Radioactivity

Physics:	Radioactivity
Grade Range:	Middle School, High School
Format:	Hands-on

This demonstration allows students to learn what a radioactive material can look like, and is a good way to introduce radioactivity in a non-threatening way. All materials for this demonstration are safe for students to handle, and give students and their parents a chance to see how we detect radiation.

Materials

• SOEKS Dosimeter
• Geiger Counter
• Uranium sample
• Fiestaware plate sample
• Trinitite sample

Safety Precautions

• This demonstration utilizes a Dosimeter, which needs to be carefully taken care of. Remove the batteries from it when it is no longer in use to preserve battery life. It is a sensitive piece of equipment, so never drop it or you may disrupt the equipment inside. If you notice that the batteries are low, be sure to plug the device in when you return to the planetarium, and allow it to charge overnight. Do not leave it plugged in for more than 24 hours.
• This demonstration uses radioactive materials. Be careful not to let small children put anything from this demonstration in their mouths. Make sure that students know to wash their hands after this demonstration if they handled any of the samples.
• Do not let anyone keep any of the radioactive samples. The pieces are safe to hold and examine, but be sure to have all pieces returned to you before the end of the demonstration.
• The plate gives off Beta-decay and Alpha-decay at moderate levels, so it should be kept in the plastic basin until needed during the presentation. The Uranium ore sample gives off Beta-decay and Alpha-decay as well, but at much lower levels, and can be kept out of the bin during the performance. The Trinitite gives off Alpha-decay. All the samples are safe to handle.
• All Science Theatre Officers who will be using this demonstration should go through the EHS Radiation Safety Refresher Training. Officers and volunteers are not required to go through this training, but officers are strongly encouraged to do so. Officers are required to instruct volunteers on safe handling of radioactive samples, the Dosimeter, and proper presentation of this demonstration.

Demonstration

1. Show the pieces of Fiestaware to the students. Allow them to hold the pieces and look at them, and explain that the pieces are glow-in-the-dark due to the paint on them. Then, explain that unlike all the modern glow-in-the-dark things we have, this paint glows because it was made with radioactive materials.
2. Using the Dosimeter, show the students that the pieces of plate give off a strong reading. Explain to them the three types of radiation, and the two that the plate gives off.
3. Show them the Uranium sample and the trinitite sample. If they wish, let them hold the samples and explain what types of radiation they give off.
4. Show the Geiger Counter, and explain how it would detect particles using the "wand", and how that same technology is in the Dosimeter. You can also point out the small radioactive sample that is on the front of the Geiger Counter, which would be used to calibrate the detector.
5. Explain to the students that they interact with several radioactive materials all the time in their everyday activities. List off things such as:
   1. Concrete (Alpha-decay)
   2. Sunlight (Gamma-decay)
   3. Banana's (fun fact: "one banana" is actually a measure used in Nuclear Physics, and is equal to one microSeivert.
   4. The air (Main source of background radiation)
6. Let students know that we are radioactive as well! Have them hold out an arm, and if you hold the Dosimeter against it you can get faint readings.

Why This Works

When we say that something is Radioactive, we are saying that it is giving off high energy particles. The type of particle and how much energy it has let us know how the material is decaying. If something is giving off Alpha-decay, that means it is losing protons, and releasing elemental Helium. This type of decay has pretty low energy, and the released Helium atom is easily blocked by thin walls like plastic, paper or our skin. If something is giving off Beta-decay, then that means that one of the Neutrons decays into a Proton, which sends an electron flying. This type of decay has more energy to it, but can still be blocked by thicker barriers. If something is giving off Gamma-decay, then that means the atom is releasing energy by launching high energy photons. This type of radiation is good for us in small doses, but in large doses can be very dangerous. Also, this type of radiation is very hard to block, requiring thick walls to shield from it.

The Fiestaware pieces are releasing Alpha and Beta radiation, so that means the atoms in the paint are releasing some protons and some electrons with high energy. The Uranium sample is also releasing Alpha and Beta radiation, but we can see that it is giving off much lower levels. The Trinitite, which is sand that was fused by the Trinity Bomb test, gives off alpha radiation, most of which is blocked by the plastic packaging on it. The sample on the front of the old Geiger counter gives off Alpha, Beta and Gamma radiation; however, it is not dangerous to be around. The sample was carefully selected so to be used for calibrating the counter, so it gives off very low doses of Gamma radiation.

There are all kinds of everyday things that are radioactive. This is important to note, so that students and parents can learn about the safe and helpful side of radioactivity. Some of the more common radioactive sources around us are:

• Concrete, which gives off alpha decay, and is good at absorbing beta and gamma radiation.
• Bananas, or more specifically potassium. Potassium gives off beta decay, which our bodies can actually use!
• Sunlight, which contains gamma radiation in the form of UV rays. This is why you should wear sunblock if you plan to be in the sun for extended periods of time, because a sunburn is a type of radiation burn! However, don't be afraid to be in the sunlight, because our bodies need it to produce vitamin D.
• Our bones, which give off beta decay! Our bodies store small amounts of carbon-13 in our bones. Carbon-13 is an Isotope of carbon, meaning that it has a different number of neutrons than carbon typically does (7 instead of 6). It has a half-life of about 5000 years, but it still decays slowly within our bones, and can be picked up on by a geiger counter!

Additional Information

• An important thing to note: Smart phones are NOT radioactive. This misconception that our phones are radioactive comes from our phones working via electromagnetic radiation. the frequencies that our technology operates on is not the same, and you can prove this by simply placing the Dosimeter on your phone during a presentation.
• This demonstration is a part of the Nuclear Physics Show