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# Physics A2: Nuclear Stability; decay schemes.. Watch

1. can someone explainvto me why this illustration shows two beta decays arrows and what do these percentages mean. Also, the energy values next to these arrows in MeV, what does it mean?
Lastly, the question asks me to calculate three possible values of the energies of the gamma ray that is emitted into bringing the nucleus to its ground state, how would you calculate that?
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2. (Original post by MSB47)
can someone explainvto me why this illustration shows two beta decays arrows and what do these percentages mean. Also, the energy values next to these arrows in MeV, what does it mean?
Lastly, the question asks me to calculate three possible values of the energies of the gamma ray that is emitted into bringing the nucleus to its ground state, how would you calculate that?
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The Mg can decay by one of two possible routes. (To one of the two excited states.)

This happens statistically 70% of the time to the 0.83MeV and 30% of the time to the other state. (Or the probability is 0.7 to the one and 0.3 to the other.)
So there are a number of possible ways of getting from the Mg at the start to the ground state. (2 via the excited states and one directly, for example.)
The energy values on the right are the actual energies associated with the two excited states. Moving to a lower state emits a gamma ray with energy equal to the difference.
The values on the left refer to the difference in energy between the initial state and the excited states.

3. (Original post by Stonebridge)
The Mg can decay by one of two possible routes. (To one of the two excited states.)

This happens statistically 70% of the time to the 0.83MeV and 30% of the time to the other state. (Or the probability is 0.7 to the one and 0.3 to the other.)
So there are a number of possible ways of getting from the Mg at the start to the ground state. (2 via the excited states and one directly, for example.)
The energy values on the right are the actual energies associated with the two excited states. Moving to a lower state emits a gamma ray with energy equal to the difference.
The values on the left refer to the difference in energy between the initial state and the excited states.
when you say 2 via the excited states does that mean one gama ray is emmitted from the top excited state energy level to the other and from there another gamma ray emitted to eventually the ground state or each excited state level emits one gamma ray directly towards the ground state? sorry this looks like a word vomit im confused on finding the possibilities of these transitions with gamma ray emmission

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4. (Original post by MSB47)
when you say 2 via the excited states does that mean one gama ray is emmitted from the top excited state energy level to the other and from there another gamma ray emitted to eventually the ground state or each excited state level emits one gamma ray directly towards the ground state? sorry this looks like a word vomit im confused on finding the possibilities of these transitions with gamma ray emmission

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It's just like electrons in an atom.
The Mg nucleus can decay first to one of the excited states, emitting a gamma, (and beta) and from there to the ground state, emitting another gamma.
The same can happen via the other excited state. Emitting a beta and two gammas in the process.

5. (Original post by Stonebridge)
It's just like electrons in an atom.
The Mg nucleus can decay first to one of the excited states, emitting a gamma, (and beta) and from there to the ground state, emitting another gamma.
The same can happen via the other excited state. Emitting a beta and two gammas in the process.
So a gamma ray is also emitted at the same time a beta particle is emitted which decays the nucleus to one of the excited states?
6. (Original post by MSB47)
So a gamma ray is also emitted at the same time a beta particle is emitted which decays the nucleus to one of the excited states?
Ah sorry. My apologies. I didn't look carefully enough at the diagram.
I've just looked back at the original.
The energy values on the left are the energies of the two possible beta particles.
The emission of the particle leaves the nucleus in one of the excited states.
These are the two states given on the right.
The nucleus can decay from either of these states to the ground state by emitting a gamma photon. I imagine the 3rd gamma could be the one emitted if the nucleus moved between the higher and lower excited state.
Sorry for the earlier confusion.
7. (Original post by Stonebridge)
Ah sorry. My apologies. I didn't look carefully enough at the diagram.
I've just looked back at the original.
The energy values on the left are the energies of the two possible beta particles.
The emission of the particle leaves the nucleus in one of the excited states.
These are the two states given on the right.
The nucleus can decay from either of these states to the ground state by emitting a gamma photon. I imagine the 3rd gamma could be the one emitted if the nucleus moved between the higher and lower excited state.
Sorry for the earlier confusion.
aha that makes sense now thanks alot

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