Do electron antineutrinos interact with anything?

[nitsuj]

Do electron antineutrinos interact with anything?

 

[mfb]

Sure. They can lead to inverse beta decay (antineutrino+proton -> positron+neutron), they can do elastic scattering (transfer some of their energy to other particles, e. g. electrons or nuclei), and at high energies even more reactions are possible.

 

[Orodruin]

Coincidentally, electron anti-neutrinos were the first neutrinos ever to be discovered by experiments.

 

[nitsuj]

Coincidentally, electron anti-neutrinos were the first neutrinos ever to be discovered by experiments.

I remember reading about that when reading for an answer to my question (Wolfgang i think). It was through deduction that there "must be" another particle. Interesting side note from wiki says Niels Bohr was "ready to accept" that energy was not conserved!

I appreciate that being experimentally confirmed means they interact with things, I should've have put the question as do they interact with things more frequently than the other neutrinos.

Sure. They can lead to inverse beta decay (antineutrino+proton -> positron+neutron), they can do elastic scattering (transfer some of their energy to other particles, e. g. electrons or nuclei), and at high energies even more reactions are possible.

It seemed strange to me that electron anti-neutrinos are the least massive of the neutrinos, have no charge and still can interact with stuff. Then read more about the left hand / right hand spin (compared to momentum) and remembered I was told here (I think it was Orodruin :) that spatial non-parity refers to this, in that b- decay results in pretty much left hand only electron anti neutrinos.

So is that why these neutrinos can interact with stuff while the other neutrinos rarely do?

Thanks mfb from what you said I went on to read about the experiment that detected them. So apparently when the electron anti neutrino interacts with a proton it eventually leads to positron and electron annihilation in turn making gamma rays!

I just got a veil of tritium. I find it odd that this tiny thing is making positrons and gamma rays! Is it actually doing that? I'm trying to understand if this veil of tritium is radiating these electron anti neutrinos to some great distances or if they all stay inside the tiny veil.

 

[Orodruin]

I remember reading about that when reading for an answer to my question (Wolfgang i think). It was through deduction that there "must be" another particle. Interesting side note from wiki says Niels Bohr was "ready to accept" that energy was not conserved!

This is different from what I was talking about. I was talking about the experimental direct detection of neutrinos in 1956. Not the theoretical introduction of the neutrino by Pauli in 1930. Pauli a priori just thought about a single neutrino participating in beta decays, he had no idea about neutrino flavours. Neither did the experimentalists in 1956, but in effect what they were seeing were electron anti-neutrinos.

It seemed strange to me that electron anti-neutrinos are the least massive of the neutrinos

None of the flavour eigenstates have definite masses. You cannot talk about a flavoured state being the "least massive".

 

[nitsuj]

This is different from what I was talking about. I was talking about the experimental direct detection of neutrinos in 1956. Not the theoretical introduction of the neutrino by Pauli in 1930. Pauli a priori just thought about a single neutrino participating in beta decays, he had no idea about neutrino flavours. Neither did the experimentalists in 1956, but in effect what they were seeing were electron anti-neutrinos.None of the flavour eigenstates have definite masses. You cannot talk about a flavoured state being the "least massive".

I hear ya, I was just saying they where looking for it. post experimental confirmation I like to give credit to the peep who deduced such a thing exists.

Thanks for the correction about the mass, I likely confused the mass of the electron, muon, tau with the neutrino counterparts.

From the bit of reading I've done particles seem so interesting, I better understand the love for particle accelerators...very cool.

 

[mfb]

So is that why these neutrinos can interact with stuff while the other neutrinos rarely do?

All neutrino types rarely interact with matter.

I just got a veil of tritium. I find it odd that this tiny thing is making positrons and gamma rays!

It does not. The decay is neutron -> proton + electron + electron antineutrino. The antineutrinos escape to space (well, something like 99.99999999999999% of them, didn't count the "9"s).

 

[snorkack]

It does not. The decay is neutron -> proton + electron + electron antineutrino. The antineutrinos escape to space (well, something like 99.99999999999999% of them, didn't count the "9"s).

And all antineutrinos of tritium decay do escape. Because the detection reaction is electron antineutrino + proton -> neutron + positron. Which requires the antineutrino to meet a high energy threshold. And antineutrinos from tritium decay cannot.
Low energy antineutrinos do interact with matter. But the only legal interaction they have is elastic scattering. If the antineutrino from your vial of tritium does undergo elastic scattering off a nucleus or an electron on its way up to space and is reflected back down (an event of very low probability), all that happens is that it passes through Earth and escapes to space in another direction. If it undergoes the second elastic scattering on its passage through Earth (massively unlikely again, though slighltly less unlikely than scattering on the way up through air), all that happens that it escapes to space in third direction.

