AQA a level physics question - beta minus decay

I was wondering if anyone could help me out with this past paper question we were given today in class:

We were given a graph of number of beta-minus particles against the kinetic energies. This graph starts at zero, has a high peak and then goes back down at the end of the graph (i hope this is clear enough).

The question says, this graph shows the distribution of the kinetic energies of beta-minus particles from the decay of Carbon-14. Explain how this graph supports the existence of the antineutrino.

If anyone could help out, it would be much appreciated!

Reply 1

AverageDolphin

4

Basically, the graph shows a range of kinetic energies for beta-minus particles from Carbon-14 decay. The existence of the antineutrino explains why not all beta-minus particles have the same energy, as some of the energy is carried away by the antineutrino.

Let's suppose for example, near the start of the graph, there would be a small number of beta-minus particles with a small amount of kinetic energy, so to balance it out, there must be another particle emitted which has the missing mass-energy.

If the antineutrino didn't exist, this would mean there would be less energy after than before the decay occurred! And as we know, mass-energy is conserved.

Hope I could help :smile:

Reply 2

ruthh.i

OP

2

thank you soo so much that was so helpful, really appreciate it :smile:

Reply 3

kristjana

Original post by AverageDolphin

Basically, the graph shows a range of kinetic energies for beta-minus particles from Carbon-14 decay. The existence of the antineutrino explains why not all beta-minus particles have the same energy, as some of the energy is carried away by the antineutrino.

Let's suppose for example, near the start of the graph, there would be a small number of beta-minus particles with a small amount of kinetic energy, so to balance it out, there must be another particle emitted which has the missing mass-energy.

If the antineutrino didn't exist, this would mean there would be less energy after than before the decay occurred! And as we know, mass-energy is conserved.

Hope I could help :smile:

but what about the energy of the proton which neutron turns into? could that proton carry that missing energy, or does every proton converted has the same amount of energy each time?

AQA a level physics question - beta minus decay

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