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I am wondering if it is theoretically possible that some kind of device/material could absorb neutrinos much better than everyday materials (preferably non-thermal absorption). This could enable a sort of neutrino antenna.

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  • $\begingroup$ Other than details on current neutrino detectors what information are you looking for in this question? $\endgroup$ Mar 13, 2017 at 21:51
  • $\begingroup$ @LioElbammalf Neutrino detectors that I know of rely on Cherenkov radiation emission in water. But as far as I know, water does not absorb significantly more energy than other materials. I would be interested in compact detector that necessarily absorbs more energy than common objects such as concrete walls, water, etc. such that it would be useful as a transceiver device. $\endgroup$
    – Real
    Mar 13, 2017 at 22:07
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    $\begingroup$ So you're looking for something that can detect transmitted neutrinos with sufficient efficiency to decode a message from? I'm fairly sure there is nothing with the density required to do this. Neutrinos travel from the center of stars largely unimpeded - the density of a star's core is much greater than anything we can create. I can't say 100% but I doubt we can get the sort of efficiencies needed for a transceiver. $\endgroup$ Mar 13, 2017 at 23:28
  • $\begingroup$ @LioElbammalf Yes, that's exactly the idea, after hearing of this property of low interactivity of neutrinos with matter. I am wondering if this property is necessarily true for any conceivable 'device'. $\endgroup$
    – Real
    Mar 13, 2017 at 23:44
  • $\begingroup$ Perhaps a neutrino antenna would have to be an astronomical object, like a neutron star or a nebula? $\endgroup$ Mar 14, 2017 at 2:15

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How does an electromagnetic antenna work at the photon, quantum mechanical level? By inducing varying electric fields which induce accelerated charges which radiate coherently photons which build the classical electromagnetic wave.

The neutrino interacts with the weak interaction , is a fermion and can in no way be in a way similar to a photon, so cannot be regimented as the photon can.

The neutrino is produced in weak interactions, beta decays naturally, and in interactions in accelerators and cosmic rays. Let us see whether a neutrino beam that could be modulated is possible.

As in radioactivity they participate in three body decays there is no way to control their energy and direction so radioactively produced they cannot be coherent in any sense.

This leaves accelerators and cosmic rays. No way to control cosmic ray neutrinos of course.

If muon beams are produced in accelerators from pion decays, at the same time there will be a neutrino beam from the two body decay. If the production of the muon beam is modulated, the production of neutrinos will be modulated The problem will be on the detection side, since there are no receiving antennas other than huge detectors, like the OPERA.

What makes neutrinos attractive for gathering signals from the sun and stars, the weak interaction, prohibits any practical uses for the beam.

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  • $\begingroup$ For electromagnetic antennas, there are reciprocity relations. Isn't it possible to likewise arrange a reverse process that captures neutrinos efficiently? $\endgroup$
    – Real
    Mar 14, 2017 at 17:17
  • $\begingroup$ The combination of the spin 1/2 ( fermions not bosons) and the weak interaction kills it . the photons couple with 1/137 strength, the neutrinos with 10^-6. Photons has no constraints in numbers in a single quantized level, neutrinos have to conserve lepton number and occupy one at a time a quantized level. there can be no antenna for neutrinos $\endgroup$
    – anna v
    Mar 14, 2017 at 19:43
  • $\begingroup$ I had a new idea. Suppose there is a nuclear process (reaction) that simply emits neutrinos. If this reaction is exposed to a neutrino flux, won't it cause a detectable change in the reaction? Then we could detect the change not from neutrinos but from other particles. $\endgroup$
    – Real
    Sep 18, 2021 at 15:19
  • $\begingroup$ @Real No, particle interactions do not work that way, there is no nuclear process that emits only neutrinos. And even if it did, it would not work as an antenna , no coherence in multiple particle interactions of neutrinos , and neutrino fluxes are not coherent up to now, though I found a proposal: link.springer.com/article/10.1007/s00340-013-5336-2 $\endgroup$
    – anna v
    Sep 18, 2021 at 17:53
  • $\begingroup$ The reversibility of the laws of physics imply that a reverse process to an emission process always exists. Of course, in practice I guess energy selectivity and thermodynamic considerations could get in the way somewhat, but I see no fundamental impediment. $\endgroup$
    – Real
    Oct 21, 2021 at 16:19

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