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Comment by xwdv | Hacker News Reader

What happens if a neutrino interacts with something?

Usually the neutrino will interact with a nucleus and what happens is the reverse of a beta decay, i.e. either a proton will be changed into a neutron or a neutron into a proton, with the emission of an electron or a positron.

So one atom will be converted into an atom of another element, which is a neighbor to it in the periodic table.

Because one neutral lepton goes in and one charged lepton goes out, you might say that the neutrino snatches an electric charge from a nucleus, transmuting it into the nucleus of another element. However this interaction happens extremely seldom. In most cases the neutrino passes by without any effects.

Nevertheless, there has been a proposal to generate extremely powerful neutrino beams, with which to destroy any hidden nuclear weapons.

So if we could force neutrino interactions at scale we could make any element we want in large quantities?

Using neutrinos is far less efficient than using gamma radiation or neutrons or high energy electrons or ions for transmutations.

The photons/neutrons/electrons/ions have a high probability of interaction with the target, while the neutrinos have a very low probability of interaction.

All the elements that do not exist in nature due to low lifetime have been produced by transmutation, but this can be done only for very small quantities at huge prices.

Thanks for a great couple of replies. I'd just add that there are almost certainly more superheavy elements not thought to exist in nature which have yet to be produced artificially, but probably will be at some point.

... but which instantly decay. So not interesting.

There are definitely unstable superheavy elements that have never yet been produced, or at least detected, but the interesting prediction (widely accepted, but far from proven) is that there are some stable ones.

[0] https://en.wikipedia.org/wiki/Island_of_stability

In some sense this is how particle collisions works. You collide something and with certain probability you get something else at the other end under the physical constraints. Probably you want to use bigger particles and lower energy though to go from subatomic to atomic/molecular scale. The laser ignition fusion experiments would be closer to that. (Mind the costs though :))

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

I imagine like a lot of the nuclear alchemy the cost is much higher than just getting the existing material you want.

But for something like a kardashev type 2 or 3 civilization with abundant energy, it would be trivial and saves time searching for and accumulating the material? It would also be conflict free.

Maybe we could start with processing nuclear waste though.

Having a big pile of random heavy elements can be a worse environmental issue.

That depends on the energy of the neutrino, for lower energies there will be some momentum exchange, but since neutrinos are extremely light, this may be neglected depending on your experimental setup.

At higher energies (>GeV) depending on the interaction type (whether a W-boson or a Z-boson is exchanged), a charged lepton comes out, which can be an electron, muon or tau (the tau decays very fast) and this is the same as the neutrino flavor. Or a hadronic shower if a nucleon is hit.

Of course it's always more complicated than that: for lower energies (sub-GeV) you get resonance scattering, where the nucleus will emit a meson (quark-anti-quark particle), or deep-inelastic scattering, where the nucleus is broken up and hadronic particles create a cascade of more particles.

Edit: see https://en.wikipedia.org/wiki/Particle_shower for more on these cascades. It's a bit bare-bone, I don't have a nice reference right now.

Do we calculate the weight of all neutrinos in the Known mass of the universe? Or is that part of Dark Matter?

What is the mass of all the neutrinos in a cubic meter of “vacuum”?

The mass of the neutrinos is not known with any reasonable precision.

It is known only that it is not likely to be zero (because the commonly accepted explanation for the so-called neutrino oscillations requires a non-null mass, even if there are alternative theories) and that it must be small because various experiments have determined some upper limits for the masses of the 3 kinds of neutrinos.

You can tell the tale. It has happened to you!

That pesky sun doing it’s pesky fusion.

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