A photofraction is the probability a crystal will interact with a photon. The total number of photons that interact at least once with a crystal sample is then plotted into a curve. The tangent to the curve is created and this tangent is the photofraction at that point. Generally, a device called a crystal scintillator is used to determine the probability of photofraction. This device basically emits light when it is excited by incoming particles.
- Crystal scintillator
- Thallium cylinder, 5-inch diameter
- Cesium iodide crystal sample
- Photomultiplier, 3-inch diameter
- Gamma ray energy
- Dark room
- Data chart
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Instructions
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1
Inside of a dark room, cover a cesium iodide crystal with the scintillator material.
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2
Place the covered crystal sample inside the thallium cylinder.
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3
Add high gamma ray energy to the cylinder.
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4
As the scintillator material begins to emit light, watch carefully with the photomultiplier.
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5
Run multiple trials -- at least three -- and record the results on a data chart.
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6
Plot a curve from the results. Find the tangent; this is the photofraction for this crystal sample.
