1. ALARA - you will be using a radioactive material and you must treat it with care.
2. Dry ice is -8oC and can "burn" you hands...be careful.

What to do:

1. The person who is to handle the radioactive material should put on nitrile gloves.
2. With a dropper, put some ethanol on the felt that is around the rim. Do your best to try and not drop the liquid on the floor of the chamber.
3. Flip he chamber over and remove the blue cap and sponge inside. Add a 0.5cm layer of dry ice pellets in the bottom of the chamber. Replace the sponge and CAREFULLY put the blue cap back on.
4. Flip over the cloud chamber and pull the cork out of the one side. In its place carefully slide in the radioactive sample of Ra-226.
5. Replace the plastic cap and turn on the light (switch your console to A, and turn the dial up to 4). Bring up the light so it is shining parallel to the radioactive sample in the clod chamber.
6. Look down on the chamber and you should see cloud 'tracks' of alpha and beta particles.

Experiments:

You should see two types of tracks - some that are extremely thick, and smaller, narrower ones as well. Once you see these, call your teacher over so he can apply a magnetic field to the sample. Make sure that you note any difference that you see in the tracks when the magnetic field is applied.

When done, carefully remove the radioactive sample and place it in the bag that accompanied the cloud chamber. Make sure that you replace the stopper in the hole. Flip over the chamber and CAREFULLY remove the blue cap and the sponge. Pour the remaining dry ice in the container that is at the back of the class. Leave the remaining apparatus on the desk as you found it.

Homework:

1. a) While Ra-226 is a 100% alpha emitter, you also see tracks that are consistent with Beta
       radiation. How is this possible? Why do the particles generally "deflect" from one another?
   b) Explain why there is a difference in the size (thickness, movement, distance travelled etc.) of the tracks
        between alpha and beta radiation.
2. What happened when the magnetic field was applied? Offer an explanation as to why this occurred.
3. In a short paragraph, explain how the cloud chamber works (i.e. allows the production of tracks mapping the movement of radioactive particles).

Schematic of Chamber

Tracks in our Cloud Chamber

What to hand in:

Answers to the questions. Send to www.turnitin.com as instructed in class.