Questions and Answers

What is an accelerator?

Previous Question

(What is an accelerator?)

Questions and Answers Main Index

Next Question

(Where and how do you get your
electrons for your accelerator?)

Where and how do you get your<br>electrons for your accelerator?

Does an atom smasher really smash atoms?

Well, yes, they do, but we now prefer to call them by their less aggression-centered name, "particle harmony disrupters." Of course some atom smashers do much more smashing than others. We use electrons in our accelerator to study the nucleus of an atom. Remember that electrons are negative, as are the electrons surrounding the target. Since like charged particles repel each other, our particles have to have enough energy to blast through that electron cloud to get to the nucleus. The electrons then speed on toward the nucleus and usually miss. Yes, most of our electrons miss the nucleus. Remember, atoms are very small and nuclei are REALLY small. Enough electrons do hit the nucleus to make the studies useful, though. Usually the electron is deflected back out of the nucleus where we note its path with the particle detectors we've built. Occasionally the electron goes in and knocks out a proton or neutron. So you see, we do smash atoms.

A really funny thing about all these particle accelerators is the unit they use to describe the energy of the accelerator, the electron volt. That is the energy equivalent to the energy of an electron passing through one volt. The funny part occurs when the speed gets really high, like it does inside an atom smasher. We're talking high enough to be VERY VERY near the speed of light. At those speeds, adding energy to the particle does not make the particle go much faster, it just becomes more massive. You'll have to take my word on that one, it came from Einstein himself and is a little bit beyond what you will study in third grade science. When the particle is going REAL fast, most of its mass comes from its speed and very little of it comes from its rest mass (this is when the atom is not moving) that you almost ignore the rest mass. Here is the quirky part. If someone were to ask you how fast you are driving you could give the answer in pounds and the answer would still be correct!

Our accelerator runs at FOUR BILLION electron volts. Jefferson Lab is a nuclear physics laboratory. Now if you really want to talk about SMASHED atoms, you need to check out one of two high energy physics labs, Fermilab, in Batavia, Illinois (near Geneva Illinois) or its European Counterpart, CERN, near Geneva, Switzerland. Both of these labs use protons in their accelerators instead of electrons. These puppies really blow atoms to bits. You might have heard of Fermilab, where the top quark was discovered recently. To get it to work, they built an accelerator that ran two beams in opposite directions and then made them smack into each other. Each of the two beams operates at EIGHT HUNDRED BILLION electron volts, making the collision ONE THOUSAND SIX HUNDRED BILLION electron volts. They smash so hard that a whole pile of stuff comes flying out, some stuff that wasn't even there in the first place. Pretty mind boggling stuff, isn't it? I know my mind gets boggled thinking about it.

Author:

Brian Kross, Chief Detector Engineer (Other answers by Brian Kross)