Neutron Activation Analysis Calculator
Introduction & Importance
Neutron activation analysis (NAA) is a powerful non-destructive analytical technique used to determine the chemical composition of materials. It’s widely used in various fields, including geochemistry, archaeology, and materials science, due to its high sensitivity and multi-element capability.
How to Use This Calculator
- Enter the sample weight in grams.
- Enter the neutron flux in n/cm²/s.
- Enter the irradiation time in seconds.
- Select the detector efficiency.
- Click ‘Calculate’ to get the results.
Formula & Methodology
The activity (A) of a radionuclide produced by neutron activation can be calculated using the following formula:
A = N * σ * φ * t * ε
Where:
- N is the number of target nuclei (sample weight * Avogadro’s number * atomic fraction of the element).
- σ is the cross-section for the activation reaction.
- φ is the neutron flux.
- t is the irradiation time.
- ε is the detector efficiency.
Real-World Examples
Data & Statistics
| Element | Cross-Section |
|---|---|
| Na-23 | 0.532 |
| Al-27 | 0.23 |
| Si-28 | 0.017 |
| Radionuclide | Half-Life |
|---|---|
| Na-24 | 15.01 |
| Al-26 | 7.17 x 10^5 |
| Si-32 | 6.47 x 10^5 |
Expert Tips
- Always ensure the sample is homogeneous to get accurate results.
- Consider the decay time before counting to avoid high background activity.
- Use appropriate shielding to minimize the effect of scattered neutrons.
Interactive FAQ
What is the minimum sample weight required?
The minimum sample weight depends on the sensitivity of the detector and the cross-section of the element of interest.
How long should the irradiation time be?
The irradiation time depends on the neutron flux and the desired activity. Longer irradiation times result in higher activities.