Revision as of 10:38, 27 February 2008

Use the space under your name to record your own work.

CERN Back to CERN mainpage

Melissa

Protons and neutrons are not fundamental because they are made up of things called quarks
Things that are fundamental cannot be broken down into smaller pieces
For every particle, there is a corresponding antiparticle or antimatter
When particles and antiparticles meet they annihilate into pure energy
Particles and antiparticles have opposite charges, the same mass, and are affected by gravity in the same way
Why is there so much more matter than antimatter in the universe?
There are 6 types of quarks: Up, down, charm, strange, top, bottom
Quarks have fractional electrical charge
Hadrons - composite particles of quarks : Baryons, any hadron made of three quarks; Mesons, contain one quark and one antiquark
Leptons - 6 types, 3 with a charge (electron, muon, tau), 3 without a charge (neutrino)
Heavy leptons, when they decay, always have one particle that decays into its corresponding neutrino
Muon and tau decay rapidly so are not normally found
Three electron families - each charged particle and another neutrino
Four fundamental interactions that cause all forces : Interactions include all forces that occur and also the decay and annhilation of particles
Forces are effects of force carrier particles on matter particles
A particular force carrier particle can only be absorbed or produced by a matter particle which is affected by that particular force
Electromagnetism : Photons - carrier particle of the electromagnetic force, zero mass, always travel at the speed of light in a vacuum
Residual electromagnetic force - allows atoms to bond together - charged parts of one atom interact with charged parts of other atoms

    Up and Down Quark Presentation Information 

Existence postulated by Murray Gell-Mann in 1964- named quarks after James Joyce's line "Three quarks for Muster Mark"
Discovered in 1980 by Maurice Jacob and Peter Lanshoff - shot high energy protons and electrons at a proton and many of these particles were deflected off of the proton at odd angles - showed existence of three solid objects within the proton
Up quark - lightest, charge of 2/3
Down quark - second lightest, charge of -1/3
Protons made of two up quarks and one down quark
Neutrons made of two down quarks and one up quark
ALICE - CERN project, attempt to place atom in an area with extremely high temperature to melt protons and neutrons to release quarks - hope to recreate gluon-quark plasma existent at the beginning of the universe

Brenden

1st Generation 4 Elementary Particles: up quark, down quark, electron, and neutrino.
Electrons and neutrinos are called leptons.

    For every particle there is an Anti-Particle.

Just look at this table:
Hadrons are composites particles made of quarks
Bayrons consist of a combination of 3 quarks
Mesons consist of 1 quark and 1 anti-quark

Anti-Bayrons consist of 3 anti-quarks

Emily

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.
the weak and electromagnetic forces have essentially equal strengths (the strength of the interaction depends strongly on both the mass of the force carrier and the distance of the interaction)
The difference between their observed strengths is due to the huge difference in mass between the W and Z particles, which are very massive, and the photon, which has no mass as far as we know.
BUT Standard Model cannot satisfactorily explain gravity (have only predicted gravity force carrier to exist but has not been found. they named it the graviton anyway.)
A summary of the different interactions, their force carrier particles, and what particles they act on (in quiz form) is on http://www.particleadventure.org/frameless/inter_summary.html Eventually they discovered that at very short distances (about 10-18 meters) the strength of the weak interaction is comparable to that of the electromagnetic. On the other hand, at thirty times that distance (3x10-17 m) the strength of the weak interaction is 1/10,000th than that of the electromagnetic interaction. At distances typical for quarks in a proton or neutron (10-15 m) the force is even tinier.

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

Bubble Chamber

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 determined by the momentum and magnetic field, the particles charge and momenta can be calculated from the track. Bubble chamber filled with protons, as other particles are put in and accelerated and collide with protons, they create new particles. The momentum can be calculated from P=.3rB, where r is the radius and B is the charge, where P is measured in gigavolts.

Kaon = group of 4 mesons

Lambda = one baryons with one up and one down quark

A Little Info about CERN: Mission

      Research: Seeking and finding answers to questions about the Universe 
      Technology: Advancing the frontiers of technology 
      Collaborating: Bringing nations together through science 
      Education: Training the scientists of tomorrow

Cool Facts

      Largest Physics Lab in World
      1957 built their first accelerator
      1971 Built first proton neutron collider
      1990 Tim Berners-Lee invents web
      2002 captured anti-hydrogen 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

Bubble Chamber

1. The tracks are all curved. 2. There is a difference in the amount of curvature per track. The differing curves are caused by the varying masses of the particles. 3. Particles that are neutral do not leave a track. 4. Particle losses energy as it travels through the chamber since forming bubbles takes energy. 5. A neutral particle decays into a positive and negative particle. 6. Particles of low mass have a low radius curve track. 7. Not much evidence for collisions.

Here's Cern: