Science -- Your Future, Scotland's Future
PP4SS Exhibits
There are six main exhibits, listed briefly below (and also in more detail by clicking the menus above), which form the arc of our particle physics story. Each exhibit comes with worksheets and supplementary information.
Electrons and Magnets 1) We begin with a simple exhibit (using what is increasingly an old-fashioned piece of equipment!) showing the relationship between electricity and magnetism – and in particular the fact that a magnetic field can bend the path of charged particles such as electrons, which have been accelerated by electric fields.
The e/m Apparatus 2) Pupils then move on to apparatus which demonstrates the way in which magnetic fields can cause electrons to travel in a circle, letting them run their own ‘mini-accelerator’, and illustrating the principle of the larger CERN devices.
The LHC/LEP Accelerator Simulator 3) This leads directly to the next exhibit – a software simulation of the CERN LEP and LHC colliders – which allows the pupils to drive their own full-size accelerator: injecting particles into vacuum tubes; accelerating and guiding them with huge electric and magnetic fields to near light-speed and enormous energies; then smashing clusters of electrons and positrons (or protons and protons) together, generating temperatures and pressures similar to those at the beginning of the universe, and giving off sprays of exotic particles. And, just perhaps, they may discover the holy grail of particle physics: the Higgs Boson, which (we believe) gives all particles their mass, but which hasn’t yet been detected. (The particle is named after Professor Peter Higgs of the University of Edinburgh, a theoretical physicist who predicted its existence in 1964.)
The Cosmic Ray Hodoscope 4) The pupil experimenters then leave the world of artificially accelerated particles, and move on to four exhibits which demonstrate the fact that we are surrounded (and permeated) by particles from outer space: cosmic rays, and the shattered debris of their collisions. First is a cosmic ray hodoscope, which will show the paths of cosmic rays (highly energetic charged particles) as they flash through the apparatus, and us! An exhibit form of the hodoscope – the 'cosmic doorway' – brings home the fact that the particles flash through our bodies...
The Diffusion Cloud Chamber 5) The hodoscope above lets pupils 'see' particles for the first time, or at least to detect individual events (especially through the cosmic doorway...) Another way to bring home the physical nature of the particles is by using a cloud chamber, where the tracks of particles are made visible. We've constructed a diffusion cloud chamber which can easily and cheaply be built by schools (with a little dry ice, alcohol and a hot water bottle). See the web page for more information on its construction, and some photographs of various particle events.
The Muon Lifetime Experiment 6) The sixth exhibit is a more subtle form of particle detector, one which can not only detect a particular kind of decay product (particles called muons) from cosmic ray collisions in the upper atmosphere, but can be used to show – as Einstein predicted in his paper on Special Relativity – that time slows down for objects moving near the speed of light, and that we can detect muons at the surface of the Earth only because their clocks are running much more slowly than ours!
Particle Tracks 7) Finally, we look at some real particle tracks – in the form of bubble chamber photographs – which let pupils investigate the ways in which particles interact through collisions, or via particle creation and decay. These real images are augmented by worksheets which illustrate the main physical laws at work.