Particle Physics

How can particles so small be studied?

Particle accelerators

How can mass and charge be observed in detectors? Notice in the following picture, some particles spin clockwise others spin counterclockwise. These are opposite charge. Recall R.H. Rule #3 !! Notice Some particles follow a path with a smaller radius, these are particles with lower mass. Remember centripetal force formula

Hadrons consist of matter which is composed of Quarks Two types of Hadrons are:

baryons- Contain three quarks Protons ( u,u,d) (+ 2/3, +2/3, -1/3 ) equal +1 Neutrons (u,d,d) ( + 2/3, - 1/3, -1/3 ) equal 0

mesons- Contain a quark and an anti-quark

www.cerncourier.com/.../42/9/ 19/1/cernparticles1_11-02 Variety of particles +,- and neutral

Quarks in proton, neutron

relative mass?

For each particle there is a corresponding anti-particle with a charge opposite that of its associated particle.

zebu.uoregon.edu/~imamura/ 203/may6/may6.html Pair of electrons (green) positrons (red)

Leptons Similar to electrons ( charge of negative 1) Other Types are more massive than electrons.

zebu.uoregon.edu/~imamura/ 203/may6/may6.html Pair of electrons (green) positrons (red)

What forces hold matter together? 1. Strong 2. Weak 3. Electromagnetic 4. Gravitational