There’s something quietly thrilling about walking through your neighbourhood with a pocket-sized Geiger counter. Not because you’re expecting to find anything sinister, but because you could — and more importantly, because now you can measure it.
I’ve been using the Radiacode 102 for about a month now, partly as a teaching tool and partly out of personal curiosity. It’s marketed as a compact, affordable, consumer-friendly radiation detector — and it largely delivers on that promise. If you’re looking for a way to bring radiation physics alive in the classroom or want to indulge your inner radiation sleuth, this is worth a look.
Hardware and Build
The Radiacode 102 is small — about the size of a chunky USB memory stick — and feels solid in the hand. It charges via USB-C (thank you), and the onboard screen is small but surprisingly legible. You can use it standalone for basic counts-per-second (CPS) readings, but the real power comes when it’s paired with the mobile or desktop app via Bluetooth.
Battery life is respectable; I’ve left it running overnight on a single charge. It’s not designed for rugged fieldwork, but for classroom demos, travel, or walking surveys, it’s perfect.
What It Measures
This isn’t just a clicky Geiger-Müller tube. The Radiacode 102 uses a scintillation detector, which means it not only counts radiation events but also gives a crude spectrum of the energies involved. That’s a game-changer for teaching the finer points of radioactivity.
You can walk around with the app open and watch the CPS rise slightly as you approach things like granite countertops, uranium glass, or even the potassium in a banana. But you can also dive into the energy histogram and see the photopeaks. It won’t rival a lab-grade multichannel analyser, but for the price and size? Very impressive.
Testing the Spitfire Clock
One of the most satisfying moments I’ve had with it so far was testing an old wartime Spitfire cockpit clock — one of those beautiful, slightly eerie artefacts with radium-lumed hands and numerals. I’ve had it for years, always knowing it was jolly radioactive.
Holding the Radiacode up to the face confirmed it instantly. CPS shot up dramatically, and the energy spectrum lit up with low-energy gamma and beta signals right where you’d expect radium daughters to appear. It was one of those moments that bridges the historical, the scientific, and the slightly macabre — a real tangible link to the past, glowing faintly into the present.
Needless to say, I’m glad it lives in a sealed tin.
Try This: Background Mapping Challenge
A great hands-on activity is to have students measure and map background radiation around the school site. How it works:
- Break students into small groups with a map of the school grounds.
- Assign each group a few locations to measure (science lab, concrete wall, brick building, field, flowerbed).
- They record counts per second at each location using the Radiacode and mark it on the map.
- Back in the classroom, they compare results, look for patterns, and try to explain anomalies (e.g. slight increase near granite paving or reinforced concrete).
It opens up a surprising amount of discussion: natural sources, building materials, cosmic rays, shielding, and statistical noise. It also introduces students to the idea that “background” radiation isn’t uniform — and that data collection needs both context and care.
You can go further and have them graph the data over time or correlate with altitude if you’re in a multistorey building.
Around the Neighbourhood
The Radiacode app logs GPS-tagged readings, which opens up possibilities for simple mapping. I’ve taken it on walks and noticed small changes in background levels between stone walls and wooden fences, or near an old quarry. Nothing alarming — just enough variation to prompt questions. I’ll do a followup on this soon.
Downsides?
The app UI is a little clunky in places, and the documentation assumes you know your way around radiation terminology. If you’re new to scintillators and spectra, expect a learning curve.
Also, while it gives energy spectra, it doesn’t do full isotope identification. It’s more of an “educational spectrum” than a lab instrument — useful, but don’t expect it to tell you exactly what isotope you’re dealing with.
Final Thoughts
The Radiacode 102 hits a sweet spot: portable, affordable, surprisingly capable. It’s not a toy — but it’s not a £5k spectrometer either. It’s a brilliant way to make radiation physics real, whether you’re in the classroom, on a field trip, or just indulging your curiosity.
Highly recommended for teachers, physics enthusiasts, and anyone who wants to see a little more of the world than meets the eye.