Particle accelerators Flashcards
What is a linear accelerator?How does it work?
- A linear accelerator is a long straight tube containing a series of electrodes.- Alternating current is applied to the electrodes so that their charge continuously changes between + and – The alternating current is timed so that the particles are always attracted to the next electrode in the accelerator and repelled from the previous one.- A particle’s speed will increase each time it passes an electrode - so if the accelerator is long enough particles can be made to approach the speed of light.- The high-energy particles leaving a linear accelerator collide with a fixed target at the end of the tube.
What is a cyclotron?How does it work?
- A cyclotron uses two semicircular electrodes to accelerate protons or other charged particles across a gap.- An alternating potential difference is applied between the electrodes-as the particles are attracted from one side to the other their energy increases.- A magnetic field is used to keep the particles moving in a circular motion.- The combination of the electric and magnetic fields makes the particles spiral outwards as their energy increases.
What are synchrotrons?How do they work?
A synchrotron can produce particle collisions with much higher energies than either a linear accelerator or a cyclotron.- Electromagnets keep the particles moving in a circular path in focused beams.- In this way, synchrotrons can produce particles with energies reaching from 500GeV to several TeV.
How does special relativity affect particle accelerators?
- Special relativity is where the idea that energy is equivalent to mass comes from. It means that the more you increases the kinetic energy of a mass, the more massive it gets. This happens to any object with kinetic energy, but it’s only noticeable at speed approaching c.- Particle accelerators have to alter their magnetic and electric fields to compensate for the relativistic mass of the accelerating particles.
What is the relativistic factor?
The relativistic factor is the total energy of a particle divided by the rest energy of the particle. For particles travelling at low speeds (v<<c), the r-factor will be very close to 1.Gamma = Etot/ErestErest = mc^2