Beginners Guide to HEP
What is High Energy Physics?
`High Energy Physics' (HEP) or `Particle Physics'
searches for the
fundamental particles and forces
which build the world around us.
Like all matter is made from atoms,
all atoms are made from even smaller particles.
Physicist discovered that
similiar to the
`Periodic System of Atoms',
there is a
list of subatomic particles.
We create those particles
(which are not a normal part of matter we encounter everyday)
by using the famous `Einstein Law' that relates energy and matter:
E = m c**2.
Compared to natural processes on earth,
like the creation of a lightning
the energy released in a nuclear decay,
the energy per particle is many magnitudes higher.
That's why this field is called `High Energy Physics'.
Particles and Fields
Besides the basic particles
(called `fermions' after E. Fermi),
there are also the basic forces between them.
We now know four different forces
(sorted by their relative strengths):
the Gravitational Force (e.g. between Sun and Earth)
the Electromagnetic Force (e.g. between magnets)
the Weak Force (e.g. in nuclear decays)
the Strong Force (e.g. binding the nucleus of the atom)
One surprising result of the last 50 years of research was,
that you can describe those forces
with the exchange of particles.
For example the photon
is created in electromagnetic processes.
You also know it as normal light.
Those particles (called `bosons', honouring S.N. Bose)
can also be produced in current experiments.
Up to now gravitation can not be completely described in this way,
but the theorists are working hard to achieve this goal.
The Particle Zoo
A basic experimental fact in HEP is,
that every particle has a `mirror counterpart',
called the anti-particle.
(This was actually a prediction by P.A.M. Dirac,
who tried to discribe the behaviour of fundamental particles)
In some rare cases the particle is its own anti-particle.
The difference between particle and anti-particle is
a sign change in all `number-like' properties,
like the charge.
All others, like the mass, are unchanged.
For instance the anti-particle of the electron is called positron,
which has the same mass but the opposite charge.
These two particles are used at
CESR, at which
CLEO is located,
to create other particles with higher mass.
In a reaction of a particle and anti-particle
both are annihilated and all energy is
available to create new particles.
(Or to drive the future WARP engine of a star ship)
Experiments with Fundamental Particles
Since the fundamental particles are even smaller in size than atoms,
you can't see them directly, even with this very good microscope.
Physicists have therefore built very complicated detectors
to find those particles and measure their properties.
Some of them are taller than a three story building!
They all rely on the fact,
that after their production those particles will interact with
parts of the detector and leave typical `traces'.
In some special experiments you even can find `missing particles'
so that very elusive particles,
like the neutrino, can be found.
The CLEO detector
How do we do HEP with CLEO?
The OSU CLEO group
is doing experimental research with the CLEO detector.
You can find a more detailed description of this
detector on this WEB server.
If you want to know,
find particles at CLEO,
follow the pictures showing a reaction inside of the detector
Do it Yourself!
After reading this,
you should try to find them for yourself,
Take a look into HEPnet
There is a HEP information center,
which beams you directly into the HEP community!
High Energy Physics Information Center
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CLEO WEB PAGES
Updated: 27. July 1995
Author: Andreas H. Wolf (email@example.com)