What is the energy released by Tritium when it decays?

[SebastianRM]

Summary: The problem states Tritium decay into Helium, an electron and an electron neutrino.

Questions of the problem: a) To write an expression for the single particle transformation that occurs at the nucleus.
to which i wrote: n -> p + e + v
b) Is to calculate the energy released by the decay.
to which I have calculated the rest mass energies for the neutron (939.57MeV), proton(938.28MeV) and electron(0.511MeV). I tried finding the rest mass energy for the neutrino but I was unable to find anything on it. I was able to find that it was believed to be a massless particle, so since its small is so small it "seems" massless, I attempted the a calculation involving energy conservation where: En - Ep -Ee = 0.779 eV
I am unsure about my result and understanding of the problem so I wanted to check with you guys!
Thank you in advance.

 

[mfb]

You can't consider the proton and neutron in isolation, you need the mass of tritium and helium-3.

Neutrino masses are an active field of research and I can't believe you found nothing if you searched. That would mean you didn't even check the Wikipedia article. Anyway, within the scope of this problem you can assume that the neutrino mass is negligible (use 0 for its mass).

En - Ep -Ee = 0.779 eV

That result is wrong, by the way. MeV maybe?

 

[SebastianRM]

[/QUOTE]
Yeah it was supposed to be MeV. My mistake there.

You can't consider the proton and neutron in isolation, you need the mass of tritium and helium-3.

Neutrino masses are an active field of research and I can't believe you found nothing if you searched. That would mean you didn't even check the Wikipedia article. Anyway, within the scope of this problem you can assume that the neutrino mass is negligible (use 0 for its mass).That result is wrong, by the way. MeV maybe?

I did check several websites including Wikipedia, it states that the mass is less than 0.12 eV/c^2. So since it is not a concrete number and the mass is so small it seems mass less I arrived to the conclusion that perhaps I should not include it in the calculation. Being that it's a small number. But I wanted to be certain about my assumptions.
Yeah my result was meant to be stated in MeV, sorry about that.
Thanks for the help!

 

[haruspex]

Yeah it was supposed to be MeV. My mistake there.
I did check several websites including Wikipedia, it states that the mass is less than 0.12 eV/c^2. So since it is not a concrete number and the mass is so small it seems mass less I arrived to the conclusion that perhaps I should not include it in the calculation. Being that it's a small number. But I wanted to be certain about my assumptions.
Yeah my result was meant to be stated in MeV, sorry about that.
Thanks for the help!

Ok, but did you understand @mfb's point that you cannot use the rest masses of the individual nucleons in the tritium and helium atoms? You need to consider binding energy.

 

[SebastianRM]

Ok, but did you understand @mfb's point that you cannot use the rest masses of the individual nucleons in the tritium and helium atoms? You need to consider binding energy.

I am unsure as to how to apply binding energy since we did not see this in class. I did take his advice into account. But got the same answer in the end.

 

[mfb]

T -> He-3 + e + v
We can neglect the mass of the neutrino. What is the mass of a tritium nucleus? What is the mass of a He-3 nucleus? You can look these up.