Calculator Inputs
Example Data Table
These sample rows use the same equations implemented in the calculator.
| Scenario | Energy (MeV) | Medium | Estimated Range | Recommended Barrier |
|---|---|---|---|---|
| Am-241 source in air | 5.486 | Air | 4.0861 cm | 46.9903 mm |
| Process stream through tissue | 5.000 | Soft Tissue | 30.4354 µm | 0.0350 mm |
| Detector entry into silicon | 7.690 | Silicon | 16.9776 µm | 0.0187 mm |
Formula Used
The calculator applies a practical engineering estimate rather than a full transport simulation.
1. Reference air range: R_air,ref = 0.318 × E^1.5 × C
2. Air areal range: AR_air = R_air,ref × ρ_air,ref × 1000
3. Medium areal range: AR_medium = AR_air ÷ S_rel
4. Gas density correction: ρ_actual = ρ_ref × (P / 101.325) × (293.15 / (T + 273.15))
5. Linear range in medium: L_medium = (AR_medium / 1000) ÷ ρ_actual
6. Conservative reach: L_safe = L_medium ÷ (1 + margin/100)
7. Barrier recommendation: t_barrier = L_medium × 10 × (1 + margin/100)
Here, E is energy in MeV, C is the empirical correction factor, S_rel is the relative stopping factor, and density is in g/cm³.
How to Use This Calculator
- Enter the alpha particle energy and choose the correct energy unit.
- Select a preset medium or choose custom values for density, phase, and stopping factor.
- Set pressure and temperature when the particle travels through a gas.
- Adjust the empirical correction factor if you have calibration data.
- Add a safety margin to create a conservative design estimate.
- Optionally enter barrier thickness to check if your shielding may stop the particle.
- Click Calculate Range and review the result block above the form.
- Use the CSV or PDF buttons to export the current result summary.
Frequently Asked Questions
1. What does this calculator estimate?
It estimates how far an alpha particle may travel in a chosen medium, then adds conservative shielding guidance using density, pressure, temperature, and stopping adjustments.
2. Is the result exact for every material?
No. It is a screening-level estimate. Complex compounds, layered shields, and detailed detector work still need measured stopping data or transport software.
3. Why do pressure and temperature matter in gases?
Gas density changes with pressure and temperature. Denser gas shortens alpha range, while thinner gas allows a longer path before the particle stops.
4. What is the relative stopping factor?
It scales the areal range from reference air into another medium. Larger values mean stronger energy loss and therefore shorter penetration depth.
5. Why is the barrier recommendation larger than the range?
The recommendation includes your chosen safety margin. That extra thickness helps cover uncertainty in material condition, particle energy spread, and modeling limits.
6. Can I use keV instead of MeV?
Yes. Select keV in the unit menu. The calculator converts keV to MeV internally before applying the range equations.
7. When should I choose a custom medium?
Choose custom when you know the medium density and want to apply your own stopping factor from test data, vendor documentation, or internal design standards.
8. Is this suitable for nuclear safety documentation?
It can support preliminary engineering reviews. Final safety documentation should reference validated stopping-power sources, measured material properties, and approved modeling methods.