Adam Para
Tracking Particles I
Charged particle traversing the
scintillator (plastic) produces light
impulses (blue)
Light ray bounces inside the
scintillator reflected by the white
coating
Until it hits the fiber (shown as
green circle) in the middle. There…
Adam Para
Tracking Particles II
Blue photons are absorbed by a
waveshifting dye inside a fiber and
green photons are emitted. (Some
of) Green photons are trapped inside
the fiber. Fiber guides the green
light to the photodetector.
A stack of scintillators
with waveshifting
fibers. A pattern of
‘hit’ fibers reveals a
trajectory of a
particle.
Adam Para
Test and Homework (Boothwork?)
• Test
Q: What color us the green fiber?
A: It depends! It appears green because it
converts blue light entering it and emits green
light. If there was no blue light (like inside a
yellow filter box) the fiber would appear
colorless.
• Homework
We do not want to operate particle sources here to
produce light inside the scintillator. But an UV lamp
will do as well. Go to the QuarkNet stand and
illuminate the scintillator with the lamp. Look at the
green light collected b the fiber. Notice that you
can use the fiber ‘to bring’ the green like to a place
of your choice.