How do we experiment with tiny particles?
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Contents
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
Electric field used to speed up particles, magnetic fields cause moving particles to turn!
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
During the Experiment
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
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