BSI Products — Education
LEARNING
RADIATION KIT
See the effects of radiation with your own eyes. Using CR-39 thermoset polymer and Th-232 alpha sources, students can observe exactly where alpha particles hit, their approximate energy, and direction of travel.
Kit Price
$75
Per Kit
+ BSI Processing
$159.99
All 14 detectors
The Science
Radiation You Can Actually See
When a high-energy particle impacts CR-39 polymer, it breaks chemical bonds along its path, allowing for preferential etching during post-exposure processing. These etched tracks can then be observed and characterized under a microscope — or with enough exposure, seen with the unaided eye.
The kit uses 2% thorium-tungsten rods as the alpha source. These rods contain thorium-232, a primordial nuclide with a half-life exceeding 14 billion years — longer than the estimated age of the universe. Its extraordinary stability makes it safe to handle while still producing measurable alpha emissions.
The alpha particles emitted are energetic helium ions at approximately 4.1 MeV — over 160 million times more energetic than their thermal motion at rest. At this energy they carry a charge of +2e and travel at roughly 0.4% the speed of light. Once slowed to rest they capture electrons and become ordinary helium atoms.
The kit's two 3D-printed holders let students vary distance and exposure time independently, turning a single experiment into a controlled investigation of inverse-square attenuation and track density.
Kit Contents
CR-39 is sensitive to energetic protons, alpha particles, heavier ions, and fast neutrons. The Th-232 rods produce 4.1 MeV alpha particles — ideal for track formation in CR-39.
In Practice
Kit and Results
2 3D-printed holders, 2 thorium-tungsten rods, 14 pieces of CR-39
Assembled kit
CR-39 after 7-day contact exposure and developing etch
50× optical microscope image — 7-day exposure at 0.6" distance
Processing Options
Send to BSI or Do It Yourself
After exposure, CR-39 must be developed in NaOH solution and imaged under a microscope. BSI offers full-service processing, or you can purchase the DIY equipment for in-house analysis — recommended for those teaching the module across multiple classes year after year.
Full Service
BSI Processing
BSI develops, images, and characterizes all 14 CR-39 particle track detectors in your kit and provides you with digital images. All 14 must be processed simultaneously.
DIY Option 1
Development Kit
BSI provides a chemical development kit to process CR-39 particle track detectors yourself. Includes a hot plate with heating instructions. Sodium hydroxide (NaOH) must be purchased separately.
DIY Option 2
Microscope System
Reconditioned optical microscope with ocular camera and computer interface. Includes a new laptop loaded with imaging and image analysis software for track counting and characterization.
Advanced AI-based analysis tools available at additional cost — differentiates particle types, arrival angles, and energies with full distribution displays. Custom analysis software available for research applications.
Get Started
Ready to Order?
Contact BSI to purchase a kit, arrange BSI processing of your exposed detectors, or discuss DIY equipment options for classroom or lab use.