 

[mfb]

There are nuclei where this reaction doesn't have any threshold. They are naturally radioactive then. That typically doesn't make them suitable for neutrino detectors, but that was not the question.

Inverse beta decay of tritium has been suggested as detector for the cosmological neutrino background (not antineutrinos): PTOLEMY.

 

[Orodruin]

Inverse beta decay of tritium has been suggested as detector for the cosmological neutrino background

PTOLEMY was not first in suggesting this. As with many things, Weinberg is to blame.

 

[mfb]

They didn't come up with the idea, but they came up with a detector proposal and they run feasibility studies and component tests (which qualify as their own experiments).

 

[nitsuj]

All neutrino types rarely interact with matter.It does not. The decay is neutron -> proton + electron + electron antineutrino. The antineutrinos escape to space (well, something like 99.99999999999999% of them, didn't count the "9"s).

Thanks mfb, that clarifies it for me. funny to catch myself staring at this tiny glowing veil in awe of its "mechanics"...well into the mechanical watch it goes lol

 

[snorkack]

The Energy level of the neutrino is very important. High energy antineutrinos (over 1.8 MEV) are more reactive causing inverse beta decay? Reference Article from Wikipedia on "Neutrino".

Consider how antineutrinos and neutrinos can be formed.
Antineutrinos can be formed by beta decay
(n)→(p)+e^-+νˇ_e
Neutrinos can be formed by positron emission
(p)→(n)+e⁺+ν_e
But since electrons, unlike positrons, are found in world, neutrinos can also be formed by electron capture
(p)+e^-→(n)+ν_e
Then think how antineutrinos and neutrinos may be absorbed.
Inverse beta decay is not likely because the final state of beta decay has three particles. It is unlikely that a nucleus would just happen to absorb an electron at the precise time it absorbs an antineutrino.
What is possible is induced positron emission. Like
(p)+νˇ_e→(n)+e⁺
But this has an energy threshold which is 1022 keV higher than the improbable actual inverse beta decay.
Now, low energy neutrinos CAN be absorbed because electron capture final state has just two products - nucleus and neutrino - and can thus be directly inverted.
The product nuclei of low energy electron captures are able to absorb low energy neutrinos.

Neutrinos less than 1.8 MEV may easily pass through the entire earth.

And so may antineutrinos more than 1,8 MeV.
The value of 1,8 MeV is relevant to antineutrino, not neutrino. But it is not relevant to passing through Earth (protium is rare there). Yes, capture probability increases with energy, but above 1,8 MeV, the neutrinos are still overwhelmingly likely to pass through entire Earth.

Nuclear Power Reactors (ie diablo canyon etc) are major sources of high energy neutrinos.

No, they are not.
Nuclear reactors cause fission of heavy nuclei into fission fragments which mostly have neutron excess, undergo beta decay and therefore emit antineutrinos. Not neutrinos.
Stars cause fusion of protons into nuclei (containing some neutrons), and the process includes positron emission and electron capture, which emits neutrinos. Not antineutrinos.

 

[mfb]

In my estimation, Anti Neutrinos account for the missing 4.5% energy release in uranium fission for US power reactors ?

What do you mean by "missing"? Some fraction of the released energy goes to antineutrinos, sure.

Thus In the US, over 15 gigawatts per year of antineutrinos are released for 99 reactors at over 300 gigawatts total thermal uranium fission.

15 GW (assuming the numbers are right). Gigawatt is a power already, "gigawatt pear year" would be a rate of power change.

Furthermore, current antineutrino theory is incomplete with some paradoxes and unknowns. For example their mass and speed are a bit uncertain.

We don't have precise mass values yet, but that is not a paradox.

 

[nitsuj]

What do you mean by "missing"? Some fraction of the released energy goes to antineutrinos, sure.15 GW (assuming the numbers are right). Gigawatt is a power already, "gigawatt pear year" would be a rate of power change.We don't have precise mass values yet, but that is not a paradox.

Ah! no mfb don't engage! :)

You already answered op anyways; thanks again!

 

[mfb]

Thus when it disintegrates in a molecule of your body or food/seed etc. It will obviously cause a mutation there.

Most of the time it won't.

Another uncertainty to add to the other 2 is: The antineutrino may be "identical" as the neutrino (as of year 2015)

Even if they turn out to be the same fundamental particle their state is clearly different.

 

[ZapperZ]

Do electron antineutrinos interact with anything?

I'm more puzzled with this question than anything else. It is SO specific to JUST "electron antineutrinos". Does that mean you are OK with all the other neutrinos within the neutrino family? Why pick on just the electron antineutrinos, which, to me, is the "most common" that we encounter since that is what we get out of the ordinary beta decay?

Zz.