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## Main Question or Discussion Point

Hi

I'm wondering if someone could help me out finding the Q-value fom a beta minus decay.

It's a

90Y → 90Zr + e

All sources I have says that the energy released is 2,28 MeV, but when i calculate i get 1,78 MeV

So far, I've looked up the mass of the 90Y and the Zr90 and the electron and done following:

Q=(m(90Y)-m(90Zr)-m(e))*c^2

According to my databook

m(90y) = 89,9071519u = 1,49294*10^-25 kg

m(90Zr) = 89,9047044u = 1,4929*10^-25 kg

m(e) = 9,10938*10^-31 kg

Giving a mass difference at 3,15323*10^-30 kg

resulting in a Q value of Q=2,83399*10^-13 J = 1,76883 MeV

If you can tell me what im doing wrong, I would appreciate if you would let me know.

Thanks in advance.

I'm wondering if someone could help me out finding the Q-value fom a beta minus decay.

It's a

90Y → 90Zr + e

All sources I have says that the energy released is 2,28 MeV, but when i calculate i get 1,78 MeV

So far, I've looked up the mass of the 90Y and the Zr90 and the electron and done following:

Q=(m(90Y)-m(90Zr)-m(e))*c^2

According to my databook

m(90y) = 89,9071519u = 1,49294*10^-25 kg

m(90Zr) = 89,9047044u = 1,4929*10^-25 kg

m(e) = 9,10938*10^-31 kg

Giving a mass difference at 3,15323*10^-30 kg

resulting in a Q value of Q=2,83399*10^-13 J = 1,76883 MeV

If you can tell me what im doing wrong, I would appreciate if you would let me know.

Thanks in advance.