet of gold foil. The resulting trajectories after collision later led to a clearer picture of the distribution of charged particles within the atom, i.e., that it had a very dense positively charged nucleus and that the negative charges were orbiting about this dense nucleus.
What scientists later on realized was that if they were somehow able to bring the projectiles (the particles that would hit the target) to even higher velocities and energies, they would be able to smash the targets into even smaller pieces. To achieve this, the projectiles, which are typically charged, are accelerated using a strong electric field.
The main idea before was that, the larger the electric fields, the greater the kinetic energies would be imparted on the projectiles. Hence, many of these type of accelerators made use of very large potential differences. But that was until scientists realized that, instead of using very large potential differences to give the particle a single large boost, it would be more efficient, not to mention safer, to use multiple smaller boosts instead.
Hence, the linear accelerator was born. It is typically made up of a series of drift tubes and gaps. An alternating polarity is used in the points joining the gaps and drift tubes to provide the needed boosts. Hence, the particle gradually gains kinetic energy as it receives them from these boosts. Linear accelerators were typically long. Later on, circular accelerators were introduced to provide a continuous acquisition of acceleration.
You can read more about particle accelerators here in Universe Today. Want to know how a natural particle accelerator dwarfs the power of the Large Hadron Collider? You may also want to read about how Fermi found a new class of super particle accelerator galaxies.
There's more about it at NASA and Physics World. Here are a couple of sources there:
Here are two episodes at Astronomy Cast that you might want to check out as well:
Filed under: Astronomy
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