Difference between revisions of "How do we experiment with tiny particles?"
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Revision as of 10:26, 15 February 2008
How Do We Experiment with Tiny Particles
Basics
Accelerators
- what we talked about in class, speed particles up using magnetic fields to gain more energy
Getting Particles:
- electrons—heat metal
- protons—ionize hydrogen;
- antiparticles—have electrical particles hit fields, and then use magnets to separate positive and negative
Design
Type of Collision
- Fixed target
- Colliding beams
Shape
-
Linear
- Particles start at one end, ends at the other, field is due to electro-magnetic wave
- Advantage of linear accelerator is that it’s easier to build and less expensive; energy radiated away at high accelerations less for linear accelerators
-
Synchrotrons
- particles go in a circle, magnets used to make it go in a circle
- Advantage of circular that can produce high-energy particles without great lengths because particles go around several times, and there is a higher chance of collisions
Types of Experiments
-
Fixed-Target
- charged particle is accelerated by an electric field,collides with a target
- detector determines the charge, momentum, mass, etc. of the resulting particles
- example of this was Rutherford’s gold-foil experiment
- linear accelerators used either as injector to circular accelerator or as linear collider
- two beams of high-energy particles are made to cross each other
- advantage that both have significant kinetic energy, so collision will produce a higher-mass particle
- particles have short wave-lengths and make excellent probes
- synchrotrons used
Colliding-Beam
The Event
- Any of the collisions, between particle and fixed target or two particles
- Many of the particles produced have very short half-lives, decay into another particle quickly and leave no trace
Detectors
- In order to determine what was produced, the decay products are examined
- Decay products are determined by using multi-component detectors; Each component of a modern detector is used for measuring particle energies and momenta, and/or distinguishing different particle types
- Detectors are built in different ways depending on what kind of accelerator is used
