Are the Energy Units in the Decay Diagram Correct for Pt-125?

[Graham87]

Homework Statement

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Relevant Equations

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In the solution below it says 22% goes to 0.0309keV. From the diagram above I interpret 22% goes to 0.1298keV with EC(L)/EC(K)=3.0 and not 4.4. Why is that wrong ?

Thanks a lot!

 

[Steve4Physics]

View attachment 322938
In the solution below it says 22% goes to 0.0309keV. From the diagram above I interpret 22% goes to 0.1298keV with EC(L)/EC(K)=3.0 and not 4.4. Why is that wrong ?
View attachment 322939

Not sure how much I can help but there are some mistakes worth (IMO) mentioning.

Two excited nuclear energy levels (of Pt-125) are given as 0.1298MeV (=129.8keV) and 0.0989MeV (=98.9keV). Note that the difference between these is 0.0309MeV (= 30.9keV).

But there are then various references (including in the model-answer) to ‘0.1298keV’, ‘0.0989keV’ and ‘0.0309keV’. It appears that units are very messed up.

Also, the model-answer refers to an ‘energy level of 0.0309keV’. Even after correcting the unit, this value is not an energy level; it is the transition energy between the two excited nuclear states. What the model answer is telling you is that for each electron-capture, there are two possible nuclear emissions: a $\gamma$ photon of energy 30.9keV or one of 98.9keV. Note that only one of these is in the energy-range of interest.

I’m not familiar with some of the symbols used (despite several years of being a medical physicist in radiotherapy a long time ago). But I would suggest that you check the energies of characteristic X-rays for Pt-125 to see which ones are in the energy range of interest.

Edit: several minor changes.

 

[Graham87]

Not sure how much I can help but there are some mistakes worth (IMO) mentioning.

Two excited nuclear energy levels (of Pt-125) are given as 0.1298MeV (=129.8keV) and 0.0989MeV (=98.9keV). Note that the difference between these is 0.0309MeV (= 30.9keV).

But there are then various references (including in the model-answer) to ‘0.1298keV’, ‘0.0989keV’ and ‘0.0309keV’. It appears that units are very messed up.

Also, the model-answer refers to an ‘energy level of 0.0309keV’. Even after correcting the unit, this value is not an energy level; it is the transition energy between the two excited nuclear states. (What the model answer is telling you is that for each electron-capture, there are two possible nuclear emissions: a $\gamma$ photon of energy 30.9keV or one of 98.9keV. Note that only one of these is in the energy-range of interest.

I’m not familiar with some of the symbols used (despite several years of being a medical physicist in radiotherapy a long time). But I would suggest that you check the energies of characteristic X-rays for Pt-125 to see which ones are in the energy range of interest.

Edit: minor changes only.

Thanks! Yes, you are right. Aparently the the solution is wrong. They wrote the wrong numbers above and used the right numbers during the calculations lol.
Thanks a lot for the explanation!