Read the world through neutrino experiments

Two maps: where detectors stand and who builds them

A detector marker shows where an apparatus stands. It does not show who designed its sensors, supplied its materials, wrote the reconstruction or analyzed the data. A large experiment can have one observing site and partner institutions on several continents.

Start with three labels for each site: where the neutrinos come from, which journey is being measured and what the detector records. A reactor detector and a sky telescope both observe weak interactions but can ask very different questions. Two dots close together on a map need not use similar methods.

The regional schematic below is a reading aid. It is neither a complete list of facilities nor a survey of national contributions. It places representative sites approximately and links them to the discussion here. The text keeps historical instruments apart from future plans.

Sources: [1] · [2] · [3]

North America: deep underground sites and a beam sent through Earth

Homestake in South Dakota hosted the historical chlorine measurement of solar neutrinos. Sudbury in Canada hosted SNO, which used heavy water to compare reaction channels. Both relied on underground shielding, but the change of target and reaction changed what could be learned about solar neutrino flavor.

The DUNE program sends a beam made at Fermilab in Illinois to far detectors at the Sanford Underground Research Facility in South Dakota. Here the line between the dots matters as much as either dot: it sets the baseline and the path through Earth.

A familiar site name does not tell you whether an experiment is running. SNO’s published historical measurement and DUNE’s construction program belong to different stages. Name the specific instrument, dataset or plan, instead of treating an underground laboratory as one unchanging experiment.

Sources: [4] · [5] · [6] · [7]

Asia: reactor distances and an accelerator beam

Kamioka in Japan has hosted several generations of water and scintillator detectors. J-PARC’s T2K beam links a source on the eastern side of Japan with the Super-Kamiokande detector. The beam geometry was chosen as part of the experiment’s design; it is not an arrow drawn after a discovery.

Reactor experiments form another kind of network. Daya Bay compares detectors at different distances from nearby reactor cores. KamLAND receives neutrinos from many reactors, and JUNO near Jiangmen uses a medium-baseline spectrum to study fine oscillation structure.

A reactor map must therefore mark the sources as well as the detectors, and account for reactor power and running time. One detector can see a changing mix of baselines. An administrative border says little about which core produced a selected antineutrino event.

Sources: [8] · [9] · [10] · [11] · [12]

Europe and deep water: the sources are often in the sky

Gran Sasso in Italy shows how deep shielding and clean materials make low-energy solar and rare-process measurements possible. The historical Borexino solar dataset and CUORE’s double-beta search share the laboratory but measure different targets and quantities.

In the Mediterranean, ARCA near Sicily and ORCA off southern France observe natural neutrinos with different array densities and science priorities. Lake Baikal adds a northern deep-water telescope. For these instruments the relevant source map is often the sky, not nearby sources on Earth.

Longitude and latitude are only the beginning. Add the medium, energy selection and useful exposure to see how two northern instruments can complement a polar telescope. Grouping names under “Europe” or “Asia” is no substitute for comparing detector responses.

Sources: [13] · [14] · [15] · [2] · [16]

Antarctica: one location, an international observatory

IceCube uses South Pole ice as both target and optical medium. The polar location changes how sky directions appear locally, and the ice with its embedded sensors shapes calibration and maintenance. Remote logistics are part of keeping the scientific exposure going.

Its institutional map reaches far beyond Antarctica. Hardware, simulation, operations and interpretation can be spread across countries. Published affiliations and acknowledgments show who took part better than coloring one country around a detector marker.

To read any experiment map carefully, follow the dot to its measurement paper, then the paper to its method and contributor list. This article lays out that route. A future searchable world map can add dated facility information without shrinking an international discovery to its host location.

Sources: [1] · [3] · [17]

Primary sources & revision

1. IceCube Collaboration · Instrumentation and Online Systems (2017; arXiv v3)
2. KM3NeT Collaboration · Letter of Intent for KM3NeT 2.0 (2016)
3. IceCube · Institution list (April 2025 snapshot)
4. Brookhaven National Laboratory · Raymond Davis Jr. and solar neutrinos
5. SNO Collaboration · Direct Evidence for Neutrino Flavor Transformation (2002)
6. SNOLAB · Underground facilities
7. LBNF/DUNE · Detectors and computing
8. Kamioka Observatory · Chronology
9. T2K Collaboration · The T2K Experiment (2011)
10. Daya Bay Collaboration · Observation of electron-antineutrino disappearance (2012)
11. KamLAND Collaboration · First Results: Evidence for Reactor Anti-Neutrino Disappearance (2002/2003)
12. JUNO Collaboration · Measurement of reactor neutrino oscillation with the first JUNO data (10 June 2026)
13. INFN · Gran Sasso laboratory overview
14. Borexino Collaboration · Detector at Gran Sasso (2009)
15. CUORE Collaboration · Search using millikelvin cryogenics (2022)
16. Baikal-GVD Collaboration · Observatory and location
17. IceCube Collaboration · Governance v9.4 (6 December 2023)

First published 2026-10-11; last revised 2026-10-11. Original explanatory text and diagrams by Sandbox Physics. Illustrations are schematic; no experimental event records are reproduced here. This is an independent educational publication, not an official Nobel or experiment collaboration publication.