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Synopsis¶

In this lab, we will look at radioactive material. There are a couple of warnings for this lab: - There are heavy metals involved; wash your hands after handling anything. - Don't eat the radioactive sources.

Radioactive decay occurs when unstable atoms of some element emit particle(s) and decay to something more stable. Customarily, there are three common types of radioactive emissions: - Alpha radiation: A helium-4 nucleus is emitted - Beta radiation: An electron or positron (anti-electron) is emitted - Gamma radiation: A high-energy photon (gamma ray) is emitted

In this lab, we will look at four radioactive sources: - Carbon-14: - Half-life: 5.7k years - Radiation type: $\beta$ - Energy: 0.16 MeV - Thallium-204: - Half-life: 3.8 years - Radiation type: $\beta$ - Energy: 0.77 MeV - Strontium-90: - Half-life: 29 years - Radiation type: $\beta$ - Energy: 0.55 MeV - Barium-133: - Half-life: 10.5 years - Radiation type: $\gamma$ - Energy: 0.52 MeV

We will measure to what extent the radiation from each source can pass through different types of material, considering four types of material: - Paper - Cardboard - Aluminum - Lead All the measurements in this lab will use a geiger counter.

Calibration¶

Measure the ambient radiation level in the room. Point the probe upward and measure the rate. The analog meter will generally give readings, but the ambient radiation level is low enough that the meter will not be very helpful. For this part, simply count the number of pings over a three minute period and divide by three to get the number of pings per minute. What do you get? - Give answer here Now, repeat the above, but point the probe downward. What do you get?

• Give answer here

Radiation vs. distance¶

Now, take an actually radioactive source (perhaps Sr-90). Measure the pings per minute five times, with the probe at five different distances from the radioactive source. Record the five rates below, along with the distances between the source and the probe (you can use the analog meter for this part; you may have to turn the knob to get an appropriate scale): - Give answer here How does the rate depend on the distance (like, what function does it follow)? Try to fit a curve to it, using your favorite program (you can technically do this here in the Jupyter notebook, but we've had issues in the past with this). - Give answer here

Radiation vs. energy and type¶

Measure the rate for each of the four radioactive sources. Record them below (note that this depends on the distance between the source and probe, so keep the distance fixed). - Give answer here Now, for each source, try placing either one sheet of paper, one sheet of cardboard, one sheet of aluminum, or one piece of lead between the source and the probe. Record the measurements below (there should be 16 new measurements, 1 for each combination of radioactive source + material). - Give answer here What is the reduction in rate for each material, for each source (there should be 16 numbers below, dividing the previous 16 numbers by the initial four numbers)? - Give answer here How do the numbers above (the rate reductions for each source+material combination) depend on the energy of the radioactive decay, e.g. does paper have a bigger impact for higher vs. lower energy radioactive emissions, does aluminum have a bigger impact for higher vs. lower energy, etc. (just comparing the $\beta$ decays)? How do the results compare for $\beta$ vs. $\gamma$ decay? - Give answer here How many sheets of paper are required to reduce the nominal rate for each material down to <10% of the nominal rate (like, stacking the sheets on top of each other)? There should be four results given here. - Give answer here How many sheets of aluminum are required to reduce the nominal rate for each material down to <10% of the nominal rate? There should be four results given. - Give answer here How do the above results depend on energy, for the $\beta$ emissions? How do they depend on $\gamma$ vs. $\beta$ decays?

• Give answer here