Noah asks :"What is the speed of light?"
The speed of light is 3 x 10 8 (or 300 million) meters per second,
or over 186,000 miles per second (or 670 million miles per hour)!
Now, that's just a number, which is hard to get a feel for, so think
of it this way... if you flew in a commercial airliner from the earth
to the sun, and started out when you were born, you'd graduate from
high school about the same time you reached the sun! But if you traveled
at the speed of light, you'd be there in just over 8 minutes! Now
that's fast!
E.T asks : "Do you handle mercury?"
No, we do not use mercury in the Test Lab. Mercury is a hazardous
substance, and while it has numerous industrial uses, we do not utilize
it in any of our processes or activities. In general we try to reduce
the amounts and kinds of dangerous chemicals and substances that
we use in performing our work, and will substitute a less hazardous
material, even if it is more expensive, in order to reduce the risk
to our staff, the public, and the environment.
Liam Slinde asked : "What is the byproduct of the accelerator
beam and where does it stop?"
The accelerator beam interacts with targets in the experimental
halls. Few of the electrons in the beam actually "collide" with
nuclei in the target materials (and therefore "scatter" out
from the interaction point) - the remainder come to rest in a "beam
stop",
a large iron and concrete block, which absorbs the energy of the
electrons, and prevents them from escaping from the experimental
hall.
Tom Hilliard asks : "What is the over all objective of the
accelerator?"
Particle accelerators are used by physicists in much the same way
as biologists use a microscope - to look deep into the structure
of microscopic entities, and learn how they are put together and
function. A biologist uses a microscope to look at the structures
of cells and tissues, while a physicist uses an accelerator (which
provides a beam of high energy particles, instead of light) to "look"
at the structure of the nuclei of atoms. The CEBAF accelerator provides
an energetic beam of electrons that are used as probes to study the
constituents of the nuclei of atoms (protons and neutrons, and the
quarks of which they are composed). This is done by colliding them
with targets made of metal or liquid gases (such as helium or hydrogen).
By measuring the energies, momenta, and angles by which these incident
electrons are scattered, we can discover the mechanisms that bind
the quarks together in a proton or neutron. In this way we hope to
further our understanding of how matter behaves. To do this efficiently,
the accelerator must provide electrons at a certain energy (chosen
by the nuclear physics experimenters), and also provide enough of
them so that the physicists can get lots of data. The accelerator
must operate in a reliable fashion, with minimal downtime, so that
the experimenters don't waste their time here without any beam.
At Jefferson Lab, the CEBAF accelerator can continuously produce
a beam of electrons with energies up to almost 6 billion electron
volts, and runs for 24 hours a day, 7 days a week, for periods lasting
many months.
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