Sn126 Decay Scheme: Gamma and Beta Emissions

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Discussion Overview

The discussion revolves around the decay scheme of Sn126 transitioning to Sb126 and then to Te126, focusing on the gamma and beta emissions associated with these decays. Participants are exploring the complexities of the decay processes, including the average number of gamma rays emitted and the energy levels involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks clarification on the average number of gamma rays emitted by Sb126 and expresses confusion regarding the decay pathways and their associated half-lives.
  • Another participant notes the complexity of calculating average gamma multiplicity due to multiple branches in the 126Sb level scheme and mentions detection limitations for low-energy emissions.
  • There is a discussion about the meaning of "100% beta decay" in the diagrams, with a participant explaining that it indicates no decay through beta+ or internal conversion, but that beta decay is typically followed by gamma decay.
  • A participant corrects their earlier post to clarify that they meant the decay from Sb126m to Te126, indicating a need for precision in referencing the decay schemes.
  • Questions are raised about the symbols used in the tables and the significance of the red text indicating specific energy levels for gamma emissions.

Areas of Agreement / Disagreement

Participants express confusion and seek clarification on various aspects of the decay scheme, indicating that there is no consensus on certain points, particularly regarding the gamma emissions and the interpretation of the decay diagrams.

Contextual Notes

Participants highlight potential limitations in the completeness of the level scheme and the challenges in detecting certain gamma emissions due to energy thresholds and half-lives.

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i am looking at the decay scheme of Sn126 > Sb 126 > Te126 and would like to know how many gamma rays Sb126 throws out on average and see if I've understood the diagram correctly;- Sn128 -> decays to (126m-Sb) 19.5min half life, where 14% decays through IT with 17.7 kev gamma and then 12.46 day half life 126 Sb. The other 86% of the isomer has 414.5kev, 666.1kev and 694.8kev gamma and various 1mev beta, according to (page 4). So only 14% goes through the 12 day decay scheme while the rest goes though a 19.5min decay scheme. What also confuses me is that is says 100% beta decay in the diagrams while there are tables for gamma emissions, is this for red numbers in the diagrams, occasional gamma emissions? eg p5
Also what is the average energy of beta given of and has anyone seen a more complex decay scheme?
thanks
+energy
 

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Calculating the average gamma multiplicity is going to be complicated, because there are many branches in the 126Sb level-scheme. Note that if you were trying to detect these, many might be too low in energy to make it into your detector, so you wouldn't necessarily have any chance of detecting as many as there really are. In addition, the experimental multiplicity you'll see will be lower than the actual multiplicity because of some of the long half-lives, which won't let you see the whole chain in coincidence. The level scheme on p. 3 also seems to be incomplete, presumably due to experimental limitations; the intensities of the 88 keV and 23 keV gammas would have to sum to 100% if the level scheme were complete.

+energy said:
What also confuses me is that is says 100% beta decay in the diagrams while there are tables for gamma emissions, is this for red numbers in the diagrams, occasional gamma emissions?
Beta decay usually doesn't occur alone; usually it's followed by gamma decay. When they say it's 100% beta- decay, they mean that there is no decay through beta+ or internal conversion.
 
sorry, i meant Sb126m->Te126 decay, i read my post and see i didn't emphasize sb126m->Te126, i think the table and diagram for Sb126m are on p4 and Sb126 on page 5-6
 
also what do the symbols E, E, I, I, mean, (just under each table) and the red text for 414kev, 666.1kev and 694.8 kev energy
thank you
+ energy
 

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