High Energy Physics: Public Information, Page 1

If you’ve ever wondered what goes on in the micro-world or the subatomic level, you’ve come to the right place. Welcome to the (KU) University of Kansas Department of Physics and Astronomy. (Yes, land of the Jayhawks) Our Experimental High Energy Group will guide our journey through the world on its smallest scale, even smaller than the atom. Don’t let words like "high energy theory" scare you. We’ll explain everything. And feel free to ask questions. That’s what science is all about. Our group is supported by the National Science Foundation.

Let’s begin our journey with the major players-- particles.

Particles are what the High Energy Groups study. By the way, high energy physics is also known as particles physics and it is the study of matter and forces at the smallest distance scale. (There are 4 forces and we’ll address them later.) The term, "high energy" is used because much of particle physics is based on experiments requiring high-energy beams.

At one time, we thought the atom was the smallest component of matter. It was early in this century that we discovered that the atom could be divided into even smaller pieces-- the nucleus, which is the center core of an atom that contains most of its mass, and surrounding electrons, which are particles with a negative charge. Later, the nucleus, in turn, was found to be made of smaller pieces-- the neutron, a particle which has no charge and the proton, a particle with a positive charge.

Wait, we ‘re not finished! Both the neutron and proton consist of three smaller particles called quarks. These quarks are held together by other particles called gluons because they "glue" the proton or neutron together. They also glue the proton and neutron to each other to form the nucleus. This finally brings us to our current picture of the world which is: Everything is made of 12 elementary particles-- 6 quarks and 6 leptons (A familiar example of a lepton is the electron.)

In 1995, the last of these quarks, called the "top" quark was discovered at a place called Fermilab, located in Batavia, Illinois. The Top quark was found in a particle accelerator. (A particle accelerator is an apparatus designed to increase energies of charged particles used for research.) The 12 particles interact with each other by the forces which we promised to address. There are 4 forces and they are:

1. Electromagnetic force- It is responsible for the forces that control atomic structure, chemical reactions and all electromagnetic phenomena.

2. Weak force- It is responsible for beta decay of particles and nuclei. Beta decay occurs when an unstable atomic nucleus changes into a nucleus of the same mass number but different proton numbers.

3. Strong force- It gives the atomic nucleus its great stability.

4. Gravity- It is the weakest of all of the forces and acts between all bodies with mass. It is always attractive. Gravity is probably the most familiar force yet, we know so little about it, especially at the smallest scale.

We have not even come near the end of our journey, click here if you wish to continue on to the next page in our public information site. There you will learn about messenger particles and antimatter.

Our KU High Energy Theory Group and Experimental Group continue to work in many areas of particle physics, including the "electroweak force" and particles called neutrinos. We will discuss these among other exciting research subjects. Science is dynamic. We are always on a quest for knowledge and application. So, join us. We invite your questions. Many graduate as well as undergraduate students have had research opportunities with our group. You are welcome to participate. Click here for information about the people who do science at KU .

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Text by Chandra Graves

Last Updated: November 9, 2009

baringer@ku.edu