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From the particle adventure website:

    How Do We Know Any of This?

The Standard Model rises out of thousands of years of scientific inquiry, but most of the experiments that have given rise to our current conception of particle physics have occurred relatively recently.
In 1909, the prevailing theory of the atom's structure was that atoms were mushy, semi- permeable balls, with bits of charge strewn around them. This theory worked just fine for most experiments about the physical world.
BUT THEN Rutherford challenged this theory: shot up a stream of alpha particles at gold foil, allowing physicists to "look into" tiny particles they couldn't see with microscopes for the first time. These particles were expected to pass through the foil, but some of the alpha particles were deflected at large angles to the foil; some even hit the screen in front of the foil
Because some alpha particles were substantially deflected, Rutherford concluded that there must be something inside an atom for the alpha particles to bounce off of that is small, dense, and positively charged: the nucleus!!!!!!!!
Rutherford set the tone for further physics experiments, now they all have
-A beam (in this case, the alpha particles)
-A target (the gold atoms in the foil)
-A detector (the zinc sulfide screen)

    What Holds it Together? (parts 11-15)

The strong force between the quarks in one proton and the quarks in another proton is strong enough to overwhelm the repulsive electromagnetic force.This is called the residual strong interaction, and it is what "glues" the nucleus together.
But all the stable matter of the universe appears to be made of just the two least-massive quarks (up quark and down quark), the least-massive charged lepton (the electron), and the neutrinos.
-Weak interactions are responsible for the decay of massive quarks and leptons into lighter quarks and leptons.
-When fundamental particles decay, it is very strange: we observe the particle vanishing and being replaced by two or more different particles. (some of the original particle's mass is converted into kinetic energy)
-stable matter: made up of the smallest quarks and leptons, which cannot decay any further
-When a quark or lepton changes type (due to a weak interaction) it is said to change flavor.
-the carrier particles of the weak interactions are the W+, W-, and the Z particles. The W's are electrically charged and the Z is neutral.

    The Standard Model has united electromagnetic interactions and weak interactions into one unified interaction called electroweak.

Amanda

Particles

• wave functions with a probability of position in a given instant of time. (never know exactly where an electron is)
  

The Nucleus

• protons: positive electric charge (equal to absolute value of electron charge)
  
• neutrons: neutral electric charge, same mass as proton.
  

Quarks

• make up protons and neutrons
  

Two Kinds of Quarks

• Up quark
  
  • charge of +2/3
    
• Down quark
  
  • charge of -1/3
    
• Proton
  
  • 2 Up quark, 1 Down quark
    
• Neutron
  
  • 2 Down quark, 1 Up quark
    

Hadrons

• composite particles that consist of quarks
  
• ex. Protons, neutrons
  
• Baryons-consist of combination of 3 quarks
  
• Mesons-consist of combination of 1 quark and 1 antiquark
  
• Antibaryons-consist of combination of 3 antiquarks

Neeraj

Neutral particles do not leave a track, can create charged particles, when split (e.g. positron + electron split into separate positron and electron.) Charged particles leave a track as they travel, the particles charge and momenta can be calculated from the track. Bubble chamber filled with protons Other particles put in Accelerated and collide with protons -> new particles

David

Low energy

velocity appears to be completely transferred in an elastic collision.

Medium energy

Particles collide, the originally stationary particle goes upward while the originally moving particle travels downward, 2 small blue particles are also emitted directly in the direction of the original motion.

High energy

everything is the same as the medium energy collision except the blue particles are now larger and red.

All particles produced in collisions add up to the same charge. This law is known as the conservation of charge