# Energy to remove a proton and a neutron from a nucleus

1. Apr 28, 2005

### Fowler_NottinghamUni

Hey guys, I know this is basic nuclear physics but i've forgotten how to do it. Given the atomic mass of Oxygen 16 (8p 8n), Oxygen 15(7n 8p) and Nitrogen 15(8n 7p), having found the average energy binding energy per nucleon (i think i have it right) find how much energy is required to remove proton from oxygen 16 and one neutron?

Many thanks Gav.

2. Apr 29, 2005

### Meir Achuz

BE/nucleon is a hard way to do that.
Find the total (accurate in MeV) mass of the 3 nuclei and of the p and n
Then E_p=O(16)-N(15)-p and E_n=O(16)-O(15)-n.
The symbols satand for the masses in MeV.

3. Apr 29, 2005

### Andrew Mason

Use $\Delta E=\Delta mc^2$ where $\Delta m$ is the total change in mass. Are you trying to remove a deuteron (proton-neutron pair) or a separate proton and neutron? A deuteron has slightly less mass than a separate proton and neutron.

AM

4. Nov 8, 2011

### shroom

Hey, I am doing a similar problem, calculating the energy required to remove one neutron from Zr with atomic number 91 using the semi empirical mass formula.

Is it simply the average binding energy of the nucleon? Which I get to be 8.795 MeV.

Someone above has mentioned to use E=mc^2. If the question is only asking for the energy required to remove a nucleon, why would you need to use this?

Many Thanks

Shroom

5. Nov 8, 2011

### Staff: Mentor

I believe that when you determine the mass difference between the initial and final products you can convert the mass difference to energy to find the required energy to remove the nucleons.

6. Nov 8, 2011

### Staff: Mentor

Yes, which is the method to which Meir Achuz and Andrew Mason alluded.

One wants the binding energy of the last proton or last neutron, which is found from the mass defect, or difference in mass energy between the inital mass and final masses of the separated nucleus and particle in question.

7. Nov 10, 2011

### shroom

Ah Ok so it's just a different (quicker) way of doing it?

Thanks

Shroom

8. Nov 16, 2011

### nevername667

I have the same problem as Shroom, and I am running out of ideas. I tried using the binding energy and subtracting by the mass of one neutron, but that was wrong. I think I am missing a key concept. Anyone have an idea?

9. Nov 16, 2011

### Staff: Mentor

Did you subtract the mass of the neutron, or the mass difference between the nucleus with the neutron and the nucleus with the neutron now free?