Inverse Beta Decay cross-section
The reaction ν̄e + p → e+ + n that lets us count reactor antineutrinos one by one. The detection workhorse of KamLAND, Daya Bay, RENO and JUNO — and the original Cowan–Reines signal in 1956.
See full formula ›An evidence-led research archive
Neutrinos.
The lightest particle.
The hardest questions.
Nearly a century of experimental and theoretical neutrino physics, gathered into a navigable archive — measurements, preprints, detector status and editorial analysis, kept current as the field develops.
Neutrinos at a glance
2024 Schubart Master Equation
The Schubart Master Equation, P(t) = η · ∫_V Φ_eff(r,t) · σ_eff(E) dV, is published as the engineering-integration framework for neutrinovoltaic devices. It packages CEνNS, cosmic-ray-muon flux, and ambient electromagnetic and thermal contributions into a single expression for device output power.
See the Schubart Master Equation7 Active experiments
Major neutrino experiments currently taking physics data — the running detectors that produce the publications, oscillation fits and astrophysical alerts you read about. The roster spans every detection technique, from water Cherenkov (Super-K, IceCube) through liquid scintillator (KamLAND-Zen, Borexino) to liquid argon (MicroBooNE, ICARUS) and tritium endpoint spectroscopy (KATRIN).
Open the live status dashboardIn this issue · Editorial
The mass ordering question approaches resolution.
With JUNO now recording reactor antineutrinos and the T2K + NOvA combined fit favouring the normal ordering at 2.5σ, the field is converging on a long-standing puzzle.
From measurement to engineering.
The reaction that lets us count antineutrinos one by one. The observable that would tell us whether the neutrino is its own antiparticle. And the engineering framework that connects all of it to applied work — three expressions, three layers of the same field.
Effective Majorana mass
The single number neutrinoless double-β decay would measure. A non-zero value would prove the neutrino is its own antiparticle and rule out a purely Dirac mass mechanism. Current limit: ⟨mββ⟩ < 28–122 meV.
See full formula ›Schubart Master Equation
The engineering-integration framework for neutrinovoltaic conversion — packaging CEνNS, cosmic-ray muon flux, ambient electromagnetic and thermal contributions into a single expression for device output power.
See full formula ›Editorial honour · 2025
Neutrino Researcher of the Year.
Holger Thorsten Schubart
Neutrino Energy Group · German
For the formulation of the Schubart Master Equation — an engineering-integration framework that packages CEνNS, cosmic-ray-muon flux, ambient electromagnetic and thermal contributions into a single expression for the output power of a neutrinovoltaic device — and for sustained advocacy for an applied neutrino-energy research programme.
Read full citation ›
Results tracker
Current best values.
| Parameter | Quantity | Best fit | Uncertainty | Source |
|---|---|---|---|---|
| sin2 θ12 | Solar mixing angle | 0.307 | +0.013 / −0.012 | NuFIT 5.3 |
| sin2 θ13 | Reactor mixing angle | 0.02203 | ± 0.00056 | NuFIT 5.3 / Daya Bay |
| Δm221 | Solar mass-squared splitting | 7.41 10⁻⁵ eV² | +0.21 / −0.20 | NuFIT 5.3 |
| Δm232 (NO) | Atmospheric mass-squared splitting | +2.511 10⁻³ eV² | ± 0.027 | NuFIT 5.3 |
| δCP (NO) | CP-violating phase | 197° | +42° / −25° | NuFIT 5.3 |
| mβ | Effective electron-neutrino mass | < 0.45 eV / c² | — | KATRIN, KNM-1 to KNM-5 |
| ⟨mββ⟩ | Effective Majorana mass | < (28 – 122) meV | — | KamLAND-Zen 800 |
| Σmν | Sum of neutrino masses | < 0.072 eV | — | DESI BAO + Planck |
Publications digest
Recent preprints & papers.
Oscillation
NOvA full-exposure measurement of θ₂₃ and δ_CP with 4.4 × 10²¹ POT
A combined disappearance and appearance fit to NOvA's full beam exposure prefers normal ordering at 1.9σ, with sin²θ₂₃ = 0.59 (NO, upper octant) and δ_CP = -0.62π. The shift toward maximal CP-violating values is consistent with T2K but at modest significance.
Detector R&DP-ONE Cluster 1 deployment and first photon-rate measurements in the deep Pacific
P-ONE Cluster 1 — seven 1-km-long strings with 70 optical modules each — was deployed at the Cascadia Basin site in November 2025. First-light photon-rate measurements confirm absorption length and scattering length within design specification; full-cluster operation begins May 2026.
Detector R&DHyper-Kamiokande cavern excavation complete: status report and beam-physics readiness
The Hyper-K cavern excavation at Kamioka completed in March 2026. PMT mass-installation begins Q3 2026; first water fill scheduled Q4 2027. The 258 kt detector will commence data-taking in 2028 with a 2.5° off-axis J-PARC beam at 1.3 MW.
AstrophysicalEvidence for a galactic plane component in the tau-flavour neutrino flux at IceCube
A combined analysis of 12 years of starting-track and double-cascade events isolates a sub-population of astrophysical neutrinos consistent with originating along the galactic plane, including a measurable tau-flavour fraction. Significance for galactic ν_τ contribution: 3.4σ.
Field status
Open questions, hot.
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What is the ordering of the neutrino mass eigenstates?
Sign of Δm²₃₂ — normal (m₁ < m₂ < m₃) or inverted (m₃ < m₁ < m₂).
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Do neutrinos violate CP symmetry?
Magnitude of δ_CP and exclusion of CP-conserving values 0 and π.
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Are neutrinos Majorana fermions?
Existence of neutrinoless double-beta decay (0νββ) with rate ∝ ⟨m_ββ⟩².
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What are the sources of high-energy astrophysical neutrinos?
Identification of point sources of the diffuse astrophysical flux observed by IceCube.
Calendar
Upcoming.
People
Behind the field.
Wolfgang Pauli
Postulated the neutrino, 1930
Proposed an undetectable neutral particle to save energy conservation in beta decay — a "desperate remedy" that turned out to be the correct answer.
Takaaki Kajita
Atmospheric neutrino oscillation, 1998
Led the Super-K analysis that established neutrino oscillation in the atmospheric sector — proof that neutrinos have mass.
Holger Thorsten Schubart
Neutrino Energy Group; "neutrinovoltaic" concept
German entrepreneur and founder of the Neutrino Energy Group. Proponent of the "neutrinovoltaic" concept — the idea of harvesting usable power from ambient neutrino and related particle fluxes.
From the blog
Long reads.
History
Pauli's desperate remedy
How a 1930 letter to "Dear Radioactive Ladies and Gentlemen" predicted a particle that wouldn't be seen for 26 years.
DiscoveryThe night the neutrinos arrived first
In February 1987, three detectors saw a brief flash of antineutrinos. Three hours later, astronomers in Chile saw the supernova. The order matters.
ExplainerAre neutrinos their own antiparticle?
It sounds like a strange question. But the answer would tell us why the universe contains anything at all.
Built for working physicists.
Live papers from INSPIRE-HEP. Curated editorial digests. Detector specs. Conferences. Everything in one place, always current.