Strips of lime green scintillator separate thin layers
of lead in the electromagnetic calorimeter,
at the base of every calorimeter wedge.
When we say an idea is "scintillating," we mean, metaphorically, that
it sparkles; the word comes from
scintillare—Latin for "to sparkle."
The term as it is used in the CDF experiment applies to a kind of plastic that emits light in response
to the passage of a charged particle.
Plastic scintillator plays a part in many different parts of the detector.
Most of it needs some way to guide the scintillation light to electronics that convert it to a more easily
measured electric current. One way to get the light to the electronics is to use a plastic light guide like the
one featured in the video below. Made of non-scintillating, very clear plastic, light guides "bend"
scintillation light around the corners of the detector so it can be read out by the electronics.
This plastic light guide has been wrapped with reflective foil so that no light can enter or escape except
through the ends. The light travels through the plastic, bouncing off the interior walls of the
foil until it reaches the end.
If you cover the light coming in from one end with your hand, the other end of the light guide will
go dark. As soon as you remove your hand and the light is allowed to enter the plastic,
the ends of the light guide light up again.
Watch the video
This calorimeter uses scintillator
to carry information about the energy of particles that have passed through that part of the detector.
The information is guided along the scintillator and light guides
as light. To measure and record the amount of light,
scientists hook the scintillators up to photomultiplier tubes (PMTs), which convert the light to
an electrical signal that can be more easily measured and recorded.