00:01
All right, so problem number 48, we're looking at particle annihilation and the amount of energy created.
00:06
So part a, so for part a, it wants to know how much energy is released from an electron and a positron annihilate.
00:15
So based on the question, we have to assume that they're both at rest or basically or very, very close to being at rest, very low energy, so enough to not to basically be neglected the kinetic energy.
00:28
So the amount of energy created is just going to be two times the rest mass energy of an electron.
00:40
Because an electron and an antideotron, an electron and a positron, they are the same mass.
00:47
So that's just going to be equal to 2 times 0 .511 m .ev.
00:53
Which is going to be equal to one.
01:01
What's pretty cool is, you know, this is actually, you can measure this.
01:06
When you're doing gamma, gamma ray spectroscopy, you get positron annihilation within your scintillator, and you pick up this particular energy.
01:18
And it's also, this is, the positron annihilation is actually, the foundation of what's called the pet scan, and a positron electron tomography...