# Calculate the energy released per decay in a alpha emitter.

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## 2 Replies - 1334 Views - Last Post: 07 May 2011 - 12:11 PM

### #1 FrozenSnake

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# Calculate the energy released per decay in a alpha emitter.

Posted 06 May 2011 - 05:48 AM

This is a physics question

Nuclide Pu is a alpha emitter. Pu(A) = 239, Pu(Z) = 94
a) Write the formula for the decay and calculate the energy per decay.

I have the formula done
Pu -> U + He | U(A) = 235, U(Z) = 92 , He(A) = 4, He(Z) = 2

Now I have to sum up the nuclide masses for He-4 and U-235 which is
4.002603u + 235.0439u = 239.0465u.

Now I am stuck, according to my solution booklet I should do this:
239.0522u (the Pu) - 239.0439 (where do this value come from?) = 0.0057u

Even if I put this 239.0522u - 239.0439u in my calculator I do not get 0.0057u I get 0.0083.
So where did 239.0439u and 0.0057 came from? I have read in the book on the chapter about this but it still doesn't makes any sense to me

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## Replies To: Calculate the energy released per decay in a alpha emitter.

### #2 Brewer

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## Re: Calculate the energy released per decay in a alpha emitter.

Posted 07 May 2011 - 05:10 AM

While I'm sure that there are some more-than-competent physicists here at DIC, your question has gone unanswered in 24 hours so I'll suggest two other websites that will probably be more helpful for such a question.

PhysicsForums is a good place with some very smart people. While I've never asked a Physics question I have had some very helpful conversations in the Math forum and I can only assume that the gravity people will be just as accommodating.

Physics - Stack Exchange is another website that I'm not very familiar with but it is on the Stack Exchange network which is generally pretty helpful.

Hope this helped!

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## Re: Calculate the energy released per decay in a alpha emitter.

Posted 07 May 2011 - 12:11 PM

```239.0522u (the Pu) - 239.0439 (where do this value come from?) = 0.0057u
```

The 239.0439 looks like an error on the part of the book. If you plug in the sum of the nuclide masses, 239.0465, the difference is as the book says.