Beta Decay PhET

Directions:

1. Click Here to run the PhET

2. Click on the tab "Single Atom" and hit pause if the sim is already running.

3. If the atom is not H-3 (tritium) click "Reset Nucleus" and then hit "Play"

4. Watch it Beta Decay.  The small blue dot that scampers away is the electron, and the tiny dot is in this case the anti electron neutrino.  The neutrino carries away a random amount of energy in the decay, so when we calculate the energy of decay from mass defect, not all of that energy becomes the KE of the Beta ray (electron).

5. Notice that the H-3 turns into He-3 as one of its Neutrons turns into a Proton in the process.

6. Now click the tab "Multiple Atoms".  Click the "Add 10" button until you have emptied the "Bucket O' Atoms" and click "Reset all Nuclei" and hit the play button if it is not already running.

7. Watch the graph at the top.  Notice the pie chart on the left, and that generally when the sim reaches the Half Life (vertical dotted red line) the pie chart show that half the nuclei have decayed.  There is significant random variation, however, with this few number of atoms, so it is not precise.  With 1023 atoms it would be precise.

Isn't that neat!