A The time between when the neutrinos are emitted in double-beta decay?

[qnach]

Double-beta decay will emit two neutrinos.
But, are they simultaneously released or separated?

 

[jedishrfu]

Looks like its a yes. They do mention another theoretical possibility where no neutrinos are emitted but it has never been observed.

https://en.wikipedia.org/wiki/Double_beta_decay

 

[mfb]

Yes, they are emitted at the same time.

There are also many isotopes that will do a normal beta decay, where the produced nucleus will do another beta decay later, but that is not called double beta decay then.

 

[qnach]

Yes, they are emitted at the same time.

There are also many isotopes that will do a normal beta decay, where the produced nucleus will do another beta decay later, but that is not called double beta decay then.

I am serious in doubt "the same time". To be emitted at the same time is really a magic unless there are some physical mechanism to make them, otherwise "the same time" only means the instrument time resolution. If you have better instrument you will be able to detect they are NOT at the same time.

 

[mfb]

To be emitted at the same time is really a magic unless there are some physical mechanism to make them

That physical mechanism is the double beta decay.

 

[Orodruin]

The entire point with double beta decay is that the parent nucleus energetically cannot undergo single beta decay.

 

[snorkack]

The entire point with double beta decay is that the parent nucleus energetically cannot undergo single beta decay.

Are you sure?
What is the decay energy and branching fraction of calcium 48 single beta decay to scandium 48?

 

[Orodruin]

Are you sure?
What is the decay energy and branching fraction of calcium 48 single beta decay to scandium 48?

That is something of an anomaly where single beta decay is allowed but not very favourable energetically compared to the double beta decay. However, the double decay is a higher order process. Together these effects happen to give similar decay widths for the two types of decay but it is not the general situation for double beta decaying nuclei.

 

[Vanadium 50]

There are two decays 48Ca -> 48Sc and 96Zr -> 96Mo where beta decay is almost but not quite energetically forbidden. However, the rates for these processes are substantially lower than for double beta decay: around 1000 for calcium and much larger for zirconium.