Neutrino SETI Sensitivity

The third SETI channel — after radio and optical. Neutrinos cross 17,900 light-years without scattering, absorption, or deflection. The question is whether a directed beam carries enough flux to beat IceCube's background.

🔬 Established Particle Physics ⚠ Speculative ETI Application
Highly speculative: No natural process at ωCen produces a narrow, directed neutrino beam of the type modelled here. This tool asks: if an advanced civilisation were transmitting such a beam in our direction, what power would be required to cross our detection threshold? The astrophysical background (atmospheric and diffuse astrophysical neutrinos) is included.
Why neutrinos? Radio and laser photons are absorbed and scattered by the ISM; neutrinos are not. They carry directional information over kiloparsec distances. A muon-neutrino beam collimates over ~1 mrad and can be produced at a muon collider with known efficiency. IceCube detects muon neutrinos at TeV energies with effective area up to ~1 km². The catch: you need enormous transmitter power, because the neutrino–nucleon cross-section is tiny.
Transmitter & Detector Parameters
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Detection Outlook — ωCen at 5.49 kpc
Flux at Earth
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ν/cm²/s at 5.49 kpc
Expected Events / Year
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Signal / Background
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Transmitter Energy Cost
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Power × 1 yr (J)
Kardashev Tier Required
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Detection Verdict
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Flux vs Distance — Current Transmitter Power

Neutrino flux 1/r². Vertical lines: IceCube detection threshold (dashed amber) and ωCen distance (solid teal). Horizontal dashed line: atmospheric νμ background in 1 yr at selected detector volume.

Detector Comparison — Current Settings
Detector Volume Events/yr S/B ratio Status

Physics model: A directed muon-neutrino beam of power P_tx (watts) at energy E_ν (eV) produces a neutrino flux at Earth of Φ = P_tx / (4π d² E_ν), where d = 5.49 kpc for ωCen. The detection rate is N = Φ × σ(E_ν) × ρ_ice × V_eff, where σ(E_ν) ≈ 6.7×10⁻³⁹ cm² × (E_ν/GeV) is the neutrino–nucleon charged-current cross-section, ρ_ice ≈ 0.917 g/cm³, and V_eff is the effective detector volume. Atmospheric background: ~100 muon neutrino events per year per km³ above 1 TeV (IceCube measurement).

Beam directionality: A real neutrino source from a muon collider would have a divergence of ~1 mrad (Anchordoqui et al. 2008). This model assumes perfect beam alignment toward Earth — an optimistic assumption. A randomly oriented beam reduces the effective flux by (solid angle factor), making detection far harder. The 1/4πd² factor used here implicitly assumes isotropic emission; a directed beam would be brighter by the beaming factor.

Background: The atmospheric neutrino background at IceCube is approximately 100,000 events/year at >100 GeV, falling to ~100/year at >1 TeV and ~1/year at >100 TeV. The astrophysical diffuse background discovered by IceCube (2013) adds ~10–50 events/year above 100 TeV. A directed SETI signal would need to exceed this background either by rate or by source localisation.

OCS IceCube proposal: The OCS IceCube proposal targets astrophysical neutrino emission from the ωCen IMBH region — not a SETI signal, but the same detector that would catch a deliberate beam. See proposal_icecube.html for the astrophysical case.

References: Anchordoqui et al. 2008 (arXiv:0803.0409) · IceCube 2013 Science 342:1242856 · Learned & Pakvasa 1995 Astropart. Phys. 3:267

Related proposals: KM3NeT/ARCA →IceCube →