Cyclotron Info

The open reference for understanding, designing, and documenting small cyclotrons. Built for cyclotron enthusiasts — students, hobbyists, amateur builders, and anyone curious about the machine that started high-energy physics.

Why this site? Practical knowledge about small cyclotrons is scattered across ninety years of journal papers, out-of-print books, student theses, defunct project pages, institutional reports, and fifty-one bodies of state regulation. This project gathers it into one place — organized, cited, and source-checked, with its review status made explicit — so the next builder starts from the literature instead of from scratch.

• Understand

  General readers and students

  1. How a cyclotron works
  2. History
  3. Applications
  4. Glossary

• Assess a project

  Educators and prospective builders

  1. Should you build one at all?
  2. What building one takes
  3. Choosing your machine
  4. Safety
  5. Legal
  6. What others built

• Design and verify

  Active project teams

  1. Calculators
  2. Design Guide
  3. Subsystem deep dives
  4. Modeling tools
  5. Library

• Try one

  Anyone, ten minutes in the browser

  The Virtual Cyclotron Laboratory (hosted; illustrative, not a calibrated replica): set field, RF frequency, dee voltage and source on an illustrative ~150 keV machine, watch an ensemble of ions accelerate, inspect a single path, sweep a control. A full workspace adds the field atlas and acceptance views.

• 1,564 cyclotrons mapped
• 92 countries
• 2,170 sourced design rules
• 325 library documents
• 27 documented amateur builds
• 7 calculators

Census figures are from the quarterly directory snapshot of 2026-10-04.

Starting a design? Open the Design Guide at level 1 — the 42 rules that govern whether any small cyclotron is feasible — and widen to the next level as the design firms up. Or start with the machines themselves, in the amateur builds census.

All sections

• Learn

  How cyclotrons work, their history, what they are used for, safety fundamentals, a realistic starter path — and subsystem deep dives from magnet design to beam dynamics.

• Design Guide

  2,170 sourced design rules for small cyclotrons — magnet, RF, vacuum, ion source, dees, chamber, extraction, and beam measurement — filterable by subsystem, each with formula and citation.

• Calculators

  Interactive calculators for energy, field, and radius; path length and turn count; vacuum requirements; coil geometry; magnet power; lid deflection; RF matching — each with the math explained.

• Legal

  Can you legally build and run a cyclotron? Federal rules and a jurisdiction-by-jurisdiction survey of all 50 US states, with an interactive map.

• Library

  An annotated bibliography of cyclotron and accelerator literature — 325 documents rated for relevance to small-machine builders, from 1930s classics to modern references, with the public-domain construction reports hosted here.

• Amateur Builds

  A census of documented home and school cyclotron builds, successful or stalled, with specs, status, and sources.

• Worldwide Cyclotron Directory

  Where the world’s cyclotrons are: research, medical, and university machines on a filterable map and list — and which ones you can tour.

• News & Jobs

  Automatically aggregated cyclotron and accelerator news, plus a directory of the job boards where accelerator posts appear.