1. 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…

2. 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.

3. 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.