# Q & A: How do particle accelerators work?

Q:
How scientists are "shooting" beams of electrons, protons and neutrons? How can they shoot one of them (one particle) at the time? What happen to the atoms that lose those particles? What will happen if i had a hand gun who can shoot a beam of particles and i will shoot at something?Thank you!
- Hagay Avivi (age 25)
Afula, Israel
A:

Hi Hagay,

The source of particles depends on the particle being used. Here are some previous Ask the Van answers about how to make  and . Electron beams can be made by using either heat or light to give the electrons enough energy to escape their atoms and then capturing them with a strong electric field. Neutron beams are formed by blasting atomic nuclei with protons.

To control the path of the particles once they're formed, accelerators use electric and magnetic fields. (This excludes neutrons, since they don't have an electric charge and are therefore harder to control.) Depending on the type of accelerator, the particles either travel in a straight line or in a loop. Because the novel physics happens at high energies, the particles are accelerated to high speeds so that they have high kinetic energy. This is also done with electric and magnetic fields; the fields are designed to pull the particles along in a similar way that gravity pulls a car downhill and increases its speed.

Particles aren't shot one at a time through accelerators. It would be impossible to do experiments that way, because the particles are so tiny its hard to aim them directly at each other. More often than not, they miss and never interact. To get around this problem, many particles are bunched together into beams. Sometimes the beams are shot at one another (as they are in the Large Hadron Collider), or sometimes at a target (as when they're used in linear accelerators or in medical devices) . The beams are made as small as possible, so that the particles are bunched closely together, increasing the probability that there will be some collisions.

A hand gun particle-shooter could be awesome or terrible for anyone close it when it's fired, depending on how you use it. Accelerating particles release electromagnetic radiation. When the particles are accelerated a large amount, they release high energy radiation such as X-rays. If that radiation wasn't contained, it would damage anyone it hit. The particles themselves also damage tissue by transferring their energy to the molecules in cells. However, there are medical therapies which are essentially hand gun particle-shooters. The sources of X-rays for diagnotics and cancer treatments are just a tube through which electrons are accelerated. Proton and neutron beams are also used for cancer treatment, because the energy they release is more localized and therefore healthy cells can be spared.