When was the neutrino discovered?

The neutrino was proposed theoretically by Wolfgang Pauli in 1930 and first detected experimentally by Frederick Reines and Clyde Cowan in 1956 — a gap of 26 years between prediction and detection. Many further discoveries followed, including neutrino oscillation in 1998 and the detection of cosmic neutrinos.

What are the biggest milestones in neutrino physics?

The prediction of the neutrino (1930), its detection (1956), the discovery of the muon neutrino (1962), the solar neutrino problem (from 1968), the detection of supernova neutrinos (1987), the discovery of oscillation and neutrino mass (1998–2002), coherent scattering (2017), and the rise of neutrino astronomy, recognised by Nobel Prizes in 2015 and 2026.

A Timeline of Neutrino Physics: From Pauli to the Present

The history of neutrino physics runs from a desperate theoretical guess in 1930 to a Nobel Prize for neutrino astronomy in 2026 — nearly a century of turning an undetectable ghost into one of the most studied particles in science. This timeline gathers the key milestones, each a step in the long effort to understand the neutrino.

1930 — Pauli proposes the neutrino

Facing a crisis in beta decay, where energy seemed to vanish, Wolfgang Pauli proposed an unseen neutral particle to carry it away — a particle he feared could never be detected. This was the birth of the idea.

1934 — Fermi’s theory

Enrico Fermi built Pauli’s idea into a full theory of beta decay and gave the particle its name — neutrino, “little neutral one.” The neutrino was now a precise theoretical object.

1956 — Reines and Cowan catch it

Frederick Reines and Clyde Cowan detected reactor antineutrinos at Savannah River, telegraphing Pauli that his particle was real — 26 years after it was proposed.

1962 — A second neutrino

The two-neutrino experiment at Brookhaven showed that the neutrino produced with a muon is distinct from the one produced with an electron — the discovery of the muon neutrino, and of the first accelerator neutrino beam.

1968 — The solar neutrino problem begins

Raymond Davis’s Homestake experiment began detecting solar neutrinos and found only about a third of the predicted number — a puzzle that would take thirty years to solve.

1973 — Neutral currents

The Gargamelle experiment at CERN observed neutral-current interactions, in which a neutrino scatters without changing into a charged lepton — a key confirmation of electroweak theory.

1987 — Neutrinos from a supernova

Detectors in Japan, the US, and the USSR caught neutrinos from Supernova 1987A — the first ever from beyond the Solar System, founding extragalactic neutrino astronomy.

1998 — Oscillation discovered

At Super-Kamiokande, Takaaki Kajita showed that atmospheric neutrinos oscillate, changing flavor with distance — the first proof that neutrinos have mass.

2001–2002 — The Sun’s puzzle solved

Arthur McDonald’s Sudbury Neutrino Observatory proved the Sun’s electron neutrinos change flavor, resolving the solar neutrino problem and confirming neutrino mass from a second direction.

2012 — The last mixing angle

The Daya Bay experiment measured the mixing angle θ₁₃, the last unknown angle, opening the door to studying CP violation and the mass ordering.

2015 — The Nobel Prize for oscillation

Kajita and McDonald shared the 2015 Nobel Prize for the discovery of neutrino oscillation and hence of neutrino mass.

2017 — Coherent scattering and a cosmic source

The COHERENT experiment observed coherent elastic neutrino-nucleus scattering, long predicted; the same year, IceCube traced a high-energy neutrino to a distant blazar, a landmark in multi-messenger astronomy.

2020 — Seeing a second stellar furnace

The Borexino experiment detected neutrinos from the CNO fusion cycle, confirming a second way stars burn.

2025 — Precision and a record

JUNO delivered its first high-precision oscillation results, while KM3NeT caught the most energetic neutrino ever recorded.

2026 — The Nobel Prize for neutrino astronomy

Francis Halzen won the Nobel Prize in Physics for the IceCube Neutrino Observatory and the discovery of high-energy astrophysical neutrinos — recognising the field of neutrino astronomy that the 1987 supernova had foreshadowed.

What the timeline shows

Read as a whole, the history has a clear shape. The first decades were about existence — proving the neutrino is real and that there are three kinds. The middle decades were about mass — the long road from the solar puzzle to the discovery of oscillation. And the most recent chapter is about astronomy — using neutrinos as messengers to observe the cosmos. At each stage the neutrino forced physics to expand, and the field it opened is still very much in motion, with the mass ordering, CP violation, and the neutrino’s Dirac or Majorana nature still to be settled.

In short

From Pauli’s 1930 postulate to Halzen’s 2026 Nobel Prize, neutrino physics has progressed from proving the particle exists, to discovering it has mass, to using it to explore the Universe. The ghost particle has repeatedly rewritten the rules — and its story is far from finished.

FAQ

Frequently asked

When was the neutrino discovered?: The neutrino was proposed theoretically by Wolfgang Pauli in 1930 and first detected experimentally by Frederick Reines and Clyde Cowan in 1956 — a gap of 26 years between prediction and detection. Many further discoveries followed, including neutrino oscillation in 1998 and the detection of cosmic neutrinos.
What are the biggest milestones in neutrino physics?: The prediction of the neutrino (1930), its detection (1956), the discovery of the muon neutrino (1962), the solar neutrino problem (from 1968), the detection of supernova neutrinos (1987), the discovery of oscillation and neutrino mass (1998–2002), coherent scattering (2017), and the rise of neutrino astronomy, recognised by Nobel Prizes in 2015 and 2026.