How to Calculate Absolute Gamma Probability from Relative Intensities?

[HaniNaber]

Hi All,

I want to ask how to calculate the absolute gamma probability from relative intensities ( found on the tables of nucliedes) following alpha or beta decay.

I mean the probabilities that all add to 1.

Many thanks.

 

[Astronuc]

the absolute gamma probability from relative intensities

I'm not sure what one means by "the absolute gamma probability". To what 'probability' is one referring. After alpha or beta decay, a nucleus of a radionuclide can be left in an excited state, and the only way to become more stable is to emit a gamma ray. A given gamma energy has a probability of occurring when compared to all the other possible decays, and some of more likely to happen, or more probable, depending on precursor decay.

To what 'chart of the nuclides' is one referring?

 

[HaniNaber]

I mean in the table of nuclides for example the IAEA table , they would list the relative intensities of all the gammas from one isotope for example one gamma from the 4th energy level to the 2nd and one from the 2nd to ground state, after adding all the relative probabilities of all the possible gammas listed they don't add to one (after adding all of them the total is 1.4 for Ac228), I'm looking to convert these relative intensities to probabilities that add to 1.

Thank You.

 

[Astronuc]

I mean in the table of nuclides for example the IAEA table , they would list the relative intensities of all the gammas from one isotope for example one gamma from the 4th energy level to the 2nd and one from the 2nd to ground state, after adding all the relative probabilities of all the possible gammas listed they don't add to one (after adding all of them the total is 1.4 for Ac228), I'm looking to convert these relative intensities to probabilities that add to 1.

Thank You.

Well, the reason that probabilities for all gamma ray energies can add up to >1 is that in some decays two gamma rays are produced successively, i.e., they both happen successively from the same decay. One sees this in radiative capture of neutrons as well, where the excited nucleus emits 1 or 2 gammas in response to absorption of a neutron. The energy of the two gammas is often nearly equal to the single gamma energy.

https://www.nndc.bnl.gov/nudat2/getdecayscheme.jsp?nucleus=228TH&dsid=228ac bM decay&unc=nds

 

[HaniNaber]

Thank you, it makes sense.

I am trying to do some calculations related to activity and mass based of the total probability of all the gammas, and for this calculation to be done, the total probability should be less than 1, otherwise I would get negative masses.

I think that accumulation of error in adding all the possible probabilities ( some might have never been observed) is the reason for greater than 1 total probability. It might just be impractical to do so.

Thanks again for your help.