Six detectors, four countries, twenty-five days — building the stations where students measure the same sky

Particle physics has always been an awkward subject for student research. The objects are invisible, and the experiments usually need an accelerator. Cosmic rays are the exception. Particles born far out in space are arriving at every point on the Earth's surface right now, which makes measuring them the one particle-physics experiment any school can actually run — provided someone hands the students a detector.

Accel Kitchen has built its programme on that fact. More than 300 detectors have been lent out free of charge; assembly workshops run more than ten times a year, and around 300 students a year solder their own unit. Over 100 of them keep measuring for more than a year, and students have proposed close to 100 research topics of their own. In 2026, two peer-reviewed papers were published with high-school students as first authors.

"Everywhere" is also, precisely, the condition for international exchange. Last year students in Japan and students in Chicago each recorded the drop in galactic cosmic-ray intensity that followed a major solar flare — independently, on opposite sides of the Pacific, with recovery taking several days. They then met online and compared the two datasets directly. A phenomenon that is global by definition was established as global by the students themselves, which no single detector could have done.

Something else came out of it. Japanese students are often hesitant to approach peers abroad, but wanting the other side's data turned out to be a far stronger motivation than wanting the conversation. Give a student a job to do and the talking starts. This trip was about widening that opportunity.

How many cosmic rays reach the ground depends on latitude. The Earth is a magnet, so closer to the equator more incoming particles are deflected away and fewer arrive. Putting the same detector, running the same protocol, at a different latitude is therefore an experiment in itself.

On 26–27 July the tour reached Cheikh Anta Diop University (UCAD) in Dakar, Senegal, hosted by Prof. Alassane Traore. After a lecture introducing the programme, the detectors were opened up and passed around: how the scintillator couples to the photosensor, how to make the box light-tight, how to set the threshold.

One detector stayed at the university.

The 43rd International Conference on High Energy Physics (ICHEP2026) ran in Natal, Brazil from 30 July to 5 August. ICHEP is one of the largest conferences in the field. Tanaka gave an oral presentation on 31 July in the Education & Outreach session, and spent the week in discussion with the particle-physics outreach groups gathered there from around the world.

From 6 to 8 August the tour was based at the Faculty of Engineering (FAIN), Universidad Nacional del Comahue in northern Patagonia.

Day one was an international lecture in the faculty auditorium, titled "Symmetry Breaking Between Particles and Antiparticles: Interdisciplinary Research Emerging from Radiation Measurement". More than 50 people attended in the room and roughly 100 more watched the YouTube stream.

Day two ran through the Ministry of Education of Neuquén Province, the Dean of Engineering, Dr. Marcelo Moreira, the university's international relations office and ANIDE, the provincial innovation agency, on educational partnerships and the exchange of students and staff. That evening came a public hands-on muon-detection workshop, open to all and streamed over Zoom to master's students at a distance.

Three detectors stayed here, hosted by the university and by the regional science club Mg. Ana Prieto works with. In 2027, Japanese high-school students selected for the Tobitate! Study Abroad Initiative are due to stay in Argentina and take cosmic-ray data together with their hosts.

On 12–13 August the tour reached the Universidad Autónoma de Santo Domingo (UASD), founded in 1538 and the oldest university in the Americas. The host was the Physics Education Area of the Institute of Physics in the Faculty of Sciences (coordinator Prof. Erika Montero; institute director Dr. Nelphy de la Cruz), with the Dominican Astronomical Society (ASTRODOM) as co-host.

The first day opened with a courtesy visit to the Rector, attended by the Ambassador of Japan to the Dominican Republic, followed by a meeting with the authorities of the Faculty of Sciences and a visit to the Japanese Embassy. The afternoon brought a lecture and a live cosmic-ray experiment in the High Technology Building, for physics students, faculty and researchers together with members of ASTRODOM and SODOFI, the Dominican physics society. In the evening came a meeting with the ASTRODOM board at the National Museum of Natural History and a tour of their workspaces. The next day the group drove some 120 km inland to the UASD Azua campus (directed by Dr. Francisco Ramírez) to discuss how physics is taught at each level of the Japanese education system with faculty and master's students in physics education.

Two detectors stayed in Santo Domingo, giving the Caribbean a new pair of points on the map that keep measuring after the visitors leave.

Shipping a detector takes a courier. Going in person is for running the first workshop together. In all four countries the same three things ended up in place: a detector, a team that can use it, and a faculty willing to host it.

The next step is people. In Argentina, plans are already moving to send a Japanese student to Patagonia to lead workshops in local schools. In parallel, simultaneous observations on a shared protocol will start between Tokyo and each new station. Different latitude, different rate — and that difference is exactly the reason for students to trade data.

The near-term target is International Cosmic Day on 19 November 2026, when schools worldwide measure cosmic rays on the same day and pool the results. The six detectors installed this summer join as new observation points.

Accel Kitchen's detector loans and research mentoring are free for secondary-school students. Enquiries from schools and universities outside Japan are welcome.