Physics Labs
Controlled Student Experiments
Vary source distance and exposure time, then compare CR-39 track density and discuss attenuation, particle energy, and measurement uncertainty.
BSI Products — Education
LEARNING RADIATION KIT
STUDENT ALPHA PARTICLE DETECTION LAB
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. The rods still produce measurable alpha emissions and should be used only with the included safety procedures and applicable institutional laboratory rules.
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
(14) CR-39 pieces with protective film
(2) 2% thorium-tungsten rods (alpha source)
(1) Varied-distance 3D-printed holder
(1) Varied-time 3D-printed holder
Instructions, safety procedures, teaching aid and student worksheet
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.
For Educators
Classroom and Teaching Lab Applications
Build a hands-on radiation detection experiment into an undergraduate physics lab, nuclear engineering course, or STEM demonstration. Students produce and compare real alpha-particle track data instead of relying only on simulations or pre-recorded results.
Engineering Courses
Detector and Instrumentation Study
Connect nuclear engineering course material to detector preparation, exposure design, chemical development, microscopy, image analysis, and data interpretation.
Class Sets
Plan for Your Course
Contact BSI about class sets, academic pricing, course scheduling, detector processing, and reusable development or microscope equipment for teaching across multiple semesters.
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.
$159.99
all 14 detectors
Contact for Processing
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.
$599
Ask About This Kit
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.
$1,299
Ask About Microscope
Frequently Asked Questions
Learning Radiation Kit FAQ
Is the Learning Radiation Kit safe for students?
The kit is designed for supervised educational use and includes safety procedures. Instructors and students should follow the supplied directions and all applicable institutional laboratory rules when handling the thorium-tungsten rods and developing CR-39.
What do students actually see?
After exposure and chemical development, students observe etched alpha-particle tracks in the CR-39 detector. They can compare track density as distance and exposure time change.
How long is the exposure?
Exposure time is an experimental variable. A seven-day exposure is shown in the example results on this page, and the included holder lets students compare different exposure times by following the kit instructions.
Do I need a microscope?
A microscope is recommended for clearly viewing and characterizing individual etched tracks. BSI can develop and image all 14 detectors, or instructors can use their own suitable equipment or ask BSI about a microscope system.
Can I buy class sets or request academic pricing?
Yes. Contact Blank Slate Innovation to discuss class-set quantities, course schedules, processing needs, and academic pricing.
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.